CN-122014211-A - Method and device for determining bottom hole flow pressure of coal-bed gas well and electronic equipment

Abstract

The embodiment of the application provides a method and a device for determining bottom hole flow pressure of a coal-bed gas well and electronic equipment. The method comprises the steps of obtaining a first volume value and a second volume value in a coal-bed gas well, wherein the first volume value represents the gas phase instant fluid volume in the coal-bed gas well, the second volume value represents the water phase instant fluid volume in the coal-bed gas well, determining the simulated working fluid level position in the coal-bed gas well according to the first volume value and the second volume value, obtaining the first temperature, the second temperature and the pressure gradient of liquid of the coal-bed gas well, determining the temperature gradient of the coal-bed gas well according to the first temperature and the second temperature, determining the simulated working fluid level temperature of the coal-bed gas well according to the simulated working fluid level position and the temperature gradient, determining the pure gas column pressure corresponding to the coal-bed gas well according to the liquid level position and the liquid level temperature, and determining the bottom hole flow pressure of the coal-bed gas well according to the pure gas column pressure, the simulated working fluid level position and the pressure gradient. The method is used for achieving the effect of accurately determining the bottom hole flow pressure of the coal-bed gas well.

Inventors

• YAN XIA
• FENG YANQING
• HOU WEI
• WU NAN
• LIU WENCHAO
• YANG YUEJIE
• GUO LELE

Assignees

• 中国石油天然气股份有限公司
• 中石油煤层气有限责任公司
• 中联煤层气国家工程研究中心有限责任公司

Dates

Publication Date

20260512

Application Date

20241111

Claims (19)

1. 1. A method for determining the bottom hole flow pressure of a coal-bed gas well, comprising: The method comprises the steps of obtaining a first volume value and a second volume value in a coal-bed gas well, wherein the first volume value represents the gas-phase instantaneous fluid volume in the coal-bed gas well, and the second volume value represents the water-phase instantaneous fluid volume in the coal-bed gas well; Acquiring a first temperature, a second temperature and a pressure gradient of liquid of the coal-bed gas well, wherein the first temperature represents a wellhead temperature of the coal-bed gas well, and the second temperature represents a reservoir temperature at a bottom of the coal-bed gas well; Determining the simulated working fluid level temperature of the coal-bed gas well according to the simulated working fluid level position and the temperature gradient; And determining the bottom hole flowing pressure of the coal-bed gas well according to the pure gas column pressure, the simulated working fluid level position and the pressure gradient, wherein the bottom hole flowing pressure represents the bottom hole pressure when the coal-bed gas well comprises coal-bed gas and liquid.
2. 2. The method of claim 1, wherein obtaining a first volumetric value in a coal-bed gas well comprises: The method comprises the steps of obtaining a first quasi-contrast pressure and a first quasi-contrast temperature, wherein the first quasi-contrast pressure is determined based on the wellhead pressure of a coal-bed gas well and the initial pressure at the bottom of a well when only gas is contained in a production shaft of the coal-bed gas well, and the first quasi-contrast temperature is determined based on the wellhead temperature of the coal-bed gas well and the initial temperature at the bottom of the well when only gas is contained in the production shaft of the coal-bed gas well; determining a first compression factor based on the first quasi-contrast pressure and the first quasi-contrast temperature; Determining a volume coefficient of the coalbed methane according to the first compression factor, the standard pressure and the standard temperature, wherein the standard pressure represents the coalbed methane pressure under the standard condition, and the standard temperature represents the coalbed methane temperature under the standard condition; and determining the first volume value according to the volume coefficient of the coalbed methane and the preset daily output of the coalbed methane.
3. 3. The method of claim 2, wherein obtaining the first quasi-contrast pressure and the first quasi-contrast temperature comprises: Acquiring wellhead pressure, wellhead temperature, bottom hole initial temperature and coal bed gas density of the coal bed gas well, wherein the bottom hole initial temperature represents the initial temperature at the bottom hole when only gas is contained in a production shaft of the coal bed gas well; determining the initial bottom pressure according to the density of the coal-bed gas, the gravity acceleration and the production well depth of the coal-bed gas well, wherein the initial bottom pressure represents the initial bottom pressure when only gas is contained in the production well of the coal-bed gas well; determining an average pressure in a first shaft of the coal-bed gas well according to the wellhead pressure and the bottom-hole initial pressure; The method comprises the steps of determining a first quasi-contrast pressure according to average pressure in a first shaft and preset pressure, wherein the preset pressure represents critical pressure of coal bed gas, determining a first quasi-contrast temperature according to average temperature in the first shaft and preset temperature, and the preset temperature represents critical temperature of the coal bed gas.
4. 4. The method of claim 1, wherein determining a pseudo-meniscus position in the coalbed methane well from the first volume value and the second volume value comprises: Obtaining a third volume value according to the sum of the first volume value and the second volume value; and determining the pseudo-working fluid level position according to the second volume value, the third volume value and the production well depth of the coal-bed gas well.
5. 5. The method of claim 1, wherein determining the temperature gradient of the coalbed methane well from the first temperature and the second temperature comprises: And determining the temperature gradient of the coal-bed gas well according to the first temperature, the second temperature and the production well depth of the coal-bed gas well.
6. 6. The method of claim 1, wherein determining the corresponding pure gas column pressure for the coalbed methane well based on the simulated meniscus position and the simulated meniscus temperature comprises: repeating the following steps until a first preset condition is reached, wherein the initial pressure obtained for the first time is determined based on the simulated working fluid level position and the wellhead pressure of the coal-bed gas well: Determining an average pressure in a second shaft of the coal-bed gas well according to the wellhead pressure of the coal-bed gas well and the initial pressure, wherein the initial pressure represents an initially acquired pure gas column pressure, the average pressure in the second shaft represents an average pressure of a pure gas column in a production shaft of the coal-bed gas well, and determining an average temperature in the second shaft of the coal-bed gas well according to the wellhead temperature of the coal-bed gas well and the simulated working fluid level temperature, wherein the average temperature in the second shaft represents an average temperature of a pure gas column in a production shaft of the coal-bed gas well; Determining a second quasi-contrast pressure according to the average pressure in the second shaft and a preset pressure, wherein the preset pressure represents the critical pressure of the coalbed methane, and determining a second quasi-contrast temperature according to the average temperature in the second shaft and a preset temperature, wherein the preset temperature represents the critical temperature of the coalbed methane; Determining a second compression factor according to the second quasi-contrast pressure and the second quasi-contrast temperature, and determining a target pressure according to the second compression factor; If the difference value between the target pressure and the initial pressure accords with a first preset condition, determining the target pressure as the pure gas column pressure corresponding to the coal-bed gas well; And if the difference value between the target pressure and the initial pressure is not in accordance with a first preset condition, updating the initial pressure to the target pressure.
7. 7. The method of claim 6, wherein determining a target pressure based on the second compression factor comprises: Determining a parameter factor according to the production well depth of the coal-bed gas well, the simulated working fluid level position, the average temperature in the second shaft, a preset gas relative density value and the second compression factor; Determining the Reynolds number in a production shaft of the coal-bed gas well according to preset gas flow, a preset gas relative density value, preset coal-bed gas viscosity, the inner diameter of a sleeve of the coal-bed gas well and the outer diameter of an oil pipe of the coal-bed gas well, wherein the preset gas flow represents the gas flow under the standard condition; Determining the friction coefficient of the coal-bed gas well according to the absolute roughness of a preset pipe, the inner diameter of a sleeve of the coal-bed gas well, the outer diameter of an oil pipe of the coal-bed gas well and the Reynolds number in a production shaft of the coal-bed gas well; And determining a target pressure according to the wellhead pressure of the coal-bed gas well, the friction coefficient of the coal-bed gas well, the average temperature in the second shaft, the second compression factor, the preset gas flow, the sleeve inner diameter of the coal-bed gas well and the outer diameter of the oil pipe of the coal-bed gas well.
8. 8. The method of any one of claims 1-7, wherein determining the bottom hole flow pressure of the coal-bed gas well from the pure gas column pressure, the pseudo-meniscus position, and the pressure gradient comprises: Repeating the following steps until a first preset condition is reached, wherein the initial bottom hole flow pressure acquired for the first time is determined based on the pure gas column pressure of the coal-bed gas well, the pressure gradient and the pseudo-working fluid level position, and the pressure gradient is determined by the liquid density and the gravity acceleration: Determining the average pressure in a third well barrel of the coal-bed gas well according to the pure gas column pressure of the coal-bed gas well and the initial bottom hole flow pressure, wherein the initial bottom hole flow pressure represents the initially acquired bottom hole flow pressure; determining the average temperature in the third well barrel of the coal-bed gas well according to the simulated working fluid level temperature of the coal-bed gas well and the initial bottom hole temperature, wherein the average temperature in the third well barrel represents the average temperature of the gas-water two-phase liquid column in the production well barrel of the coal-bed gas well; Determining a third quasi-contrast pressure according to the average pressure in the third well barrel and a preset pressure, wherein the preset pressure represents the critical pressure of the coal bed gas, and determining a third quasi-contrast temperature according to the average temperature in the third well barrel and a preset temperature, wherein the preset temperature represents the critical temperature of the coal bed gas; Determining a third compression factor according to the third quasi-contrast pressure and the third quasi-contrast temperature, and determining a target bottom hole flow pressure according to the third compression factor; If the difference value between the target bottom-hole flow pressure and the initial bottom-hole flow pressure accords with a first preset condition, determining the target bottom-hole flow pressure as the bottom-hole flow pressure corresponding to the coal-bed gas well; And if the difference value between the target bottom-hole flow pressure and the initial bottom-hole flow pressure is not in accordance with a first preset condition, updating the initial bottom-hole flow pressure into the target bottom-hole flow pressure.
9. 9. The method of claim 8, wherein determining a target bottom hole flow pressure based on the third compression factor comprises: determining the apparent flow rate of gas according to the preset gas flow rate, the average temperature in a third well barrel of the coal-bed gas well, the average pressure in the third well barrel of the coal-bed gas well, the third compression factor, the standard pressure, the standard temperature and the annular cross-sectional area between the sleeve and the oil pipe of the coal-bed gas well, wherein the annular cross-sectional area between the sleeve and the oil pipe of the coal-bed gas well is determined by the inner diameter of the sleeve of the coal-bed gas well and the outer diameter of the oil pipe of the coal-bed gas well; If the apparent flow rate of the gas is determined to meet the second preset condition, determining the preset parameter as a first preset parameter; If the apparent flow rate of the gas is determined to be not in accordance with a second preset condition, determining the preset parameter as a second preset parameter; Determining the void fraction according to the preset parameters and the apparent gas flow rate; determining a third related parameter according to the preset gas flow, the standard temperature, the average temperature in the third well barrel, the third compression factor, the standard pressure and the annular cross-sectional area between the casing pipe and the oil pipe of the coal-bed gas well; Determining a first related parameter according to the third related parameter, the void fraction, the preset parameter, the wellhead pressure of the coal-bed gas well, the pressure difference of a pure gas column, the simulated dynamic liquid level position and the pressure gradient, wherein the pressure difference of the pure gas column is obtained by the difference between the wellhead pressure of the coal-bed gas well and the corresponding pure gas column pressure of the coal-bed gas well; Determining a second correlation coefficient according to the third correlation coefficient, the void fraction, the preset parameter, a preset gas constant, a preset molar mass, the simulated dynamic liquid level position, the third compression factor, the average temperature in the third well barrel, the pressure gradient, the wellhead pressure of the coal-bed gas well and the pressure difference of the pure gas column, wherein the gas constant represents a general gas constant; And determining a target bottom hole flow pressure according to the wellhead pressure of the coal-bed gas well, the pressure difference of the pure gas column, the pressure gradient, the simulated dynamic liquid level position, the first related parameter and the second related parameter.
10. 10. A device for determining the bottom hole flow pressure of a coal-bed gas well, comprising: The system comprises a first acquisition module, a second acquisition module, a first control module and a second control module, wherein the first volume value is used for acquiring a first volume value and a second volume value in the coal-bed gas well, the first volume value represents the gas-phase instantaneous fluid volume in the coal-bed gas well, and the second volume value represents the water-phase instantaneous fluid volume in the coal-bed gas well; The system comprises a first acquisition module, a second acquisition module, a first temperature detection module, a second acquisition module and a control module, wherein the first temperature is used for acquiring a first temperature, a second temperature and a pressure gradient of liquid of the coal-bed gas well, the first temperature represents a wellhead temperature of the coal-bed gas well, the second temperature represents a reservoir temperature at a bottom of the coal-bed gas well, and the temperature gradient of the coal-bed gas well is determined according to the first temperature and the second temperature; The first determining module is used for determining the simulated working fluid level temperature of the coal-bed gas well according to the simulated working fluid level position and the temperature gradient; And determining the bottom hole flow pressure of the coal-bed gas well according to the pure gas column pressure, the simulated liquid level position and the pressure gradient, wherein the bottom hole flow pressure represents the bottom hole pressure when the coal-bed gas well comprises coal-bed gas and liquid.
11. 11. The apparatus of claim 10, wherein the first acquisition module comprises: The system comprises a first acquisition submodule, a second acquisition submodule and a third submodule, wherein the first quasi-comparison pressure is determined based on the wellhead pressure of the coal-bed gas well and the initial pressure at the bottom of the well when only gas is contained in the production well of the coal-bed gas well, and the first quasi-comparison temperature is determined based on the wellhead temperature of the coal-bed gas well and the initial temperature at the bottom of the well when only gas is contained in the production well of the coal-bed gas well; a third determining module configured to determine a first compression factor according to the first quasi-contrast pressure and the first quasi-contrast temperature; The fourth confirmation module is used for determining the volume coefficient of the coalbed methane according to the first compression factor, the standard pressure and the standard temperature, wherein the standard pressure represents the coalbed methane pressure under the standard condition, and the standard temperature represents the coalbed methane temperature under the standard condition; And the fifth confirmation module is used for determining the first volume value according to the volume coefficient of the coalbed methane and the preset daily output of the coalbed methane.
12. 12. The apparatus of claim 11, wherein the first acquisition sub-module comprises: The second acquisition submodule is used for acquiring wellhead pressure, wellhead temperature, bottom hole initial temperature and coal bed gas density of the coal bed gas well, wherein the bottom hole initial temperature represents the initial temperature at the bottom hole when only gas is contained in a production shaft of the coal bed gas well; A sixth confirmation module, configured to determine a bottom hole initial pressure according to the coalbed methane density, the gravity acceleration, and the production well depth of the coalbed methane well, where the bottom hole initial pressure characterizes an initial pressure at a bottom hole when only gas is contained in a production well of the coalbed methane well; The seventh confirmation module is used for determining average pressure in a first shaft of the coal-bed gas well according to the wellhead pressure and the bottom hole initial pressure; The eighth confirmation module is used for determining a first quasi-contrast pressure according to the average pressure in the first shaft and a preset pressure, wherein the preset pressure represents the critical pressure of the coal bed gas, and determining a first quasi-contrast temperature according to the average temperature in the first shaft and a preset temperature, and the preset temperature represents the critical temperature of the coal bed gas.
13. 13. The apparatus of claim 10, wherein the first acquisition module further comprises: The calculation module is used for obtaining a third volume value according to the sum of the first volume value and the second volume value; And a ninth confirmation module, configured to determine the pseudo-working fluid level position according to the second volume value, the third volume value, and the production well depth of the coalbed methane well.
14. 14. The apparatus of claim 10, wherein the second acquisition module comprises: And a tenth confirmation module, configured to determine a temperature gradient of the coalbed methane well according to the first temperature, the second temperature, and a production well depth of the coalbed methane well.
15. 15. The apparatus of claim 10, wherein the second determining module comprises: The first circulation module is used for repeatedly executing the following steps until a first preset condition is reached, wherein the initial pressure acquired for the first time is determined based on the simulated liquid level position and the wellhead pressure of the coal-bed gas well: The system comprises a first confirmation sub-module, a second confirmation sub-module, a first confirmation sub-module, a second confirmation sub-module and a first confirmation sub-module, wherein the first confirmation sub-module is used for confirming average pressure in a second shaft of the coal-bed gas well according to the wellhead pressure of the coal-bed gas well and the initial pressure, wherein the initial pressure represents the initially acquired pure gas column pressure; The system comprises a first determination submodule, a second determination submodule, a first comparison submodule and a second comparison submodule, wherein the first determination submodule is used for determining a first comparison pressure according to average pressure and preset pressure in a first shaft, the preset pressure represents critical pressure of coal bed gas, and determining a first comparison temperature according to average temperature and preset temperature in the first shaft, and the preset temperature represents critical temperature of the coal bed gas; The third confirmation sub-module is used for determining a second compression factor according to the second quasi-contrast pressure and the second quasi-contrast temperature, and determining a target pressure according to the second compression factor; A fourth confirmation sub-module, configured to determine the target pressure as the pure gas column pressure corresponding to the coalbed methane well if it is determined that the difference between the target pressure and the initial pressure meets a first preset condition; And the first updating module is used for updating the initial pressure to the target pressure if the difference value between the target pressure and the initial pressure is determined to be not in accordance with a first preset condition.
16. 16. The apparatus of claim 15, wherein the third acknowledgment submodule comprises: a fourth determination submodule, configured to determine a parameter factor according to the production well depth of the coalbed methane well, the pseudo-working fluid level position, the average temperature in the second wellbore, a preset gas relative density value, and the second compression factor; A fifth confirmation sub-module, configured to determine a reynolds number in a production wellbore of the coalbed methane well according to a preset gas flow, a preset gas relative density value, a preset coalbed methane viscosity, a sleeve inner diameter of the coalbed methane well, and an oil pipe outer diameter of the coalbed methane well, where the preset gas flow represents a gas flow under a standard condition; A sixth confirmation submodule, configured to determine a friction coefficient of the coal-bed gas well according to a preset absolute roughness of a pipe, an inside diameter of a sleeve of the coal-bed gas well, an outside diameter of an oil pipe of the coal-bed gas well, and a reynolds number in a production well bore of the coal-bed gas well; And a seventh confirmation sub-module, configured to determine a target pressure according to the wellhead pressure of the coal-bed gas well, the friction coefficient of the coal-bed gas well, the average temperature in the second wellbore, the second compression factor, the preset gas flow, the sleeve inner diameter of the coal-bed gas well, and the oil pipe outer diameter of the coal-bed gas well.
17. 17. The apparatus of any one of claims 10-16, wherein the second determining module further comprises: The second repeating module is used for repeatedly executing the following steps until a first preset condition is reached, wherein the initial bottom hole flow pressure acquired for the first time is determined based on the pure gas column pressure, the pressure gradient and the pseudo-working fluid level position of the coal-bed gas well, and the pressure gradient is determined by the liquid density and the gravity acceleration: An eighth determination submodule, configured to determine a third in-wellbore average pressure of the coal-bed gas well according to the pure gas column pressure of the coal-bed gas well and the initial bottom-hole flow pressure, where the initial bottom-hole flow pressure represents an initial acquired bottom-hole flow pressure, and the third in-wellbore average pressure represents an average pressure of a gas-water two-phase liquid column in a production wellbore of the coal-bed gas well; A ninth confirmation sub-module, configured to determine a third quasi-contrast pressure according to the average pressure in the third well casing and a preset pressure, where the preset pressure represents a critical pressure of the coalbed methane, and determine a third quasi-contrast temperature according to the average temperature in the third well casing and a preset temperature, where the preset temperature represents a critical temperature of the coalbed methane; A tenth confirmation sub-module for determining a third compression factor according to the third quasi-contrast pressure and the third quasi-contrast temperature, and determining a target bottom hole flow pressure according to the third compression factor; An eleventh determination submodule, configured to determine the target bottom-hole flow pressure as a bottom-hole flow pressure corresponding to the coal-bed gas well if it is determined that the difference between the target bottom-hole flow pressure and the initial bottom-hole flow pressure meets a first preset condition; And the second updating module is used for updating the initial bottom-hole flow pressure into the target bottom-hole flow pressure if the difference value between the target bottom-hole flow pressure and the initial bottom-hole flow pressure is determined to be not in accordance with the first preset condition.
18. 18. The apparatus of claim 17, wherein the tenth acknowledgment submodule comprises: A twelfth confirmation sub-module, configured to determine a gas apparent flow rate according to the preset gas flow rate, the average temperature in a third well barrel of the coal-bed gas well, the average pressure in the third well barrel of the coal-bed gas well, the third compression factor, the standard pressure, the standard temperature, and the annular cross-sectional area between the casing and the oil pipe of the coal-bed gas well, where the annular cross-sectional area between the casing and the oil pipe of the coal-bed gas well is determined by the casing inner diameter of the coal-bed gas well and the oil pipe outer diameter of the coal-bed gas well; A thirteenth confirmation sub-module, configured to determine the preset parameter as the first preset parameter if it is determined that the gas apparent flow rate meets a second preset condition; A fourteenth confirmation sub-module, configured to determine the preset parameter as a second preset parameter if it is determined that the gas apparent flow rate does not meet a second preset condition; A fifteenth determination submodule, configured to determine a void fraction according to the preset parameter and the apparent gas flow rate; A sixteenth determination submodule, configured to determine a third related parameter according to the preset gas flow, the standard temperature, the average temperature in the third wellbore, the third compression factor, the standard pressure, and an annular cross-sectional area between the casing of the coalbed methane well and the oil pipe; A seventeenth confirmation sub-module, configured to determine a first related parameter according to the third related parameter, the void fraction, the preset parameter, the wellhead pressure of the coal-bed gas well, the pressure difference of a pure gas column, the pseudo-working fluid level position, and the pressure gradient, where the pressure difference of the pure gas column is obtained by a difference between the wellhead pressure of the coal-bed gas well and the pressure of the pure gas column corresponding to the coal-bed gas well; An eighteenth confirmation sub-module, configured to determine a second correlation coefficient according to the third correlation coefficient, the void fraction, the preset parameter, a preset gas constant, a preset molar mass, the pseudo-working fluid level position, the third compression factor, an average temperature in the third well barrel, the pressure gradient, a wellhead pressure of the coal-bed gas well, and a pressure difference of the pure gas column, where the gas constant represents a universal gas constant; And the nineteenth confirmation submodule is used for determining a target bottom hole flow pressure according to the wellhead pressure of the coal-bed gas well, the pressure difference of the pure gas column, the pressure gradient, the quasi-working fluid level position, the first related parameter and the second related parameter.
19. 19. An electronic device is characterized by comprising a memory and a processor; The memory stores computer-executable instructions; the processor executing computer-executable instructions stored in the memory, causing the processor to perform the method of any one of claims 1-9.

Description

Method and device for determining bottom hole flow pressure of coal-bed gas well and electronic equipment Technical Field The application relates to the technical field of development of coal-bed gas wells, in particular to a method and a device for determining bottom hole flow pressure of a coal-bed gas well and electronic equipment. Background In the exploitation process of the coal-bed gas well, the state of natural gas in a shaft of the coal-bed gas well needs to be determined, in the prior art, the bottom hole flow pressure of the coal-bed gas well needs to be determined, and modeling is carried out based on the bottom hole flow pressure to determine the state of the natural gas. Further, a need exists for a solution that can accurately determine the bottom hole pressure of a coal-bed gas well. Disclosure of Invention The embodiment of the application provides a method and a device for determining the bottom hole flow pressure of a coal-bed gas well and electronic equipment, which are used for achieving the effect of accurately determining the bottom hole flow pressure of the coal-bed gas well. In a first aspect, an embodiment of the present application provides a method for producing a bottom hole flow pressure of a coal-bed gas well, including: The method comprises the steps of obtaining a first volume value and a second volume value in the coal-bed gas well, wherein the first volume value represents the gas-phase instantaneous fluid volume in the coal-bed gas well, the second volume value represents the water-phase instantaneous fluid volume in the coal-bed gas well, and determining the pseudo-working fluid level position in the coal-bed gas well according to the first volume value and the second volume value. The method comprises the steps of obtaining a first temperature, a second temperature and a pressure gradient of liquid of the coal-bed gas well, wherein the first temperature represents the wellhead temperature of the coal-bed gas well, the second temperature represents the reservoir temperature at the bottom of the coal-bed gas well, and the temperature gradient of the coal-bed gas well is determined according to the first temperature and the second temperature. And determining the simulated working fluid level temperature of the coal-bed gas well according to the simulated working fluid level position and the temperature gradient. And determining the bottom hole flowing pressure of the coal-bed gas well according to the pure gas column pressure, the simulated working fluid level position and the pressure gradient, wherein the bottom hole flowing pressure represents the bottom hole pressure when the coal-bed gas well comprises coal-bed gas and liquid. In one possible embodiment, obtaining a first volumetric value in a coal-bed gas well comprises: and obtaining a first quasi-contrast pressure and a first quasi-contrast temperature, wherein the first quasi-contrast pressure is determined based on the wellhead pressure of the coal-bed gas well and the initial pressure at the bottom of the well when only gas is contained in the production well of the coal-bed gas well, and the first quasi-contrast temperature is determined based on the wellhead temperature of the coal-bed gas well and the initial temperature at the bottom of the well when only gas is contained in the production well of the coal-bed gas well. A first compression factor is determined based on the first quasi-contrast pressure and the first quasi-contrast temperature. Determining a volume coefficient of the coalbed methane according to the first compression factor, the standard pressure and the standard temperature, wherein the standard pressure represents the coalbed methane pressure under the standard condition, and the standard temperature represents the coalbed methane temperature under the standard condition; and determining the first volume value according to the volume coefficient of the coalbed methane and the preset daily output of the coalbed methane. In one possible embodiment, obtaining the first quasi-contrast pressure and the first quasi-contrast temperature comprises: and acquiring wellhead pressure, wellhead temperature, bottom hole initial temperature and coal bed gas density of the coal bed gas well, wherein the bottom hole initial temperature represents the initial temperature at the bottom hole when only gas is contained in a production shaft of the coal bed gas well. And determining the initial bottom pressure according to the density of the coal-bed gas, the gravity acceleration and the production well depth of the coal-bed gas well, wherein the initial bottom pressure represents the initial bottom pressure when only gas is contained in the production well of the coal-bed gas well. And determining the average temperature in the first shaft of the coal-bed gas well according to the wellhead temperature and the bottom hole initial temperature. The method comprises the steps of determining a first quasi-contrast