阅读说明：本技术 裂缝孔隙型油藏水平井产能预测方法及装置 (Method and device for predicting capacity of fractured-pore oil reservoir horizontal well ) 是由 王铭显 赵文琪 范子菲 赵伦 李伟强 邢国强 王淑琴 孙猛 于 2019-02-19 设计创作，主要内容包括：本发明提供一种裂缝孔隙型油藏水平井产能预测方法及装置,其中,该方法包括以下步骤：获取所属储层和流体的静态参数及所研究水平井相关生产参数；根据所述静态参数和所述相关生产参数确定井底流动压力低于油藏泡点压力时水平井油气两相流入状态方程的校正因子；将所述静态参数、所述相关生产参数和所述校正因子代入裂缝孔隙型油藏水平井流入动态方程得到不同井底流动压力下的产油量；根据所述不同井底流动压力下的产油量预测所研究水平井的产油能力。由于该方案综合考虑了应力敏感性、裂缝闭合、油藏压力变化和油气两相流,提高了裂缝孔隙型油藏水平井产能的预测精度,为裂缝孔隙型油藏的高效开发提供技术支持。(The invention provides a method and a device for predicting the productivity of a fractured-porosity oil reservoir horizontal well, wherein the method comprises the following steps: obtaining static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched; determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameters and the related production parameters; substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures; and predicting the oil production capacity of the horizontal well to be researched according to the oil production under the different bottom hole flowing pressures. According to the scheme, stress sensitivity, crack closure, reservoir pressure change and oil-gas two-phase flow are comprehensively considered, so that the prediction precision of the horizontal well energy production of the fractured porous reservoir is improved, and technical support is provided for efficient development of the fractured porous reservoir.)

1. The method for predicting the productivity of the horizontal well of the fractured-porosity oil reservoir is characterized by comprising the following steps of:

obtaining static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched;

determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameters and the related production parameters;

substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures;

and predicting the oil production capacity of the horizontal well to be researched according to the oil production under the different bottom hole flowing pressures.

2. The method for predicting the horizontal well productivity of a fractured-pore reservoir according to claim 1, wherein the static parameters of the reservoir and the fluid comprise: bubble point pressure p of oil reservoir_bVolume coefficient B of crude oil, viscosity mu of stratum crude oil, thickness h of oil layer and initial permeability K of fracture system_f0Initial permeability K of the matrix system_m0Initial porosity phi of fracture system_f0Radius r of reservoir fracture closure_fInitial reservoir pressure p₀Average reservoir pressure at productionRadius r of oil drainage_eStress sensitivity index α for fracture-open reservoirs₁And stress sensitivity index α of fracture-closed reservoir₂(ii) a Relevant production parameters of the horizontal well studied included: half length of horizontal shaft l, radius of shaft r_wSkin factor S and bottom hole flow pressure p_wf。

3. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 1, wherein the step of determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameter and the related production parameter comprises the following steps:

determining an oil reservoir saturation type according to the static parameters;

and determining a correction factor of the horizontal well oil-gas two-phase inflow state equation corresponding to the corresponding oil reservoir saturation type when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the oil reservoir saturation type and the related production parameters.

4. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 3, wherein the step of substituting the static parameters, the related production parameters and the correction factors into an inflow dynamic equation of the fractured-porosity reservoir horizontal well to obtain the oil production at different bottom hole flowing pressures comprises the steps of:

determining the initial equivalent permeability of the fractured reservoir according to the static parameters;

and substituting the initial equivalent permeability, the static parameters, the related production parameters and the correction factors into a fracture pore type oil deposit horizontal well inflow dynamic equation corresponding to the corresponding oil deposit saturation type according to the oil deposit saturation type to obtain the oil production under different bottom hole flowing pressures.

5. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 1, further comprising:

drawing a relation curve of the oil production and the bottom hole flowing pressure according to the oil production under different bottom hole flowing pressures;

and predicting the oil production capacity of the horizontal well to be researched according to the oil production under the different bottom hole flowing pressures, wherein the method comprises the following steps:

and predicting the oil production capacity of the horizontal well to be researched according to the relation curve of the oil production and the bottom flowing pressure.

6. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 5, further comprising:

determining the oil production index of the horizontal well under different bottom hole flowing pressures according to the oil production under different bottom hole flowing pressures;

and predicting the oil production index of the horizontal well to be researched according to the oil production index of the horizontal well under the different bottom hole flowing pressures.

7. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 6, further comprising:

drawing a relation curve of the oil production index and the bottom hole flowing pressure according to the oil production index of the horizontal well under the different bottom hole flowing pressures;

predicting the oil production index of the horizontal well under study according to the oil production indexes of the horizontal wells under different bottom hole flowing pressures, wherein the predicting comprises the following steps:

and predicting the oil production index of the horizontal well to be researched according to the relation curve of the oil production index and the bottom hole flowing pressure.

8. The method for predicting the productivity of a fractured-pore reservoir horizontal well according to claim 3, wherein the determining the reservoir saturation type according to the static parameters comprises:

when p is₀≥p_bWhen the oil reservoir is saturated, the oil reservoir is unsaturated; when p is₀＜p_bWhen the oil reservoir saturation type is a saturated oil reservoir;

wherein p is₀Representing the initial pressure of the reservoir; p is a radical of_bRepresenting reservoir bubble point pressure.

9. The method for predicting the productivity of a fractured-pore reservoir horizontal well according to claim 8, wherein when the reservoir saturation type is an unsaturated reservoir, a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure is determined according to the following formula according to the static parameters and the related production parameters:

wherein R is_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the horizontal well of the unsaturated reservoir without dimension;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the reservoir, MPa.

10. The method for predicting the productivity of a fractured-pore reservoir horizontal well according to claim 8, wherein when the reservoir saturation type is a saturated reservoir, a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure is determined according to the following formula according to the static parameters and the related production parameters:

wherein R'_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the saturated reservoir horizontal well, and having no dimension;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the reservoir, MPa.

11. The method for predicting the horizontal well productivity of a fractured-pore reservoir according to claim 4, wherein the initial equivalent permeability of the fractured-pore reservoir is determined according to the static parameters according to the following formula:

wherein the content of the first and second substances,denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；φ_f0Representing the initial porosity of the fracture system without dimension; k_f0Denotes the initial permeability, μm, of the fracture system²。

12. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 4, wherein when the reservoir saturation type is an unsaturated reservoir, the fracture-porosity reservoir horizontal well inflow dynamic equation is as follows:

wherein Q is_hRepresents the ground oil production of the horizontal well, m³/d；Denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；R_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the horizontal well of the unsaturated reservoir without dimension; h represents the oil layer thickness, m; l represents the horizontal wellbore half-length, m; μ represents formation crude oil viscosity, mpa.s; b represents the volume coefficient of crude oil, m³/m³(ii) a S represents the epidermis coefficient and is dimensionless; r is_eRepresents the drainage radius, m; r is_wRepresents the wellbore radius, m; f. of_wThe water content of the oil well is expressed without dimension; p is a radical of₀Represents the initial pressure of the reservoir, MPa;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the oil reservoir, MPa; r is_fRadius representing reservoir fracture closure, m α₁Stress sensitivity index, MPa, for a reservoir that has not been fractured^-1；α₂Stress sensitivity index, MPa, for a fracture-closed reservoir^-1。

13. The method for predicting the productivity of a fractured-porosity reservoir horizontal well according to claim 4, wherein when the reservoir saturation type is a saturated reservoir, the fracture-porosity reservoir horizontal well inflow dynamic equation is as follows:

wherein Q is_hRepresents the ground oil production of the horizontal well, m³/d；Denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；R_c′_bExpressing a correction factor of an oil-gas two-phase inflow state equation of the saturated reservoir horizontal well, and having no dimension; h represents the oil layer thickness, m; l represents the horizontal wellbore half-length, m; μ represents formation crude oil viscosity, mpa.s; b represents the volume coefficient of crude oil, m³/m³(ii) a S represents the epidermis coefficient and is dimensionless; r is_eRepresents the drainage radius, m; r is_wRepresents the wellbore radius, m; f. of_wThe water content of the oil well is expressed without dimension; p is a radical of₀Represents the initial pressure of the reservoir, MPa;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the oil reservoir, MPa; r is_fRadius representing reservoir fracture closure, m α₁Stress sensitivity index, MPa, for a reservoir that has not been fractured^-1；α₂Stress sensitivity index, MPa, for a fracture-closed reservoir^-1。

14. The method for predicting the productivity of a fractured-pore reservoir horizontal well according to claim 6, wherein the oil production index of the horizontal well under different bottom hole flowing pressures is determined according to the oil production under different bottom hole flowing pressures according to the following formula:

wherein, J_hlRepresents the oil production index of the horizontal well, m³/d/MPa；Q_hlRepresents the ground oil production of the horizontal well, m³/d；Represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresenting the bottom hole flow pressure, MPa.

15. The utility model provides a crack hole type oil deposit horizontal well productivity prediction device which characterized in that includes:

the parameter acquisition module is used for acquiring static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched;

the correction factor determination module is used for determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameters and the related production parameters;

the oil production determining module is used for substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures;

and the oil production capacity prediction module is used for predicting the oil production capacity of the horizontal well to be researched according to the oil production quantities under the different bottom hole flowing pressures.

16. The fractured-pore reservoir horizontal well productivity prediction device of claim 15, wherein the static parameters of the reservoir and the fluid comprise: bubble point pressure p of oil reservoir_bVolume coefficient B of crude oil, viscosity mu of stratum crude oil, thickness h of oil layer and initial permeability K of fracture system_f0Initial permeability K of the matrix system_m0Initial porosity phi of fracture system_f0Radius r of reservoir fracture closure_fInitial reservoir pressure p₀Average reservoir pressure at productionRadius of drainager_eStress sensitivity index α for fracture-open reservoirs₁And stress sensitivity index α of fracture-closed reservoir₂(ii) a Relevant production parameters of the horizontal well studied included: half length of horizontal shaft l, radius of shaft r_wSkin factor S and bottom hole flow pressure p_wf。

17. The fractured-pore reservoir horizontal well productivity prediction device of claim 15, wherein the correction factor determination module is specifically configured to:

determining an oil reservoir saturation type according to the static parameters;

and determining a correction factor of the horizontal well oil-gas two-phase inflow state equation corresponding to the corresponding oil reservoir saturation type when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the oil reservoir saturation type and the related production parameters.

18. The fractured-pore reservoir horizontal well productivity prediction device of claim 17, wherein the oil production determination module is specifically configured to:

determining the initial equivalent permeability of the fractured reservoir according to the static parameters;

and substituting the initial equivalent permeability, the static parameters, the related production parameters and the correction factors into a fracture pore type oil deposit horizontal well inflow dynamic equation corresponding to the corresponding oil deposit saturation type according to the oil deposit saturation type to obtain the oil production under different bottom hole flowing pressures.

19. The fractured-pore reservoir horizontal well productivity prediction device of claim 15, further comprising:

the relation curve drawing module is used for drawing a relation curve between the oil production and the bottom hole flowing pressure according to the oil production under different bottom hole flowing pressures;

the oil production capacity prediction module is specifically configured to:

and predicting the oil production capacity of the horizontal well to be researched according to the relation curve of the oil production and the bottom flowing pressure.

20. The fractured-pore reservoir horizontal well productivity prediction device of claim 19, further comprising:

the oil production index determining module is used for determining the oil production index of the horizontal well under different bottom hole flowing pressures according to the oil production amount under different bottom hole flowing pressures;

and the oil production index prediction module is used for predicting the oil production index of the researched horizontal well according to the oil production indexes of the horizontal wells under different bottom hole flowing pressures.

21. The fractured-pore reservoir horizontal well productivity prediction device of claim 20, wherein the relational graph plotting module is further configured to:

drawing a relation curve of the oil production index and the bottom hole flowing pressure according to the oil production index of the horizontal well under the different bottom hole flowing pressures;

the oil production index prediction module is specifically used for:

and predicting the oil production index of the horizontal well to be researched according to the relation curve of the oil production index and the bottom hole flowing pressure.

22. The fractured-pore reservoir horizontal well productivity prediction device of claim 17, wherein the correction factor determination module is specifically configured to:

determining the reservoir saturation type according to the static parameters in the following way:

when p is₀≥p_bWhen the oil reservoir is saturated, the oil reservoir is unsaturated; when p is₀＜p_bWhen the oil reservoir saturation type is a saturated oil reservoir;

wherein p is₀Representing the initial pressure of the reservoir; p is a radical of_bRepresenting reservoir bubble point pressure.

23. The fractured-pore reservoir horizontal well productivity prediction device of claim 22, wherein the correction factor determination module is specifically configured to:

when the oil reservoir saturation type is an unsaturated oil reservoir, determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the following formula:

wherein R is_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the horizontal well of the unsaturated reservoir without dimension;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the reservoir, MPa.

24. The fractured-pore reservoir horizontal well productivity prediction device of claim 22, wherein the correction factor determination module is specifically configured to:

when the oil reservoir saturation type is a saturated oil reservoir, determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the following formula according to the static parameters and the related production parameters:

wherein R'_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the saturated reservoir horizontal well, and having no dimension;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the reservoir, MPa.

25. The fractured-pore reservoir horizontal well productivity prediction device of claim 18, wherein the oil production determination module is specifically configured to:

determining the initial equivalent permeability of the fractured-pore reservoir according to the static parameters according to the following formula:

wherein the content of the first and second substances,denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；φ_f0Representing the initial porosity of the fracture system without dimension; k_f0Denotes the initial permeability, μm, of the fracture system²。

26. The capacity prediction device for the fractured-pore reservoir horizontal well according to claim 18, wherein when the reservoir saturation type is an unsaturated reservoir, the fracture-pore reservoir horizontal well inflow dynamic equation is as follows:

wherein Q is_hRepresents the ground oil production of the horizontal well, m³/d；Denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；R_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the horizontal well of the unsaturated reservoir without dimension; h represents the oil layer thickness, m; l represents the horizontal wellbore half-length, m;μ represents formation crude oil viscosity, mpa.s; b represents the volume coefficient of crude oil, m³/m³(ii) a S represents the epidermis coefficient and is dimensionless; r is_eRepresents the drainage radius, m; r is_wRepresents the wellbore radius, m; f. of_wThe water content of the oil well is expressed without dimension; p is a radical of₀Represents the initial pressure of the reservoir, MPa;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the oil reservoir, MPa; r is_fRadius representing reservoir fracture closure, m α₁Stress sensitivity index, MPa, for a reservoir that has not been fractured^-1；α₂Stress sensitivity index, MPa, for a fracture-closed reservoir^-1。

27. The capacity prediction device for the fractured-pore reservoir horizontal well according to claim 18, wherein when the reservoir saturation type is a saturated reservoir, the fracture-pore reservoir horizontal well inflow dynamic equation is as follows:

wherein Q is_hRepresents the ground oil production of the horizontal well, m³/d；Denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；R′_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the saturated reservoir horizontal well, and having no dimension; h represents the oil layer thickness, m; l represents the horizontal wellbore half-length, m; μ represents formation crude oil viscosity, mpa.s; b represents the volume coefficient of crude oil, m³/m³(ii) a S represents the epidermis coefficient and is dimensionless; r is_eRepresents the drainage radius, m; r is_wRepresents the wellbore radius, m; f. of_wRepresenting water content of oil well, dimensionless；p₀Represents the initial pressure of the reservoir, MPa;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the oil reservoir, MPa; r is_fRadius representing reservoir fracture closure, m α₁Stress sensitivity index, MPa, for a reservoir that has not been fractured^-1；α₂Stress sensitivity index, MPa, for a fracture-closed reservoir^-1。

28. The fractured-pore reservoir horizontal well productivity prediction device of claim 20, wherein the oil production index determination module is specifically configured to:

and determining the oil production index of the horizontal well under different bottom hole flowing pressures according to the oil production under different bottom hole flowing pressures according to the following formula:

wherein, J_hlRepresents the oil production index of the horizontal well, m³/d/MPa；Q_hlRepresents the ground oil production of the horizontal well, m³/d；Represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresenting the bottom hole flow pressure, MPa.

29. A computer apparatus comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the computer program implements the method for predicting capacity of a fractured-porous reservoir horizontal well according to any one of claims 1 to 14.

30. A computer readable storage medium storing a computer program for performing the method for predicting horizontal well productivity of a fractured-pore reservoir according to any one of claims 1 to 14.

Technical Field

The invention relates to the technical field of oil well productivity prediction in oil development, in particular to a method and a device for predicting the productivity of a fractured-porosity oil reservoir horizontal well.

Background

Reservoirs containing natural fractures can be generally considered as fractured-pore reservoirs, including low-permeability sandstone fractured reservoirs, conglomerate fractured reservoirs, carbonate fractured reservoirs, igneous fractured reservoirs, and the like. The fracture pore type oil reservoir is a dual medium system consisting of a fracture system and a matrix system, and the classical fracture pore type describing model comprises the following components: the model comprises a Warren-Root model, a Kazemi model and a de Swaan model, and the models lay important foundations for researching the capacity characteristics of the fractured pore type oil reservoir.

The fractured-pore type oil reservoir often shows stress sensitivity in the pressure reduction exploitation process, and the permeability of the reservoir and the productivity of an oil well are greatly reduced due to the deformation of the reservoir. When the stress sensitivity is severe, the decrease in formation pressure will cause the reservoir fracture to close, which is more prominent near the bottom of the well. In addition, under the condition of small pressure difference of the saturation, degassing is easy to occur near the bottom of the well in the production process, and oil-gas two-phase flow occurs. Compared with a vertical well, the horizontal well can cross more natural fractures when a fracture pore type oil deposit is developed, so that the contact area between the oil well and the oil deposit is increased, and the productivity of the oil well is improved. However, due to the common influences of reservoir stress sensitivity, fracture closure and oil-gas two-phase flow problems, the conventional pure oil phase or oil-gas two-phase horizontal well productivity equation can be inaccurate when the oil reservoir productivity is predicted, and challenges are brought to oil well extract optimization and oil field productivity construction.

For example, the existing pure oil phase productivity equations (borinov formula, Giger formula and Joshi formula) of some horizontal wells have the disadvantages that research is carried out on the basis of a single medium oil reservoir, the influences of stress sensitivity and fracture closure of the reservoir are not considered, steady-state flow in the reservoir is assumed, and the steady-state flow is not consistent with the characteristic that pseudo-steady-state flow often occurs in the actual oil reservoir.

On the basis of predecessors, the Wanglie strength, the tensing strength and the like adopt different methods to carry out research on the pure oil phase productivity equation of the horizontal well of the stress sensitive oil reservoir, and provide respective formulas:

1) formula of Wanglie

By adopting an equivalent seepage resistance method and a conformal transformation method, a horizontal well steady-state yield formula considering stress sensitivity is provided as follows:

in formula (1): q-horizontal well yield, m³D; a' -oil drainage ellipse major semiaxis, m; b' -oil drainage ellipse minor semi-axis, m; l-horizontal well length, m; h-oil layer thickness, m; r is_w-wellbore radius, m; (ii) a p is a radical of_wf-bottom hole flow pressure, MPa; p is a radical of_r-average reservoir pressure, MPa; s_v-epidermal factor in the vertical plane, dimensionless; s_h-horizontal surface epidermal factor, dimensionless; k₀Initial permeability of the reservoir, 10^-3μm²Mu-formation oil viscosity, mPa.s, α_kReservoir stress sensitivity index, MPa^-1；G₀Initial starting pressure gradient, m^-1(ii) a G-Start pressure gradient, m^-1。

2) Formula of tensile strength

By adopting an equivalent seepage resistance method and a conformal transformation method, the steady-state yield formula of another stress-sensitive oil reservoir horizontal well is provided as follows:

in formula (2): q-horizontal well yield, m³D; l-horizontal well length, m; h-oil layer thickness, m;r_w-wellbore radius, m; r_e-reservoir feed radius, m; p is a radical of_wf-bottom hole flow pressure, MPa; p is a radical of_e-supply boundary pressure, MPa; k_i-reservoir original permeability, mD; c_ρLiquid isothermal compressibility factor, MPa^-1；B_oCrude oil volume factor, m³/m³Mu-formation oil viscosity, mPa.s, α -reservoir stress sensitivity index, MPa^-1。

Although stress sensitivity of a reservoir is considered, the stress sensitivity of the reservoir is not considered in the Wanglie's formula and the Zhang's formula, research is carried out based on a single medium oil reservoir, and steady-state flow in the reservoir is also assumed to be inconsistent with the characteristic that pseudo-steady-state flow often occurs in an actual oil reservoir.

The pure oil phase productivity equations of the horizontal well are mentioned above, and some scholars propose several oil-gas two-phase productivity equations of the horizontal well, such as Cheng equation, Bendahlia equation, Liu Xiang Ping equation and Sunzhong equation, and the four productivity equations have the defects: firstly, research is carried out aiming at a single medium oil reservoir, and stress sensitivity and fracture closure of the reservoir are not considered; and secondly, the method is only suitable for saturated oil reservoirs and is not suitable for unsaturated oil reservoirs.

In general, the previous capacity equation for horizontal wells has certain limitations, and the dual medium characteristics of fractured pore type reservoirs are not considered, the stress sensitivity and fracture closure of the reservoirs are not considered, the oil-gas two-phase flow occurring at the bottom of the well is not considered, the steady-state flow of the reservoirs is assumed, or the average pressure of the reservoirs in the production process is assumed to be approximately constant. Therefore, in view of the high drilling cost of the horizontal well relative to the vertical well, a method which is complete in system and wide in application range, considers the stress sensitivity of a reservoir, the fracture closure, the reservoir pressure change and the oil-gas two-phase flow influence, and can quickly and accurately predict the capacity of the fracture pore type reservoir horizontal well is urgently to be established.

Disclosure of Invention

The embodiment of the invention provides a method and a device for predicting the capacity of a horizontal well of a fractured-pore reservoir, which comprehensively consider stress sensitivity, fracture closure, reservoir pressure change and oil-gas two-phase flow, improve the prediction precision of the capacity of the horizontal well of the fractured-pore reservoir and provide technical support for efficient development of the fractured-pore reservoir.

The embodiment of the invention provides a method for predicting the productivity of a fractured-porosity oil reservoir horizontal well, which comprises the following steps:

obtaining static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched;

determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameters and the related production parameters;

substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures;

and predicting the oil production capacity of the horizontal well to be researched according to the oil production under the different bottom hole flowing pressures.

The embodiment of the invention also provides a device for predicting the productivity of the horizontal well of the fractured-porosity oil reservoir, which comprises the following components:

the parameter acquisition module is used for acquiring static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched;

the correction factor determination module is used for determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameters and the related production parameters;

the oil production determining module is used for substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures;

and the oil production capacity prediction module is used for predicting the oil production capacity of the horizontal well to be researched according to the oil production quantities under the different bottom hole flowing pressures.

In the embodiment of the invention, static parameters of the reservoir and the fluid and related production parameters of the researched oil well are obtained, and correction factors of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir are determined according to the static parameters and the related production parameters; and substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain the oil production amount under different bottom hole flowing pressures, wherein the stress sensitivity, fracture closure, oil reservoir pressure change and oil-gas two-phase flow are comprehensively considered, and finally, the oil production capacity of the horizontal well to be researched is predicted according to the oil production amount under the different bottom hole flowing pressures. The method improves the prediction precision of the horizontal well productivity of the fractured-porosity reservoir and provides technical support for the efficient development of the fractured-porosity reservoir.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of a method for predicting the horizontal well capacity of a fractured-pore reservoir according to an embodiment of the invention;

FIG. 2 is a flow chart of a method for predicting the horizontal well capacity of a fractured-porosity reservoir according to an embodiment of the invention (II);

FIG. 3 is a flow chart of a method for predicting the horizontal well capacity of a fractured-porosity reservoir according to an embodiment of the invention (III);

FIG. 4 is a flow chart of a method for predicting the horizontal well capacity of a fractured-porosity reservoir according to an embodiment of the Invention (IV);

FIG. 5 is a flow chart of a method for predicting the horizontal well capacity of a fractured-porosity reservoir according to an embodiment of the invention (V);

FIG. 6 is a structural block diagram (I) of a horizontal well productivity prediction device for a fractured-pore reservoir according to an embodiment of the present invention;

FIG. 7 is a structural block diagram of a horizontal well productivity prediction device for a fractured-porosity reservoir according to an embodiment of the invention;

FIG. 8 is a structural block diagram of a device for predicting the horizontal well capacity of a fractured-pore reservoir according to an embodiment of the invention (III);

fig. 9 is a structural block diagram (iv) of a device for predicting the horizontal well capacity of a fractured-porosity reservoir according to an embodiment of the present invention;

FIG. 10 is a comparison graph of predicted horizontal well oil production versus bottom hole flow pressure under various conditions provided by an embodiment of the present invention;

FIG. 11 is a comparison graph of the calculated horizontal well oil production index versus bottom hole flow pressure under different conditions, according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The method has three characteristics in the development process of the fracture pore type oil reservoir, namely stress sensitivity of the reservoir, closure of the fractures in partial areas due to pressure reduction of the oil reservoir, and degassing of the stratum near the bottom of a well to generate oil-gas two-phase flow. The superposition of the three makes the method in the prior art difficult to accurately predict the horizontal well oil production capacity of the fractured-pore oil reservoir. The invention provides a horizontal well productivity prediction method which comprehensively considers stress sensitivity, fracture closure, reservoir pressure change and oil-gas two-phase flow and has a wide application range, so that the prediction precision of the horizontal well productivity of the fractured porous reservoir is improved, and technical support is provided for efficient development of the fractured porous reservoir.

Fig. 1 is a flowchart (one) of a method for predicting horizontal well productivity of a fractured-pore reservoir according to an embodiment of the present invention, and as shown in fig. 1, the method includes:

step 101: obtaining static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched;

step 102: determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the reservoir bubble point pressure according to the static parameters and the related production parameters;

step 103: substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures;

step 104: and predicting the oil production capacity of the horizontal well to be researched according to the oil production under the different bottom hole flowing pressures.

In an embodiment of the present invention, the static parameters of the reservoir and the fluid include: bubble point pressure p of oil reservoir_bVolume coefficient B of crude oil, viscosity mu of stratum crude oil, thickness h of oil layer and initial permeability K of fracture system_f0Initial permeability K of the matrix system_m0Initial porosity phi of fracture system_f0Radius r of reservoir fracture closure_fInitial reservoir pressure p₀Average reservoir pressure at productionRadius r of oil drainage_eStress sensitivity index α for fracture-open reservoirs₁And stress sensitivity index α of fracture-closed reservoir₂(ii) a Relevant production parameters of the horizontal well studied included: half length of horizontal shaft l, radius of shaft r_wSkin factor S and bottom hole flow pressure p_wf。

Wherein, the parameters are obtained by the following method:

1) obtaining the bubble point pressure p of the oil deposit by sampling the underground fluid and carrying out a high-pressure physical property analysis experiment_bVolume factor B and formation crude oil viscosity mu;

2) obtaining the half length l and radius r of horizontal shaft through well drilling data_w；

3) Obtaining the thickness h of an oil layer and the initial permeability K of a fracture system through conventional well logging explanation_f0Initial permeability K of the matrix system_m0And initial porosity of fracture system_f0；

4) Obtaining the initial pressure p of the oil reservoir according to dynamic tests such as pressure recovery well testing or pressure drop well testing₀Average reservoir pressure at productionRadius r of oil drainage_eRadius r of reservoir fracture closure_fAnd the epidermal coefficient S;

5) obtaining bottom hole flowing pressure p by conventional pressure test_wf；

6) Stress sensitivity index α of a fracture unclosed reservoir obtained by a stress sensitivity experiment₁And stress sensitivity index α of fracture-closed reservoir₂。

In the embodiment of the invention, because the oil reservoir saturation types are divided into the unsaturated oil reservoir and the saturated oil reservoir, the horizontal well oil production prediction equation is respectively established for the unsaturated oil reservoir and the saturated oil reservoir, and the method is still feasible when the average pressure of the oil reservoir changes in the production process, so that the method has great significance for the fractured oil reservoir developed by pressure reduction and has wider application range. Therefore, as shown in fig. 2, step 102 specifically includes:

step 1021: determining the oil reservoir saturation type according to the static parameters (namely according to the bubble point pressure of the oil reservoir and the initial pressure of the oil reservoir);

step 1022: and determining a correction factor of the horizontal well oil-gas two-phase inflow state equation corresponding to the corresponding oil reservoir saturation type when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the oil reservoir saturation type and the related production parameters.

The determination standard of the oil reservoir saturation type is as follows:

when p is₀≥p_bWhen the oil reservoir is saturated, the oil reservoir is unsaturated; when p is₀＜p_bWhen the oil reservoir saturation type is a saturated oil reservoir;

wherein p is₀Representing the initial pressure of the reservoir; p is a radical of_bRepresenting reservoir bubble point pressure.

Aiming at different oil reservoir saturation types, the formulas of correction factors of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the oil reservoir bubble point pressure are respectively as follows:

1) unsaturated reservoirs (p)₀≥p_b)

2) Saturated oil reservoir (p)₀＜p_b)

In formulae (3) and (4): r_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the horizontal well of the unsaturated reservoir without dimension; r_c′_bExpressing a correction factor of an oil-gas two-phase inflow state equation of the saturated reservoir horizontal well, and having no dimension;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the reservoir, MPa.

In the embodiment of the present invention, as shown in fig. 2, step 103 specifically includes:

step 1031: determining the initial equivalent permeability of the fractured reservoir according to the static parameters;

step 1032: and substituting the initial equivalent permeability, the static parameters, the related production parameters and the correction factors into a fracture pore type oil deposit horizontal well inflow dynamic equation corresponding to the corresponding oil deposit saturation type according to the oil deposit saturation type to obtain the oil production under different bottom hole flowing pressures.

Wherein, the calculation formula of the initial equivalent permeability of the fracture pore type oil reservoir is as follows:

wherein the content of the first and second substances,denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；φ_f0Representing the initial porosity of the fracture system without dimension; k_f0Denotes the initial permeability, μm, of the fracture system²。

Aiming at different oil reservoir saturation types, the dynamic equation formula for calculating the inflow of the fracture pore type oil reservoir horizontal well of the oil production amount is respectively as follows:

1) unsaturated reservoirs (p)₀≥p_b)

2) Saturated oil reservoir (p)₀＜p_b)

In formulae (6) and (7), Q_hRepresents the ground oil production of the horizontal well, m³/d；Denotes the initial equivalent permeability, μm, of the reservoir²；K_m0Denotes the initial permeability, μm, of the matrix system²；R_cbExpressing a correction factor of an oil-gas two-phase inflow state equation of the horizontal well of the unsaturated reservoir without dimension; r_c′_bExpressing a correction factor of an oil-gas two-phase inflow state equation of the saturated reservoir horizontal well, and having no dimension; h represents the oil layer thickness, m; l represents the horizontal wellbore half-length, m; μ represents formation crude oil viscosity, mpa.s; b represents the volume coefficient of crude oil, m³/m³(ii) a S represents the epidermis coefficient and is dimensionless; r is_eRepresents the drainage radius, m; r is_wRepresents the wellbore radius, m; f. of_wIndicating water content of oil wellNo dimension; p is a radical of₀Represents the initial pressure of the reservoir, MPa;represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresents the bottom hole flow pressure, MPa; p is a radical of_bThe bubble point pressure of the oil reservoir, MPa; r is_fRadius representing reservoir fracture closure, m α₁Stress sensitivity index, MPa, for a reservoir that has not been fractured^-1；α₂Stress sensitivity index, MPa, for a fracture-closed reservoir^-1。

In the present invention, when the stress sensitivity index is 0, the stress sensitivity is not considered.

In an embodiment of the present invention, after obtaining the oil production at different bottom-hole flowing pressures, the oil production at different bottom-hole flowing pressures can be directly used to predict the oil production capability of the oil well under study, step 104. However, since the oil production under different bottom hole flowing pressures is a pile of values, the prediction situation cannot be observed well intuitively, and based on this, as shown in fig. 3, the method for predicting the productivity of the horizontal well of the fractured-porosity reservoir of the invention may further include:

step 105: drawing a relation curve of the oil production and the bottom hole flowing pressure according to the oil production under different bottom hole flowing pressures;

step 104 specifically includes:

and predicting the oil production capacity of the horizontal well to be researched according to the relation curve of the oil production and the bottom flowing pressure.

In the embodiment of the invention, the oil production capacity is predicted by only using the oil production amount under different underflow pressures, and the oil production index can also be predicted by using the horizontal well oil production index under different underflow pressures. Based on this, as shown in fig. 4, the method for predicting the productivity of the horizontal well of the fractured-porosity reservoir of the invention may further include:

step 106: determining the oil production index of the horizontal well under different bottom hole flowing pressures according to the oil production under different bottom hole flowing pressures;

the calculation formula of the oil production index of the horizontal well under different bottom hole flowing pressures is as follows:

in the formula (8), J_hlRepresents the oil production index of the horizontal well, m³/d/MPa；Q_hlRepresents the ground oil production of the horizontal well, m³/d；Represents the average reservoir pressure in MPa during production; p is a radical of_wfRepresenting the bottom hole flow pressure, MPa.

Step 107: and predicting the oil production index of the horizontal well to be researched according to the oil production index of the horizontal well under the different bottom hole flowing pressures.

Similarly, because the oil production index of the horizontal well under different bottom hole flowing pressures is a pile value, the prediction condition cannot be observed well intuitively, and based on the pile value, as shown in fig. 5, the method for predicting the capacity of the horizontal well of the fractured-porosity reservoir can further comprise the following steps:

step 108: drawing a relation curve of the oil production index and the bottom hole flowing pressure according to the oil production index of the horizontal well under the different bottom hole flowing pressures;

step 107 specifically includes:

and predicting the oil production index of the horizontal well to be researched according to the relation curve of the oil production index and the bottom hole flowing pressure.

Based on the same inventive concept, the embodiment of the invention also provides a device for predicting the horizontal well productivity of a fractured-pore oil reservoir, which is described in the following embodiment. Because the principle of solving the problems of the fractured-porosity oil reservoir horizontal well productivity prediction device is similar to that of the fractured-porosity oil reservoir horizontal well productivity prediction method, the fractured-porosity oil reservoir horizontal well productivity prediction device can be implemented according to the fractured-porosity oil reservoir horizontal well productivity prediction method, and repeated parts are not repeated. As used hereinafter, the term "unit" or "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.

Fig. 6 is a structural block diagram (one) of a device for predicting the horizontal well capacity of a fractured-pore reservoir according to an embodiment of the present invention, as shown in fig. 6, including:

the parameter acquisition module 601 is used for acquiring static parameters of the reservoir and the fluid and related production parameters of the horizontal well to be researched;

a correction factor determination module 602, configured to determine, according to the static parameter and the related production parameter, a correction factor of a horizontal well oil-gas two-phase inflow state equation when a bottom hole flowing pressure is lower than a reservoir bubble point pressure;

the oil production determining module 603 is used for substituting the static parameters, the related production parameters and the correction factors into a fracture pore type oil reservoir horizontal well inflow dynamic equation to obtain oil production under different bottom hole flowing pressures;

and the oil production capacity prediction module 604 is used for predicting the oil production capacity of the horizontal well to be researched according to the oil production quantities under the different bottom hole flowing pressures.

In an embodiment of the present invention, the static parameters of the reservoir and the fluid include: bubble point pressure p of oil reservoir_bVolume coefficient B of crude oil, viscosity mu of stratum crude oil, thickness h of oil layer and initial permeability K of fracture system_f0Initial permeability K of the matrix system_m0Initial porosity phi of fracture system_f0Radius r of reservoir fracture closure_fInitial reservoir pressure p₀Average reservoir pressure at productionRadius r of oil drainage_eStress sensitivity index α for fracture-open reservoirs₁And stress sensitivity index α of fracture-closed reservoir₂(ii) a Relevant production parameters of the horizontal well studied included: half length of horizontal shaft l, radius of shaft r_wSkin factor S and bottom hole flow pressure p_wf。

In an embodiment of the present invention, the correction factor determining module 602 is specifically configured to:

determining an oil reservoir saturation type according to the static parameters;

and determining a correction factor of the horizontal well oil-gas two-phase inflow state equation corresponding to the corresponding oil reservoir saturation type when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the oil reservoir saturation type and the related production parameters.

In an embodiment of the present invention, the oil production determining module 603 is specifically configured to:

determining the initial equivalent permeability of the fractured reservoir according to the static parameters;

and substituting the initial equivalent permeability, the static parameters, the related production parameters and the correction factors into a fracture pore type oil deposit horizontal well inflow dynamic equation corresponding to the corresponding oil deposit saturation type according to the oil deposit saturation type to obtain the oil production under different bottom hole flowing pressures.

In the embodiment of the present invention, as shown in fig. 7, the method further includes:

a relation curve drawing module 605 for drawing a relation curve between the oil production and the bottom hole flowing pressure according to the oil production under the different bottom hole flowing pressures;

the oil production capacity prediction module 604 is specifically configured to:

and predicting the oil production capacity of the horizontal well to be researched according to the relation curve of the oil production and the bottom flowing pressure.

In the embodiment of the present invention, as shown in fig. 8, the method further includes:

an oil production index determining module 606, configured to determine the oil production index of the horizontal well at different bottom-hole flow pressures according to the oil production at different bottom-hole flow pressures;

and the oil production index prediction module 607 is used for predicting the oil production index of the horizontal well under study according to the oil production indexes of the horizontal wells under different bottom hole flowing pressures.

In the embodiment of the present invention, as shown in fig. 9, the relation graph plotting module 605 is further configured to:

drawing a relation curve of the oil production index and the bottom hole flowing pressure according to the oil production index of the horizontal well under the different bottom hole flowing pressures;

the oil production index prediction module 607 is specifically configured to:

and predicting the oil production index of the horizontal well to be researched according to the relation curve of the oil production index and the bottom hole flowing pressure.

In an embodiment of the present invention, the correction factor determining module 602 is specifically configured to:

determining the reservoir saturation type according to the static parameters in the following way:

when p is₀≥p_bWhen the oil reservoir is saturated, the oil reservoir is unsaturated; when p is₀＜p_bWhen the oil reservoir saturation type is a saturated oil reservoir;

wherein p is₀Representing the initial pressure of the reservoir; p is a radical of_bRepresenting reservoir bubble point pressure.

In an embodiment of the present invention, the correction factor determining module 602 is specifically configured to:

when the oil reservoir saturation type is an unsaturated oil reservoir, determining a correction factor of a horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the formula (3);

and when the oil reservoir saturation type is a saturated oil reservoir, determining a correction factor of the horizontal well oil-gas two-phase inflow state equation when the bottom hole flowing pressure is lower than the bubble point pressure of the oil reservoir according to the formula (4).

In an embodiment of the present invention, the oil production determining module 603 is specifically configured to: and (5) determining the initial equivalent permeability of the fractured-pore type oil reservoir according to the formula (5).

In the embodiment of the invention, when the saturated type of the oil reservoir is an unsaturated oil reservoir, the inflow dynamic equation of the horizontal well of the fractured-porosity oil reservoir is shown as a formula (6); when the oil reservoir saturation type is a saturated oil reservoir, the inflow dynamic equation of the horizontal well of the fractured-porosity oil reservoir is formula (7).

In an embodiment of the present invention, the oil production index determining module 606 is specifically configured to: and (4) determining the oil production index of the horizontal well under different bottom hole flowing pressures according to the formula (8).