CN108547610B

CN108547610B - Method and device for determining horizontal well productivity under volume fracturing

Info

Publication number: CN108547610B
Application number: CN201810121741.3A
Authority: CN
Inventors: 刘立峰; 陈福利; 闫林; 童敏; 王拥军
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2018-02-07
Filing date: 2018-02-07
Publication date: 2021-06-01
Anticipated expiration: 2038-02-07
Also published as: CN108547610A

Abstract

The embodiment of the application provides a method and a device for determining horizontal well productivity under volume fracturing, wherein the method comprises the following steps: acquiring geological characteristic parameters of a target area where a horizontal well under volume fracturing is located; dividing the target area into: a first seepage area, a second seepage area and a third seepage area; the production cycle is divided into: a first production stage, a second production stage and a third production stage; respectively determining the horizontal well productivity of different production stages according to geological characteristic parameters and the seepage characteristics of different seepage regions in different production stages, considering the influence of a complex fracture network structure and reservoir pores under volume fracturing on seepage, and dividing a target region into a plurality of seepage regions according to specific structural characteristics; and respectively determining the horizontal well productivity in different production stages according to the seepage characteristics of different seepage areas in different production stages, thereby solving the technical problem that the determination of the horizontal well productivity by the existing method is inaccurate.

Description

Method and device for determining horizontal well productivity under volume fracturing

Technical Field

The application relates to the technical field of oil and gas development, in particular to a method and a device for determining horizontal well productivity under volume fracturing.

Background

Prior to hydrocarbon development, it is often necessary to predict the productivity of an oil or gas well in order to direct specific hydrocarbon production.

At present, in order to predict the horizontal well productivity under volume fracturing, the influence of artificial main fractures in an area where a production well is located after volume fracturing on seepage is generally analyzed firstly; and predicting the productivity of the production well under the volume fracture according to the influence of the artificial main fracture on the seepage. However, the existing method only simply considers the influence of the artificial main fracture on seepage, so that the technical problem that the horizontal well productivity under the determined volume fracturing is not accurate is always existed in the concrete implementation.

In view of the above problems, no effective solution has been proposed.

Disclosure of Invention

The embodiment of the application provides a method and a device for determining horizontal well productivity under volume fracturing, so that the technical problem that the horizontal well productivity under volume fracturing is inaccurate in determination in the existing method is solved, and the technical effects of comprehensively analyzing seepage characteristics of different structural regions in different production stages and accurately determining the horizontal well productivity under volume fracturing are achieved.

The embodiment of the application provides a method for determining horizontal well productivity under volume fracturing, which comprises the following steps:

acquiring geological characteristic parameters of a target area where a horizontal well under volume fracturing is located;

dividing the target area into: a first, second, and third percolation region, wherein the first percolation region comprises a percolation region of an artificial primary fracture, the second percolation region comprises a percolation region of an artificial secondary fracture and a reservoir percolation region within an SRV volume, and the third percolation region comprises a reservoir percolation region outside the SRV volume;

dividing the production cycle of the horizontal well under the volume fracturing into the following steps according to the propagation distance of the pressure wave: a first production stage, a second production stage and a third production stage;

determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In one embodiment, the target area is divided into: after the first, second, and third percolation regions, the method further comprises:

acquiring the temperature of the fracturing fluid and the quality of the fracturing fluid;

determining the temperature distribution of the target area according to the temperature of the fracturing fluid and the quality of the fracturing fluid;

determining a viscosity of the crude oil in the target region from the temperature profile;

correspondingly, determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage, wherein the determination comprises the following steps:

determining the horizontal well productivity of the first production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In one embodiment, determining the temperature distribution of the target zone based on the temperature of the fracturing fluid and the quality of the fracturing fluid comprises:

determining a temperature distribution of the target area according to the following formula:

wherein T (r) is the temperature of the location of the measurement point in the target zone, r is the distance from the location of the measurement point in the target zone to the wellbore, T_{Fracturing fluid}Temperature of the fracturing fluid, T_{Formation of earth}Is the formation temperature, T, in the target zone_AverageIs the average temperature of the target zone, Δ T is the difference between the average temperature of the target zone and the formation temperature in the target zone, K_obIs the top layer thermal conductivity of the formation in the target zone, t is the time, h is the thickness of the reservoir in the target zone, φ is the porosity of the reservoir in the target zone, (ρ₀C₀) Is the heat capacity of the crude oil in the target zone, (ρ C)_P)_RIs the heat capacity of the formation rock in the target zone, C is the specific heat capacity of the fracturing fluid, M is the mass of the fracturing fluid, M_obIs the top layer heat capacity of the formation in the target zone.

In one embodiment, determining the viscosity of the crude oil in the target region from the temperature profile comprises:

determining the viscosity of the crude oil in the target region according to the following formula:

wherein mu (r) is the viscosity of the r position in the target area, D is the ratio of the top layer thermal conductivity and the top layer heat capacity of the stratum in the target area, and M is the heat capacity of the reservoir in the target area.

In one embodiment, determining the horizontal well productivity for a first production phase based on the crude oil viscosity, the geologic characteristic parameter, and the seepage characteristics of a first seepage zone in the first production phase comprises:

calculating the horizontal well capacity of the first production stage according to the following formula:

wherein q is₁Horizontal well capacity for the first production phase, w_FIs the fracture width of the first seepage zone, h is the thickness of the reservoir in the target zone, k_F0Is the original permeability, k, of the first zone of seepage_FPermeability of the first seepage zone, k_iIs the permeability of the second percolation region, alpha_FIn order to be the sensitive coefficient of permeability,

to mean formation pressure, p_wTo downhole fluid pressure, p_eIs the original formation pressure, r_wIs the barrel radius of the well, /)₁(t) is the propagation distance of the pressure wave in the first region of seepage.

In one embodiment, determining the horizontal well productivity in the second production stage according to the crude oil viscosity, the geological characteristic parameter, and the seepage characteristics of the first seepage area and the second seepage area in the second production stage comprises:

calculating the horizontal well capacity of the second production stage according to the following formula:

wherein q is₂Horizontal well capacity for the second production phase, w_FIs the fracture width of the first seepage zone, h is the thickness of the reservoir in the target zone, M isHeat capacity, x, of reservoir in target zone_fIs half the length of the crack in the first zone, p_wTo downhole fluid pressure, p_eTo the original formation pressure,/₂(t) is the propagation distance of the pressure wave in the second region of seepage, k_iIs the permeability of the second percolation region.

In one embodiment, determining the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameter, and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage comprises:

and calculating the horizontal well productivity of the third stage according to the following formula:

wherein q is₃Horizontal well productivity for the third production stage, p_eIs the original formation pressure, p_wIs the bottom hole fluid pressure, G is the starting pressure gradient, Ω_{General assembly}Is the total seepage resistance of the target area, /)₃(t) is the propagation distance of the pressure wave in the third region of seepage.

In one embodiment, the total seepage resistance of the target area is determined according to the following formula:

wherein omega₁Is the seepage resistance, omega, of the linear flow region in the third seepage region₂Is the seepage resistance, omega, of the radial flow region in the third seepage region₃Is the percolation resistance of the second percolation region.

In one embodiment, after determining the horizontal well productivity of the first production phase, the horizontal well productivity of the second production phase, and the horizontal well productivity of the third production phase, the method further comprises:

and carrying out crude oil exploitation on the target area where the horizontal well under the volume fracture is located according to the horizontal well productivity of the first production stage, the horizontal well productivity of the second production stage and the horizontal well productivity of the third production stage.

The embodiment of the present application further provides a device for determining horizontal well productivity under volume fracturing, including:

the acquisition module is used for acquiring geological characteristic parameters of a target area where a horizontal well under volume fracturing is located;

the first dividing module is used for dividing the target area into the following parts according to the seepage network structure under volume fracturing and the seepage characteristics in the production process: a first, second, and third percolation region, wherein the first percolation region comprises a percolation region of an artificial primary fracture, the second percolation region comprises a percolation region of an artificial secondary fracture and a reservoir percolation region within an SRV volume, and the third percolation region comprises a reservoir percolation region outside the SRV volume;

the second division module is used for dividing the production cycle of the horizontal well under the volume fracture into the following steps according to the propagation distance of the pressure wave: a first production stage, a second production stage and a third production stage;

the determining module is used for determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In one embodiment, the apparatus further comprises a crude oil viscosity determination module for determining the viscosity of crude oil in the target region.

In one embodiment, the crude oil viscosity determination module comprises:

the acquisition unit is used for acquiring the temperature of the fracturing fluid and the quality of the fracturing fluid;

the first determination unit is used for determining the temperature distribution of the target area according to the temperature of the fracturing fluid and the quality of the fracturing fluid;

a second determination unit for determining the viscosity of the crude oil in the target region based on the temperature distribution.

In the embodiment of the application, the influence of a complex fracture network structure and reservoir pores under volume fracturing on seepage is comprehensively considered, and the target area is divided into a plurality of different seepage areas according to specific structural characteristics; and respectively determining the horizontal well productivity in different production stages according to the seepage characteristics of different seepage areas in different production stages, thereby solving the technical problem of inaccurate horizontal well productivity under volume fracturing in the existing method, and achieving the technical effects of comprehensively analyzing the seepage characteristics of different structural areas in different production stages and accurately determining the horizontal well productivity under volume fracturing.

Drawings

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

Fig. 1 is a process flow diagram of a method for determining horizontal well productivity under volumetric fracturing provided in accordance with an embodiment of the present application;

fig. 2 is a composition structural diagram of a horizontal well productivity determination device under volume fracturing according to an embodiment of the present application;

FIG. 3 is a schematic flow chart illustrating capacity determination of a tight oil horizontal well in a certain area by applying the method and the device for determining horizontal well capacity under volume fracturing provided by the embodiment of the application in one example scenario;

FIG. 4 is a schematic diagram of a fracturing fluid injection to form a "cold zone" near a wellbore, in one example scenario, using the method and apparatus for determining horizontal well productivity under volumetric fracturing provided by embodiments of the present application;

FIG. 5 is a schematic diagram of changes in crude oil viscosity in a "cold zone" obtained by applying the method and apparatus for determining horizontal well capacity under volumetric fracturing provided by the embodiments of the present application in one example scenario;

FIG. 6 is a schematic diagram of a tight oil horizontal well volume fracturing physical model obtained by applying the method and device for determining horizontal well productivity under volume fracturing provided by the embodiment of the application in one scenario example;

FIG. 7 is a schematic diagram of a tight oil horizontal well volume fracturing flow model obtained by applying the method and apparatus for determining horizontal well productivity under volume fracturing provided by the embodiments of the present application in one example scenario;

FIG. 8 is a schematic diagram of a seepage situation in the midproductive phase of a horizontal well in tight reservoir volume fracturing obtained by applying the method and device for determining horizontal well productivity under volume fracturing provided by the embodiment of the application in one scenario example;

fig. 9 is a schematic diagram illustrating the seepage situation of an external oil reservoir in the late-stage production of a horizontal well fractured by a tight reservoir volume, obtained by applying the method and the device for determining the horizontal well productivity under volume fracturing provided by the embodiment of the application in one example scenario;

fig. 10 is a schematic diagram illustrating a comparison result of predicted cumulative yield and actual cumulative yield of a tight oil fractured horizontal well obtained by applying the method and the device for determining horizontal well productivity under volumetric fracturing provided by the embodiment of the application in one scenario example;

fig. 11 is a schematic structural diagram of an electronic device based on the method for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.

In consideration of the existing method, only the influence of the artificial main fracture on the seepage is usually considered in the specific implementation, and the influence of other structural regions on the seepage is not comprehensively analyzed, so that the technical problem that the horizontal well productivity under the volume fracturing is not accurate in the specific implementation of the existing method is always caused. For the root cause of the technical problem, the application considers that in fact, besides the artificial main fracture, the artificial secondary fracture, the Reservoir pores in the volume fracture modified volume SRV (fractured Reservoir volume), and the Reservoir outside the SRV all affect the flow of oil and gas, and further affect the specific productivity. In order to more accurately predict the horizontal well productivity under volume fracturing, the specific influence of a complex fracture network structure and reservoir pores under volume fracturing on seepage can be comprehensively analyzed, and a target area is divided into a plurality of different seepage areas according to specific structural characteristics; and respectively determining the horizontal well productivity in different production stages according to the seepage characteristics of different seepage areas in different production stages, thereby solving the technical problem of inaccurate horizontal well productivity under volume fracturing in the existing method, and achieving the technical effects of comprehensively analyzing the seepage characteristics of different structural areas in different production stages and accurately determining the horizontal well productivity under volume fracturing.

Based on the thought, the embodiment of the application provides a method for determining the productivity of a horizontal well. Specifically, please refer to a process flow chart of a method for determining horizontal well productivity according to an embodiment of the present application shown in fig. 1. The method for determining the horizontal well productivity under the volume fracturing can comprise the following steps in specific implementation.

S11: and acquiring geological characteristic parameters of a target area where the horizontal well under the volume fracturing is located.

In one embodiment, the horizontal well may be a horizontal well for producing tight oil. The compact oil can be crude oil with a relatively fine oil hole throat and relatively high viscosity. Generally, the compact oil has no natural capacity, and can be effectively exploited only by the modes of horizontal well volume modification and the like. Of course, the horizontal wells used for producing tight oil listed above need to be described only to better illustrate the embodiments of the present application. In specific implementation, the method for determining the horizontal well productivity provided by the embodiment of the application can be applied to other types of horizontal wells according to specific conditions and construction requirements. The present application is not limited thereto.

In one embodiment, the volume fracturing may specifically be hydraulic fracturing, etc., so that natural fractures are continuously expanded and shear slippage occurs in brittle rocks, and then a fracture network in which natural fractures and artificial fractures are staggered with each other is formed, so as to increase the reconstruction volume and improve the initial yield and the final recovery rate of oil and gas. The modified volume is specifically a structure for modifying a Reservoir through volume fracturing, so that natural fractures are continuously expanded, brittle rocks generate shear slip, and communication between the natural fractures and rock bedding is realized.

In this embodiment, the target region may specifically refer to a formation region where a horizontal well under volume fracturing is located, where the formation region includes structures such as an artificial main fracture, an artificial secondary fracture, and a natural fracture and a pore in a reservoir.

In this embodiment, the geological characteristic parameter of the target area may be specifically parameter data to be used for calculating the horizontal well capacity in the volume fracture. Specifically, the geological characteristic parameters of the target region may include a plurality of parameters from the following parameters: temperature T (r), mesh of the survey point location in the target areaDistance r from measuring point position in standard area to shaft and temperature T of fracturing fluid_{Fracturing fluid}Temperature T of the formation in the target zone_{Formation of earth}Average temperature T of target area_AverageTop layer thermal conductivity K of the formation in the target zone_obThickness h of the reservoir in the target zone, porosity phi of the reservoir in the target zone, heat capacity (rho) of the crude oil in the target zone₀C₀) Heat capacity of formation rock in target zone (ρ C)_P)_RSpecific heat capacity C of the fracturing fluid, mass M of the fracturing fluid, and top layer heat capacity M of the formation in the target zone_obThe heat capacity M of a reservoir in a target area, the heat conductivity K of fracturing fluid, the permeability of different structures and the permeability sensitivity coefficient alpha_FAverage formation pressure

Bottom hole fluid pressure p_wOriginal formation pressure p_eRadius r of well bore_wCrack width, half crack length, G starting pressure gradient and total seepage resistance omega of target area_{General assembly}And so on. It should be noted that the various parameters listed above are only for better illustration of the embodiments of the present application. In specific implementation, according to specific conditions and construction requirements, other parameters except the above listed parameters can be introduced to perform subsequent calculation of the horizontal well productivity under volume fracturing.

In this embodiment, it should be added that the geological characteristic parameters of the target area listed above may be obtained by performing a related measurement experiment on the target area, or may be obtained by performing analysis and calculation based on the log data, geological background data, and data obtained by the measurement experiment. The specific manner of acquiring the geologic feature parameters of the target region is not limited in this application.

S12: dividing the target area into: the fracture management system comprises a first seepage area, a second seepage area and a third seepage area, wherein the first seepage area comprises a seepage area of an artificial main fracture, the second seepage area comprises a seepage area of an artificial secondary fracture and a reservoir seepage area in an SRV volume, and the third seepage area comprises a reservoir seepage area outside the SRV volume.

In one embodiment, in order to predict the capacity of a horizontal well under volume fracturing more accurately subsequently, the embodiments of the present application, unlike the existing method, perform comprehensive and fine analysis and research on the seepage network structural characteristics of a target region under volume fracturing, not simply analyze the influence of a main fracture on seepage, but also deeply analyze the influence of a secondary fracture, a reservoir matrix inside an SRV, a natural fracture, a reservoir matrix outside the SRV, and natural fracture on seepage; and the seepage mechanism is combined, the corresponding seepage characteristics of different types of structural bodies in the seepage network in different production stages in the production process are further analyzed, and then the target area can be divided into seepage areas of different types according to the specific seepage characteristics of the different structural bodies in different production stages in the production process, so that the capacity of the horizontal well can be accurately determined according to the specific seepage conditions of the seepage areas of different types in the production process.

In one embodiment, the seepage area of the artificial main fracture can be divided into the first seepage area in consideration that the fluid seepage in the artificial main fracture is mostly dominated by Darcy flow and the fracture stress sensitivity is relatively remarkable in the production process. Considering that, during production, the fluids in the seepage zone of the artificial secondary fracture and the reservoir seepage zone in the SRV volume (where the reservoir seepage zone in the SRV volume includes the reservoir matrix and the natural fractures in the SRV volume) mostly dominate darcy flow, but the matrix stress sensitivity is relatively significant, the seepage zone of the artificial secondary fracture and the reservoir seepage zone in the SRV volume may be divided into the second seepage zone. Considering that during production, the fluid seepage in the reservoir seepage zone outside the SRV volume (including the reservoir matrix and the natural fractures outside the SRV volume) is mainly low-speed nonlinear flow, and the fluid flow is usually related to the starting pressure gradient, the reservoir seepage zone outside the SRV volume can be divided into a third seepage zone. Therefore, when the specific horizontal well productivity is determined subsequently, the horizontal well productivity can be calculated more accurately according to the corresponding seepage characteristics of different types of seepage areas in the production process.

S13: dividing the production cycle of the horizontal well under the volume fracturing into the following steps according to the propagation distance of the pressure wave: a first production stage, a second production stage, a third production stage.

In one embodiment, it is considered that different types of percolation regions at different production stages in the production process contribute differently to the fluid flow in the production process based on the respective percolation characteristics, since different types of percolation regions have different percolation characteristics. For example, during the initial stages of production, the first percolation region contributes significantly to the fluid flow; during the production period, the contribution to fluid flow by the second percolation region begins to be significant; and at the end of production, the contribution of the third seepage zone to the fluid flow begins to be significant. Therefore, the contribution conditions of different types of seepage areas to flow in the production process can be divided into a plurality of production stages, so that the productivity corresponding to different production stages can be accurately determined respectively according to the contribution conditions of different types of seepage areas to flow in different production stages, and the productivity of the horizontal well can be accurately determined.

In one embodiment, the production cycle of the level under the volume pressure can be divided into three phases by taking the propagation distance of the pressure wave as a dividing basis: a first production phase (i.e., early production), a second production phase (i.e., middle production), and a third production phase (i.e., late production). In particular implementations, the pressure waves propagate outward during the production of the horizontal well. When the propagation distance of the pressure wave is equal to or less than the half-length of the fracture, it is considered that the first seepage region has a relatively large influence on the flow of the fluid during the time period, and the time period may be determined as the first production stage. When the propagation distance of the pressure wave is greater than the half length of the crack and less than or equal to the width of the SRV, it is considered that the first seepage area and the second seepage area have relatively large influence on the flow of the fluid in the time period, the contribution of the second seepage area cannot be ignored, and the time period may be determined as the second production stage. When the propagation distance of the pressure wave is greater than the width of the SRV, it can be considered that the first, second, and third seepage areas have relatively large influence on the flow of the fluid in the time period, and the contribution of the second and third seepage areas cannot be ignored, and the time period can be determined as the third production stage.

S14: determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In this embodiment, in specific implementation, the horizontal well productivity of the first production stage can be calculated in a targeted manner according to the geological characteristic parameters and the seepage characteristics of the first seepage area in the first production stage; the horizontal well productivity of the second production stage can be calculated in a targeted manner according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and calculating the horizontal well productivity of the third production stage in a targeted manner according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage. And determining the horizontal well productivity by obtaining the horizontal well productivity of the first production stage, the horizontal well productivity of the second production stage and the horizontal well productivity of the third production stage.

In one embodiment, the viscosity of crude oil, especially compact oil, is considered to have a significant effect on seepage flow, and the viscosity is generally greatly influenced by temperature; considering that when volume fracturing is carried out, a fracturing fluid is usually added, and the temperature of the fracturing fluid is usually different from that of a target area, so that the filtration loss of the fracturing fluid in the volume fracturing process influences the temperature of the target area, further influences the viscosity of crude oil in the target area, changes seepage flow and influences the yield of a horizontal well. Based on the analysis, in order to further improve the accuracy of determining the productivity of the horizontal well, the influence of the temperature of the fracturing fluid on the viscosity of the crude oil is determined, and then the influence is introduced into the subsequent process of determining the productivity of the horizontal well, so that more accurate productivity of the horizontal well is obtained through calculation.

In one embodiment, in order to determine the influence of the temperature of the fracturing fluid on the original viscosity, the method can be implemented according to the following steps:

s1: acquiring the temperature of the fracturing fluid and the quality of the fracturing fluid;

s2: determining the temperature distribution of the target area according to the temperature of the fracturing fluid and the quality of the fracturing fluid;

s3: determining a viscosity of the crude oil in the target region based on the temperature profile.

In the embodiment, after the influence of the fracturing fluid is introduced to determine the crude oil viscosity of the target area, correspondingly, the horizontal well productivity of the first production stage is determined according to the geological characteristic parameters and the seepage characteristics of the first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage, wherein the determination specifically comprises the following steps: determining the horizontal well productivity of the first production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In one embodiment, the temperature distribution of the target zone is determined according to the temperature of the fracturing fluid and the quality of the fracturing fluid, and in specific implementation, the temperature distribution of the target zone may be determined according to the following formula:

wherein T (r) may specifically be a temperature of a measurement point position in the target zone, r may specifically be a distance from the measurement point position in the target zone to the wellbore, T_{Fracturing fluid}May in particular be the temperature, T, of the fracturing fluid_{Formation of earth}In particular, the formation temperature, T, in the target zone_AverageSpecifically, the average temperature of the target area may be used, and Δ T may specifically be a difference between the average temperature of the target area and the formation temperature in the target area, K_obSpecifically, the thermal conductivity of the top layer of the formation in the target region, t specifically may be time, h specifically may be the thickness of the reservoir in the target region, and Φ specifically may be the porosity of the reservoir in the target region, (ρ₀C₀) Specifically, the heat capacity of crude oil in the target region (ρ C)_P)_RSpecifically, the heat capacity of stratum rock in the target area can be determined, C specifically can be the specific heat capacity of the fracturing fluid, M specifically can be the mass of the fracturing fluid, and M specifically can be the mass of the fracturing fluid_obIn particular the top layer heat capacity of the formation in the target zone.

In one embodiment, the viscosity of the crude oil in the target region is determined according to the temperature distribution, and in particular, the viscosity of the crude oil in the target region can be determined according to the following formula:

wherein μ (r) may specifically be the viscosity at the r position in the target region, D may specifically be the ratio of the top layer thermal conductivity and the top layer heat capacity of the formation in the target region, and M may specifically be the heat capacity of the reservoir in the target region.

In one embodiment, when implemented, the ratio of the top layer thermal conductivity to the top layer heat capacity of the formation in the target zone may be calculated according to the following equation:

wherein D may specifically be a ratio of a top layer thermal conductivity and a top layer heat capacity of the formation in the target region, K_obIn particular, the top layer thermal conductivity, M, of the formation in the target zone_obIn particular the top layer heat capacity of the formation in the target zone.

In one embodiment, considering that in the first production phase, the fluid flow (i.e., seepage) of the first seepage area is mainly used as the main flow, the first seepage area is mostly used as the main flow, and the fracture stress sensitivity is relatively significant, the capacity determination formula of the first production phase is reanalyzed and derived in consideration of the seepage characteristics, and accordingly, the horizontal well capacity of the first production phase is determined according to the crude oil viscosity, the geological characteristic parameter and the seepage characteristics of the first seepage area in the first production phase, and in particular, the horizontal well capacity of the first production phase can be calculated according to the following formula:

wherein q is₁The horizontal well capacity, w, of the first production stage can be specifically_FThe fracture width of the first seepage zone can be specifically defined, and h can be specifically the thickness of a reservoir in the target zone, k_F0In particular, the initial permeability, k, of the first percolation region_FIn particular, the permeability, k, of the first percolation region_iIn particular, the second seepage flow can bePermeability of the zone, α_FIn particular it may be a permeability sensitivity factor,

in particular, the average formation pressure, p_wIn particular, it may be a downhole fluid pressure, p_eIn particular, the pressure of the original formation, r_wIn particular, the radius of the well bore, l₁(t) may be specifically the propagation distance of the pressure wave in the first region of seepage.

In this embodiment, it is added that, in implementation, the propagation distance of the pressure wave in the first seepage region can be calculated according to the following formula:

wherein l₁(t) may be in particular the propagation distance of the pressure wave in the first region of seepage, C_tIn particular the fracture complex compressibility of the first seepage zone,

in particular the fracture porosity of the first seepage zone,

in particular, the average formation pressure, w_FIn particular, the fracture width k of the first seepage zone_FIn particular, the permeability, p, of the first percolation region may be_eIn particular, the pressure of the original formation, alpha_FIn particular, the permeability sensitivity factor can be used.

In one embodiment, considering that in the second production stage, the fluid flow (i.e. seepage) of the first seepage area and the fluid flow (i.e. seepage) of the second seepage area are both significant, and the second seepage area mostly mainly takes darcy flow, and the matrix stress sensitivity is relatively significant, the capacity determination formula of the second production stage is reanalyzed and derived in consideration of the seepage characteristics, and accordingly, the capacity determination formula of the second production stage is determined according to the crude oil viscosity, the geological characteristic parameters, and the seepage characteristics of the first seepage area and the second seepage area in the first production stage, and the capacity determination formula of the second production stage can be calculated according to the following formula:

wherein q is₂The horizontal well capacity, w, can be specifically the second production stage_FSpecifically, the fracture width of the first seepage area, h specifically may be the thickness of the reservoir in the target area, M specifically may be the heat capacity of the reservoir in the target area, x_fIn particular, the half-length of the crack, p, of the first seepage zone_wIn particular, it may be a downhole fluid pressure, p_eIn particular, the pressure of the original formation,/, may be₂(t) the propagation distance, k, of the pressure wave in the second region of seepage_iIn particular, the permeability of the second percolation region may be mentioned.

In this embodiment, it is added that, in implementation, the propagation distance of the pressure wave in the second seepage area can be calculated according to the following formula:

wherein l₂(t) may be in particular the propagation distance of the pressure wave in the second region of seepage, C_tParticularly, the comprehensive compression coefficient of the reservoir and the micro-fractures of the second seepage area,

in particular the fracture porosity of the second seepage zone,

in particular, the average formation pressure, k_iIn particular, the permeability, p, of the second percolation region may be_eMay be embodied as a raw groundLamination pressure, alpha_FIn particular, the permeability sensitivity coefficient of the second seepage area can be used.

In an embodiment, considering that in the third production phase, the fluid flow (i.e. seepage) of the first seepage area, the fluid flow (i.e. seepage) of the second seepage area and the fluid flow (i.e. seepage) of the third seepage area are all obvious, and the fluid seepage in the third seepage area mostly takes low-speed nonlinear flow as a main part, and the fluid flow is usually related to the starting pressure gradient, in consideration of the seepage characteristics, the production capacity determination formula of the third production phase is reanalyzed and derived, and accordingly, the production capacity horizontal well of the third production phase is determined according to the crude oil viscosity, the geological characteristic parameter, and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the first production phase, and the production capacity horizontal well of the third production phase can be calculated according to the following formula:

wherein q is₃The horizontal well productivity, p, of the third production stage can be specifically_eIn particular, the pressure of the original formation, p_wIn particular, the downhole fluid pressure, G in particular the initiation pressure gradient, Ω_{General assembly}In particular, the total seepage resistance of the target area, l₃(t) may be, in particular, the propagation distance of the pressure wave in the third region of seepage.

In this embodiment, it is added that, in implementation, the propagation distance of the pressure wave in the third seepage zone can be calculated according to the following formula:

l₃＝r＝w_f+[-Q/2+((Q/2)²+(P/3)³)^(1/2)]^(1/3)+[-Q/2-((Q/2)²+(P/3)³)^(1/2)]^(1/3)

wherein G may in particular be the starting pressure gradient, α_mIn particular, the stress sensitivity coefficient of the crack, C_tIn particular the reservoir integrated compressibility of the third percolation region,

in particular the fracture porosity of the third seepage zone,

in particular, the average formation pressure, k_oIn particular, the permeability, p, of the third percolation region may be_eIs the original formation pressure.

In one embodiment, when implemented, the total seepage resistance of the target area may be determined according to the following formula:

wherein omega₁Specifically, the seepage resistance, Ω, of the linear flow region in the third seepage region₂In particular, the seepage resistance, Ω, of the radial flow region in the third seepage region₃In particular, the seepage resistance of the second seepage zone may be mentioned.

In one embodiment, the seepage resistance of the second seepage zone may be calculated according to the following formula:

wherein, w_FIn particular, the fracture width k of the first seepage zone_FSpecifically, the permeability of the first seepage zone may be mentioned, and h specifically may be the thickness of the reservoir in the target zone, k_iMay be specifically the firstPermeability of the zone of bi-percolation, x_fMay be in particular the half-length of the fracture, l, of the first zone of seepage₃(t) may be, in particular, the propagation distance of the pressure wave in the third region of seepage.

In one embodiment, the seepage resistance of the linear flow region in the third seepage region may be calculated according to the following formula:

wherein k is_oMay specifically be the permeability of the third percolation region, h may specifically be the thickness of the reservoir in the target region, m' may specifically be the width of the SRV formed by the volume fracturing, x_fIn particular the half-length of the fracture of the first percolation region, dp in particular the differential form of the formation pressure, q_o1In particular, the flow rate of the planar flow portion in the third seepage zone,/, may be₃(t) may specifically be the propagation distance of the pressure wave in the third region of seepage, and G may specifically be the onset pressure gradient.

In one embodiment, the seepage resistance of the radial flow region in the third seepage region may be calculated according to the following formula:

wherein q is_o2Specifically, the flow rate of the radial flow portion in the third seepage area may be, and a may be a preset corner radius.

In the embodiment of the application, compared with the existing method, the specific influence of a complex fracture network structure and reservoir pores under volume fracturing on seepage respectively is comprehensively considered, and the target area is divided into a plurality of different seepage areas according to specific structural characteristics; and respectively determining the horizontal well productivity in different production stages according to the seepage characteristics of different seepage areas in different production stages, thereby solving the technical problem of inaccurate horizontal well productivity under volume fracturing in the existing method, and achieving the technical effects of comprehensively analyzing the seepage characteristics of different structural areas in different production stages and accurately determining the horizontal well productivity under volume fracturing.

In one embodiment, in order to effectively perform crude oil extraction on a horizontal well under volume fracture, after determining the horizontal well productivity of a first production stage, the horizontal well productivity of a second production stage, and the horizontal well productivity of a third production stage, the method may further include the following steps:

In this embodiment, during specific implementation, the calculated horizontal well productivity of the first production stage, the calculated horizontal well productivity of the second production stage, and the calculated horizontal well productivity of the third production stage may be used as reference bases to guide effective crude oil extraction on a target area.

From the above description, it can be seen that the method for determining the horizontal well productivity under volume fracturing provided by the embodiment of the present application, because specific influences of a complex fracture network structure and reservoir pores under volume fracturing on seepage are comprehensively considered, a target area is firstly divided into a plurality of different seepage areas according to specific structural characteristics; the horizontal well productivity in different production stages is respectively determined according to the seepage characteristics of different seepage areas in different production stages, so that the technical problem that the horizontal well productivity under volume fracturing is inaccurate in determination in the existing method is solved, and the technical effects of comprehensively analyzing the seepage characteristics of different structural areas in different production stages and accurately determining the horizontal well productivity under volume fracturing are achieved; and considering that the viscosity of crude oil in a target area can be influenced by the temperature of the fracturing fluid, the accuracy of determining the yield of the horizontal well under volume fracturing is improved by introducing the influence of the fracturing fluid on the viscosity of the crude oil.

Based on the same inventive concept, the embodiment of the invention also provides a device for determining the horizontal well productivity under volume fracturing, which is described in the following embodiment. Because the principle of solving the problems of the determining device for the horizontal well productivity under the volume fracturing is similar to the determining method for the horizontal well productivity under the volume fracturing, the implementation of the determining device for the horizontal well productivity under the volume fracturing can refer to the implementation of the determining method for the horizontal well productivity under the volume fracturing, 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 determination of horizontal well productivity under volumetric fracturing described in the examples below is preferably implemented in software, implementations in hardware, or a combination of software and hardware are also possible and contemplated. Referring to fig. 2, a structural diagram of a device for determining horizontal well productivity under volume fracturing provided in an embodiment of the present application is shown, where the device specifically includes: the obtaining module 21, the first dividing module 22, the second dividing module 23, and the determining module 24, which will be described in detail below.

The obtaining module 21 is specifically configured to obtain geological characteristic parameters of a target area where a horizontal well under volume fracturing is located;

the first dividing module 22 may be specifically configured to divide the target area into: a first, second, and third percolation region, wherein the first percolation region comprises a percolation region of an artificial primary fracture, the second percolation region comprises a percolation region of an artificial secondary fracture and a reservoir percolation region within an SRV volume, and the third percolation region comprises a reservoir percolation region outside the SRV volume;

the second dividing module 23 may be specifically configured to divide the production cycle of the horizontal well under the volume fracture into: a first production stage, a second production stage and a third production stage;

the determining module 24 is specifically configured to determine the horizontal well productivity of the first production stage according to the geological feature parameters and the seepage characteristics of the first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In one embodiment, the apparatus further comprises a crude oil viscosity determination module, which may be specifically configured to determine the viscosity of crude oil in the target region. Specifically, the crude oil viscosity determining module comprises the following structural units:

the acquisition unit can be specifically used for acquiring the temperature of the fracturing fluid and the quality of the fracturing fluid;

the first determining unit may be specifically configured to determine a temperature distribution of the target region according to the temperature of the fracturing fluid and the quality of the fracturing fluid;

a second determination unit, in particular, may be configured to determine the viscosity of the crude oil in the target region based on the temperature distribution.

The crude oil viscosity determining module is connected with the determining module 24, and when the determining module 24 is implemented specifically, the crude oil viscosity determining module can be used for determining the horizontal well productivity of a first production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In one embodiment, in order to determine the temperature distribution of the target zone according to the temperature of the fracturing fluid and the quality of the fracturing fluid, the first determining unit may determine the temperature distribution of the target zone according to the following formula:

In one embodiment, in order to determine the viscosity of the crude oil in the target region according to the temperature distribution, the second determination unit may determine the viscosity of the crude oil in the target region according to the following formula:

In one embodiment, in order to determine the horizontal well productivity of the first production stage according to the crude oil viscosity, the geological characteristic parameter and the seepage characteristics of the first seepage area in the first production stage, when the determining module 24 is implemented, the horizontal well productivity of the first production stage may be calculated according to the following formula:

wherein q is₁The horizontal well capacity, w, of the first production stage can be specifically_FThe fracture width of the first seepage zone can be specifically defined, and h can be specifically the thickness of a reservoir in the target zone, k_F0In particular, the initial permeability, k, of the first percolation region_FIn particular, the permeability, k, of the first percolation region_iIn particular, the permeability, α, of the second percolation region_FIn particular it may be a permeability sensitivity factor,

In one embodiment, in order to determine the horizontal well productivity of the second production stage according to the crude oil viscosity, the geological characteristic parameter, and the seepage characteristics of the first seepage area and the second seepage area in the second production stage, when the determining module 24 is implemented, the horizontal well productivity of the second production stage may be calculated according to the following formula:

wherein q is₂The horizontal well capacity, w, can be specifically the second production stage_FSpecifically, the fracture width of the first seepage area, h specifically may be the thickness of the reservoir in the target area, M specifically may be the heat capacity of the reservoir in the target area, x_fIn particular, the half-length of the crack, p, of the first seepage zone_wIn particular, it may be a downhole fluid pressure, p_eIn particular, the pressure of the original formation,/, may be₂(t) may be, in particular, the propagation distance, k, of the pressure wave in the second region of seepage_iIn particular, the permeability of the second percolation region may be mentioned.

In an embodiment, in order to determine the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameter, and the seepage characteristics of the first seepage area, the second seepage area, and the third seepage area in the third production stage, when the determining module 24 is implemented, the horizontal well productivity of the third stage may be calculated according to the following formula:

In one embodiment, the determining module 24 may be implemented to determine the total seepage resistance of the target area according to the following formula:

In an embodiment, the device may further include a construction module, wherein the construction module is connected to the determination module 24, and when the construction module is implemented, the construction module may be configured to perform crude oil extraction on a target region where the horizontal well under volume fracture is located according to the horizontal well productivity of the first production stage, the horizontal well productivity of the second production stage, and the horizontal well productivity of the third production stage.

The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

It should be noted that, the systems, devices, modules or units described in the above embodiments may be implemented by a computer chip or an entity, or implemented by a product with certain functions. For convenience of description, in the present specification, the above devices are described as being divided into various units by functions, and are described separately. Of course, the functionality of the units may be implemented in one or more software and/or hardware when implementing the present application.

Moreover, in the subject specification, adjectives such as first and second may only be used to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. References to an element or component or step (etc.) should not be construed as limited to only one of the element, component, or step, but rather to one or more of the element, component, or step, etc., where the context permits.

From the above description, it can be seen that the device for determining the horizontal well productivity under volume fracturing provided by the embodiment of the present application, because the specific influences of the complex fracture network structure and the reservoir pores under volume fracturing on the seepage respectively are comprehensively considered, and the target area is divided into a plurality of different seepage areas according to specific structural characteristics; the horizontal well productivity in different production stages is respectively determined according to the seepage characteristics of different seepage areas in different production stages, so that the technical problem that the horizontal well productivity under volume fracturing is inaccurate in determination in the existing method is solved, and the technical effects of comprehensively analyzing the seepage characteristics of different structural areas in different production stages and accurately determining the horizontal well productivity under volume fracturing are achieved; and considering that the viscosity of crude oil in a target area can be influenced by the temperature of the fracturing fluid, the accuracy of determining the yield of the horizontal well under volume fracturing is improved by introducing the influence of the fracturing fluid on the viscosity of the crude oil.

In a specific implementation scenario example, the determination method and the determination device for providing the horizontal well productivity under the volume fracturing are applied to predict the tight oil horizontal well productivity under the volume fracturing of a certain area. In a specific implementation process, referring to the flow diagram shown in fig. 3, which is used in a scenario example and is provided by the application of the method and the device for determining the horizontal well productivity under volume fracturing to determine the productivity of a tight oil horizontal well in a certain area, the following is performed.

During specific implementation, the influence of the fracturing fluid filtration on the viscosity of crude oil, seepage characteristics of a seepage area in different production stages in a volume fracturing mode and the like can be analyzed, so that the horizontal well capacity under the volume fracturing in a certain area can be accurately calculated.

1. The effect of fracturing fluid loss on crude oil viscosity was analyzed.

In the embodiment, the influence of the fluid loss of the fracturing fluid on the viscosity of the high-viscosity compact crude oil in the horizontal well volume fracturing mode can be analyzed according to the following steps in specific implementation:

step 1: basic parameters are acquired. The method specifically comprises the following steps:

a. determining a temperature parameter including a formation-virgin temperature T_{Formation of earth}(ii) a Fracturing fluid temperature of T_{Fracturing fluid}。

b. Determining fracturing fluid parameters including the mass m of the fracturing fluid_{Fracturing fluid}Kg; the specific heat capacity of the fracturing fluid is CkJ/(kg-DEG C).

c. Determining stratum parameters including reservoir thickness h, m; porosity of the reservoir phi; heat capacity of formation rock (ρ C)_P)_R，kJ/(m³DEG C.); heat capacity ρ of crude oil in the formation_oC_o(ii) a Of the top layerCoefficient of thermal conductivity K_obkJ/(m.d.DEG C); wherein the minor half-axis length b, m of the cold zone.

Step 2: and calculating the influence of the fracturing fluid filtration loss on the formation temperature.

In the present embodiment, considering that the fracturing fluid is injected into the ground and the time to reach the ground is short at the time of high-displacement injection, T can be considered as_{Fracturing fluid}Approximately equal to ground temperature, and therefore has T_{Fracturing fluid}＜T_{Formation of earth}So that during the fracturing process, the fracturing fluid will form a zone of lower temperature around the bottom of the well, called the "cold zone". Specifically, fig. 4 is a schematic diagram of a method and an apparatus for determining horizontal well productivity under volume fracturing, which are provided by the embodiment of the present application, for injecting a fracturing fluid to form a "cold zone" near a wellbore, in one scenario example. The energy change of the injected formation fracturing fluid can be equal to the energy loss in the reservoir and the loss of the reservoir to the top and bottom surrounding rock according to the law of conservation of energy.

The change in thermal energy injected into the formation fracturing fluid may be expressed as:

Q_i＝m_{fracturing fluid}C(T_{Fracturing fluid}-T_{Area averaging})

Because the temperature influence area injected by the fracturing fluid is smaller relative to the area of the reservoir, the temperature can be approximately considered to be linearly distributed in the cold zone, the edge temperature of the cold zone is the formation temperature, the central temperature of the cold zone is the fracturing fluid temperature, and the average temperature of the cold zone is

The energy loss in the reservoir can be expressed as:

Q_O＝AhMΔT

where M ═ phi (ρ)_oC_o)+(1-φ)(ρC_P)_RIs the heat capacity of the reservoir, Δ T ═ T_{Area averaging}-T_{Formation of earth}。

The loss of the reservoir to the top and bottom surrounding rock can be expressed as:

wherein,

t is the time, which is the ratio of the top layer thermal conductivity to the top layer heat capacity.

The calculated cold zone area can be expressed as:

it should be noted that, because the cold zone is distributed along the crack and is approximately an ellipse, according to the ellipse area formula, there are:

wherein b is the minor half-axis length of the cold zone, m.

The temperature distribution in the cold zone can be expressed as:

and step 3: and calculating the viscosity change of the crude oil of the stratum.

In the present embodiment, the viscosity-temperature curve of the formation crude oil can be obtained by regression from the laboratory test data, and may be, for example, in the following form: mu-m × TⁿAnd the change of the viscosity of the crude oil can be obtained by distributing the temperature in the cold region. Taking the compact oil in a certain area as an example, the viscosity-temperature curve of the compact oil in a certain area is as follows: mu-27815 XT^-1.69Then the change in crude oil viscosity in the cold zone can be expressed as:

specifically, fig. 5 is a schematic diagram of a change of viscosity of crude oil in a "cold zone" obtained by applying the method and the device for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application in a scenario example.

2. And dividing a seepage area in a volume fracturing mode.

In the embodiment, in specific implementation, as the horizontal well develops multiple seepage media such as artificial fractures, natural fractures, matrix pores and the like in different levels in a volume fracturing mode, different seepage areas can be divided according to the coupling flow relationship among the media.

In particular, complex fracture network systems of combinations of primary fractures and different levels of secondary fractures are readily formed in reservoirs due to large scale hydraulic fracturing in tight reservoirs where the microfractures are relatively developed. This system of stitches is generally deployed along the artificial primary fracture and is distributed mainly over a distance from the artificial primary fracture. The fluid seepage zone after fracture-network fracturing of a fracture-pore type reservoir can thus be equivalent to three sections of seepage in an artificial main fracture (i.e., the first seepage zone), seepage within the SRV volume in which the secondary fracture system and the matrix are coupled (i.e., the second seepage zone), and seepage of a tight oil reservoir outside the SRV volume (i.e., the third seepage zone). Specifically, fig. 6 is a schematic diagram of a physical model of tight oil horizontal well volume fracturing obtained by applying the method and the device for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application in one scenario example.

In the early stages of production, seepage in artificial primary fractures is predominant, and darcy seepage is a major concern because of the limited width of the primary fractures due to the presence of secondary fractures. As production progresses, the pressure in the artificial main fracture decreases, internal reservoir within the SRV volume begins to seep, fluid flows from the internal reservoir where the secondary fracture system and reservoir are coupled to the artificial main fracture and finally into the horizontal wellbore, and seepage is dominated by darcy seepage due to the relative development of the internal reservoir fractures. At the later stage of production, the internal reservoir pressure drops, the pressure gradient on the boundary reaches the start pressure gradient, and the external reservoir region begins to seep. Fluid flows from the outer reservoir first into the inner reservoir, through the artificial main fracture, and finally into the horizontal wellbore.

3. And analyzing the capacity condition of each production stage.

In this embodiment, in a horizontal well + volume fracturing mode, because the artificial main fracture is directly connected to the horizontal wellbore, the internal SRV seepage zone consisting of the secondary fracture, the natural microfractures and the reservoir matrix is outside the main fracture, they can be equivalent to a medium when establishing a model, and generally the medium has poorer physical properties than the artificial main fracture but better physical properties than the reservoir matrix. The outside of the SRV is the outer seepage zone consisting of natural microfractures and the reservoir matrix, also treated equivalently as a medium. Specifically, fig. 7 is a schematic diagram of a tight oil horizontal well volume fracturing flow model obtained by applying the method and the device for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application in one scenario example.

Step 1: and (4) calculating the horizontal well productivity at the initial stage of production (namely the horizontal well productivity at the first production stage).

The initial stage of production is the flow within the fracture. In the actual flowing process, the fracture and the internal matrix flow together, but because the reservoir pressure is higher in the initial production stage, the permeability in the fracture is high, the flowing speed is high, and the flow rate in the matrix is small and can be ignored in comparison, only the fracture flows at the beginning. The initial linear flow phase in the well test curve also illustrates the feasibility of this assumption.

The equation of motion is as follows:

the flow in the fracture away from the wellbore is a parallel flow along the fracture with a converging flow effect in the region near the wellbore. The linear flow equation away from the wellbore is as follows:

the skin that is created by wellbore confluence is considered to be:

the stress sensitivity equation of the crack is obtained through experimental data regression, namely:

k＝k₀exp[α_F(p-p_e)]

seepage in the quarter area of a single crack is as follows:

the calculation of unsteady state seepage can be performed using a steady state iterative approach, with each time step being steady state production. The flow rate is the same for each cross-section for steady state, but for stress sensitivity, the pressure difference at each cross-section results in a different permeability, and no calculation can be made for any cross-section. However, since permeability is pressure dependent, and pressure in a planar linear flow is linearly distributed, the change in permeability is also linearly distributed. The stress sensitivity calculation can be performed by approximately replacing the pressure at each point with the average formation pressure, and therefore:

considering that the confluence skin in the fracture can obtain the pressure distribution in the fracture pore type reservoir fracture network fracturing main fracture:

obtaining a capacity formula at the initial production stage after simplification:

step 2: and calculating the horizontal well productivity in the middle production stage (namely the horizontal well productivity in the second production stage).

In the middle of the production period of the compact reservoir fracture network fracturing, as the pressure in the fracture is reduced, the secondary fracture, the artificial fracture and the matrix in the SRV also participate in the flow, and the model at the moment is divided into two parts of seepage of an internal reservoir and seepage in the artificial fracture for consideration. Specifically, fig. 8 is a schematic diagram of a seepage situation in the midproductive phase of a tight reservoir volume fractured horizontal well, which is obtained by applying the method and the device for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application in one scenario example.

Internal reservoir seepage

The seepage continuity equation inside the oil reservoir is as follows:

since the seepage in the SRV volume is Darcy seepage, the equation of motion is:

pressure distribution within the internal reservoir region:

in the artificial main fracture, the continuity equation is obtained by considering the influence of the pressure sensitive effect:

for computational complexity considerations, one can approximate:

for convenience of description, it may be set as:

considering the additional pressure drop caused by the convergence near the wellbore, a pressure distribution equation can be obtained:

wherein, the yield of the quarter region is:

and step 3: and (4) calculating the horizontal well productivity in the later production stage (namely the horizontal well productivity in the third production stage).

In the later stage of production of fracture network fracturing of a compact reservoir, along with the reduction of the pressure of an internal reservoir, the seepage of an external reservoir area is started, the seepage of the external reservoir area is divided into planar linear flow parallel to the boundary of the internal reservoir and the external reservoir and four fan-shaped seepage areas pointing to fixed points of the boundary of the internal reservoir and the external reservoir, and the capacity calculation in the later stage of production is carried out by utilizing an equivalent seepage resistance method. Specifically, fig. 9 is a schematic diagram of the seepage condition of the external oil reservoir at the late production stage of the volume fractured horizontal well of the tight reservoir, which is obtained by applying the method and the device for determining the horizontal well productivity under volume fracturing provided by the embodiment of the present application in one scenario example.

The internal oil reservoir productivity is as follows:

the internal reservoir's percolation resistance can then be calculated:

because the external oil reservoir is mainly a substrate of a compact reservoir and develops the nano-micron pore throats, the seepage is mainly low-speed nonlinear seepage, and the motion equation is as follows:

wherein v is_ooIs the flow velocity of the external seepage, m; k is a radical of_ooIs the permeability of the external reservoir, mD; p is a radical of_ooIs the reservoir pressure, MPa, of the external reservoir.

The flow of the plane flow part in the external oil reservoir seepage area is as follows:

q_o1＝2(2x_f+m)hv_o1

wherein q is_o1Is the flow rate of the planar flow portion; m is the width of the SRV, m; v. of_o1Is the fluid velocity of the planar flow, m/s.

The flow of the radial flow part in the external oil reservoir seepage area is as follows:

q_o2＝2πrhv_o2

wherein q is_o2Is the flow rate of the radial flow portion; v. of_o2Is the fluid velocity of the planar flow, m/s.

The flow rate during planar linear seepage is as follows:

the seepage resistance of the flow part of the external oil reservoir plane is as follows:

the flow rate during radial seepage is as follows:

considering that there is no flow at the corner points of the inner boundary of the external reservoir, the corner points are infinitesimal points in mathematical concept, and it is meaningless to calculate the flow of the infinitesimal points, so that it can be considered that there is flow only in a small area near the corner points, and the radius of the area is a.

Calculating the seepage resistance of radial seepage as follows:

and the equivalent seepage resistance method shows that the radial flow and the linear flow of the external oil reservoir are in parallel relation, and the seepage in the external oil reservoir and the seepage in the internal oil reservoir are in series relation, so that the equivalent seepage resistance of the whole seepage area can be calculated:

thus, the capacity at the later stage of production is:

then, according to the conclusion of the analysis, on the basis of a productivity formula, the horizontal well yield of the corresponding production stage can be calculated according to the change of the flow pressure at different bottoms of the wells, so that the horizontal well productivity is determined. Referring to a schematic diagram of a comparison result between predicted cumulative yield and actual cumulative yield of a tight oil fractured horizontal well obtained by applying the method and the device for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application in a scene example shown in fig. 10, it can be seen that the coincidence degree between predicted cumulative yield and actual cumulative yield of the tight oil fractured horizontal well obtained by the method and the device for determining horizontal well productivity under volume fracturing provided by the embodiment of the present application is higher, that is, more accurate.

Through the scene example, the method and the device for determining the horizontal well capacity under volume fracturing provided by the embodiment of the application are verified, the specific influence of a complex fracture network structure and reservoir pores under volume fracturing on seepage is comprehensively considered, and a target area is divided into a plurality of different seepage areas according to specific structural characteristics; and respectively determining the horizontal well productivity in different production stages according to the seepage characteristics of different seepage areas in different production stages, thereby really solving the technical problem of inaccurate horizontal well productivity under volume fracturing in the existing method, and achieving the technical effects of comprehensively analyzing the seepage characteristics of different structural areas in different production stages and accurately determining the horizontal well productivity under volume fracturing.

The embodiment of the present application further provides an electronic device, and specifically, refer to fig. 11, which is a schematic structural diagram of an electronic device based on the method for determining horizontal well productivity under volume fracturing, where the electronic device specifically includes an input device 1101, a processor 1102, and a memory 1103. The input device 1101 may specifically input a geological characteristic parameter of a target region where a horizontal well under volume fracturing is located. The processor 1102 may be specifically configured to divide the target area into: a first, second, and third percolation region, wherein the first percolation region comprises a percolation region of an artificial primary fracture, the second percolation region comprises a percolation region of an artificial secondary fracture and a reservoir percolation region within an SRV volume, and the third percolation region comprises a reservoir percolation region outside the SRV volume; dividing the production cycle of the horizontal well under the volume fracturing into the following steps according to the propagation distance of the pressure wave: a first production stage, a second production stage and a third production stage; determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage. The memory 1103 may be specifically configured to store the input geologic feature parameters, as well as intermediate data that occurs during the calculation process.

In this embodiment, the input device may be one of the main apparatuses for information exchange between a user and a computer system. The input device may include a keyboard, a mouse, a camera, a scanner, a light pen, a handwriting input board, a voice input device, etc.; the input device is used to input raw data and a program for processing the data into the computer. The input device can also acquire and receive data transmitted by other modules, units and devices. The processor may be implemented in any suitable way. For example, the processor may take the form of, for example, a microprocessor or processor and a computer-readable medium that stores computer-readable program code (e.g., software or firmware) executable by the (micro) processor, logic gates, switches, an Application Specific Integrated Circuit (ASIC), a programmable logic controller, an embedded microcontroller, and so forth. The memory may in particular be a memory device used in modern information technology for storing information. The memory may include multiple levels, and in a digital system, the memory may be any memory as long as it can store binary data; in an integrated circuit, a circuit without a physical form and with a storage function is also called a memory, such as a RAM, a FIFO and the like; in the system, the storage device in physical form is also called a memory, such as a memory bank, a TF card and the like.

In this embodiment, the functions and effects specifically realized by the electronic device can be explained by comparing with other embodiments, and are not described herein again.

The present application further provides a computer storage medium for a method for determining horizontal well capacity under volumetric fracturing, where the computer storage medium stores computer program instructions, and when the computer program instructions are executed, the computer program instructions implement: acquiring geological characteristic parameters of a target area where a horizontal well under volume fracturing is located; dividing the target area into: a first, second, and third percolation region, wherein the first percolation region comprises a percolation region of an artificial primary fracture, the second percolation region comprises a percolation region of an artificial secondary fracture and a reservoir percolation region within an SRV volume, and the third percolation region comprises a reservoir percolation region outside the SRV volume; dividing the production cycle of the horizontal well under the volume fracturing into the following steps according to the propagation distance of the pressure wave: a first production stage, a second production stage and a third production stage; determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; and determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage.

In this embodiment, the storage medium includes, but is not limited to, a Random Access Memory (RAM), a Read-Only Memory (ROM), a Cache (Cache), a Hard Disk Drive (HDD), or a Memory Card (Memory Card). The memory may be used to store computer program instructions. The network communication unit may be an interface for performing network connection communication, which is set in accordance with a standard prescribed by a communication protocol.

In this embodiment, the functions and effects specifically realized by the program instructions stored in the computer storage medium can be explained by comparing with other embodiments, and are not described herein again.

Although various specific embodiments are mentioned in the disclosure of the present application, the present application is not limited to the cases described in the industry standards or the examples, and the like, and some industry standards or the embodiments slightly modified based on the implementation described in the custom manner or the examples can also achieve the same, equivalent or similar, or the expected implementation effects after the modifications. Embodiments employing such modified or transformed data acquisition, processing, output, determination, etc., may still fall within the scope of alternative embodiments of the present application.

Although the present application provides method steps as described in an embodiment or flowchart, more or fewer steps may be included based on conventional or non-inventive means. The order of steps recited in the embodiments is merely one manner of performing the steps in a multitude of orders and does not represent the only order of execution. When an apparatus or client product in practice executes, it may execute sequentially or in parallel (e.g., in a parallel processor or multithreaded processing environment, or even in a distributed data processing environment) according to the embodiments or methods shown in the figures. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the presence of additional identical or equivalent elements in a process, method, article, or apparatus that comprises the recited elements is not excluded.

The devices or modules and the like explained in the above embodiments may be specifically implemented by a computer chip or an entity, or implemented by a product with certain functions. For convenience of description, the above devices are described as being divided into various modules by functions, and are described separately. Of course, in implementing the present application, the functions of each module may be implemented in one or more pieces of software and/or hardware, or a module that implements the same function may be implemented by a combination of a plurality of sub-modules, and the like. The above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is merely a logical division, and other divisions may be realized in practice, for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not executed.

Those skilled in the art will also appreciate that, in addition to implementing the controller as pure computer readable program code, the same functionality can be implemented by logically programming method steps such that the controller is in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Such a controller may therefore be considered as a hardware component, and the means included therein for performing the various functions may also be considered as a structure within the hardware component. Or even means for performing the functions may be regarded as being both a software module for performing the method and a structure within a hardware component.

The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote computer storage reservoirs including memory storage devices.

From the above description of the embodiments, it is clear to those skilled in the art that the present application can be implemented by software plus necessary general hardware platform. Based on such understanding, the technical solutions of the present application may be embodied in the form of a software product, which may be stored in a storage layer, such as a ROM/RAM, a magnetic disk, an optical disk, or the like, and includes several instructions for enabling a computer device (which may be a personal computer, a mobile terminal, a server, or a network device) to execute the method according to the embodiments or some parts of the embodiments of the present application.

The embodiments in the present specification are described in a progressive manner, and the same or similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. The application is operational with numerous general purpose or special purpose computing system environments or configurations. For example: personal computers, server computers, hand-held or portable devices, tablet-type devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.

While the present application has been described by way of examples, those of ordinary skill in the art will appreciate that there are numerous variations and permutations of the present application that do not depart from the spirit of the present application and that the appended embodiments are intended to include such variations and permutations without departing from the present application.

Claims

1. A method for determining the productivity of a horizontal well under volume fracturing is characterized by comprising the following steps:

determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage;

dividing the target area into: after the first, second, and third percolation regions, the method further comprises: acquiring the temperature of the fracturing fluid and the quality of the fracturing fluid; determining the temperature distribution of the target area according to the temperature of the fracturing fluid and the quality of the fracturing fluid; determining a viscosity of the crude oil in the target region from the temperature profile;

correspondingly, determining the horizontal well productivity of the first production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; determining the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage; and calculating the horizontal well productivity of the second production stage according to the following formula:

wherein q is₂Horizontal well capacity for the second production phase, w_FIs the fracture width of the first seepage zone, h is the thickness of the reservoir in the target zone, M is the heat capacity of the reservoir in the target zone, x_fIs the first seepage flowHalf crack length of region, p_wTo downhole fluid pressure, p_eTo the original formation pressure,/₂(t) is the propagation distance of the pressure wave in the second region of seepage, k_iIs the permeability of the second percolation region.

2. The method of claim 1, wherein determining the temperature profile of the target zone based on the temperature of the fracturing fluid, the quality of the fracturing fluid, comprises:

3. The method of claim 2, wherein determining the viscosity of the crude oil in the target region from the temperature profile comprises:

4. The method of claim 3, wherein determining the horizontal well productivity for the first production phase from the crude oil viscosity, the geologic feature parameter, and the seepage characteristics of the first seepage zone in the first production phase comprises:

5. The method of claim 3, wherein determining the horizontal well productivity of the third production phase from the crude oil viscosity, the geological feature parameter, and the seepage characteristics of the first seepage zone, the second seepage zone, and the third seepage zone in the third production phase comprises:

6. The method of claim 5, wherein the total seepage resistance of the target area is determined according to the following formula:

7. The method of claim 1, wherein after determining the horizontal well productivity of the first production phase, the horizontal well productivity of the second production phase, and the horizontal well productivity of the third production phase, the method further comprises:

8. A device for determining horizontal well productivity under volume fracturing is characterized by comprising:

the determining module is used for determining the horizontal well productivity of the first production stage according to the geological characteristic parameters and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; determining the horizontal well productivity of the third production stage according to the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage;

the apparatus also includes a crude oil viscosity determination module for determining a viscosity of crude oil in the target region;

correspondingly, the determining module is specifically used for determining the horizontal well productivity of the first production stage according to the crude oil viscosity, the geological characteristic parameter and the seepage characteristics of a first seepage area in the first production stage; determining the horizontal well productivity of the second production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area and the second seepage area in the second production stage; determining the horizontal well productivity of the third production stage according to the crude oil viscosity, the geological characteristic parameters and the seepage characteristics of the first seepage area, the second seepage area and the third seepage area in the third production stage; the determining module calculates the horizontal well productivity of the second production stage according to the following formula:

wherein q is₂Horizontal well capacity for the second production phase, w_FIs the fracture width of the first seepage zone, h is the thickness of the reservoir in the target zone, M is the heat capacity of the reservoir in the target zone, x_fIs half the length of the crack in the first zone, p_wTo downhole fluid pressure, p_eTo the original formation pressure,/₂(t) is the propagation distance of the pressure wave in the second region of seepage, k_iIs the permeability of the second percolation region.

9. The apparatus of claim 8, wherein the crude oil viscosity determination module comprises: