Method for determination of parameters for well bottomhole and bottomhole area

FIELD: oil and gas industry.

SUBSTANCE: invention is related to the area of wells completion and testing in oil industry and intended for calculation of parameters for the well bottomhole and bottomhole area. The method where in process of string movement in the well pressure is measured by two sensors, at that one sensor is installed over the packer while the second one is installed below the packer. According to results of pressure measurement fluid density is determined and then flowing bottomhole pressure is determined on the basis of fluid density, gravity constant, preset rate of drilling string motion, cross-sectional area of the drilling string, formation pressure, and productivity index of the well.

EFFECT: potential determination of parameters for the well bottomhole and bottomhole area during round-trip operations with further calculation of liquid influx/reflux at the bottomhole and calculation of skin factor, permeability or thickness of the reservoir.

13 cl, 5 dwg

 

The invention relates to the completion and testing of wells in the oil and gas industry and is designed to calculate the parameters of the face and the bottom zone of the well, such as, for example, skin factor, permeability, power collector, the bottomhole pressure and the outflow or inflow in this area.

In the prior art there are known various methods for determining the parameters of the face and the bottom zone. Thus, in U.S. patent No. 4799157 described method of test wells for evaluation of permeability and skin factor of two reservoirs, one reservoir. The method consists in performing two consecutive hydrodynamic investigations of wells (well testing) by creating a depression on the bottom with a permutation of the logging sonde and the subsequent interpretation of the data on the flow rates and pressures.

In U.S. patent No. 5337821 the method of calculating the maximum hydroconductivity collector, as well as the method and measuring device for measuring flow rates, the full potential of the flow rate at the flowing well and whether violations of the permeability zone of the formation from production. Measurements shall be conducted after the descent of the tool into the borehole to a predetermined depth and isolating intervals using inflatable rubber packers.

In U.S. patent No. 7675287 describes how to assess the skin factor podzemnih the collector inside the wellbore by lowering the measuring device at a certain depth and dimension properties of nuclear magnetic resonance formation at multiple depths.

In the patent application U.S. No. 2011/0087471 proposed to establish a functional relationship between reservoir properties, characteristics of the bottomhole zone/completions, as well as measured characteristics of the well. Confirmed values of reservoir properties such as permeability, characteristics of the bottomhole zone/completion, such as the skin factor is determined by establishing a functional dependency.

A common shortcoming of these patents and patent applications is that they all require special equipment or special operations in the borehole to determine the properties of the face and the bottom zone. The difference of the present invention is that to define the properties of the face and the bottom zone is usually available when the investigation or operation of the wells. In other words, to define the parameters is not required of non-standard equipment or additional operations.

Technical result achieved during the implementation of the claimed invention, is to provide the possibility of determining the timing of slaughter and the bottom zone, such as downhole pressure during tripping with subsequent calculation of the inflow/outflow of the liquid at the bottom and calculate the skin factor and permeability or power collector. realizacija the proposed method can be implemented using a conventional pressure gauges, which are widely used in the oil industry, without descent special tools into the well.

In accordance with the proposed method in the process of moving the tubing in the borehole carry out measurements of pressure and temperature, the results of which estimate the parameters of the face and the bottom zone.

The parameters of the face and the bottom zone can be dynamic bottom hole pressure, the dynamics of the absorption of the liquid collector, the dynamics of inflow of fluid from the reservoir, the total amount of acquisitions or inflow, skin factor, permeability or rate of a header.

Measurement of pressure and temperature can be performed via at least one pressure sensor and the temperature set in any place the pipe string.

Measurement of pressure and temperature can be carried out by means of two pressure sensors and temperature, one of which is mounted above the packer and the second below the packer.

Measurement of pressure and temperature can be performed by means of a pressure sensor and a temperature that is installed in the string of pipe so that it is as close as possible to the collector at the end of the descent of the column to the desired depth.

Measurement of pressure and temperature can be performed via at least one gauge and one sensor is temperature, installed in any location in the pipe string.

Measurement of pressure and temperature can be performed via at least one gauge and one temperature sensor installed in the string of pipe so that it is as close as possible to the collector at the end of the descent of the column to the desired depth.

Column pipe may be provided with any additional instruments such as samplers.

In accordance with one variant of the invention the measurement of pressure and temperature is carried out in the process of lowering the pipe string into the well.

Measurement of pressure and temperature can be carried out in the process of lowering the pipe string into the borehole before the work on the perforation interval.

In accordance with another variant of realization of the invention the measurement of pressure and temperature is carried out in the process of lifting the pipe string from the well.

Measurement of pressure and temperature can be carried out in the process of lifting the pipe string from the well after the perforation interval.

In accordance with another variant of the invention the measurement of pressure and temperature is carried out in the process of lowering the pipe string into the well and in the process lifting the pipe string from the well.

The invention is illustrated by drawings, where Fig.1 shows the system for the implementation of tripping and measurements; in Fig.2 - the process of displacement, shown in a simplified geometric form; Fig.3 - geometry used in the example implementation of the calculations of Fig.4 - position/level of the liquid in the annulus and the position of the drill pipe with the layout of the test reservoir (reservoir) along the borehole with respect to time, Fig.5 - certain hydrodynamic downhole pressure and total volume of acquisitions.

The present invention is as follows.

As shown in Fig.1, column 1 pipe or column 1 pipes with additional tools lowered into the borehole 2 from the surface 3 to perform certain operations. Sensor 4 for measuring pressure and temperature is set in the column pipe 1. The system can be installed additional sensor 5 or more additional sensors for measuring pressure and temperature. Column 1 of pipe is lowered into the well 2 until it reaches the position 6 at a certain point in front or close to the underground reservoir 7. Readings of pressure and temperature recorded during the whole period of the descent of the column 1 pipe from the surface 3 to the point of slaughter 6. After the operation of the descent, all operations scheduled in the hole, and lifting tubes, temperature sensors and pressure are retrieved on the surface of the measurements, which were taken during tripping, and measurements obtained during schedule execution.

In the case of using two pressure sensors and one temperature sensor can be installed above the packer, and the other below the packer. The layout with the installation of two sensors allows to determine the density p on the basis of the pressure difference between the readings of the two gauges. Using the equation of hydrostatic pressure, we obtain:

ρ(t)=Δpg(t)glgcosθg

where g is the constant of gravity, lg- the distance between the gauges and θg- the average angle of inclination of this part well. Note that the last formula holds for slow processes, in which the pressure loss by friction play a less significant role than the hydrostatic pressure drop. Temperature measurement can be used to establish the relationship between the properties of the liquid on the surface and measuring point data in underground conditions.

Consider the volume balance during the downward movement of the tubing in the well. For simplicity we neglect the compressibility of the fluid is in and will make the assumption, the fluid level in the annulus rises vertically, while the movement of the drill pipe or column tubing layout for testing formations (reservoirs) is carried out on an inclined (see Fig.2).

Moving a column of drill pipe layout for testing formations (reservoirs) displaces a certain volume of liquid ΔVDSTduring the period of time Δt. At the same time, the volume of fluid in the annulus is increased by ΔVanand the volume ΔVris absorbed by the collector. Therefore, in this case we have

ΔVDST=ΔVan+ΔVr(1)

Data volumes can be easier expressed in the following form

ΔVDST=ADSTΔzDST

ΔVan=AanΔzan

ΔVr=2πrwhΔr=QlossΔt

where ΔzDST- measured the depth of advancement of the drill pipe during the time Δt (8 in Fig.2), Δzan- lifting height of the liquid column in the annulus during the time Δt (9 in Fig.2), Aan- the cross-sectional area available for flow in the annulus, A DST- the cross-sectional area of the drill pipe, the calculated outer diameter, h is the difference between the measured depths of the sole and roof collector (power collector 10 of Fig.2) or the length of the perforated interval, Δr is the depth of penetration of the liquid from the well into the reservoir (11 in Fig.2), rwis the radius of the borehole (12 in Fig.2), Qlossvolumetric flow rate of outflow of fluid from the well into the reservoir.

Substituting the last expression in equation (1) and dividing by Δt, we obtain

ADSTΔzDSTΔt=AanΔzanΔt+Qloss(2)

Member in the left-hand side of equation (2) expresses the rate of descent of the drill pipe layout for testing formations (reservoirs)

νDST(t)=ΔzDSTΔt

The value is their velocity ν DSTis accepted as a given value. Usually this rate is of the order of several centimeters per second. Now consider the first term in the right-hand side of equation (2). The increase in liquid level in the annulus proportionally increasing hydrodynamic downhole pressure, which for slow processes in almost a vertical well is basically the hydrostatic component.

ΔzanΔt=1ρgΔpwfΔt

where Δpwfindicates a change in downhole pressure during the time Δt.

Note that more complex geometric features and the interval velocities can be taken into account in the last equation. The second term in the right-hand side of the equation can be expressed, for example, of the stationary ratio of the flow of fluid in the production well (the ratio of hydrostatic pressure spouting with flow rate).

Qloss=2πkhμ(ln(re/rw )+s)(pwf-pe)

Here k is the permeability, µ is the viscosity, re- the radius of the pressure, s is the skin factor, pe- reservoir pressure, defined on the radius of the pressure.

Replacing three of the last equality in equation (2) when Δt→0, we get a simple ordinary differential equation of the first order.

dpwfdt=ρgAan(ADSTνDST(t)-PI(pwf-pe))(3)

where PI is the productivity index of the well.

PI=2πkhμ(ln(re/rw)+s )

Equation (3) can be written in explicit discretized form.

pwfn+1=pwfn+ΔtρgAan(ADSTνDSTn-PI(pwfn-pe))(4)

Equation (4) is easily solved numerically to calculate the hydrodynamic hydrostatic pressure pwfthat, in turn, allows us to calculate the volumetric flow rate of liquid absorption by the collector of Qloss(t). The skin factor s is determined by selecting values that meet the specified parameters, conditions, and requirements test parameters (see below). It should be noted that in this problem the value of the permeability k can be unknown (defined) value. In this case, it could be found at a given skin factor and the capacity of the reservoir h. the other hand, the power collector h could also be unknown (defined) value. In this case, it can be found for a given skin factor and permeability k.

The reliability of the results predicted by the model can be verified by calculating the following test parameters: the position of the drill pipe layout for testing formations (reservoirs)

zDST(t)=zDST(0)-0tνDST(t)dt(5)

Mark the liquid level in the annulus

zan(t)=zan(0)+pwf(t)-peρg(6)

and the pressure of the lower pressure gauge

pgc(t)=pe-ρgzDST(t)cosθ(7)

You must note that for simplicity, the values of zDST(t) and zan(t) measured along the borehole, since the borehole bottom.

As a specific example of implementation of the invention consider the configuration of the wells shown in Fig.3, which is characterized by the following parameters: the length of the inclined section l1=2127.04 m (13 in Fig.3), the length of the vertical section of the l2=500 (14 in Fig.3) m and the angle θ=20° (15 in Fig.3). The length of the interval punching is h=10 m, the reservoir pressure is pe=200 bar (the radius of the pressure re=500 m), and the permeability is k=50 MD. In this example, the value of the skin factor s is an unknown quantity. The density of the fluid in the flow is ρ=1000 kg/m3and viscosity µ=1. Suppose that during the descent the column for the first time in contact with the liquid at the point of inflection, in which the bottomhole pressure equal to the hydrostatic pressure ρgh1=pe. From this equation we see that the height of the column of liquid the spine in the wellbore before the operation was equal to h 1=2000 m (16 in Fig.3).

Trip operation in this case consists of two periods of descent of the drill string in the borehole and a short period of lifting from wells between these periods, until the end of the movement of the column. The average speed was adjusted so that the value'zdst calculated using equation (5), is zero when the column stops moving (the lower the unit reaches the final measured depth of the wellbore, the curve 17 in Fig.4). As a result of this correction, we obtain the absolute value of the νDST=0.03735 m/s (see Fig.4).

After the selected value of the νDSTto set parameters need to make sure that the value max(zan)=l1+l2at the end of the trip operation (curve 18 in Fig.4) indicated that the level of liquid in the annulus rose to the level corresponding to the indication of the correct hydrostatic pressure on the manometer. It automatically equalizes the calculated bottomhole pressure design pressure on the manometer, which is obtained using equation (7). Good agreement is obtained for the value of the skin factor s=60 (see Fig.5, where curve 19 represents the dynamic downhole pressure curve 20 indicates the pressure on the pressure gauge, obtained using equation (7) and curve 21 indicates the amounts of the RNA outflow in the collector). The diagram also shows the total losses ∫Qlossdt.

The proposed method can also be applied to cases with more complex geometries.

1. The method for determining the parameters of the face and the bottom zone of the well, in accordance with which
in the process of moving the tubing in the borehole perform pressure measurement with two sensors, one of which is mounted above the packer and the second below the packer,
- the pressure measurements to determine the density of the fluid and determine the dynamic bottom hole pressure from the equation

where ρwfdynamic bottom hole pressure, ρ is the density of fluid, g is the constant gravity, νDST(t) - set speed of movement of the drill pipe string, ADST- the cross-sectional area of the drill pipe, ρe- reservoir pressure, PI is the productivity index of the well defined by the formula

where k is the permeability, h - power manifold, µ is the viscosity, re- the radius of the pressure, rwis the radius of the borehole, s is the skin factor.

2. The method according to p. 2, under which determine the volumetric flow rate of liquid absorption by the collector according to the formula

where Qloss- volumetric flow rate of liquid absorption by the collector, ρwfdynamic bottom hole pressure, ρe- reservoir pressure, k is the permeability, h - power manifold, µ is the viscosity, re- the radius of the pressure, rwis the radius of the borehole, s is the skin factor.

3. The method according to claim 2, whereby the total amount of acquisitions is determined by integrating the volumetric flow rate of liquid absorption by the collector over time.

4. The method according to p. 1, according to which if one value from the group consisting of skin factor, permeability and the capacity of the collector is unknown, the value of the unknown quantity picked by substitution in the equation for determining the dynamic downhole pressure and further variation of this value to ensure the satisfaction of specified parameters and requirements for all test parameters.

5. The method according to p. 4, in accordance with which the test parameters are:
the position of the drill pipe layout for testing collectors

where zDST(t) is the position of the drill pipe string, zDST(0) - the position of the drill pipe string at the initial moment of time, νDST(t) - set speed of movement of the drill pipe during the movement,
- mark the liquid level in the annulus

where zan(t) - the level of fluid in the annular por the space zan(0) - the liquid level in the annulus at the initial moment of time, ρwfdynamic bottom hole pressure, ρe- reservoir pressure, ρ is the density of fluid, g is the constant of gravity, compared with the level of liquid in the annulus defined by the readings of the pressure sensor, and
- estimated pressure at the point where a lower pressure sensor

where ρgc(t) is the estimated pressure at the point where a lower pressure sensor, ρe- reservoir pressure, ρ is the density of fluid, g is the constant of gravity, zDST(t) is the position of the drill pipe layout for testing collectors, θ is the angle of inclination of the borehole, measured relative to the vertical, which is compared with the pressure measured bottom pressure sensor.

6. The method according to p. 1, according to which the pressure sensors are pressure gauges.

7. The method according to p. 1, according to which in the process of moving the tubing in the well additionally carry out temperature measurements.

8. The method according to p. 1, according to which a column of pipes fitted with additional tools.

9. The method according to p. 1, in accordance with which the pressure measurement is carried out in the process of lowering the pipe string into the well.

10. The method according to p. 9, under the which the pressure measurement is carried out until the work on the perforation interval.

11. The method according to p. 1, in accordance with which the pressure measurement is carried out in the process of lifting the pipe string from the well.

12. The method according to p. 11, in accordance with which the measurement of pressure and temperature is carried out after the work on the perforation interval.

13. The method according to p. 1, in accordance with which the pressure measurement is carried out in the process of lowering the pipe string into the well and in the process lifting the pipe string from the well.



 

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1 dwg

FIELD: mining, particularly oil and gas well testing.

SUBSTANCE: method involves lowering sample taking device suspended to wire or logging cable to take two or more deep fluid, gas or fluid and gas mixture samples in air-tight manner simultaneously, wherein the sample taking device comprises at least two sample taking chambers; communicating well space with sample taking chamber interiors by closing or opening the chambers with the use of hydraulic drive, which is actuated since sample taking sample taking device was lowered in well, wherein lowering, lifting operations, as well as operation for sample taking device retaining at sampling point are carried out along with measurement of pressure, temperature and sample taking device location depth. The sample taking chambers are opened or closed synchronously or alternatively. Hydraulic drive is operated by electromagnetic valve under control of electronic programmable controller, which controls valve opening and closing in accordance with preset time period or well pressure value. In the case of cable communication line usage the valve is controlled by control signal given from land-based unit. Sample taking device comprises electronic module, hydraulic drive assembly, one or several sample taking chambers, temperature and pressure sensors and programmable controller, which operates electromagnetic valve of hydraulic drive assembly, magnetic collar locator, natural radioactivity recording unit. All information fixed by sensors is digitized and stored in nonvolatile memory means. Sample taking device also has sensor system, which detects sample taking chamber valves opening and closing independently for each sample taking chamber. All measured parameters are digitized and stored in electronic module memory or is supplied to land surface in the case of cable communication line usage.

EFFECT: possibility to take sealed samples simultaneously in one well point or in several points located at different depths, possibility to perform continuous depth, temperature and pressure measurements inside the well in sampling point and along well bore, provision of independent control of each sample taking chamber.

9 cl, 3 dwg

FIELD: oil production well operation survey, particularly to control productive formation pressure along with information transmission via wireless communication channel.

SUBSTANCE: method involves lowering subsurface pressure gage connected to flow string and to well sucker-rod, wherein the subsurface pressure gage comprises pressure sensor and information transmission device, which transmits information via wireless communication channel; measuring pressure and transmitting information to day surface via wireless electromagnetic communication channel with the use of decompressor having variable base, wherein base length is defined by distance from productive formation roof to end of well sucker-rod filter and magnitude of temperature flow string length change adjusted for geometrical factor equal to 1 - 1.01. Device for above method realization comprises subsurface pressure gage provided with electromagnetic wave transmitter, which transmits electromagnetic waves generated by electric signal sent by decompressor electrically linked to well sucker-rod. The decompressor has variable base and is terminated in electrode located in lower variable base part. The electrode is electrically connected to casing pipe through centrator. Pressure sensor is arranged in electrode body and connected to electronic circuit. Device may be provided with additional pressure sensors connected with each other and forming pressure sensor string. Number of pressure sensors in the array is equal to number of production strings. Pressure sensors may be located opposite to corresponding productive formation center. Pressure sensors may be connected with each other through electric insulators adapted to receive multiple-strand electric cable passing inside the insulators. The pressure sensors may have electrodes electrically linked to casing pipe through centrator.

EFFECT: reduced time of pressure measurement and data transmission.

7 cl, 1 dwg

FIELD: testing the nature of borehole walls and formation testing particularly for obtaining fluid samples or testing fluids, in boreholes or wells.

SUBSTANCE: device comprises tubular body to be secured inside drilling string arranged in well bore. The tubular body is provided with one or several extensions created along body axis and forming expanded axial part. Probe is arranged in expanded axial body part zone having minimal cross-section. The probe may be moved between extended and retracted positions. In extended position probe may touch well wall to gather information from formation. To protect probe during drilling operation probe in brought into retracted position. Drive adapted to move the probe between extended and retracted positions is installed on the body.

EFFECT: increased accuracy of well and formation testing.

38 cl, 29 dwg

FIELD: survey of boreholes or wells, particularly measuring temperature or pressure in running wells.

SUBSTANCE: device comprises land-based assembly and submersed assembly including pressure transducer made as pressure unit linked to measuring resistor with output connected to land-based assembly inlet through diode and communication line. Land-based assembly includes power source, computing unit, digital indicator, the first analog-digital power source voltage converter, and the second analog-digital power source voltage converter. Land-based assembly input is linked to input of the first analog-digital converter having output linked to the first input of the computing unit. Land-based assembly input is also connected with the first output of power source having the second output linked with ground through resistor and with input of the second analog-digital converter. Output of the second analog-digital converter is connected to the second input of computing unit. The first output of computing unit is connected to digital indicator. The second output thereof is linked to power source input.

EFFECT: increased operational reliability.

1 dwg

FIELD: well survey, particularly geothermal well survey.

SUBSTANCE: temperature probe assembly comprises temperature sensors installed in upper or lower assembly part and uniformly distributed around a circle having radius r>R3/2, where R3 is probe assembly radius. Circle center coincides with probe assembly axis. Assembly also has safety lamp made as a pipe with orifices. Summary orifice area is not less than pipe cross-sectional area. The probe assembly may be provided with two centralizers arranged in upper and lower parts thereof. In some variants temperature sensor is arranged along assembly axis in upper or lower part thereof, probe assembly has safety lamp made as a pipe with orifices, wherein summary orifice area is not less than pipe cross-sectional area, and pressing device. The pressing device includes two springs arranged in upper and lower probe assembly parts. Temperature sensor is 1-2 mm under or over safety lamp end plane correspondingly. In other variants safety lamp has beveled end and is pressed to pipe string by short generator thereof. Probe assembly variants including temperature sensors and two centrators in upper and lower parts are also disclosed. The temperature sensors are arranged on each spring of upper centrator in upper part thereof or each spring of lower centrator in lower part thereof is provided with one temperature sensor spaced a distance from pipe string or production string axes. The distance is determined from equation. In just other variants probe assembly has centrators arranged in upper and lower parts thereof and temperature sensors carried by substrate formed of resilient material and arranged in lower probe assembly part between springs of lower centrator or in upper probe assembly part between upper centrator springs. Each spring is provided with limiting strip to restrict substrate and temperature sensor displacement with respect to probe assembly axis. Temperature sensors are located in upper or lower probe assembly parts in dependence of downhole instrument movement direction during well survey performance.

EFFECT: increased accuracy of continuous temperature measurement along generator defined by temperature sensor movement due to elimination of liquid mixing in front of temperature sensor.

12 cl, 7 dwg

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