A method, device and medium for dividing the post-pressure drainage stages of sandstone reservoirs

Abstract

The present invention relates to a method for dividing the post-pressure drainage stage of a sandstone reservoir, comprising: collecting the daily liquid production of an oil well, and collecting the oil pressure and the pressure drop value per cubic meter at the wellhead; calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure; dividing the drainage stage into a fracture diversion stage and a matrix seepage stage according to the first relationship curve; calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure; dividing the fracture diversion stage into a turbulent stage and a linear fracture diversion stage according to the second relationship curve. The present invention provides a theoretical basis for guiding the engineering practice of sandstone oil exploitation.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas production technology, and in particular to a method and device for dividing the post-pressure drainage stages of a sandstone reservoir, and a computer-readable storage medium. Background Art

[0002] Shale oil, usually stored in sandstone layers in shale, is also called sandstone oil. It is an important unconventional energy source with the advantages of great resource potential and long life. Shale has complex lithology, serious heterogeneity, and uneven distribution of oil sand bodies. There are problems such as rapid pressure exhaustion during the production process, and the accumulation of return fluid at the bottom of the well affects oil production. In the process of oil reservoir exploitation, reservoir pressure is often required. In the early stage, fracturing is often used to increase the degree of reservoir crude oil utilization. In the middle and late stages, gas and water injection are often used to supplement the formation energy to continue to exploit the oil field. The early stage of oil well exploitation belongs to the self-flowing stage. For economic benefits, it is often necessary to extend the self-flowing time of the oil well by adjusting the return flow rate to obtain the maximum self-flowing production capacity.

[0003] However, there is no clear understanding of the characteristics of shale oil backflow in the self-flowing stage in China, and it is impossible to provide guidance on site. In actual operation, construction personnel often adjust the backflow volume based on experience, which may cause a series of serious accidents such as burying the perforation section and damaging the construction equipment. Therefore, it is necessary to study the characteristics of the post-pressure drainage stage of shale oil reservoirs. However, there is no clear theoretical basis for the understanding of the drainage stage of rock sand oil in China. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method, device and computer-readable storage medium for dividing the post-pressure drainage stages of sandstone oil reservoirs, which can establish the division standards of the drainage stages based on set parameters and provide a theoretical basis for guiding the engineering practice of sandstone oil extraction.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present application provides a method for dividing the post-pressure drainage stages of a sandstone reservoir, the method comprising:

[0007] Collect the daily liquid production of the oil well, and collect the oil pressure and pressure drop value per cubic meter at the wellhead;

[0008] Calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop per cubic meter value, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure;

[0009] According to the first relationship curve, the drainage stage is divided into a fracture diversion stage and a matrix seepage stage;

[0010] Calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure;

[0011] According to the second relationship curve, the fracture conduction stage is divided into a turbulent stage and a linear fracture conduction stage.

[0012] In one implementation of the present application, the collecting of the daily liquid production of the oil well, and the collecting of the oil pressure and the pressure drop value per cubic meter at the wellhead include:

[0013] Collect daily liquid production, oil pressure and pressure drop per cubic meter of several oil wells under the same geological conditions;

[0014] Specifically, it includes: obtaining the daily liquid production of each oil well through a flow meter installed at the wellhead of each oil well; and obtaining the oil pressure at the wellhead of each oil well and the pressure drop value per cubic meter for each cubic meter of liquid produced through a pressure gauge installed at the wellhead of each oil well.

[0015] In one implementation of the present application, according to the first relationship curve, the drainage stage is divided into a fracture diversion stage and a matrix seepage stage, including:

[0016] According to the inflection point of the curve of the pressure drop per unit daily liquid production and the oil pressure in the first relationship curve, the drainage stage is divided into a fracture diversion stage and a matrix seepage stage.

[0017] In one implementation of the present application, according to the relationship between daily fluid production, hydraulic pressure drop per cubic meter and wellhead oil pressure, if an exponential equation is met:

[0018] △P=a / p t 2 +b

[0019] It is determined that the drainage stage enters the matrix seepage stage;

[0020] In the above exponential equation: △P is the pressure drop per cubic meter; p t is the wellhead oil pressure; a, b are coefficients respectively.

[0021] In an implementation of the present application, the oil pressure at the critical point between the fracture diversion stage and the matrix seepage stage is reduced to 10.4%-10.9% of the well opening pressure.

[0022] In an implementation of the present application, dividing the fracture conduction stage into a turbulent stage and a linear fracture conduction stage according to the second relationship curve includes:

[0023] According to the linear segment and the nonlinear segment in the fitted second relationship curve, the fracture conduction stage is divided into a linear fracture conduction stage and a turbulent stage.

[0024] In one implementation of the present application, according to the relationship between daily fluid production, hydraulic pressure drop per cubic meter and wellhead oil pressure, if the linear equation is met:

[0025] V / ΔP=k×p t

[0026] Then the drainage stage is determined to be the linear fracture diversion stage;

[0027] In the above linear equation, V is the daily liquid production; ΔP is the pressure drop per cubic meter; p t is the wellhead oil pressure; k is the equation coefficient.

[0028] In one implementation of the present application, the oil pressure at the critical point between the linear fracture diversion stage and the turbulence stage is reduced to 80.4%-85.5% of the well opening pressure.

[0029] In a second aspect, the present application provides a device for dividing the post-pressure drainage stages of a sandstone oil reservoir, the device comprising:

[0030] The measurement module is used to collect the daily liquid production of the oil well, and collect the oil pressure and pressure drop value per cubic meter at the wellhead;

[0031] a first curve fitting module, for calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure;

[0032] A first division module, used for dividing the drainage stage into a fracture diversion stage and a matrix seepage stage according to the first relationship curve;

[0033] a second curve fitting module, for calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure;

[0034] The second division module is used to divide the fracture conduction stage into a turbulent stage and a linear fracture conduction stage according to the second relationship curve.

[0035] In a third aspect, the present application provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for dividing the post-pressure drainage stages of sandstone oil reservoirs described in the first aspect.

[0036] In a fourth aspect, the present application provides a computer device, comprising a processor and a memory; the memory stores a computer program; the processor runs the computer program to control the computer device to execute the method for dividing the post-pressure drainage stages of the sandstone oil reservoir described in the first aspect.

[0037] Since the present invention adopts the above technical scheme, it has the following advantages: the application scheme of the present invention collects the daily liquid production, oil pressure and pressure drop value per cubic meter of the oil well, and then calculates the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishes a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure, and then divides the drainage stage into a fracture diversion stage and a matrix seepage stage according to the first relationship curve, and further calculates the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishes a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure, and divides the fracture diversion stage into a disorder stage and a linear fracture diversion stage according to the second relationship curve, so that the division standard of the drainage stage can be established, providing a theoretical basis for guiding the engineering practice of sandstone oil mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of a method for dividing the post-pressure drainage stages of a sandstone reservoir provided in this application;

[0039] Figure 2 is a schematic diagram of stage division based on the first relationship curve in this application;

[0040] Figure 3 It is a schematic diagram of stage division based on the second relationship curve in this application. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0042] The problem that the existing technology urgently needs to provide a clear theoretical basis for the division of sandstone oil drainage and production stages. The technical solution of the present invention provides a method, device and computer-readable storage medium for dividing the post-pressure drainage and production stages of sandstone oil reservoirs. Among them, the method includes: collecting the daily liquid production of the oil well, and collecting the oil pressure and the pressure drop value per cubic meter at the wellhead; according to the daily liquid production and the pressure drop value per cubic meter, calculating the pressure drop per unit daily liquid production of the oil well, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure; according to the first relationship curve, dividing the drainage and production stage into a fracture diversion stage and a matrix seepage stage; according to the daily liquid production and the pressure drop value per cubic meter, calculating the daily liquid production per unit pressure drop of the oil well, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure; according to the second relationship curve, dividing the fracture diversion stage into a turbulent stage and a linear fracture diversion stage. The technical solution of the present invention establishes the division standard of the drainage and production stages with set parameters, providing a theoretical basis for guiding the engineering practice of sandstone oil mining.

[0043] Please refer to more drawings of the embodiments of the present invention, in which the method, device and medium provided by the present invention are further explained in more detailed embodiments of the present invention.

[0044] like Figure 1 In one aspect of the embodiments of the present application, a method for dividing the post-pressure drainage stages of a sandstone reservoir is provided, which specifically includes:

[0045] S1, collect the daily liquid production of the oil well, and collect the oil pressure and pressure drop value per cubic meter at the wellhead;

[0046] Specifically, the daily liquid production q, oil pressure p and pressure drop value ΔP per cubic meter of several oil wells under the same geological conditions are collected.

[0047] The daily liquid production q of the oil well can be obtained through a flow meter installed at the wellhead of the oil well. The oil pressure at the wellhead of the oil well and the pressure drop value ΔP per cubic meter of liquid produced can be obtained through a pressure gauge installed at the wellhead of the oil well.

[0048] S2, calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure;

[0049] Specifically, the pressure drop per unit daily fluid production is calculated as ΔP / q. After calculation, a large amount of sample data is obtained by taking ΔP / q as the ordinate and the oil pressure as the abscissa, and curve fitting is performed on the sample data to obtain a first relationship curve.

[0050] S3, dividing the drainage stage into a fracture diversion stage and a matrix seepage stage according to the first relationship curve;

[0051] Specifically, according to the inflection point of the curve of the pressure drop per unit daily liquid production and the oil pressure in the first relationship curve, the drainage stage is divided into a fracture diversion stage and a matrix seepage stage.

[0052] During the fracture diversion stage, the pressure drop per unit daily fluid production decreases linearly with the decrease of oil pressure. Suddenly, the pressure drop per cubic meter increases sharply with the decrease of pressure. This is the critical point and the matrix seepage stage begins. Figure 2 shown.

[0053] More specifically, based on the relationship between daily fluid production, hydraulic pressure drop per cubic meter and wellhead oil pressure, if it conforms to the exponential equation:

[0054] ΔP=a / p t 2 +b

[0055] It is determined that the drainage stage has entered the matrix seepage stage.

[0056] Where ΔP is the hydraulic pressure drop per cubic meter, MPa / m 3 ;p t is the wellhead oil pressure, MPa; a and b are coefficients. When the hydraulic pressure drop ΔP increases sharply in an exponential manner, it indicates that the matrix seepage stage has begun.

[0057] S4, calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure;

[0058] Specifically, the daily liquid production per unit pressure drop is calculated as q / ΔP.

[0059] S5. Dividing the fracture conduction stage into a turbulent stage and a linear fracture conduction stage according to the second relationship curve.

[0060] In the early turbulent stage, the daily liquid production per unit pressure drop (q / ΔP) increases rapidly and discontinuously with the decrease of oil pressure, and then a sudden change occurs. The daily liquid production per unit pressure drop (q / ΔP) decreases linearly with the decrease of oil pressure, entering the mid-term linear fracture diversion stage. When the daily liquid production per unit pressure drop (q / ΔP) changes its slope with the decrease of oil pressure and increases sharply, it enters the late matrix seepage stage.

[0061] More specifically, according to the relationship between daily fluid production, hydraulic pressure drop per cubic meter and wellhead oil pressure, if it conforms to the linear equation:

[0062] V / ΔP=k×p t

[0063] Then the drainage stage is determined to be the linear fracture diversion stage;

[0064] In the above linear equation, V is the daily liquid production, m 3 / d; △P is the hydraulic pressure drop per cubic meter, MPa / m 3 ;p t is the wellhead oil pressure, MPa; k is the equation coefficient.

[0065] The above can be summarized as follows:

[0066] In the early stage of production well exploitation, most of the rock sand oil flows out from large cracks, but there are also other flows such as partial seepage and small crack diversion, so it is called the turbulent stage; however, as the oil pressure drops, large cracks gradually close and nearby cracks gradually spread, and this process is called the fracture diversion stage; after that, it is mainly a process of liquid diffusion into the matrix, which is called the matrix seepage stage.

[0067] From the quantitative point of view, the oil pressure at the critical point of the fracture diversion stage and the matrix seepage stage is reduced to 10.4%-10.9% of the well opening pressure. The oil pressure at the critical point of the linear fracture diversion stage and the turbulence stage is reduced to 80.4%-85.5% of the well opening pressure.

[0068] The above-mentioned application scheme of the present invention collects the daily liquid production, oil pressure and pressure drop value per cubic meter of the oil well, and then calculates the pressure drop per unit daily liquid production of the oil well based on the daily liquid production and the pressure drop per cubic meter, and establishes a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure, and then divides the drainage stage into a fracture diversion stage and a matrix seepage stage based on the first relationship curve, and further calculates the daily liquid production per unit pressure drop of the oil well based on the daily liquid production and the pressure drop per cubic meter, and establishes a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure, and divides the fracture diversion stage into a turbulent stage and a linear fracture diversion stage based on the second relationship curve, so that the division standard of the drainage stage can be established, providing a theoretical basis for guiding the engineering practice of sandstone oil extraction.

[0069] In an embodiment of the present application, a device for dividing the post-pressure drainage stages of a sandstone reservoir is also provided, the device comprising:

[0070] The measurement module is used to collect the daily liquid production of the oil well, and collect the oil pressure and pressure drop value per cubic meter at the wellhead;

[0071] a first curve fitting module, for calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure;

[0072] A first division module, used for dividing the drainage stage into a fracture diversion stage and a matrix seepage stage according to the first relationship curve;

[0073] a second curve fitting module, for calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure;

[0074] The second division module is used to divide the fracture conduction stage into a turbulent stage and a linear fracture conduction stage according to the second relationship curve.

[0075] In another aspect of the embodiments of the present application, a computer storage medium is also provided accordingly.

[0076] The embodiment of the present application also provides a computer-readable storage medium, the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the above method. The specific implementation process will not be repeated here.

[0077] The present application also provides a computer device. The computer device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the aforementioned method in the embodiment is implemented. To avoid repetition, it is not described one by one here. Alternatively, when the computer program is executed by the processor, the functions of each model / unit in the device in the embodiment are implemented. To avoid repetition, it is not described one by one here.

[0078] The computer device may be a computing device such as a desktop computer, a notebook, a PDA, a server, a cloud server, etc. The computer device may include, but is not limited to, a processor and a memory. Those skilled in the art will appreciate that the computer device may include more or fewer components than shown in the figure, or may combine certain components, or may include different components. For example, the computer device may also include input and output devices, network access devices, buses, etc.

[0079] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0080] The memory may be an internal storage unit of a computer device, such as a hard disk or memory of the computer device. The memory may also be an external storage device of the computer device, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the computer device. Furthermore, the memory may include both an internal storage unit of the computer device and an external storage device. The memory is used to store computer programs and other programs and data required by the computer device. The memory may also be used to temporarily store data that has been output or is to be output.

[0081] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0082] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the above units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0083] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (Processor) to perform some steps of the above-mentioned method of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.

[0084] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for dividing the post-pressure drainage stages of a sandstone reservoir, characterized in that: The method comprises: Collect the daily liquid production of the oil well, and collect the oil pressure and pressure drop value per cubic meter at the wellhead; Calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop per cubic meter value, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure; According to the first relationship curve, the drainage stage is divided into the fracture diversion stage and the matrix seepage stage. If the exponential equation is met: ΔP = a / p t 2 +b, it is determined that the drainage stage enters the matrix seepage stage; ΔP is the pressure drop value per cubic meter; p t is the wellhead oil pressure; a and b are coefficients respectively; Calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure; According to the second relationship curve, the fracture conduction stage is divided into a turbulent stage and a linear fracture conduction stage, wherein, if the linear equation is met: V / ΔP=k×p t , then the drainage stage is determined to be the linear fracture diversion stage; V is the daily liquid production; ΔP is the pressure drop per cubic meter; p t is the wellhead oil pressure; k is the equation coefficient.

2. The method for dividing the post-pressure drainage stages of sandstone reservoirs according to claim 1, characterized in that: The method of collecting the daily liquid production of the oil well, and collecting the oil pressure at the wellhead and the pressure drop value per cubic meter includes: Collect daily liquid production, oil pressure and pressure drop per cubic meter of several oil wells under the same geological conditions; Specifically, it includes: obtaining the daily liquid production of each oil well through a flow meter installed at the wellhead of each oil well; and obtaining the oil pressure at the wellhead of each oil well and the pressure drop value per cubic meter for each cubic meter of liquid produced through a pressure gauge installed at the wellhead of each oil well.

3. The method for dividing the post-pressure drainage stages of sandstone reservoirs according to claim 1, characterized in that: According to the first relationship curve, the drainage stage is divided into a fracture diversion stage and a matrix seepage stage, including: According to the inflection point of the curve of the pressure drop per unit daily liquid production and the oil pressure in the first relationship curve, the drainage stage is divided into a fracture diversion stage and a matrix seepage stage.

4. The method for dividing the post-pressure drainage stages of sandstone reservoirs according to claim 3 is characterized in that: The oil pressure at the critical point between the fracture conduction stage and the matrix seepage stage is reduced to 10.4%-10.9% of the well opening pressure.

5. The method for dividing the post-pressure drainage stages of a sandstone reservoir according to claim 1, characterized in that: The method of dividing the fracture conduction stage into a turbulent stage and a linear fracture conduction stage according to the second relationship curve includes: According to the linear segment and the nonlinear segment in the fitted second relationship curve, the fracture conduction stage is divided into a linear fracture conduction stage and a turbulent stage.

6. The method for dividing the post-pressure drainage stages of sandstone reservoirs according to claim 5, characterized in that: The oil pressure at the critical point between the linear fracture diversion stage and the turbulence stage is reduced to 80.4%-85.5% of the well opening pressure.

7. A device for dividing the post-pressure drainage stages of sandstone reservoirs, characterized in that: The device comprises: The measurement module is used to collect the daily liquid production of the oil well, and collect the oil pressure and pressure drop value per cubic meter at the wellhead; a first curve fitting module, for calculating the pressure drop per unit daily liquid production of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a first relationship curve between the pressure drop per unit daily liquid production and the oil pressure; The first division module is used to divide the drainage stage into a fracture diversion stage and a matrix seepage stage according to the first relationship curve, wherein if the exponential equation is met: ΔP = a / p t 2 +b, it is determined that the drainage stage enters the matrix seepage stage; ΔP is the pressure drop value per cubic meter; p t is the wellhead oil pressure; a and b are coefficients respectively; a second curve fitting module, for calculating the daily liquid production per unit pressure drop of the oil well according to the daily liquid production and the pressure drop value per cubic meter, and establishing a second relationship curve between the daily liquid production per unit pressure drop and the oil pressure; The second division module is used to divide the fracture conduction stage into a turbulent stage and a linear fracture conduction stage according to the second relationship curve, wherein if the linear equation is met: V / ΔP=k×p t , then the drainage stage is determined to be the linear fracture diversion stage; V is the daily liquid production; ΔP is the pressure drop per cubic meter; p t is the wellhead oil pressure; k is the equation coefficient.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the method for dividing the post-pressure drainage stages of sandstone oil reservoirs according to any one of claims 1 to 6.

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