Method of analysing productivity of inclined well that exposed productive bed

FIELD: oil-and-gas industry.

SUBSTANCE: set of inventions can be used in geophysical and hydrodynamic research. It allows estimating the productivity of gas wells exposing the productive isotropic bed at preset zenith angle and optimising their structure.

EFFECT: higher accuracy of estimation at whatever zenith angles, possibility to analyse gas discharge to inclined well.

4 cl, 6 dwg

Group of inventions relates to the oil and gas industry for drilling and production of gas. The group of inventions can be used when conducting geophysical and hydrodynamic studies to assess the productivity of gas wells that discover productive isotropic layer at a given Zenith angle, and to optimize their design.

The prior art method of determining the flow rate of oil wells (patent RU №2354825 C2, EV 47/10, publ. 10.05.2009). The known method includes sampling of oil in a given amount taken in any convenient location of the wells. The selected sample is homogenized to obtain a homogeneous mass properties, and then determine the coefficient of viscosity of this sampleunder appropriate conditions: P=P₁T=T₁P=P₂=P₁T=T₂>T₁and R=R₃>R₂T=T₃=T₂where P₁, R₂, R₃, T₁T₂T₃- the values of pressure P and temperature T in each of the three measurements of viscosity of the given oil sample. Using mathematical formulas to determine the parameters α, β, γ. Then measure the pressure P_L, R₀and temperature T_LT₀at levels perforated is twisty and determine the parameters of the coefficients of viscosity of according to the mathematical formulas. The known method does not disclose how to determine the profile of the wellbore.

There is a method of determining the position of the trunk directional well (patent RU №2300631 C2, EV 47/022, publ. 10.06.2007).

There is a method of determining the position of the trunk directional borehole includes the deepening of the well, the circulation of the drilling fluid, the measurement of the hydrostatic pressure of the drilling fluid and the determination of the Zenith angle of the wellbore. According to the invention produce the descent of the drill string, align and measure the average density of the drilling fluid in the wellbore to measure hydrostatic pressure in the drill pipe depth gauge and in wells with values of the Zenith angle of the wellbore is less than and greater than 90°, determine the vertical and horizontal projections and average values of the Zenith angle of the well bore in a given ratio. The disadvantage of this method is that when determining the inclination angle of the barrel of a controlled directional wells are not considered options nedostroi" part of the layer that does not allow for sufficient accuracy in determining the profile.

The objective of the proposed group of inventions is created the e research method, flow of gas to a controlled directional wells to determine its productivity, optimal design of the operational part of the trunk of a controlled directional wells and her profile.

The technical result, which directed the proposed solution is to increase the accuracy of evaluation of productivity of directional wells that discover isotropic gas reservoir, at all Zenith angles of their operational part of the trunk.

Another technical result, which directed the proposed group of inventions is to provide a design optimization of a controlled directional wells and her profile, i.e. to ensure the selection of optimum values of the length, radius and inclination angle of tilt of the trunk in the productive part of the formation.

The technical result of the method of determining the flow of gas to a controlled directional wells (HHC) is due to the fact that the diaphragm meter critical gas flow (PRES), mounted on vertical gas well, use a diaphragm with a small diameter of an orifice. Then open a root valve x-Mas tree and run vertical gas wells in operation until steady state, in which the pressure and temperature of the gas before PRES and in the annulus does not change in time. The readings register on but Itel information. Closing root valve, vertical gas well stop. Then PRES install the diaphragm with a large diameter gauge holes and re-derive vertical gas well at steady state. Again record the results of measurements on the media and stop vertical gas well. The operation is repeated by the number of available apertures with different diameters. According to field studies of vertical gas wells on a stationary filtering modes determine the linear and quadratic coefficients of filtration resistance, reservoir R_PLand downhole P_Cpressure characteristics of the performance of the reservoir. Assessing flow of gas to the well and its productivity. On the basis of the results obtained vertical gas wells construct the model profile HHC, which is projected on the vertical and horizontal axis. Plot HHC, lying within the reservoir is conventionally divided into N equal length horizontal and vertical intervals. For a given value of the Zenith angle φ HHC determine the length of the horizontal I_Gand vertical I_Inprojections of the wellbore as

l_G=L sin φ

and

l_In=L cos φ, respectively,

where L is the length of the barrel of the operational part of the HHC. ZAT is m define linear and quadraticthe filter coefficients of resistance for the i-th area of the vertical projection of the wellbore

where i=1, 2,...N,

a, b is not dependent on well design a multiplier that takes into account the influence of the reservoir properties of the formation and physico-chemical properties of the fluids defined for vertical gas wells,

effective thickness of a single open interval of the vertical projection of the barrel, To_dog- factor ones,

R_kVis the radius of the contour drainage vertical gas wells,

where R_withis the radius of the barrel HHC.

Determine the productivity ofeach of the i-th area of the vertical projection of the well

and then determine the total productivity HHC

.

The technical result of the method of determining the flow of gas to a controlled directional wells (NNN) (the second option) is due to the fact that the diaphragm meter critical gas flow (PRES), the mouth is fixed on a vertical gas well use the diaphragm with a small diameter of an orifice, open radical latch x-Mas tree and run vertical gas wells in operation until steady state, in which the pressure and temperature of the gas before PRES and in the annulus does not change in time. The readings recorded on the storage medium. Closing root valve, vertical gas well stop. In the PRES then install the diaphragm with a large diameter gauge holes and re-derive vertical gas well at steady state. Then register the measurement results to the media and stop vertical gas well. Perform redo operations available on the number of apertures with different diameters. According to field studies of vertical gas wells on a stationary filtering modes determine the linear and quadratic coefficients of filtration resistance, reservoir R_PLand downhole P_Cpressure characteristics of the performance of the reservoir. Then assess flow of gas to the well and its productivity. On the basis of the results obtained vertical gas wells construct the model profile HHC, which is projected on the vertical and horizontal axis. Teaching the current HHC, lying within the reservoir is conventionally divided into N equal length horizontal and vertical intervals. Then determine for a given value of the Zenith angle φ HHC the horizontal length l_Gand vertical l_Inprojections of the wellbore as

l_G=L sin φ

and

l_In=L cos φ, respectively,

where L is the length of the barrel of the operational part of the HHC. Define linearand quadraticthe filter coefficients of resistance for the i-th horizontal projection of the wellbore

where i=1, 2,...N,

j=I, II - drainage zone gas (figure 1);

h_ijis the effective thickness of the i-th section j drainage area;

- the length of a single open interval (see figure 1).

Then determine the productivity of each interval of the horizontal projection of the wellbore

and then

determine the total productivity HHC

.

The technical result of the method of determining the critical inclination angle is controlled directional wells is due to the fact, stoopidest total productivity HHC ways of determining the flow of gas to the IRB by the first and second variants for different values of Zenith angle. Then in the same coordinate system build graphs normalized based productivity HHC, obtained by replacing HHC vertical and horizontal projections of the wellbore from the values of the Zenith angle. As the critical inclination angle HHC take the angle corresponding to the value of the Zenith angle at the point of intersection of the mentioned curves.

The value of the critical inclination angle is equal to 50°.

The essence of the claimed group of inventions is illustrated technological schemes presented in figure 1-4.

Figure 1 presents the scheme of the flow of gas to the trunk of a controlled directional borehole radius R_with(m), length L (m), which revealed prooobably layer of thickness H_PL(m) with Zenith angle φ (deg.). The distance from the well axis to its contour drainage is equal to R_kg(m). The length of the horizontal projection of the uncovered part of the value I_g(m).

Figure 2 presents the scheme of the flow of gas to the trunk of a controlled directional borehole radius R_withlength L, located in the productive layer with the Zenith angle φ, which revealed the formation from the roof to a certain depth, when pokoritelem fluid inflow. The radius of the contour drainage is equal to R_kV(m). The thickness of the exposed part of the layer is equal to I_in(m).

Figure 3 presents a graph of the storm relative error you is ilenia productivity controlled directional well from the number of partitions of the trunk (at a fixed Zenith angle φ) on the elementary intervals.

Figure 4 shows a graph of the normalized feature dependency productivity controlled directional wells from Zenith angle.

The proposed group of inventions can be implemented as follows.

Drilling of the sidetrack and posting a controlled directional wells (FNS) of the vertical pilot wells (SU)uncovered productive isotropic layer, or by reconstructing the operational aircraft requires preliminary research productivity Q (thousand m³/day) sun. In this case, the productivity of the well understood or dependency discharge from depression or volumetric flow of gas to the wellbore in a unit of time. The study was conducted, given the design of the FNS (in the extreme case - vertical or horizontal wellbore). Based on the chosen design HHC used on a given field drilling equipment and tools, carry out the following selection: type of barrel operating part (not open cased, perforated in a predetermined interval, equipped with a filter shank), its length L (m), outer radius R_with(mm) and Zenith angle φ in the reservoir. Taking into account the specific features of the field and the conditions of its development, conduct field studies geological and physical parameters of the reservoir and gas dynamic research is ia vertical wells.

Study of gas wells, for example, by the method of steady-state selection under stationary gas filtration can be conducted in the following order.

At the wellhead carry out preparatory operations: perform installation of instruments and equipment; carry out purging of the well; make the sealing of the mouth, fully restore the wellhead pressure by technological sludge. In the diaphragm meter critical gas flow (PRES) install the diaphragm with a small diameter of an orifice. Then open a root valve wellhead Christmas tree, let the hole in the work before the onset of steady state, in which the pressure and temperature of the gas before PRES and in the annulus does not change in time. Instrument readings are registered, then stop the well, closing the root latch. Then PRES install the diaphragm with a large diameter gauge holes and re-derive the well at steady state. The measurement results also record, as well stop. These operations repeat 6 to 10 times depending on the number of available apertures. Selectively control measurements for a decreasing sequence of diameters of the calibration hole of the diaphragm.

According to field research the deposits of gas well on stationary filtering modes define linear (MPa ²/thousand m³/day)) and quadratic (MPa²/thousand m³/day)²factors filtration resistance, reservoir R_PL(MPa) and downhole P_C(MPa) pressure characteristics of the productive formation: General H_PL(m) and effective H_eff(m) thickness of the formation along the borehole, the dimensionless ratio of ones To_dogand the radius of the contour drainage SU R_kV(m). Then assess flow of gas to the well and its productivity Q, using the quadratic dependence of the stationary filter

Based on the known formulas (Gritsenko A.I. and others, Guide the exploration wells. - M.: Nauka, 1995, str-183, (15.4), (16.4), (17.4)determine not dependent wellbore multipliers a (MPa²/(thousand m²/day)) and b (MPa²/(thousand m²/day)²), taking into account the influence of the reservoir properties of the formation and physico-chemical properties of fluids

where C₁With₃and C₂With₄factors imperfections on the degree and nature of strata SU, respectively.

To determine the coefficients of the imperfections in the degree of opening (C₁With₃) there are a number of dependencies (for example, Gritsenko, A.I. and others, Guide the exploration wells. - M: the ka, 1995, str-186, (19.4), (21.4), (22.4), (24.4), (29.4)).

The influence coefficients imperfections on the nature of the opening for the inflow of gas (₂and C₄), usually not considered, and it is believed that the wellbore either the public or a sufficient number of perforations of the production casing in the interval of the effective thickness of the reservoir, i.e. With₂=C₄=0.

The calculated filter coefficients of the flow of gas to the sun And_Sunand In_Sun(i.e. the coefficients a and b in equation (1)) is determined using the same well-known formulas (Gritsenko A.I. and others, Guide the exploration wells. - M.: Nauka, 1995, str-183, (16.4), (17.4)).

The calculated filter coefficients of the gas flow to horizontal wells (GS) A_GSand In_GSdetermined using different methods. For example, when schematization of the flow of gas to the HS (see figure 1), which revealed an isotropic prooobably reservoir, the filter coefficients of resistance are the following (Aliyev SS and others, the Determination of the performance of horizontal wells that discover gas and oil reservoirs. M.: Nedra, 1995, p.53, (2.21)):

where R_kg- the distance from the axis of the horizontal wells to its power line, which is determined on the basis of field studies and extracting the aqueous radius contour drainage SU R _kV

R_kg≈0,8·R_kV.

When forming the model of the flow of gas to HHC uncovered isotropic reservoir, plot HHC, lying within the reservoir is conventionally divided into N equal length horizontal or vertical intervals (see figure 1 and 2). The total length of these intervals is equal to the length of the horizontal projection of the wellbore: l_G=L sin φ or the length of the vertical projection: l_In=L cos φ.

For any value of the Zenith angle φ in the case of replacement FNS elementary horizontal sections of a sufficient number of partitions is N=50·L/N_PL. Justification of the choice of the number N is illustrated using vypilivaya dependence of the relative error of the calculation of productivity on the number of interval partitions of N (see figure 3). For intervals of the vertical projection of the value of N does not matter at the opening of the isotropic layer and can be taken equal to the same value as for the HS.

The desired productivity HHC determine the total productivity of all these intervals. Depending on the position of each interval, as well as on the basis of compliance with equality filtration area is assigned a hydrodynamically equivalent to the radius of the element of the stem

for vertical projection -;

for horizontal projection - .

For the entire range of Zenith angle radius (or length) of the contour drainage is described by the following dependence obtained experimentally:

.

Based on sophisticated instrumentation and software solutions for research of parameters of a gas well built model profile HHC and define derived data from its vertical and horizontal projections.

If the local interval HHC is located under the Zenith angle from 0° up to a certain critical value φ_kr(characteristics & Phi;_krbelow), the filter coefficients determined in accordance with formula (3). The coefficients C₁and C₃determining the degree of opening of the reservoir, have a significant impact on the productivity of the well. Imperfection in their degree of vertical opening HHC is expressed in "redowskii" layer on its geometrical thickness depending on the Zenith angle φ. On figb shaded area corresponds to the uncovered part of the reservoir. Then formula (3) for the i-th element of the well is converted to the following form:

where i=1, 2,...N;

effective thickness of a single open interval.

Next, determine the efficiency of each i-th interval with the neighbors inflow equation (1), presented in the form

Accordingly, the total productivity HHC will be

If the local interval HHC is located under the Zenith angle from a certain critical value φ_krup to 90°, its filter coefficients A_GSand In_GSdetermined in accordance with formulas (4). In this case, the imperfection of penetration of HHC is expressed in "redowskii" of the reservoir along its length defined by the Zenith angle φ. This is illustrated by the shaded area on figb. With that said, the formula (4) can be written in the following form:

where i=1, 2,...N;

j=I, II - drainage zone gas (figure 1);

h_ijis the effective thickness of the i-th section j drainage area;

- the length of a single open interval (see figure 1).

Further, the productivity of each interval is determined based on the equations of gas influx into the well (1)

Accordingly, the total productivity ins

Critical angle (φ_kr) is determined by comparing the normalized dependency productivity HHC from the corner decl is on (see figure 4). Curve 1, as a function offrom φ, obtained on the basis of modeling the performance of the reservoir by replacement FNS horizontal elements. Curve 2, as a function offrom φ, obtained on the basis of modeling the performance of the reservoir by replacement FNS vertical elements. The point of intersection of the two curves is an indicator (critical angle) change considered computational algorithms to correctly determine the productivity of HHC on the whole range of change of the Zenith angle from 0° to 90°, namely, from 0° to φ_krthe productivity of elementary intervals are calculated by the formulas (6) and (7); from & Phi;_krup to 90°, the productivity of elementary intervals are calculated by the formulas (9) and (10). In a normalized according to the value of the critical inclination angle φ_krvaries from an average of 49.3° to 50.3°, i.e. conditionally can be considered a constant, equal to 50°.

Applying the proposed model to conduct commercial gas dynamic research pilot vertical wells, it is possible, with a sufficiently high accuracy to evaluate the efficiency of the designed controlled directional wells for opening isotropic gas reservoir at any Zenith angle of the tilt operating part of the trunk, or by using predlozenog is in this decision research tool to optimize the design of a controlled directional wells and her profile i.e. to choose the optimum values of the length, radius and inclination angle of tilt of the trunk in the productive part of the formation.

1. The method of determining the flow of gas to a controlled directional wells (HHC), which consists in the fact that the diaphragm meter critical gas flow (PRES), mounted on vertical gas well, use a diaphragm with a small diameter of an orifice, open radical latch x-Mas tree and run vertical gas wells in operation until steady state, in which the pressure and temperature of the gas before PRES and in the annulus does not change in time, the readings recorded on the storage medium, closing root valve, vertical gas well stop, PRES install the diaphragm with a large diameter gauge holes and re-derive vertical gas well at steady state, record the measurement results to the media and stop vertical gas well, repeat the operations available on the number of apertures with different diameters, according to field studies of vertical gas wells on a stationary filtering modes determine the linear and quadratic coefficients of filtration resistance, reservoir R_PLand dis is Noah R _Cpressure characteristics of formation productivity, estimating inflow of gas to the well and its productivity, on the basis of the results obtained vertical gas wells construct the model profile HHC, which is projected on the vertical and horizontal axes, plot HHC, lying within the reservoir is conventionally divided into N equal length horizontal and vertical intervals, determine for a given value of the Zenith angle φ HHC the horizontal length l_Gand vertical l_Inprojections of the wellbore as
l_G=L sin φ
and
l_In=L cos φ, respectively,
where L is the length of the barrel of the operational part of the HHC,
define linearand quadraticthe filter coefficients of resistance for the i-th area of the vertical projection of the wellbore


where i=1, 2,...N,
a, b is not dependent on well design a multiplier that takes into account the influence of the reservoir properties of the formation and physico-chemical properties of the fluids defined for vertical gas wells,
effective thickness of a single open interval of the vertical projection of the barrel is, To_dog- factor ones,
R_KVis the radius of the contour drainage vertical gas wells,
where R_Withis the radius of the barrel HHC,
determine the productivity ofeach of the i-th area of the vertical projection of the well

determine the total productivity HHC
.

2. The method of determining the flow of gas to a controlled directional wells (HHC), which consists in the fact that the diaphragm meter critical gas flow (PRES), mounted on vertical gas well, use a diaphragm with a small diameter of an orifice, open radical latch x-Mas tree and run vertical gas wells in operation until steady state, in which the pressure and temperature of the gas before PRES and in the annulus does not change in time, the readings recorded on the storage medium, closing root valve, vertical gas well stop, PRES install the diaphragm with a large diameter gauge holes and re-derive vertical gas well at steady state, record the measurement results to the media information is AI and stop vertical gas well, repeat the operations available on the number of apertures with different diameters, according to field studies of vertical gas wells on a stationary filtering modes determine the linear and quadratic coefficients of filtration resistance, reservoir R_PLand downhole P_Cpressure characteristics of formation productivity, estimating inflow of gas to the well and its productivity, on the basis of the results obtained vertical gas wells construct the model profile HHC, which is projected on the vertical and horizontal axes, plot HHC, lying within the reservoir is conventionally divided into N equal length horizontal and vertical intervals, determine for a given value of the Zenith angle φ HHC the horizontal length l_Gand vertical l_Inprojections of the wellbore as
l_G=L sin φ
and
l_In=L cos φ, respectively,
where L is the length of the barrel of the operational part of the HHC,
define linearand quadraticthe filter coefficients of resistance for the i-th horizontal projection of the wellbore


where i=1, 2,...N,
j=I, II - drainage area gas is;
h_ijis the effective thickness of the i-th section j drainage area;
- the length of a single open interval,
R_kg- the distance from the axis of the horizontal wells to its power line,
where R_Withis the radius of the barrel HHC,
determine the productivity of each interval of the horizontal projection of the wellbore

determine the total productivity HHC
.

3. The method of determining the critical inclination angle is controlled directional wells (HHC), which determine the total productivity HHC method according to claim 1 for different values of the Zenith angle, which also determine the total productivity HHC method according to claim 2 for different values of Zenith angle, build graphs of normalized based productivity HHC, obtained by replacing HHC vertical and horizontal projections of the wellbore from the values of the Zenith angle, as the critical inclination angle HHC take the angle corresponding to the value of the Zenith angle at the point of intersection of the mentioned curves.

4. The method according to claim 3, characterized in that the value of the critical inclination angle is equal to 50°.