CN112983399B - Method, device and storage medium for acquiring bottom hole flow pressure depressurization speed - Google Patents
Method, device and storage medium for acquiring bottom hole flow pressure depressurization speed Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 94
- 238000003860 storage Methods 0.000 title claims abstract description 9
- 230000035699 permeability Effects 0.000 claims abstract description 88
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 53
- 239000011148 porous material Substances 0.000 claims abstract description 45
- 230000006835 compression Effects 0.000 claims abstract description 40
- 238000007906 compression Methods 0.000 claims abstract description 40
- 238000012544 monitoring process Methods 0.000 claims abstract description 15
- 239000003245 coal Substances 0.000 claims description 64
- 238000003795 desorption Methods 0.000 claims description 61
- 238000005086 pumping Methods 0.000 claims description 33
- 230000007423 decrease Effects 0.000 claims description 3
- 208000019888 Circadian rhythm sleep disease Diseases 0.000 claims description 2
- 208000001456 Jet Lag Syndrome Diseases 0.000 claims description 2
- 208000033915 jet lag type circadian rhythm sleep disease Diseases 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 23
- 238000011161 development Methods 0.000 abstract description 13
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 20
- 230000008569 process Effects 0.000 description 20
- 238000004364 calculation method Methods 0.000 description 10
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
- E21B47/06—Measuring temperature or pressure
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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Abstract
The application provides a method, a device and a storage medium for acquiring a bottom hole flow pressure reducing speed. The method comprises the following steps: and acquiring reservoir permeability of the target well in the production area, original reservoir pressure of the target well, differential pressure of the ground solution of the target well, porosity of the target well, irreducible water saturation of the target well and initial compression coefficient of the pores of the target well, and then acquiring the bottom hole flow pressure depressurization rate of the target well based on a functional relation between each parameter data of the target well and the bottom hole flow pressure depressurization rate. In the method, the monitoring data of the well on the exploitation site is more flexibly applied, and the rationality of the final result and the adaptability to the actual development environment are ensured; the method has the advantages of simplifying the working flow, saving the acquisition time and being better popularized and applied in the exploitation site.
Description
Technical Field
The application relates to the technical field of coalbed methane exploitation, in particular to a method, a device and a storage medium for acquiring a bottom hole flow pressure reducing speed.
Background
The coalbed methane is mainly in an adsorption state and is endowed on the surface of a coal matrix, and in the development process of the coalbed methane, the pressure of a reservoir is reduced to be lower than the desorption pressure through continuous drainage and depressurization, so that the coalbed methane can be desorbed and produced. Wherein reservoir pressure is affected by the bottom hole flow pressure, and the rate of decline of reservoir pressure is in positive correlation with the rate of decline of bottom hole flow pressure. In the depressurization desorption process, the rate of well bottom flow depressurization has an important influence on the reservoir permeability due to strong sensitivity of coal and rock stress: the bottom hole flow pressure is reduced too fast, so that the permeability of the reservoir is greatly damaged, and the yield of a coal-bed gas well is affected; the bottom hole flow pressure is slow to reduce, the drainage and depressurization time is long before desorption, and the drainage and production efficiency is low. Therefore, in order to ensure the effect of coal bed gas exploitation, the reasonable depressurization rate of the bottom hole flow pressure needs to be determined.
In the related art, the method for determining the bottom hole flow pressure depressurization speed of the coal-bed gas well mainly comprises 2 methods: firstly, a numerical simulation method, namely, determining the influence of the bottom hole flow pressure dropping speed on the reservoir permeability through numerical simulation, calculation and the like. Secondly, an indoor experiment method is adopted, experimental tests are carried out on collected coal rock samples in a laboratory, and the influence of different depressurization speeds on permeability is simulated.
However, the numerical simulation method requires a technician with professional knowledge to obtain a simulation result by using professional software, has higher workload and working cost, and limits the application range of the numerical simulation method; the indoor experimental method is greatly influenced by the scale of the coal rock sample, and the method can be applied to actual reservoir development after complicated similar transformation, so that the calculation process is complicated.
Disclosure of Invention
The embodiment of the application provides a method, a device and a storage medium for acquiring a bottom hole flow pressure reducing speed, so that monitoring data of a mining site are fully utilized to acquire the bottom hole flow pressure reducing speed.
In a first aspect, a method for obtaining a down hole pressure rate of depressurization is provided, the method comprising:
acquiring reservoir permeability of the target well based on the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well; acquiring the original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping; acquiring a ground solution pressure difference of the target well based on the original reservoir pressure of the target well and the desorption pressure of the target well; and acquiring the bottom hole flow pressure depressurization speed of the target well based on the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the ground solution of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the pores of the target well.
According to the method provided by the embodiment of the application, the reservoir permeability of the target well in the production area, the original reservoir pressure of the target well, the ground pressure difference of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the porosity of the target well are obtained, and the bottom hole flow pressure depressurization rate of the target well is obtained based on the functional relation between the parameter data and the bottom hole flow pressure depressurization rate.
In one possible implementation, obtaining reservoir permeability of the target well based on the depth-to-depth lateral resistivity difference of the target well and the sonic jet lag of the target well comprises: acquiring a depth lateral resistivity difference value of the target well and an acoustic time difference of the target well based on logging information of the target well; and acquiring the reservoir permeability of the target well corresponding to the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well based on the functional relation among the reservoir permeability, the depth lateral resistivity difference value and the acoustic time difference.
In one possible implementation, before obtaining the reservoir permeability of the target well corresponding to the depth-to-side resistivity difference of the target well and the acoustic time difference of the target well based on a functional relationship between the reservoir permeability, the depth-to-side resistivity difference, and the acoustic time difference, the method further includes:
Based on the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference of each of the plurality of parameter wells, a functional relationship among the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference is obtained, wherein the parameter wells are wells used for surveying geological conditions in an exploration stage.
In one possible implementation, obtaining an original reservoir pressure for a target well based on a bottom hole pressure at a pull-up of the target well comprises:
acquiring the bottom hole flow pressure of the target well during pumping based on the monitoring data of the target well; and acquiring the original reservoir pressure of the target well corresponding to the bottom hole flow pressure when the target well is started to be pumped based on the functional relation between the bottom hole flow pressure when the target well is started to be pumped and the original reservoir pressure.
In one possible implementation, before obtaining the target well primary reservoir pressure corresponding to the bottom hole flow pressure at the time of pumping of the target well based on the functional relationship between the bottom hole flow pressure at the time of pumping and the primary reservoir pressure, the method further includes:
and acquiring a functional relation between the bottom hole flow pressure at the time of pumping and the original reservoir pressure based on the original reservoir pressure of each parameter well in the plurality of parameter wells and the bottom hole flow pressure at the time of pumping.
In one possible implementation, obtaining a differential pressure of the target well based on the original reservoir pressure of the target well and the desorption pressure of the target well comprises:
Obtaining the desorption pressure of the adjacent parameter well of the target well, determining the desorption pressure of the target well based on the desorption pressure of the adjacent parameter well, or obtaining the gas-finding pressure of the adjacent drainage well of the target well, and determining the desorption pressure of the target well based on the gas-finding pressure of the adjacent drainage well; the difference between the original reservoir pressure of the target well and the desorption pressure of the target well is obtained as the differential earth pressure of the target well.
In one possible implementation, before obtaining the down hole pressure depressurization rate of the target well based on the reservoir permeability of the target well, the raw reservoir pressure of the target well, the differential pressure across the target well, the porosity of the target well, the irreducible water saturation of the target well, and the initial compression coefficient of the pores of the target well, further comprising:
determining porosity and irreducible water saturation of adjacent parameter wells based on experimental data of coal core samples of adjacent parameter wells of the target well; the porosity and the irreducible water saturation of the adjacent parameter wells are taken as the porosity of the target well and the irreducible water saturation of the target well.
In one possible implementation, before obtaining the down hole pressure depressurization rate of the target well based on the reservoir permeability of the target well, the raw reservoir pressure of the target well, the differential pressure across the target well, the porosity of the target well, the irreducible water saturation of the target well, and the initial compression coefficient of the pores of the target well, further comprising:
Acquiring the permeability of the coal core sample under different effective stress based on experimental data of the coal core sample of the adjacent parameter well of the target well; determining pore initial compression coefficients of adjacent parameter wells based on the effective stress and the corresponding permeability; and taking the initial compression coefficient of the pores of the adjacent parameter wells as the initial compression coefficient of the pores of the target well.
In a second aspect, there is provided an apparatus for obtaining a down hole pressure let down rate, the apparatus comprising:
the first acquisition module is used for acquiring the reservoir permeability of the target well based on the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well; the second acquisition module is used for acquiring the original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping; a third acquisition module for acquiring a differential pressure of the target well based on the original reservoir pressure of the target well and the desorption pressure of the target well; and a fourth acquisition module for acquiring a bottom hole flow pressure depressurization rate of the target well based on the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the porosity of the target well.
In one possible implementation manner, the first obtaining module is configured to:
acquiring a depth lateral resistivity difference value of the target well and an acoustic time difference of the target well based on logging information of the target well; and acquiring the reservoir permeability of the target well corresponding to the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well based on the functional relation among the reservoir permeability, the depth lateral resistivity difference value and the acoustic time difference.
In one possible implementation, the apparatus further includes:
the first construction module is used for acquiring a functional relation among the reservoir permeability, the depth lateral resistivity difference value and the acoustic wave time difference based on the reservoir permeability and the depth lateral resistivity difference value of each parameter well in the plurality of parameter wells, wherein the parameter wells are used for surveying geological conditions in the exploration stage.
In one possible implementation, the second acquisition module is configured to:
acquiring the bottom hole flow pressure of the target well during pumping based on the monitoring data of the target well; and acquiring the original reservoir pressure of the target well corresponding to the bottom hole flow pressure when the target well is started to be pumped based on the functional relation between the bottom hole flow pressure when the target well is started to be pumped and the original reservoir pressure.
In one possible implementation, the apparatus further includes:
And the second construction module is used for acquiring a functional relation between the bottom hole flow pressure and the original reservoir pressure when the pumping is started based on the original reservoir pressure and the bottom hole flow pressure when the pumping is started in each parameter well of the plurality of parameter wells.
In one possible implementation manner, the third obtaining module is configured to:
obtaining the desorption pressure of the adjacent parameter well of the target well, determining the desorption pressure of the target well based on the desorption pressure of the adjacent parameter well, or obtaining the gas-finding pressure of the adjacent drainage well of the target well, and determining the desorption pressure of the target well based on the gas-finding pressure of the adjacent drainage well; the difference between the original reservoir pressure of the target well and the desorption pressure of the target well is obtained as the differential earth pressure of the target well.
In one possible implementation, the apparatus further includes:
a fifth acquisition module for determining porosity and irreducible water saturation of adjacent parameter wells of the target well based on experimental data of coal core samples of the adjacent parameter wells; the porosity and the irreducible water saturation of the adjacent parameter wells are taken as the porosity of the target well and the irreducible water saturation of the target well.
In one possible implementation, the apparatus further includes:
the sixth acquisition module is used for acquiring the permeability of the coal core sample under different effective stress based on experimental data of the coal core sample of the adjacent parameter well of the target well; determining pore initial compression coefficients of adjacent parameter wells based on the effective stress and the corresponding permeability; and taking the initial compression coefficient of the pores of the adjacent parameter wells as the initial compression coefficient of the pores of the target well.
In a third aspect, a computer readable storage medium having at least one program code stored therein, the program code loaded and executed by a processor to cause a computer to implement a method of obtaining a bottomhole flow rate step-down speed as in any of the first aspects.
In a fourth aspect, a computer program or computer program product is provided, the computer program or computer program product having stored therein at least one computer instruction that is loaded and executed by a processor to cause the computer to implement any one of the methods of obtaining a down hole pressure lowering speed.
According to the technical scheme provided by the embodiment of the application, the monitoring data of the mining site is more flexibly applied, and the reasonability of the final result and the adaptability to the actual development environment are ensured; the method has the advantages of simplifying the working flow, saving the acquisition time and being better popularized and applied in the exploitation site.
Drawings
FIG. 1 is a flow chart of a method for obtaining a down hole pressure lowering speed provided by an embodiment of the present application;
FIG. 2 is a graph of raw reservoir pressure as a function of bottom hole flow pressure at the time of pump-up provided by an embodiment of the present application;
FIG. 3 is a graph of permeability as a function of effective stress provided by an embodiment of the present application;
FIG. 4 is a schematic diagram of an apparatus for obtaining a down hole pressure lowering speed according to an embodiment of the present application;
FIG. 5 is a schematic diagram of an apparatus for obtaining a down hole pressure lowering speed according to an embodiment of the present application;
fig. 6 is a block diagram of a computer device according to an embodiment of the present application.
Detailed Description
Unless defined otherwise, all technical terms used in the embodiments of the present application have the same meaning as commonly understood by one of ordinary skill in the art, and are used only for explanation of the embodiments of the present application, not for limitation of the present application.
In the field of coalbed methane exploitation, coalbed methane exploitation is a process of draining, depressurizing and desorbing a coal reservoir, and when the pressure of the reservoir is reduced below the desorption pressure, the coalbed methane is desorbed and produced. In the exploitation process, reservoir pressure is influenced by the change of bottom hole flow pressure, and the descending speed of the bottom hole flow pressure can influence the reservoir permeability of a coal reservoir, so that the exploitation effect of coal bed gas is influenced. The bottom hole flow pressure is controlled to be at a reasonable depressurization speed, so that higher yield is obtained in the development process of the coal bed gas, and the high-efficiency development of the coal bed gas is realized.
The embodiment of the application provides a method for obtaining the down-hole flow pressure speed, which is used for determining the reasonable down-hole flow pressure speed, keeping and improving the reservoir permeability to the maximum extent and ensuring that the exploitation process is in a high-efficiency and high-yield state. Referring to fig. 1, the method includes the following steps 101-104.
101. And acquiring the reservoir permeability of the target well based on the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well.
Determining a target well in a production area, wherein the target well is a coal bed gas development well needing to determine the bottom hole flow pressure reducing speed; multiple parameter wells are selected from wells drilled in the exploration phase in the same production zone, the multiple parameter wells being in a region surrounding the target well and having similar geological conditions as the target well. Because the purpose of drilling wells in the exploration stage is to know the address condition of the exploitation area, various data of the selected multi-parameter wells are perfect, and therefore, the data of the multi-parameter wells are used as reference data in the implementation process of the embodiment of the application and are used for fitting and determining various functional relations.
Wherein having similar geological conditions for the parameter well and the target well means that the geological survey data for each parameter well and the target well are the same or that the difference between the survey data is within an allowable standard range that is empirically set, as embodiments of the present application are not limited.
In the step, acquiring the reservoir permeability of the target well requires acquiring a depth lateral resistivity difference value of the target well and an acoustic time difference of the target well based on logging data of the target well; and then, based on a functional relation among the reservoir permeability, the depth lateral resistivity difference value and the acoustic wave time difference, acquiring the depth lateral resistivity difference value of the target well and the reservoir permeability of the target well corresponding to the acoustic wave time difference of the target well.
The depth-to-depth lateral resistivity of the target well, the shallow lateral resistivity of the target well and the acoustic wave time difference of the target well can be directly obtained based on logging information of the target well, and the depth-to-depth lateral resistivity difference of the target well is obtained by calculating the difference between the depth-to-depth lateral resistivity of the target well and the shallow lateral resistivity of the target well.
The above-mentioned process is applied to the functional relation among the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference, so before the reservoir permeability of the target well is obtained, the functional relation among the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference is required to be obtained based on the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference of each parameter well in the selected multiple parameter wells, and the parameter wells are the coal-bed gas wells which are in the same exploitation area as the target well and have similar geological conditions. The method for acquiring the reservoir permeability, the depth lateral resistivity difference value and the acoustic wave time difference of each parameter well is not limited. For example, logging operations such as micro-resistivity logging and acoustic time difference logging are performed on the selected multiple parameter wells.
In one possible implementation, the injection pressure drop test is performed on the selected multiple parameter wells to obtain the reservoir permeability of each parameter well; acquiring the depth lateral resistivity difference value and the acoustic wave time difference of each parameter well in the acquired logging data of each parameter well; based on the obtained reservoir permeability, depth lateral resistivity difference and acoustic wave time difference of each parameter well, constructing reservoir permeability (K), depth lateral resistivity difference (delta I) and acoustic wave time difference (A) c ) Functional relationship between: k=f (Δi, a c ). The construction mode in the process is not limited, and a multiple regression method, a numerical simulation method and the like can be utilized, and the application is not limited to the method.
In this possible implementation manner, the obtaining manner of the depth lateral resistivity difference value of the parameter well is similar to the obtaining manner of the depth lateral resistivity difference value of the target well, the depth lateral resistivity of the parameter well and the shallow lateral resistivity of the parameter well are obtained from the logging data of the parameter well respectively, and then the depth lateral resistivity difference value of the parameter well is obtained by performing difference processing.
The logging data of the target well and the parameter well are related data obtained from a professional logging department, and the logging data can be obtained by various logging methods, such as micro resistivity logging, nuclear magnetic resonance logging, and the like, which are not limited in the application.
102. And acquiring the original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping.
In the step, based on the monitoring data of the target well, acquiring the bottom hole flow pressure of the target well during pumping; and acquiring the original reservoir pressure of the target well corresponding to the bottom hole flow pressure when the target well is started to be pumped based on the functional relation between the bottom hole flow pressure when the target well is started to be pumped and the original reservoir pressure. The monitoring data of the target well is obtained by monitoring the target well in the development process, and then the bottom hole flow pressure of the target well during pumping is obtained from the monitoring data. Illustratively, a target well is drilled in the production zone, a downhole pressure gauge is run in after the target well is completed, and the bottom-hole pressure of the target well at the beginning of drainage, i.e., the bottom-hole pressure at the beginning of pumping of the target well, is directly read.
In the above process, the functional relationship between the bottom hole flow pressure at the time of pumping and the original reservoir pressure is utilized, so before the original reservoir pressure of the target well is obtained, the functional relationship between the bottom hole flow pressure at the time of pumping and the original reservoir pressure is required to be obtained based on the original reservoir pressure of each parameter well in the plurality of parameter wells and the corresponding bottom hole flow pressure at the time of pumping.
In one possible implementation, the original reservoir pressure of the parameter well may be obtained by an injection pressure drop test performed on the parameter well in step 101; the bottom hole pressure of the parameter well is directly obtained by a down hole pressure gauge which is put in after the completion of the parameter well. Based on the obtained parametric well data, a raw reservoir pressure is built (P r ) And bottom hole flow pressure (P) at the time of pumping i ) Functional relation P between r ＝F(P i ). The application is not limited to the construction mode of the functional relation, such as regression fit and other methods.
In an optional mode, in a rectangular coordinate system, drawing a scatter diagram of parameter well data by taking the original reservoir pressure of the parameter well as an ordinate and taking the bottom hole flow pressure of the parameter well during pumping as an abscissa; and then, fitting to obtain a functional relation between the original reservoir pressure and the bottom hole flow pressure at the time of pumping by a linear regression method.
103. The differential earth pressure of the target well is obtained based on the original reservoir pressure of the target well and the desorption pressure of the target well.
In the step, the difference value between the original reservoir pressure of the target well and the desorption pressure of the target well is obtained through calculation, and the difference value is the ground desorption pressure difference of the target well. The original reservoir pressure of the target well is obtained in step 102, and the desorption pressure of the target well is obtained based on the adjacent parameter well of the target well or the adjacent drainage well of the target well. In addition, the desorption pressure is expressed as P de The differential pressure is expressed as delta P c . In different scenes, the target well desorption pressure is obtained in different modes.
Scene one: the selected mining area belongs to the exploration stage and does not enter large-scale development.
And selecting at least one adjacent parameter well of the target well, acquiring the desorption pressure of the adjacent parameter well, and determining the desorption pressure of the target well based on the desorption pressure of the adjacent parameter well.
If a single adjacent parameter well is selected, obtaining the desorption pressure of the single adjacent parameter well, and taking the desorption pressure of the single adjacent parameter well as the desorption pressure of a target well; if a plurality of adjacent parameter wells are selected, the desorption pressure of each parameter well in the plurality of adjacent parameter wells is obtained, and then the desorption pressure of each adjacent parameter well is processed to obtain the desorption pressure of the target well.
The treatment of the desorption pressure of adjacent parameter wells includes a variety of methods, and embodiments of the present application are not limited in this regard. Illustratively, the average value of the desorption pressures of each adjacent parameter well is directly calculated, and the average value is taken as the desorption pressure of the target well; or based on the difference of the geological conditions of the adjacent parameter wells, a weighted average of the desorption pressures of the adjacent parameter wells is obtained, and the weighted average is used as the desorption pressure of the target well. In the mode of calculating the weighted average, the weight corresponding to the barometric pressure of each adjacent parameter well is determined based on experience and geological conditions corresponding to each adjacent parameter well; the matching degree of the method for calculating the weighted average value and the actual condition of the development environment is higher, and the accuracy of the obtained result is higher.
The selection of adjacent parameter wells is made empirically and based on survey data, as the application is not limited in this regard. Illustratively, adjacent parameter wells may be selected from among the parameter wells in the preceding steps, or reselected near the target well, if the geological conditions are guaranteed to be similar. The method for obtaining the desorption pressure of the adjacent parameter wells can be determined according to the actual conditions of the production area. In one possible implementation, the desorption pressure of the adjacent parameter wells is calculated from measured gas content and isothermal adsorption curve data.
Scene II: the selected mining area is a developed area, and a large number of coal-bed gas wells are put into production.
And selecting at least one adjacent drainage well of the target well, acquiring the gas-finding pressure of the adjacent drainage well of the target well, and determining the desorption pressure of the target well based on the gas-finding pressure of the adjacent drainage well.
If a single adjacent drainage and production well is selected, acquiring the gas-finding pressure of the single adjacent drainage and production well, and taking the gas-finding pressure of the single adjacent drainage and production well as the desorption pressure of a target well; if a plurality of adjacent drainage and production wells are selected, the gas-finding pressure of each adjacent drainage and production well in the plurality of adjacent drainage and production wells is obtained, and then the gas-finding pressure of each adjacent drainage and production well is processed to obtain the desorption pressure of the target well.
There are various methods for treating the pressure of the gas in the adjacent drainage wells, and the embodiment of the application is not limited to this. Illustratively, the average value of the gas-finding pressure of each adjacent drainage well is directly obtained, and the average value is taken as the desorption pressure of the target well; or based on the difference of geological conditions of each adjacent drainage well, a weighted average of the gas-finding pressures of each adjacent drainage well is obtained, and the weighted average is used as the desorption pressure of the target well. In the process of calculating the weighted average, the weight corresponding to the gas pressure of each adjacent drainage well is determined based on experience and the geological condition corresponding to each adjacent drainage well; the method for calculating the weighted average value avoids errors caused by a development environment to the calculation result, and the accuracy of the obtained result is higher.
The method for obtaining the gas pressure of the adjacent drainage well is not limited, and the gas pressure is obtained by directly monitoring the pressure in the underground. The gas pressure is the bottom hole flow pressure of the adjacent drainage well at the moment when the coal bed gas starts to be collected.
Based on the actions of the parameter wells and the drainage wells and the state of the drainage wells, the distance between the parameter wells is larger than the distance between the drainage wells, in the developed area, the distance between the drainage wells and the target well is smaller, and the geological condition and the actual production condition are more similar to those of the target well.
104. And acquiring the bottom hole flow pressure depressurization speed of the target well based on the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the ground solution of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the pores of the target well.
Before the bottom hole flow pressure depressurization rate of the target well is obtained, the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the pores of the target well need to be obtained respectively. Illustratively, the reservoir permeability of the target well, the raw reservoir pressure of the target well, and the differential pressure of the target well are obtained from steps 101, 102, 103, respectively; the porosity of the target well and the irreducible water saturation of the target well are obtained by the following method (1), and the initial compressibility of the pores of the target well is obtained by the following method (2).
Determining the porosity and irreducible water saturation of adjacent parameter wells based on experimental data of coal core samples of the adjacent parameter wells of the target well; the porosity and the irreducible water saturation of the adjacent parameter wells are taken as the porosity of the target well and the irreducible water saturation of the target well.
Adjacent parameter wells of the target well are selected in the production zone, and the adjacent parameter wells are determined empirically and according to the actual conditions of the production zone. The adjacent parameter well may be the same as or different from the adjacent parameter well in step 103; the adjacent parameter wells may or may not belong to the plurality of parameter wells determined in step 101, which is not limited in the present application.
In the method, based on experimental data of coal core samples in adjacent parameter wells, a porosity formula and an irreducible water saturation formula are utilized to calculate, so that the porosity and the irreducible water saturation of the adjacent parameter wells are obtained, and the obtained result is used as the porosity and the irreducible water saturation of a target well.
Wherein, the porosity (phi) formula is:wherein V is p Represents the pore volume of the coal core sample, V b Representing the apparent volume of the coal core sample; irreducible water saturation (S) wi ) The formula is: />In which W is s Represents the initial weight, W, of the coal core sample g Represents the dry coal core sample weight and ρ represents the coal bed water density.
The data in the above formula can be obtained by indoor experiments, wherein the porosity volume V p Apparent volume V b Initial weight W s And dry coal core sample weight W g All can be obtained by measuring and calculating the coal core sample; the formation water density ρ may be obtained by measuring a formation water sample, in one possible implementation, a sample of the coal seam water is obtained in an adjacent parameter well, and the density of the coal seam water is measured by a densitometer.
In one possible implementation, coring is performed in adjacent parameter wells to obtain coal core samples of adjacent parameter wells. Weighing the coal core sample to obtain the initial weight of the coal core sample; calculating the apparent volume of the coal core sample; acquiring the weight of a dried coal core sample after the drying treatment of the coal core sample; measuring the pore volume of the coal core sample by using a porosity tester; substituting each experimental data of the obtained coal core samples in the adjacent parameter wells into a porosity calculation formula and an irreducible water saturation calculation formula to obtain the porosity and the irreducible water saturation of the adjacent parameter wells. Wherein the apparent volume is the sum of the actual volume and the pore volume.
In order to facilitate the acquisition of the apparent volume of the core sample, the acquired core sample may be processed into a regular cylindrical plunger or a cubic plunger, as the application is not limited in this regard. After obtaining the porosity and irreducible water saturation of the adjacent parameter wells, the result is taken as the porosity and irreducible water saturation of the target well.
The method comprises the steps of (2) obtaining the permeability of a coal core sample under different effective stress based on experimental data of the coal core sample of an adjacent parameter well of a target well; determining pore initial compression coefficients of adjacent parameter wells based on the effective stress and the corresponding permeability; and taking the initial compression coefficient of the pores of the adjacent parameter wells as the initial compression coefficient of the pores of the target well.
Coring in adjacent parameter wells, processing the obtained coal core samples according to experimental standards to obtain cylindrical plungers with certain specifications, and carrying out indoor experiments to test the permeability of the cylindrical plungers under different effective stress. The experimental standard is correspondingly determined according to the characteristics of different coal reservoirs, the adjacent parameter wells are the same as those in the method (1), and the used coal core samples are different from those in the method (1).
Using the experimental data obtained, i.e. the permeability of the coal core sample at different effective stresses in the indoor experiment, in combination with the known functional relationship between effective stress (Δp) and permeability (k):and obtaining the initial compression coefficient of the pores of the adjacent parameter wells, and taking the initial compression coefficient of the pores of the adjacent parameter wells as the initial compression coefficient of the pores of the target well. Wherein k is 0 Is a fixed constant, C 0 Is the initial compression coefficient of the coal rock pore.
After the parameter data of the target well are obtained, the parameter data of the target well are the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the pores of the target well; substituting each parameter data of the target well into the following empirical formula for representing the relationship between the bottom hole flow pressure reducing speed and the number of each parameter data in a polynomial form to obtain the bottom hole flow pressure reducing speed of the target well.
V opt ＝0.81ln(K)-ln(Φ)-(0.081P r 3 -1.81P r 2 +12.69P r )+(0.15ΔP c 2 -0.22ΔP c )-(11.24S wi 2 -4.11S wi )-(20.6C 0 2 -4.11C 0 )+33
Wherein V is opt For reasonable depressurization rate, the unit is m/d; k is the reservoir permeability in mD; phi is the porosity and participates in the operation in the form of decimal; p (P) r For the original reservoir pressure, the units are MPa; ΔP c For differential pressure, the unit is MPa; s is S wi To irreducible water saturation, the calculation is participated in the form of decimal; c (C) 0 The initial pore compression coefficient is given in MPa -1 . The formula can be obtained by fitting real data in the traditional coal bed methane exploitation process.
In one possible implementation manner, when the format of the parameter data of the target well is not standard, for example, when the units are not uniform, the percentages and the decimal formats are not uniform, the parameter data of the target well is converted into a format meeting the requirements of an empirical formula according to the requirements; substituting the parameter data of the target well after format conversion into the formula to obtain the bottom hole flow pressure reducing speed of the target well.
The embodiment of the application provides a method for acquiring the bottom hole flow pressure depressurization rate, which is used for acquiring the bottom hole flow pressure depressurization rate of a target well based on various parameter data of the target well in a production area and a functional relation between the various parameter data and the bottom hole flow pressure depressurization rate. In the method, the monitoring data of the well on the exploitation site is more flexibly applied, and the rationality of the final result and the adaptability to the actual development environment are ensured; the method has the advantages of simplifying the working flow, saving the acquisition time and being better popularized and applied in the exploitation site.
The method for acquiring the down hole pressure reducing speed according to the embodiment of the application is described below with reference to an exemplary embodiment of the application. Illustratively, a coalbed methane well is selected as the target well Q in a coalbed methane production area, while a plurality of parameter wells with similar geological conditions drilled during the exploration phase are selected in the same production area, the number of parameter wells being empirically determined. By adopting the method for acquiring the bottom hole flow pressure depressurization rate, the bottom hole flow pressure depressurization rate of the target well Q is acquired, and the process comprises steps 201 to 206.
201. And acquiring the reservoir permeability of the target well based on the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well.
In this exemplary embodiment, 17 parameter wells, designated sequentially as parameter 1 through parameter 17, are selected within the investigation region in which target well Q is located. Performing injection pressure drop test on the 17 parameter wells to obtain reservoir permeability K of the parameter wells 1 The method comprises the steps of carrying out a first treatment on the surface of the Logging data obtained by logging the 17 parameter wells are used for obtaining the deep lateral resistivity of each parameter well, the shallow lateral resistivity of the parameter well and the acoustic wave time difference A of the parameter well c1 Performing difference calculation on the deep lateral resistivity and the shallow lateral resistivity of each parameter well to obtain a deep and shallow lateral resistivity difference delta I of each parameter well 1 。
And displaying the obtained various parameter well data by using a table to obtain a partial parameter well data display table of the area where the target well Q is located as shown in the table 1.
TABLE 1
Based on the parameter data of the parameter wells in the above table, the differential Δi between the permeability K and the lateral resistivity of the depth and the acoustic wave time difference a in this exemplary embodiment are established by using a multiple regression method c And (3) the functional relation between the two to obtain a functional relation formula:
in the exemplary embodiment, using the logging data of the target well Q, the difference of the lateral resistivity of the depth and the lateral resistivity of the target well Q is 261 Ω & m, the acoustic time difference of the target well Q is 419s/m, and the reservoir permeability of the target well Q is calculated by substituting the above functional relation (1) 2 =0.042 mD. The process for obtaining the depth lateral resistivity difference value of the target well Q comprises the following steps: and acquiring the deep lateral resistivity of the target well Q and the shallow lateral resistivity of the target well Q by using logging data of the target well Q, and then carrying out difference value calculation on the acquired deep lateral resistivity of the target well Q and the shallow lateral resistivity of the target well Q.
202. And acquiring the original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping.
In the exemplary embodiment, injection pressure drop testing of the parameter well is performed in step 201, and the reservoir permeability of the parameter well is obtained along with the original reservoir pressure P of the parameter well r1 The method comprises the steps of carrying out a first treatment on the surface of the In addition, by monitoring the parameter well, for example by a down-hole pressure gauge, the bottom hole flow pressure P of the parameter well during pumping is directly obtained i1 . In a rectangular coordinate system, drawing to obtain a scatter diagram shown in figure 2 by taking the original reservoir pressure of the parameter well as an ordinate and the bottom hole flow pressure of the parameter well during pumping as an abscissa; obtaining a functional relation P between the original reservoir pressure and the bottom hole flow pressure during pumping by linear regression fitting of the two relations r ＝F(P i ) The specific form of this functional relationship in this exemplary embodiment is shown in fig. 2:
y＝0.8487x (2)
Wherein y represents the original reservoir pressure, x represents the bottom hole flow pressure when pumping, R 2 Representing the goodness of fit, the closer the goodness of fit to 1 indicates the better the fitting effect, i.e., the more accurate the resulting functional relationship, meaning that the original reservoir pressure of the target well predicted using the functional relationship is closer to the actual situation.
The bottom hole flow pressure of the target well Q obtained through experimental test is 5.2MP when the pumping is starteda, substituting the pressure into the linear relation to predict and obtain the original reservoir pressure P of the target well Q r2 ≈4.41MPa。
203. And acquiring the ground pressure differential of the target well based on the original reservoir pressure of the target well and the bottom hole flow pressure of the target well.
In the exemplary embodiment, an adjacent drainage well of target well Q is selected to obtain a desorption pressure for target well Q.
The well distance between the adjacent extraction well and the target well Q is 280 meters, and the desorption pressure P of the target well Q is estimated when the gas pressure of the adjacent extraction well is 2.8MPa in the extraction process de2 About 2.8MPa.
Combining the original reservoir pressure of the target well Q obtained in the step 203, and calculating to obtain the differential pressure delta P of the target well Q c2 ＝P r2 -P de2 ＝1.61MPa。
204. And obtaining the porosity of the target well and the irreducible water saturation of the target well.
In this exemplary embodiment, the porosity and irreducible water saturation of the neighboring parameter wells of the target well Q obtained through the in-house experiment are approximately taken as the porosity and irreducible water saturation of the target well Q.
Coring in the adjacent parameter well of the target well Q, and processing the obtained coal core sample into a cylindrical plunger; performing weighing operation to obtain initial weight W of the coal core sample s1 35.69g; performing measurement operation to obtain a coal core sample with a diameter of 2.55cm and a length of 5.12cm; calculating to obtain apparent volume V of the coal core sample by using volume formula of cylinder b1 About 26.15cm 3 。
Subsequently, the coal core sample is dried at 100 ℃ and then weighed, the drying and weighing operations are repeated until the mass is unchanged, and the weight W of the dry coal core sample is recorded g1 35.35g; then, using a porosity tester to test the pore volume V of the dry coal core sample p1 1.69cm 3 。
Further, in the present exemplary embodiment, the coal seam water density in the adjacent parameter well is taken to be ρ 1 ＝1g/cm 3 。
Knowing the porosity formula and the irreducible water saturation formula, substituting each parameter of the adjacent parameter wells of the target well Q into the formula can be calculated:
the porosity of adjacent parameter wells is:
the irreducible water saturation of adjacent parameter wells is:
determining the porosity of the target well Q as phi 2 Approximately 0.065 and determining the irreducible water saturation of the target well Q as S wi2 ≈0.201。
205. An initial compressibility of the pores of the target well is obtained.
In this exemplary embodiment, the pore initial compression coefficient of the target well Q is approximately taken as the pore initial compression coefficient of its neighboring parameter well, which is obtained through laboratory test.
Coring in an adjacent parameter well of the target well Q, wherein the obtained coal core sample is required to meet experimental standards, and processing the coal core sample into a cylindrical plunger; the permeability of the cylindrical plunger of the coal core sample under different effective stresses was tested, corresponding experimental data were recorded to construct a scatter plot as shown in FIG. 3, and a formula was used to characterize the functional relationship of effective stress (ΔP) and permeability (k)Fitting the experimental data yields the formula shown in fig. 3, which fits the functional relationship of effective stress and permeability in this exemplary embodiment:
y＝0.6669e -0.121x (3)
wherein y represents the permeability of the coal rock, x represents the effective stress of the coal rock, R 2 Representing the goodness of fit, the closer the goodness of fit to 1 indicates the better the fitting effect, i.e., the more accurate the resulting functional relationship.
Can be obtained by comparing the two formulasIn the exemplary embodiment, the initial compression coefficient C of the coal-rock pores of adjacent parameter wells 01 The equation is satisfied: -3C 01 -0.121; further obtain C 01 ≈0.04。
Determining the initial compression coefficient of the pore of the target well Q as C 02 ≈0.04。
206. And acquiring the bottom hole flow pressure depressurization speed of the target well based on the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the ground solution of the target well, the porosity of the target well, the irreducible water saturation of the target well and the initial compression coefficient of the pores of the target well.
In this exemplary embodiment, the empirical formula for calculating the target well Q bottom hole pressure let down rate is:
V opt ＝0.81ln(K)-ln(Φ)-(0.081P r 3 -1.81P r 2 +12.69P r )+(0.15ΔP c 2 -0.22ΔP c )-(11.24S wi 2 -4.11S wi )-(20.6C 0 2 -4.11C 0 )+33 (4)
in the empirical formula, V opt For reasonable depressurization rate, the unit is m/d; k is the reservoir permeability in mD; phi is the porosity and participates in the operation in the form of decimal; p (P) r For the original reservoir pressure, the units are MPa; ΔP c For differential pressure, the unit is MPa; s is S wi To irreducible water saturation, the calculation is participated in the form of decimal; c (C) 0 The initial pore compression coefficient is given in MPa -1 。
The parameter values K obtained in the steps are processed 2 ＝0.042mD，Φ 2 ≈0.065，S wi2 ≈0.201，C 02 ≈0.04，ΔP c2 ＝1.61MPa，P r2 Substituting 4.41MPa into the corresponding position of the formula, and calculating to obtain the bottom hole flow pressure dropping speed V of the target well Q opt2 ＝5.99MPa/d。
In the exemplary embodiment, the methods employed in acquiring log data for the parameter well and the target well in steps 201, 202 are not limited.
In an exemplary embodiment of the application, parameter data of a target well in a coal-bed gas well production area is obtained, and the bottom-hole flow pressure depressurization rate of the target well is obtained based on a functional relationship between the parameter data and the bottom-hole flow pressure depressurization rate. In the method, the monitoring data of various wells on the exploitation site are more flexibly applied, and the rationality of the final result and the adaptability to the actual development environment are ensured; the method has the advantages of simplifying the working flow, saving the acquisition time and being better popularized and applied in the exploitation site.
Referring to fig. 4, an embodiment of the present application further provides an apparatus 400 for obtaining a down hole pressure decreasing speed, the apparatus comprising:
a first obtaining module 401, configured to obtain a reservoir permeability of the target well based on the depth-to-depth lateral resistivity difference of the target well and the acoustic time difference of the target well; a second obtaining module 402, configured to obtain an original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping; a third obtaining module 403, configured to obtain a differential pressure of the target well based on the original reservoir pressure of the target well and the desorption pressure of the target well; a fourth obtaining module 404, configured to obtain a bottom hole pressure depressurization rate of the target well based on the reservoir permeability of the target well, the original reservoir pressure of the target well, the differential pressure of the target well, the porosity of the target well, the irreducible water saturation of the target well, and the initial compression coefficient of the porosity of the target well.
In one possible implementation, the first obtaining module 401 is configured to:
acquiring a depth lateral resistivity difference value of the target well and an acoustic time difference of the target well based on logging information of the target well; and acquiring the reservoir permeability of the target well corresponding to the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well based on the functional relation among the reservoir permeability, the depth lateral resistivity difference value and the acoustic time difference.
Referring to fig. 5, in one possible implementation, the apparatus 400 further includes:
a first construction module 405, configured to obtain a functional relationship between the reservoir permeability, the depth lateral resistivity difference, and the acoustic time difference based on the reservoir permeability, the depth lateral resistivity difference, and the acoustic time difference of each of the plurality of parameter wells, where the parameter wells are wells used for surveying geological conditions in the exploration phase.
In one possible implementation, the second obtaining module 402 is configured to:
acquiring the bottom hole flow pressure of the target well during pumping based on the monitoring data of the target well; and acquiring the original reservoir pressure of the target well corresponding to the bottom hole flow pressure when the target well is started to be pumped based on the functional relation between the bottom hole flow pressure when the target well is started to be pumped and the original reservoir pressure.
Referring to fig. 5, in one possible implementation, the apparatus 400 further includes:
a second building block 406 is configured to obtain a functional relationship between the pump-up bottom hole flow pressure and the original reservoir pressure based on the original reservoir pressure and the pump-up bottom hole flow pressure for each of the plurality of parameter wells.
In one possible implementation, the third obtaining module 403 is configured to:
obtaining the desorption pressure of the adjacent parameter well of the target well, determining the desorption pressure of the target well based on the desorption pressure of the adjacent parameter well, or obtaining the gas-finding pressure of the adjacent drainage well of the target well, and determining the desorption pressure of the target well based on the gas-finding pressure of the adjacent drainage well; and obtaining the difference value between the original reservoir pressure of the target well and the desorption pressure of the target well as the ground solution pressure difference of the target well.
Referring to fig. 5, in one possible implementation, the apparatus 400 further includes:
a fifth obtaining module 407, configured to determine the porosity and the irreducible water saturation of the adjacent production parameter wells based on experimental data of the coal core samples of the adjacent parameter wells of the target well; the porosity and the irreducible water saturation of the adjacent parameter wells are taken as the porosity of the target well and the irreducible water saturation of the target well.
Referring to fig. 5, in one possible implementation, the apparatus 400 further includes:
a sixth acquisition module 408 that acquires permeability of the coal core sample under different effective stresses based on experimental data of the coal core samples of adjacent parameter wells of the target well; determining pore initial compression coefficients of adjacent parameter wells based on the effective stress and the corresponding permeability; and taking the initial compression coefficient of the pores of the adjacent parameter wells as the initial compression coefficient of the pores of the target well.
The apparatus provided in fig. 4 and fig. 5 is only exemplified by the division of the above functional modules when implementing the functions thereof, and in practical applications, the above functional allocation may be implemented by different functional modules according to needs, i.e. the internal structure of the device is divided into different functional modules to implement all or part of the functions described above. In addition, the apparatus and the method embodiments provided in the foregoing embodiments belong to the same concept, and specific implementation processes of the apparatus and the method embodiments are detailed in the method embodiments and are not repeated herein.
There is provided a computer readable storage medium having at least one program code stored therein, the program code loaded and executed by a processor to implement a method of obtaining a bottomhole pressure step-down rate as in any of the method embodiments.
Alternatively, the above-mentioned computer readable storage medium may be a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a Read-Only optical disk (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, and the like.
In an exemplary embodiment, a computer program or computer program product is also provided, having at least one computer instruction stored therein, the at least one computer instruction being loaded and executed by a processor to cause the computer to implement any of the methods of obtaining a bottom hole pressure lowering speed described above.
In an exemplary embodiment, a computer device is also provided, the computer device comprising a processor and a memory, the memory having at least one computer program stored therein. The at least one computer program is loaded and executed by one or more processors to implement any of the methods of obtaining a bottomhole pressure lowering speed described above.
Fig. 6 is a schematic structural diagram of a computer device according to an embodiment of the present application, where the computer device 600 may have a relatively large difference due to different configurations or performances, and may include one or more processors (Central Processing Units, CPU) 601 and one or more memories 602, where the one or more memories 602 store at least one program instruction, and the at least one program instruction is loaded and executed by the one or more processors 601 to implement the method for obtaining the down hole flow pressure step-down speed according to the foregoing method embodiments. Of course, the computer device 600 may also have a wired or wireless network interface, a keyboard, an input/output interface, and other components for implementing the functions of the device, which are not described herein.
It should be understood that, in the embodiments of the present application, the sequence number of each process does not mean the sequence of execution, and the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
The term "at least one" in the present application means one or more, and the term "plurality" in the present application means two or more.
It should be understood that the terminology used in the description of the various examples herein is for the purpose of describing particular examples only and is not intended to be limiting. As used in the description of various examples and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It should be appreciated that determining B from a does not mean determining B from a alone, but may also determine B from a and/or other information.
It should also be understood that the terms "if" and "if" may be interpreted to mean "when" ("white" or "upon") or "in response to a determination" or "in response to detection". Similarly, the phrase "if determined" or "if [ a stated condition or event ] is detected" may be interpreted to mean "upon determination" or "in response to determination" or "upon detection of [ a stated condition or event ] or" in response to detection of [ a stated condition or event ] "depending on the context.
It should be further appreciated that reference throughout this specification to "one embodiment," "an embodiment," "one possible implementation" means that a particular feature, structure, or characteristic described in connection with the embodiment or implementation is included in at least one embodiment of the present application. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment," "one possible implementation" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
The above is only an optional embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily conceivable by those skilled in the art within the technical scope of the present application should be covered in the scope of the present application.
Claims (10)
1. A method of obtaining a down hole pressure rate of depressurization, the method comprising:
acquiring reservoir permeability of a target well based on a depth lateral resistivity difference value of the target well and an acoustic time difference of the target well;
acquiring the original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping;
Acquiring a differential pressure of the target well based on an original reservoir pressure of the target well and a desorption pressure of the target well;
acquiring a bottom hole flow pressure depressurization rate of the target well through data fitting based on reservoir permeability of the target well, original reservoir pressure of the target well, differential pressure of the target well, porosity of the target well, irreducible water saturation of the target well and an initial pore compression coefficient of the target well:
wherein the V is opt For reasonable depressurization rate, the unit is m/d; k is the reservoir permeability in mD; the phi is porosity and is in a decimal form; the P is r For the original reservoir pressure, the units are MPa; the delta P c For differential pressure, the unit is MPa; the S is wi In decimal form for irreducible water saturation; the C is 0 The initial pore compression coefficient is given in MPa -1 。
2. The method of claim 1, wherein the obtaining reservoir permeability of the target well based on the depth-to-depth lateral resistivity difference of the target well and the sonic jet lag of the target well comprises:
acquiring a depth lateral resistivity difference value of the target well and a sonic time difference of the target well based on logging information of the target well;
And acquiring the reservoir permeability of the target well corresponding to the depth side resistivity difference value of the target well and the acoustic time difference of the target well based on a functional relation among the reservoir permeability, the depth side resistivity difference value and the acoustic time difference.
3. The method of claim 2, wherein prior to obtaining the reservoir permeability of the target well corresponding to the depth-to-lateral resistivity difference of the target well and the sonic time difference of the target well based on a functional relationship between reservoir permeability, depth-to-lateral resistivity difference, and sonic time difference, further comprising:
and obtaining a functional relation among the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference based on the reservoir permeability, the depth lateral resistivity difference and the acoustic time difference of each of the plurality of parameter wells, wherein the parameter wells are wells used for surveying geological conditions in the exploration stage.
4. A method according to any one of claims 1-3, wherein the obtaining the original reservoir pressure of the target well based on the pump-up bottom hole pressure of the target well comprises:
acquiring the bottom hole flow pressure of the target well during pumping based on the monitoring data of the target well;
And acquiring the original reservoir pressure of the target well corresponding to the bottom hole flow pressure when the target well is started to be pumped based on a functional relation between the bottom hole flow pressure when the target well is started to be pumped and the original reservoir pressure.
5. The method of claim 4, wherein prior to obtaining the original reservoir pressure of the target well corresponding to the pump-up bottom hole pressure of the target well based on the functional relationship between the pump-up bottom hole pressure and the original reservoir pressure, further comprising:
and acquiring a functional relation between the bottom hole flow pressure at the time of pumping and the original reservoir pressure based on the original reservoir pressure of each parameter well in the plurality of parameter wells and the bottom hole flow pressure at the time of pumping.
6. The method of any one of claims 1-3, 5, wherein the obtaining a differential pressure of the target well based on the original reservoir pressure of the target well and the desorption pressure of the target well comprises:
obtaining a desorption pressure of an adjacent parameter well of the target well, determining a desorption pressure of the target well based on the desorption pressure of the adjacent parameter well, or,
acquiring the gas-visible pressure of an adjacent drainage well of the target well, and determining the desorption pressure of the target well based on the gas-visible pressure of the adjacent drainage well;
And obtaining the difference value between the original reservoir pressure of the target well and the desorption pressure of the target well as the ground desorption pressure difference of the target well.
7. The method of any one of claims 1-3, 5, wherein the obtaining, by data fitting, a bottom hole flow rate depressurization rate for the target well based on the reservoir permeability for the target well, a raw reservoir pressure for the target well, a differential pressure across the target well, a porosity of the target well, a irreducible water saturation for the target well, and an initial compressibility of a pore of the target well, further comprises:
determining porosity and irreducible water saturation of adjacent parameter wells of the target well based on experimental data of coal core samples of the adjacent parameter wells;
and taking the porosity and the irreducible water saturation of the adjacent parameter wells as the porosity and the irreducible water saturation of the target well.
8. The method of any one of claims 1-3, 5, wherein the obtaining, by data fitting, a bottom hole flow rate depressurization rate for the target well based on the reservoir permeability for the target well, a raw reservoir pressure for the target well, a differential pressure across the target well, a porosity of the target well, a irreducible water saturation for the target well, and an initial compressibility of a pore of the target well, further comprises:
Acquiring the permeability of the coal core sample under different effective stress based on experimental data of the coal core sample of the adjacent parameter well of the target well;
determining an initial compression coefficient of the pores of the adjacent parameter wells based on the effective stress and the corresponding permeability;
and taking the initial compression coefficient of the pores of the adjacent parameter wells as the initial compression coefficient of the pores of the target well.
9. An apparatus for obtaining a down hole pressure rate of decrease, the apparatus comprising:
the first acquisition module is used for acquiring the reservoir permeability of the target well based on the depth lateral resistivity difference value of the target well and the acoustic time difference of the target well;
the second acquisition module is used for acquiring the original reservoir pressure of the target well based on the bottom hole flow pressure of the target well during pumping;
a third acquisition module for acquiring a differential pressure of the target well based on an original reservoir pressure of the target well and a desorption pressure of the target well;
a fourth obtaining module, configured to obtain a bottom hole flow pressure depressurization rate of the target well through data fitting based on a reservoir permeability of the target well, an original reservoir pressure of the target well, a differential pressure of the target well, a porosity of the target well, a irreducible water saturation of the target well, and an initial pore compression coefficient of the target well:
Wherein the V is opt For reasonable depressurization rate, the unit is m/d; k is the reservoir permeability in mD; the phi is porosity and is in a decimal form; the P is r For the original reservoir pressure, the units are MPa; the delta P c For differential pressure, the unit is MPa; the S is wi In decimal form for irreducible water saturation; the C is 0 The initial pore compression coefficient is given in MPa -1 。
10. A computer readable storage medium having stored therein at least one program code loaded and executed by a processor to cause a computer to implement the method of obtaining a bottomhole flow pressure step-down rate of any one of claims 1 to 8.
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| CN111027789A (en) * | 2020-01-13 | 2020-04-17 | 中国地质大学（北京） | Calculation method for quantitative optimization of working system of coal-bed gas well |
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| US20040060351A1 (en) * | 2002-09-30 | 2004-04-01 | Gunter William Daniel | Process for predicting porosity and permeability of a coal bed |
| CN105569613A (en) * | 2014-10-10 | 2016-05-11 | 中国石油天然气股份有限公司 | Medium-high-rank coal bed gas drainage and mining method |
| CN105158803A (en) * | 2015-07-27 | 2015-12-16 | 中国石油天然气集团公司 | Method for selecting advantaged reservoir stratum |
| CN107389521A (en) * | 2017-06-22 | 2017-11-24 | 中国石油天然气集团公司 | It is a kind of that the method that coal petrography physical property is determined by well-log information is tested based on the coal heart |
| CN111027789A (en) * | 2020-01-13 | 2020-04-17 | 中国地质大学（北京） | Calculation method for quantitative optimization of working system of coal-bed gas well |
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