Method of evaluating pressure in underground reservoirs

FIELD: oil and gas production.

SUBSTANCE: invention refers to oil producing industry and is designed for evaluating properties of reservoirs surrounding underground well. To achieve the object of the invention the method consists in recording time after completion of drilling at the depth interval, in determining permeability of reservoirs at the depth interval, in generating time cycling of pressure in a borehole of the well and in assessing periodic and un-periodic constituents of pressure measured in reservoirs at the depth interval. By time, periodic constituent and permeability there is determined coefficient of diffusion of pressure and water-permeability of reservoirs, also there is assessed area of zone of pressure build-up around the borehole of the well at the depth interval. Further, by time, coefficient of diffusion of pressure, water-permeability of reservoirs and un-periodic constituent there is determined an indicator of filtration of clay coating at the depth interval. By the indicator of filtration there is evaluated pressure gradient at the depth interval and extrapolation is carried out to determine reservoir pressure by pressure gradient and by area of zone of pressure build-up.

EFFECT: upgraded accuracy of evaluation of primary reservoir pressure due to more accurate determining parametres of filtrate leakage.

21 cl, 15 dwg

 

The technical field to which the invention relates.

The invention relates to determining properties of formations surrounding an underground borehole, and more particularly, to a method for determining the characteristics, including the rate of filtration of the mud cake, disturbing the filtering action of the drilling fluid and the unperturbed initial reservoir pressure.

Background of invention

Serious difficulty determining formation pressure during drilling operations due to increasing pressure around the wellbore exposed to repressional pressure caused by leakage of filtrate into the formation and called excessive pressure due to slow pressure equalization after penetration of the filtrate into the formation. Due to the penetration of mud filtrate into the formation, this increase in pressure is accompanied by deposition of the mud cake and the growth of its outside, on the surface of the sand, and inside. Therefore, the water permeability clay cover change over time, influencing the process of pressure on it and, consequently, the pressure behind it, on the surface of the sand. This makes difficult the prediction of changes of the pressure prole in time, even if was recorded pattern of variation with time of the local pressure in the wellbore.

Existing methods measured the th reservoir pressure, carried out using the so-called devices for testing of formations due to the effect of excess pressure in the wellbore area often give inflated readings at a distance from the borehole compared to the actual formation pressure. Currently unknown practicable on an industrial scale in the process of drilling techniques for determining formation pressure at a relatively low permeability reservoir tanks (below approximately 1 MJ/SP), which adequately takes into account the excess pressure in the wellbore area. The main difficulties are related to (1) poor property of the mud cake, (2) prolonged the actual exposure time repressional pressure in the wellbore, and (3) real-time constraints under which it is necessary to measure pressure within a fairly short time interval compared with the duration increasing pressure around the wellbore. These limitations make it hard, if not impossible, measurement of reservoir pressure in the far zone at the border zone of increasing pressure conventional known from the prior art methods of study of the transition pressure, as for formations with low permeability, low propagation velocity of the pressure wave.

So hot the existing devices and methods often work well in relation to the layers with a relatively high permeability, in which excessive pressure in the wellbore area is easily dispersed, for example, during descent of the device, there is a need for a method that can be used successfully in relation to the layers with relatively low permeability. It is also desirable to have a method, which is applicable to reservoirs with permeability varying within wide limits, regardless of the cause of the excess pressure in the wellbore area. In addition, there is a need for precise determination of the parameters of the percolation of leachate. Among the objects of the present invention are designed to meet these needs.

The invention

In accordance with the embodiment of the invention, a method for determining an initial reservoir pressure at a single depth interval of underground formations surrounding a borehole drilled using mud, and on which was formed the clay crust, containing the following steps: tracking of time after cessation of drilling at the specified depth interval; obtaining permeability layers at the specified depth interval; urge the pressure in the wellbore to periodic change with time and determination on the specified depth interval periodic component and the aperiodic component of the pressure, izmerennogo layers, adjacent to the clay crust; determination of the diffusion coefficient pressure and hydroconductivity layers by using the specified time, the specified periodic component and the specified permeability and estimation of the size of the zone of increased pressure around the wellbore to the specified depth interval of layers; determination of rate of filtration of the mud cake on the specified depth interval by using the specified time, the specified diffusion coefficient pressure and hydroconductivity layers and the non-periodic component; determining the pressure gradient in the layers adjacent to the clay crust on the specified depth interval, by using a specified rate of filtration; and extrapolation to determine the initial reservoir pressure, by using the specified pressure gradient and the specified the size of the zone of increased pressure.

In accordance with a further embodiment of the invention, a method for determining the rate of filtration of the mud cake formed on a single depth interval in the well, drilled in formations with the use of drilling mud, containing the following steps: obtaining permeability layers in the depth interval; urge the pressure in the wellbore to periodic changes in time and smirenje on the depth interval time-varying pressure in the borehole and a time varying pressure in the reservoir, adjacent to the clay crust; determine the depth interval evaluation of the resistance to flow of the mud cake on the obtained permeability and the components of the measured downhole pressure and the measured pressure in the formations adjacent to the clay crust; and determining the depth interval of the rate of filtration of the mud cake on the estimated flow resistance and the measured pressure in the borehole, and the measured pressure in the formations adjacent to the clay crust. Then the initial reservoir pressure can be obtained by: determining the depth interval of excess pressure in the formations adjacent to the clay crust, received the specified permeability, the specified rate of filtration and the specified time after the cessation of drilling; and determining the specified depth interval initial reservoir pressure measured at the specified pressure in the formations adjacent to the clay crust, and the specified excess pressure in the reservoir.

Additional characteristics and advantages of the invention will become clearer from the following detailed description made in conjunction with the accompanying drawings.

Brief description of drawings

In the drawings:

figure 1 - schematic view, partly in block diagram, borehole installation, which can be used in the practical use of var is the preferable embodiment of the invention;

figure 2 - schematic view of the downhole device that can be used in practice of embodiments of the invention;

figure 3 - schematic view of an installation for research in the borehole during drilling, which can be used in practice of embodiments of the invention;

4 is a graph of the profile quasistability pore pressure around the wellbore;

5 is a graph of the dimensionless depth of propagation of the pressure wave in the layer reservoir;

6 is a graph of the reaction layer on the surface of the sand;

7 is a graph of the average pore pressure around the wellbore during impulse testing; solid lines correspond to the case of the presence of increasing pressure; dashed lines correspond to the case there is no improvement;

Fig is a graph illustrating the reaction pressure in the wellbore to the formation of multiple pulses;

Fig.9 is a graph illustrating the effect of conservation in the wellbore at the reaction of the pore pressure near the wellbore in step extraction with different relations of the characteristic times of the reservoir and the stored volume;

figure 10 - block diagram of steps of a variant embodiment of the invention;

11 and 12 illustrate, respectively, the mode of injection pump and mode of production;

pig who engages in itself figa and 13B, placed one below another, is a block diagram of the stages further variant embodiment of the invention;

Fig graphics module (upper curve) and argument (lower curve) of the complex transfer function linking the pressure on the surface of the sand with the pressure in the wellbore, depending on the frequency (in Hz); and

Fig graphics module (two upper curves) and argument (lower curve) of the complex transfer function linking the pressure on the surface of the sand layer with the pressure in the wellbore, depending on the dimensionless frequencyfor some values of the skin effect of the mud cake; in the top two graphs repeats the same information, but in a linear and logarithmic y axes.

Detailed description the preferred option of carrying out the invention

Figure 1 shows a typical equipment that can be used in practical applications of embodiments of the invention. 1 shows a borehole 32, which is drilled into the reservoir 31 is known from the prior art method by means of drilling equipment and when using a drilling fluid or drilling mud, which leads to the formation of mud cake, indicated by the position 35. For each depth interval of interest, remapable termination of the drilling track in a known manner, for example, using a clock or other means of determining time, the processor and/or the Registrar. Installation or device 100 for testing of formations suspended in the borehole 32 on an armored multi-conductor cable 33, the length of which is essentially determined by the depth of the lowering device 100. To measure the movement of the cable block (not shown) and, therefore, the depth of lowering the downhole device 100 in the hole 32 provided by known prior art device for measuring the depth (not shown). Circuit 51 shown on the surface, although some of them can usually be in the wellbore, represent a scheme of control and communication research facility. On the surface also shows the processor 50 and the recorder 90. As a rule, they can be of a known type and include the appropriate clock or other means of determining a time.

The downhole device or the device 100 has an elongated body 105, which includes a downhole portion of the control device, camera, measuring tools, etc. For example, you can reference the U.S. patents No. 3934468 and No. 4860581, which describes the device suitable General type. One or more rods 123 can be mounted on the plungers 125, which are, for example, when the control surface, for fixing the device. Squag the TES device includes one or more modules of the probes, which include probe node 210 with the probe, which shifted outwards into contact with the hole wall, while pierces mud cake 35 and is in communication with the reservoir. Equipment and methods for the implementation of individual measurements of hydrostatic pressure and/or measurement of the pressure probes are well known in the technical field to which the invention relates, and the downhole device 100 is inherent in these known features. Refer to figure 2, which shows a portion of the downhole device 100, which can be used for implementation variant of the invention, in which a pressure change in the well through the downhole device (which for these purposes includes any downhole equipment, wireline or anything else), and posted on the interval on which the device is located in the borehole at a predetermined point in time. (You can refer to U.S. patent No. 5789669.) The device includes an inflatable packers 431 and 432, which may be of the type known in the art to which the invention relates, together with appropriate means of actuation (not shown). When inflating the packers 431 and 432 isolate the interval 450 wells, and probe 446, shown together with its installation plungers 447, the current state is the duty to regulate within the isolated interval and is in communication with the reservoir, adjacent to the clay crust. A suction module 475, which may be of a known type (see, for example, U.S. patent No. 4860581), includes a pump and a valve and a suction module 475 is the message through line 478 to the well outside the isolated interval 450, but via line 479, through the packer 431 isolated interval 450 wells. Packers 431, 432 and pumping module 475 can be controlled from the surface. Well pressure in the isolated interval measured by the pressure gauge 492, and the pressure in the probe is measured with a manometer 493. The pressure in the borehole outside the isolated interval can be measured by the pressure gauge 494. In embodiments of the invention in the test phase can be used openings for discharge and/or suction, and it should be clear that it is possible to provide a large number of holes for discharge and/or suction.

Embodiments of the present invention can also be applied to the use of equipment for borehole investigations in the drilling process (which include measurement during tripping operations). Figure 3 shows the drilling rig, which includes a drill string 320, drill bit 350 and equipment 360 for borehole investigations in the drilling process, which can be associated with itemnum equipment (not shown) using known telemetry means. Preferably, the equipment for borehole investigations in the drilling process was provided by packers 361 and 362. Also shows the device 365, which includes the probe (probes) and endowed with measuring capabilities similar to the device described in conjunction with figure 2.

In the case of layers with relatively low permeability (such that k=10-1MD) increase pressure around the wellbore during drilling is a slow process that usually lasts a few days and affects a relatively small immediate vicinity of the wellbore. The radius of the zone of increased pressure around the wellbore can be estimated using dimensional analysis.

Assuming that the flow in reservoir tank is determined by the Darcy law

where υ is the velocity of the fluid flow;

µ is the viscosity of the fluid and

p is the pore pressure, which satisfies the equation of diffusion coefficient pressure

where t - time;

B is the bulk modulus of elasticity of rocks saturated with fluid;

ϕ is the porosity and

η is the diffusion coefficient of pressure (see G.I. Barenblatt, V.M. Entov and Ryznik V.M. Theory of fluid flows through natural rocks”, Dordrecht: Kluwer, 1990).

If the time teimpact on wellbore repressional pressure is known, the radius of the zone of increased giving is the group around him can be estimated as

For example, using the following data: k=10-3-10-1SB, B=1 GPA, µ=1 JV and ϕ=0,2, you can obtain η=(5-500)·10-6m2/s For the duration of the pressure increase, part of te=1 day, find the

The depth of ristudies in normal measurement of the transition pressure can be estimated using the same formula (3). For example, if the duration of the research are ti=2 h 20 min and 2 min, the ratio ri/recan be estimated respectively as

This means that only the first 29%, 12% and 4%, respectively, the thickness of the zone of pressure increase can be detected using the methods of the study of the transition pressure.

For analysis of increasing pressure around the wellbore during drilling requires joint consideration of the propagation of the pressure wave and the growth of the mud cake, caused by seepage of mud filtrate and usually limited circulation of the drilling fluid within the wellbore. If repressione pressure used in the process of drilling, does not change excessively, the process of changing the transition pressure around the wellbore can be approximated mode quasistability pressure

where po- initial pressure;

psf(t) is the pressure at the surface of the sand;

rωis the radius of the wellbore and

re(t) - radius zone around the borehole with high blood pressure.

Schematically, the pore pressure profile shown in figure 4. During the initial phase of the impact of repression on the wellbore pressure psfon the surface of sand is equal to the pressure pωin the wellbore. Then the pressure on the surface of the sand decreases with increasing the thickness of the mud cake and its hydraulic resistance due to the drop Δp=pω-psfpressure on the clay crust.

If the permeability of the filter cake less than permeability of the formation, the pressure psfon the surface of the sand falls quickly back to the original reservoir pressure p0. However, if the permeability of the reservoir is small and, therefore, the seepage through the surface sand is limited, clay crust is not growing now and the impact repressional pressure in the reservoir may continue indefinitely.

The unknown functions of psf(t) and re(t) can be found from equation (2) diffusion coefficient of the pressure associated with the growth model of the mud cake on the surface of the sand. This analysis can be performed for a simple growth model of the mud cake, based n the following assumptions: the porosity and permeability of the filter cake are constant; the volume concentration of particles of sand in the mud, filling the wellbore, is constant; the filtrate joining layer, completely miscible with the reservoir fluid; the viscosity of the filtrate is equal to the viscosity of the formation fluid; and as the instantaneous fluid loss and formation of the internal filter cake can be neglected. This analysis also assumes that the permeability of the filter cake is much less compared to the permeability of the reservoir, and the thickness of the mud cake, growing over time, is small compared with the radius of the wellbore. Under these assumptions, the flow through the mud cake can be considered quasistability and one-dimensional at any point in time, and therefore, as shown in figure 4, the change in pressure on the clay crust is linear.

Pressure psf(t) on the surface of the sand is influenced by several factors, including the water permeability of the reservoir, the rate of infiltration and the circulation rate of the drilling fluid. It also depends on the hydraulic resistance of the filter cake, which varies with time. Despite this complexity, it was found that the boundary of re(t) zone pressure disturbances depicted depending on the relevant dimensionless variables, practically does not depend on the dynamics and growth of the mud cake and can be approximated by a universal function of Z e(T), shown in figure 5, where

Because the duration of teimpact on wellbore repressional pressure is usually known, then the only option that is required for estimation of radius re(tezones with perturbed pressure is the factor η diffusion pressure, which is included in the definition of dimensionless time T.

Suppose that the value of η somehow found, and, consequently, the boundary of re(te) will be

Then you need to measure the pore pressure psf(teon the surface of the sand and in the intermediate point r=rmwithin region rω<r<re(teto find pressure

Pressure psf(teon the surface of the sand can be measured using currently available test equipment, re-entry into the well on a cable, and therefore, to obtain reservoir pressure p0, you only need to define two parameters, the ratio η diffusion pressure and the pressure pmat some distance from the wellbore, or alternatively, the pressure gradient on the surface of the sand

Therefore, if the water permeability kh/µ reservoir, which includes interval the second thickness h, known, determination of reservoir pressure p0equivalent definition quasistability flow qL(te) filtrating the liquid in the late stage of pressure increase

As shown below, qLyou can define using the test pulse-harmonic method, you can perform when properly selected test frequency and speed of injection.

In the following analysis to determine the formation pressure in the far field by using a test pulse-harmonic method assumes that the total test duration less than duration of pressure increase (lasting impact on the well of repression pressure); the amount of preliminary tests compared with the total volume performed during the test, and clay crust is removed during the preliminary tests. For simplicity, changes of the diffusion coefficient pressure and hydroconductivity layer as functions of the distance from wells are ignored.

Consider the situation directly before the test pulse-harmonic method, i.e. at time t=te. Pressure pe(r)=p(r,te) around the wellbore defines the initial condition with respect to time τ=t-tetests. is using the same notation for the pressure p(r,τ), have

As mentioned above, the function pe(r) generally unknown except for its boundary values of pω0=pe(rω), which can be measured or estimated using conventional formation testing. Using equation (6), the original profile of the pressure around the wellbore before the test can be expressed in the form

and the corresponding quasistability the flow of filtered fluid from the interval of the wellbore thickness h as

This flow qLfilterable fluid is unknown, and its definition is equivalent to the definition of two parameters: radius re(tezone pressure and reservoir pressure p0.

Using equation (14), the initial pressure prole can be represented in an equivalent form

Generally speaking, the parameter φLcan be determined using, for example, a conventional method of increasing the pressure, if you can instantly seal the surface of the sand on the interval of the well and control the relaxation of pω(τ) pressure behind the surface of the sand depending on time. Indeed, due to the superposition principle, the reaction pressure on the compacted surface of the sand to a step change in flow rate can the be expressed in the form

In this case, the function F0(a), whereprovides a well-known solution of the equation of diffusion coefficient of pressure (see, for example, H.S. Carslaw and J.C. Jaeger: “Conduction of heat in solids”, 2ndEdition, Oxford: Clarendon Press, 1959)

where Jiand Yiare Bessel functions, respectively, the first and second kind, of order i, i=0, 1,

and as shown figure 6, reproduced from Carslaw et al., see above. Because at the big time

you can define two parameters, φLandby plotting the dependence of ψω(τ) from logτ.

However, this direct method, which is widely used in the technology of well testing (see Streltsova T.D.: “Well testing in heterogeneous formations, Exxon Monograph, John Wiley and Sons, 1988), is actually quite difficult to implement. This is true for several reasons. First of all, in the case of reservoirs with low permeability required long duration tests. Secondly, the initial flow of fluid filtered in a low permeability reservoir, usually very small, and it can be very difficult to measure. Seal the surface of the sand and the pressure control is preferably carried out with great care so as not to create disturbances of the reservoir and in which Moudania pressure on the surface of the sand. It should also be noted that the sealing surface of the wellbore may be replaced by a procedure of relaxation pressure, which will prevent leakage, but it is not much easier to implement, since the detection of very small leaks may require even greater efforts. Therefore, the necessary procedures study the pressure of various kinds. The test pulse-harmonic method provides the advantage that the measurement accuracy is not worse, and the amount of information extracted from the data, compared with the quantity of information that can be extracted is known from the prior art method.

Consider the process of change of pressure around the wellbore during the test pulse-harmonic method at the current rate of qω(τ), with period. Using the superposition principle, one can imagine the outrage q(τ)=qω(τ)+qLthe current production rate during the test as the sum of its periodic component qp(τ) with zero mean flow and a constant average flow rate of qa

where

Unknown flow qLfilterable liquid added to the current rate of qω(τ) for payment of the initial non-uniform profile (15) of the pressure around the trunk with the vazhiny. The advantage of this test procedure is that the periodic part of qp(τ) can be adjusted for different depthsresearch by changing the corner frequency(see above Streltsova). The test length is comparable with the periodand usually much shorter than the duration of the pressure increase after closing. At the same time, the average consumptionshould not be strongly dependent on the characteristics of the equipment (pumps, pressure gauges, flow meters). This can be achieved by selecting, for example, the respective amplitudes of q0and duration of t0working pulses and relationships(Fig). After that, the interpretation of the reactions of the current flow on a periodic component of qp(τ) and non-periodic component of qacan be done independently.

Another advantage of this superposition is that the periodic component of qp(τ) does not include the unknown initial flow rate of qLfilterable liquid, and removing the reaction pressure at periodic flow qp(τ) on the basis of measured changes ψω(τ) pressure in the wellbore is a standard task in the practice test pulse-Gard is onionskin method (see above Streltsova). Processing of the reaction pressure on the periodic component allows to determine the coefficient η diffusion pressure and water permeability kh/µ reservoir. Thereby, the number of unknown parameters in the source view of the profile of the pressure before the test, defined by equations (13) and (8), is reduced to only one, to reservoir pressure p0.

To determine the p0you want to handle the reaction pressure in the wellbore on a non-periodic component of the current flow, which is characterized by an average constant flow rate of qa. By using the principle of superposition this reaction can be expressed as in (16)

Here ψa(τ) are the measured reaction pressure minus the periodic component;already known, and the parameter φLstill unknown.

Function F0(a) is determined by equation (17) and shown in Fig.6. Since the coefficient η diffusion pressure is already defined by the reaction pressure to a periodic component, we can calculate the argument. Now compare equation (16) and equation (21). Equation (21), which corresponds to the standard test with increasing pressure, includes two unknowns, φLand η, while equation (21) includes SEB is only one unknown parameter φ L. This advantage can be fully used. Indeed, using the data of the test pulse-harmonic method, the parameter φLcan be estimated as

Thus, the last term on the right-hand side of equation (22), which is formally depends on the duration τ of the test, really should be permanent. This member can be estimated using measurements of pressure in the wellbore, ψa(τ), and F0(a)characterizing the dimensionless reaction reservoir pressure at the average speed of the current flow.

After defining the parameter φLthe required pressure can be estimated as

Moreover, equation (22) can be interpreted as follows. In the absence of a source of increasing pressure and at the proper flow rate of filtered fluid, the last term on the right side must be exactly equal to. This means that the difference between the two members when qL≠0 characterizes the effect of “boundary conditions” on the virtual mobile boundary corresponding to the pressure wave propagating in the layer, as shown in Fig.7. In this case, the pressure profiles are depicted in logarithmic scale l=logr for three consecutive moments τ12 3tests. Since the average current flow is constant, the solid lines indicating the pressure profiles in the presence of a source of pressure increase, pw0-p0have the same slope. Dashed lines shows the profiles of the pressure, which should be observed in the absence of a source of pressure increase. In addition, it is assumed that the speed of the virtual front of the pressure wave, l=lmpropagating in the reservoir is not affected by the increase of pressure. For this reason, the difference between the characteristics of the pressure in the wellbore in these two cases increases depending on time: Δp1<Δp2<Δp3. Due to this accumulated difference member-ψa(τ)=pω0-pω(τ)included in equation (22), is compared with denominatorthat reflects the response to step consumptioncorresponding to a uniform initial pressure profile.

In the following example, we consider a test procedure using the multiple pulses shown in Fig, when the amplitude of the q0desktop pulse duration of t0desktop pulse periodand time delaybetween two consecutive pulses. The average current on the bit can be found from (20) in the form

Using the superposition principle, the reaction pressure in the first working pulse in the borehole can be represented as

where θ(τ) - function unit Heaviside jump; and

Using the results of measurements of the perturbation pressure at the first overlay (point a on Fig) and at the beginning of the second working period (dot), ψAand ψByou can obtain the equation for the coefficient η diffusion pressure

After finding η water permeability of the reservoir can be calculated as

Now you need from the measured curve 0ABCD...shown in Fig, extract the reaction pressure in the wellbore to nonperiodic flow ψa(τ). This means that preferably at least the first three working pulse were included in the interpretation to allow reliable determination of ψa(τ). Finally, the parameter φL, which is proportional to the initial flow rate of qLfilterable liquid, can be found using equation (22), and then from equation (23) to calculate the reservoir pressure

where the function Ze(T) shown in figure 5.

Graphical interpretation of figure 7 is sposobstvuet understanding of the requirements of the program pulse test, the implementation of which should decrease the possible errors due to incorrect interpretation of data. It is obvious that the average current flowshould not be too high compared with the consumption of filtered fluid, otherwise the right side of equation (22) will be small compared with the members included in the family balance, and therefore the error of their measurements can affect the accuracy of the estimate φL. Higher resolution should be achieved when the value ofclose to the flow rate of filtered fluid. In this case, the local slopes of the profiles of the transition pressure profile, the pressure increase is equal, but have opposite signs.

The volume of fluid located between the pump and the surface of the wellbore (or sand surface), which is also known as the stored volume, may distort the working pulses generated near the pump. As a result of this distortion of the boundary condition on the surface of the wellbore is not precisely aligned with the program of production, determined by the pump, and therefore, the reaction pressure is different from the obtained solution. This phenomenon, known as the effect of conservation in the wellbore (or device)may be significant, if the stored volume is large compared to about what their production in one test cycle. Indeed, the pressure stored in the volume is reduced during production and increases during discharge cycles, campfire change of flow created by the pump and, consequently, reduces the reaction layer on it. If the compressibility of the fluid stored in the volume is constant, the effect of preservation can be investigated using the method of Laplace transformation (see above Barenblatt et al. and Carslaw et al., also above).

The fundamental solution for the speed of the current flow with an amplitude of q0and zero initial conditions is solved (Carslaw et al., above) by the formula

They include additional dimensionless parameter γ, which is defined as

and who is the ratio of two characteristic times τSand τFcorresponding to the stored volume and the reservoir, respectively. Here VSis a saved volume, and c0the essence of the compressibility of the fluid, which is associated with the change ΔVSstored volume with change in pressure Δp as ΔVS=-c0VSΔP. The solution of (31)-(32) becomes identical to (17) with γ=0. The dependence of the function (2π)-1FS(a) from log10(a) for γ-1=0,5, 1, 2, 4 and ∞ are shown in figure 9 (reproduced from Carslaw et al.). Can wee the et, what is the effect of conservation is more pronounced at small value of time, especially in case of large γ values. This solution can be used instead of solving (16)-(17) for data interpretation method of impulse testing described above.

It should be clear that the described method can be extended to the case of accounting changes of reservoir properties, i.e. the dependence of the diffusion coefficient pressure and hydroconductivity distance from the wellbore caused by the penetration of mud filtrate into the formation during drilling. The test pulse-harmonic method at various frequencies can be used to distinguish between the reactions of the damaged zone and undamaged reservoir. In this case, for planning the test procedure requires some a priori information (at least the evaluation order of magnitude) relative to the hydroconductivity and diffusivity of the reservoir. If they change significantly with distance from the wellbore, it is necessary to modify the interpretation of reaction pressure on the non-periodic component, and in General requires a large duration of the test.

Figure 10 shows the block diagram of the stages in the practice of the described embodiment of the invention. Block 1003 characterizes the tracking of time after precedentemente on the interval (intervals) of the depths of interest. Perform a preliminary test (block 1005) and is measured in the usual way (block 1010), the well parameters, including permeability. The pressure in the well area increase (block 1020) and form a pulsation flow (block 1030). As discussed, the pressure can be adjusted, for example, from the wellhead or between two packers. Determine (block 1040), the first set of parameters of the well. In the present invention that includes the determination of the diffusion coefficient pressure and hydroconductivity layer by using the periodic component of the measured pressure and the estimation of the size of the zone of increased pressure around the wellbore. Then, as described, the number of well parameters and non-periodic component of the measured pressure is used to determine (block 1060) consumption resulting filtrate and/or the pressure gradient. Then by extrapolation may be determined (block 1075) reservoir pressure.

On 11 and 12 is illustrated a test mode of the pumping/injection (11) and in the mode of production (Fig).

In case of pumping/injection of 11 main goal is to measure the hydroconductivity mud cake, which should not significantly damaged, deleted or modified when through it into the reservoir pumped liquid. Compacted interval for the l can be used for: a) mitigating the effects of retention device, b) selective isolation of specific depth interval for test and/or C) to increase surface area and to maintain the proper rate of discharge, in which, in particular, it will generate a measurable reaction pressure behind the mud cake without breaking formation. Figure 11 timeline begins upon installation of the device and passing the probe through mud cake with subsequent pre-test a small amount (shown by item (a)), to clear the boundary between the probe and the reservoir and establish a good flow communication between the pressure gauge (for example, 493 figure 2) and the surface of the sand layer. After increasing the pressure (shown by item (b)), the liquid is pumped into the reservoir during the compact interval covered cake, using pulses (shown by item (C)), creating a transient response of the pressure behind the mud cake. The pressure on the surface of the sand, measured by the probe increases during injection impulses and relaxes between them, whereas the interval pressure during nagatani is kept constant. Dimension two pressure gauges 492 (interval) and 493 (probe) allows, as described above, to calculate the water permeability clay cover. Using known from the prior art methods, it is possible ODA is to divide respectively the diffusion coefficient and the coefficient of appointest, applying a low frequency and a relatively high frequency.

As shown in Fig, testing in production mode aims: (1) determination of reservoir parameters (diffusion coefficient pressure and hydroconductivity under pressure, or kh/µ) by using a batch reaction pressure on the surface of the sand on the working pulses and then (2) evaluation of the initial flow rate of filtered fluid from the wellbore into the formation through the use of non-periodic reaction pressure. The analysis was described in detail above. As shown in Fig, preliminary test (a) perform cleaning of the mud cake and establishing good hydrodynamic messages between the device and the reservoir, followed by several working pulses. Preferably, the number of work pulses were equal to at least three. With a larger number of pulses will tend to increase the resolution of the residual part of the reaction pressure.

Next will be described further variant of the invention, this variant implementation includes a method for estimating the parameters of the mud cake, which affects the flow of the filtrate, and use, in turn, this assessment to evaluate the true formation pressure from the measured value on the surface of the sand. The block diagram of the steps for applying for PR is ctice this alternative implementation is shown in Fig.

Track (block 1103) time after drilling. As reflected by block 1105, well place the device for measuring formation pressure and set about the formation of interest. Perform (block 1110) estimate formation permeability. This can be done using standard methods; for example, the interpretation of the transient pressure in the preliminary test. This assessment combined with the estimate of the total compressibility of the reservoir to provide an estimate of the diffusion coefficient of the pressure reservoir (block 1115). Create (block 1125), as described above, the periodic time variation of the pressure in the well with a large harmonic content in the appropriate frequency range and further treated as described below. Measure and record (block 1130) time-varying pressure via a pressure sensor in reservoir probe and pressure sensor in the wellbore (figure 2). Analyze periodic in time part of the results of measurements of the pressure in the well and reservoir pressure, using also information on formation permeability obtained in the preliminary test, to estimate the flow resistance of the mud cake (block 1140).

Then evaluated the resistance to the flow of the mud cake together with the measured pressures in the wellbore and to the surface of the sand used to evaluated the I-flow percolating leachate (block 1150). Further, as reflected by block 1160, the flow of percolating leachate used in conjunction with the estimated permeability of the formation and duration of exposure formation after drilling for the evaluation of excess pressure on the surface of the sand, caused by seepage (i.e. excess pressure due to slow pressure equalization after penetration of the filtrate into the reservoir). This excess pressure is subtracted from the measured pressure to obtain an estimate of the true formation pressure without the influence of excess pressure due to slow pressure equalization after penetration of the filtrate into the formation (block 1170).

Hereinafter will be described in more detail sequence for this variant embodiment of the invention. With regard to step 1125, after the probe device is installed and is in the message to the pressure reservoir, the steps used to create the borehole periodic time changes in absolute pressure with moderate amplitude to cause (a) measurable perturbation of pressure on the device within a wellbore, and (b) a measurable response to this perturbation, defined by the pressure sensor being in communication with the reservoir through a tube (as, for example, figure 2).

Well pressure can be written aswherehereafter the denotes the (constant) background pressure in the wellbore, with respect to which fluctuations occur,denotes “real part” of the argument,denotes the amplitude of the oscillation, ω is the frequency. The mechanisms of formation of measurements of pressure inside the reservoir include the reaction to the change in the flow rate of loss of filtrate through the mud cake (although other processes may contribute, for example, elastic deformation of the breed or deformation of the clay cover). The frequency fluctuations of the pressure in the well should be chosen so that the measured attenuation of pressure fluctuations on the clay crust satisfactorily met the resistance to flow created cake. The calculated reaction pressure is shown in Fig and 15, and their review indicates a satisfactory choice of frequency in the rangebecause the reaction is not too small, and the dimensionless frequency is not too low (rωis the radius of the borehole, measured on the side of the rocks from the mud cake, η is the diffusion coefficient of the pressure in the reservoir and ω is the angular frequency of the generated pressure pulsations). The choice of frequency was discussed above. An additional consideration in the choice of frequency is that it must be low enough that the depth of penetration of the perturbation pressure was more than the woman of the mud cake, and this becomes a requirement ϕwithswithωd2/kc<<1, where d is the thickness of the mud cake, withwiththe compressibility of the mud cake, ϕwiththe porosity of the mud cake, kwith- permeability clay cover and kwithwithswith- measure the diffusion coefficient of the pressure in the clay crust.

With regard to the interpretation of the attenuation of pressure fluctuations in the case of the skin-effect of the mud cake, the complex amplitude of the axisymmetric time-harmonic fluctuations of the pressure in the reservoir, with angular frequency ω, satisfy the following relations :

in which the actual pressure is determined by the expression

,

η=k/ϕµct,

where k is the permeability;

ϕ is the porosity of the reservoir;

µ is the viscosity of the fluid in the pore space and

ctthe compressibility of the system of fluid-solid phase (reservoir full of fluid).

Pressure fluctuations decrease at large distances, so that when r→∞,. On the wall of the wellbore clay crust is modeled infinitely small thin “skin layer”, the pressure loss which is proportional to the instantaneous flow rate, so

where the dimensionless parameter S is a generally accepted indicator of skin effect, known the technique of test wells. It can be shown that

where K is the modified Bessel functions, and the branch of the square root is chosen so that it is guaranteed decay of the perturbation pressure at large distances.

On Fig and 15 shows graphs of the module and of the function argumentdefined by the above formula, built depending on ω orfor several values of S. For Fig the permeability is 10 MD, porosity 20% when the viscosity of the formation fluid 1 MPa·s, full compressibility of 10-8PA-1the radius of the wellbore 0.1 m and the index of the skin effect of the mud cake S=99,49 (corresponding to the crust thickness of 1 mm with a permeability of 0.001 MD). In the case of this mud cake filtration rate of fluid generated by the differential pressure of 100 pounds/inch2that is 6.8×10-5cm/S. Fig shows that, if the values of η, ω and rwand, therefore, ωDknown, it is possible to estimate the value of S measured by the relationthe amplitudes of the pressure fluctuations on the surface of the sand in the well. In the present embodiment of the invention the values ofandreceive from the measured time series of pw(t) and p(rw,t), using conventional methods of signal processing.

As he gave the biggest improvement you can also change the speed of circulation of the drilling fluid and/or the average pressure in the wellbore at a long time interval. Changes in the velocity of circulation will lead to erosion (or further increase) clay cover, and changes in pressure filtration will lead to a more compact crust (or to a slightly extended). The rate of skin-peel effect at each speed circulation or repression can be estimated using the method just described, and using this method it is possible to form a table of values of S depending on the speed of circulation (denotedand/or pressure pw-p(rwt) filter, denoted as Δp. Values listed in this table can be used at the stage of block 1150 (additionally explain below), so that the value S corresponding to the current conditions of the circulation, is used in the estimation of consumption of filtered liquid. You can use interpolation between measured values.

With regard to phase out of the block 1150, the instantaneous pressure drop on the clay crust is associated with the pressure gradient on the surface of the sand through

and using the Darcy law in the sand

to relate the pressure gradient on the surface of the sand flux q seeping filtrate, you can get

Using this expression in the assumption that (a) the Yeri fluid can be adequately described by the parameter S skin effect, estimated above, and (b) in the previous stages collected sufficient data to allow extrapolation and interpolation with the aim of estimating S in the whole range of flows and pressures in the wellbore observed between the first stimulation and measurement of reservoir pressure or to obtain a mechanistic model for the binding of S values measured under one set of conditions, with values relating to a different set), and the flow q(t) of the filtrate can be estimated from the measured time dependences of the pressure in the wellbore and to the surface of the sand, respectively; pw(t) and p(rw,t), and information regarding the circulation rate of the drilling mud.

As for the steps 1160 and 1170, the pressure on the surface of the sand is associated with a flow rate of filtered fluid in the usual convolution integral

where t0indicates the point in time at which the reservoir was first drilled;

p- reservoir pressure at large distances from the borehole;

G - pulse reaction layer, which contains as parameters the permeability (k) of the reservoir and the ratio (η) diffusion pressure; and

q(t') is the time dependence of the flow seeping filtrate described above.

The functional form of G is well known in the prior art to which the invention relates.

By comparing the predicted pressure at the surface of the sand obtained from the previous equation, the pressure on the surface of the sand is really measured, we can estimate the p. In other formulated the way the value ofcan be used as an estimate of repression due to excess pressure due to slow pressure equalization and subtracted from the measured pressures to obtain an estimate of the true formation pressure. It should be clear that this variant embodiment of the invention is based on the indirect assessment of repression by the resistance of the mud cake, which affects the accuracy of the method. In the model interpretation assumes that the clay crust is thin and behaves like a simple additional resistance to fluid flow between the wellbore and the reservoir. The method can be modified to take into account the finite thickness of the crust, unsteady diffusion pressure inside the peel and/or interactions between the hydrodynamic properties of the crust and the change in pressure in the well.

Although the invention has been described with reference to a limited number of embodiments, specialists in the field of technology to which the invention relates, receiving the benefit of this disclosure, should understand that without derogating from the volume image is the shadow, disclosed in this application can be developed other ways of implementation. For example, variants of the implementation can be easily adapted and used to perform specific operations on a sample survey or formation testing without straying from the invention. Therefore, the scope of the invention should be limited only by the attached claims.

1. The method of determining the initial reservoir pressure at a single depth interval of underground formations surrounding a borehole drilled using mud, and on which was formed the clay crust, containing the following steps:
tracking of time after cessation of drilling at the specified depth interval;
obtaining permeability layers at the specified depth interval;
the motive pressure in the wellbore to periodic change with time and determination on the specified depth interval periodic component and the aperiodic component of the pressure measured in the layers adjacent to the clay crust;
determination of diffusion coefficient of pressure and hydroconductivity layers by using the specified time, the specified periodic component and the specified permeability and estimation of the size of the zone of increased pressure around the wellbore at a specified interval the depths of the layers;
determination of the rate of filtration of the mud cake on the specified depth interval by using the specified time, the specified diffusion coefficient pressure and hydroconductivity layers and the non-periodic component;
the determination of the pressure gradient in the layers adjacent to the clay crust on the specified depth interval, by using a specified rate of filtration; and
extrapolation in order to determine the initial reservoir pressure, by using the specified pressure gradient and the specified size of the zone of increased pressure.

2. The method according to claim 1, wherein said step of determining the periodic component and the aperiodic component of the pressure measured in the layers adjacent to the clay crust, includes a delivery device for testing seams at the specified depth interval and measurement of reservoir pressure probe specified device, which is injected through the mud cake in layers adjacent to the clay crust.

3. The method according to claim 2, wherein said step of determining the periodic component and the aperiodic component of the specified pressure, measured in the layers adjacent to the clay crust, includes the definition of said non-periodic component, the average value of the pressure measured indicated the probe, and the definition of said periodic component variations from this average value.

4. The method according to claim 3, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the well on wireline.

5. The method according to claim 3, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the borehole on the drill string.

6. The method of determining the initial reservoir pressure at a single depth interval of underground formations surrounding a borehole drilled using mud, and on which was formed the clay crust, containing the following steps:
the motive pressure in the wellbore to periodic change in time;
the definition at the specified depth interval periodic component and the aperiodic component of the pressure measured in the layers adjacent to the clay crust;
definition and estimation of the size of the zone of increased pressure around the wellbore to the specified depth interval of layers by using the periodic component;
determination of the rate of filtration of the mud cake on the specified depth interval by using the non-periodic component and
definition pervonachalnogo the reservoir pressure by using a specified rate of filtration and the specified size of the zone of increased pressure.

7. The method according to claim 6, wherein said step of determining an initial reservoir pressure by using a specified rate of filtration includes the determination of the pressure gradient in the layers adjacent to the clay crust on the specified depth interval at the specified index filtering and extrapolation in order to determine the initial reservoir pressure, by using the specified pressure gradient and the specified size of the zone of increased pressure.

8. The method according to claim 7, further containing the step of tracking time after the cessation of drilling at the specified depth interval, and in which the specified time is used at this stage of assessment size of the specified zone of increasing pressure and at a specified stage of the definition of a specified pressure gradient.

9. The method according to claim 6, wherein said step of determining the periodic component and the aperiodic component of the pressure measured in the layers adjacent to the clay crust, includes a delivery device for testing seams at the specified depth interval and measurement of reservoir pressure probe specified device, which is injected through the mud cake in layers adjacent to the clay crust.

10. The method according to claim 9, wherein said step of determining the periodic component and not uridicheskoi component specified pressure, measured in the layers adjacent to the clay crust, includes the definition of said non-periodic component, the average value of the pressure measured by the specified probe, and the definition of said periodic component variations from this average value.

11. The method according to claim 9, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the well on wireline.

12. The method of determining the initial reservoir pressure at a single depth interval of underground formations surrounding a borehole drilled using mud, and on which was formed the clay crust, containing the following steps:
tracking of time after cessation of drilling;
obtaining permeability layers at the specified depth interval;
the motive pressure in the wellbore to periodic changes in time and the measurement on the specified depth interval time-varying pressure in the borehole and a time varying pressure in the formations adjacent to the clay crust;
the definition at the specified depth interval evaluation of the resistance to flow of the mud cake on the specified received permeability and components specified measured downhole pressure and the measured pressure in the reservoir is x, adjacent to the clay crust;
the definition at the specified depth interval of the rate of filtration of the mud cake on the specified estimated flow resistance provided to the measured pressure in the well and indicated measured pressure in the formations adjacent to the clay crust;
the definition at the specified depth interval of excess pressure in the formations adjacent to the clay crust, received the specified permeability, the specified rate of filtration and the specified time after the cessation of drilling; and
the definition at the specified depth interval initial reservoir pressure measured at the specified pressure in the formations adjacent to the clay crust, and the specified excess pressure in the reservoir.

13. The method according to item 12, wherein said step of measuring a time varying pressure in the borehole and a time varying pressure in the formations adjacent to the clay crust, includes a delivery device for testing seams at the specified depth interval and measurement of reservoir pressure probe specified device, which is injected through the mud cake in layers adjacent to the clay crust.

14. The method according to item 13, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the well on wireline.

15. Pic is b according to item 13, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the borehole on the drill string.

16. The method for determining the rate of filtration of the mud cake formed on a single depth interval in the well, drilled in formations with the use of drilling mud, containing the following steps:
obtaining permeability layers at the specified depth interval;
the motive pressure in the wellbore to periodic changes in time and the measurement on the specified depth interval time-varying pressure in the borehole and a time varying pressure in the formations adjacent to the clay crust;
the definition at the specified depth interval evaluation of the resistance to flow of the mud cake on the specified received permeability and components specified measured downhole pressure and the measured pressure in the formations adjacent to the clay crust; and
the definition at the specified depth interval of the rate of filtration of the mud cake on the specified estimated flow resistance provided to the measured pressure in the well and indicated measured pressure in the formations adjacent to the clay crust.

17. The method according to item 16, wherein said step of measuring a time varying pressure in the well and change is eghosa time pressure in the reservoir, adjacent to the clay crust, includes a delivery device for testing seams at the specified depth interval and measurement of reservoir pressure probe specified device, which is injected through the mud cake in layers adjacent to the clay crust.

18. The method according to 17, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the well on wireline.

19. The method according to 17, wherein said phase delivery device for testing of formations includes delivery of the specified device specified in the borehole on the drill string.

20. The method according to item 16, further comprising:
determining during a time interval, the speed of circulation and the corresponding repressional pressure in the well;
definition over the time interval of the rate of filtration for the speed of each circulation and the corresponding repressional pressure in the well;
definition over the time interval of the relationship between the rate of filtration and the speed of each circulation and appropriate repressional pressure and
estimation of the rate of filtration for the previous time interval, based on a certain relationship.

21. The method according to claim 20, further comprising:
clarification of the measured layer is about pressure, based on the estimated rate of filtration.



 

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Depth sampler // 2360109

FIELD: mining.

SUBSTANCE: depth sampler consists of ballast chamber, of actuator with module of control, of main and additional sample taking chambers equipped with medium-separating pistons, hydro-resistors and valve units. Each medium-separating piston is equipped with a compensating tube, which connects under-piston cavities of sampling chambers between them. Also hydro-resistor is assembled at the end of each tube.

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1 dwg

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1 ex, 2 tbl, 4 dwg

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86 cl, 9 dwg

FIELD: oil and gas industry.

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36 cl, 9 dwg

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25 cl, 13 dwg

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18 cl, 10 dwg

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3 cl, 1 ex, 2 dwg

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19 cl, 27 dwg

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FIELD: mining.

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52 cl, 4 dwg

FIELD: oil and gas industry.

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7 dwg

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7 dwg

FIELD: mining.

SUBSTANCE: invention relates to determination of various well characteristics in the underground formation, through which the borehole passes. For this purpose a pressure drop is created due to the difference between the internal pressure of fluid that passes through the drilling tools and pressure in the circular space in the borehole. The device contains an extension arm that can be connected with the drilling tools and has an opening that enters into the chamber in the extension arm. A piston is located in the chamber with a rod passing through the opening. The piston can move from the closed position when the rod blocks the opening to the open position when the rod is retracted into the chamber to form a cavity for intake of well fluid. A sensor is located inside the rod, which is intended for data collection from the well fluid contained in the cavity.

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34 dwg, 9 dwg

FIELD: mining.

SUBSTANCE: invention refers to gas and oil industry and can be used, in particular, to select technology of well building and construction, as well as to monitor technical condition thereof inside permafrost rocks (PFR) and in permafrost zone. According to proposed method, a well is drilled, temperature is measured in depth of a well and then geothermic gradient is defined. On the basis of the results of these measurements, lower boundary depth of PFR ground bed is defined. For this purpose, before temperature in well depth is measured, a casing string (CS) is let down in a well along its sidewall and cemented. After cementing of CS is completed, measurements of temperature inside a well are carried out in the process of cement setting during thermal recovery. The results of temperature measurements are used to plot temperature curve of a well depending on the depth of a well. According to the depressed temperature level of the temperature curve, upper zone of PFR mass bedding inside it and lower zone under it are indicated. Lower zone is the zone of thawed, cooled and/or waterflooded rocks with higher temperature level when the average temperature gradient does not exceed 0.02-0.05°C/m. Between them, an intermediate transition "step" zone is indicated. This is a zone with rapid increase in temperature and high value of temperature gradient (G = 0.06-0.45°C/m and higher). According to the temperature curve and indicated connection point of the "step", which is an intermediate, high-gradient temperature zone with lower thawed, cooled and/or waterflooded zone, the depth of PFR mass bedding is defined. Inside PFR mass, separate local zones of thawed rocks with higher temperature level, frozen zones with depressed temperature level and intermediate high-gradient temperature zones lying between them are indicated simultaneously. According to junction points of intermediate zones and thawed zones, the boundaries between thawed and frozen zones located inside PFR mass are defined. In this case, temperature measurements inside a well are made using a highly sensitive thermometer with intervals of temperature measurement in depth of not more than 0.1-0.2 m.

EFFECT: more accurate definition of bottom depth of permafrost rock mass.

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FIELD: oil and gas industry.

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EFFECT: simplification of method for designing gas-condensate formation development, research time reduction and increased precision.

1 dwg, 6 tbl, 1 ex

FIELD: mining.

SUBSTANCE: invention refers to the mining industry, namely to the drilling equipment, and is designed for research of optimal drilling mode parameters based on the temperature rise criteria in the contact zone of the drilling tool and the rock. The device includes the core holder with a rock sample as the core installed at the spindle of the core drill, the thermal frictional tool, the optic cable laid along the gallery hole of the tool frame with its end at the friction tool end plane, connected in series with the receiver-amplifier and the registering device, the core tube with a nozzle for water input, the anti-spatter protection cover, and the water collector with water drain. There is a gallery hole connecting the internal and the external cavities of the tool in the thermal friction tool frame. This allows to cool the optic cable with water coming to the core tube, which reduces the additional IR-radiation being a hindrance to the main signal.

EFFECT: setting the optimal drilling mode parameters by the contact zone temperature of the tool and the rock, as measured on the testing bench.

2 cl, 2 dwg

FIELD: mining.

SUBSTANCE: invention refers to the mining industry, namely to the drilling equipment, and is designed for research of optimal drilling mode parameters based upon the temperature rise criteria in the contact zone of the drilling tool and the rock. For this purpose, the temperature of the contact zone of the drilling tool and the rock is measured by the pyrometry method by rotating the rock sample while the tool remains steady. IR-radiation is directed to the receiver by the means of a fiber optic cable laid through the tool's cannelure and connected to the IR-radiation receiver. Then, it is transformed into analog signal, got amplified and fed to the recording device. Besides, cold water is fed to the cannelure through the tool inner cavity, in order to reduce the hindrances from additional IR-radiation of heated fiber optic cable walls by cooling the cable down. The working end of the optic cable is insulated from the water-bearing cavity with sealer.

EFFECT: setting the optimal drilling mode parameters by the contact zone temperature of the tool and the rock, as measured on the testing bench.

2 dwg

FIELD: oil and gas production, particularly to perform measurements during well drilling (initial well completion) to obtain information concerning temperature and pressure of drilling mud flow injected in well directly from well bottom to area of drilling mud flowing through jet bit nozzles and turbine blades, as well as in hole annuity of the well after rock cutting by bit and turbine blades and crushed rock washing-out from well bottom.

SUBSTANCE: device comprises sub with container connected to outer surface thereof installed between drilling pipe or tubing assembly and drilling tool assembly. The container has orifices in upper and lower parts thereof. Self-contained measuring instrument is installed inside container. Two mutually independent temperature and pressure sensors are arranged in upper and lower parts of measuring instrument so that temperature and pressure are located in immediate proximity to container orifices. Distance between container orifices does not exceed two meters. Heat-insulation sleeve is installed in central container part in fluid-tight manner. Self-container measuring instrument may be supported by springing support and does not touch container body.

EFFECT: increased reliability of results obtained during thermobaric drilling mud or flushing liquid condition measuring in pipe string and annular spaces simultaneously, possibility to take measurements during any technological operation, well construction and development.

4 cl, 2 dwg

FIELD: well boring, particularly for measuring pressure in well during drilling thereof.

SUBSTANCE: device has body with central flushing orifice and grooves. Arranged in the grooves are electrical circuits and positive pressure transducers isolated by pressure-resistant shell. The first pressure transducer is connected with central flushing orifice in tube, another one - with annular tube space. The device is provided with power source and two differential amplifiers with outputs connected to summing unit inputs. Supply diagonal units are linked correspondingly with power source inputs. The first units of measuring diagonals of the first and the second pressure transducers are connected correspondingly with inverting and non-inverting inputs of the first differential amplifier. The second units of measuring diagonals of the first and the second pressure transducers are linked correspondingly to inverting and non-inverting inputs of the second differential amplifier. The first and the second pressure transducers may be arranged in the body at 0°-45° and 153°-180° angles to vertical device axis correspondingly or may be inversely arranged. The body may be formed of titanic alloy.

EFFECT: increased measuring reliability.

4 cl, 2 dwg

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