CN-121995030-A - Method, device, equipment and storage medium for determining natural gas content in rock

CN121995030ACN 121995030 ACN121995030 ACN 121995030ACN-121995030-A

Abstract

The application discloses a method, a device, equipment and a storage medium for determining the content of natural gas in rock, and belongs to the technical field of petroleum and natural gas exploitation. The method comprises the steps of determining the relative molecular weight of natural gas in rock, determining the total void space of the rock with unit mass, determining first formation pressure of an oilfield stratum at a stratum depth under normal pressure, determining second formation pressure of the rock under standard condition, determining first density of the natural gas of the rock under the standard condition, determining first gas content of the rock under the standard condition based on the relative molecular weight of the natural gas, the first density, the volume ratio of the natural gas in the rock, the total void space and the volume ratio of the natural gas with unit mole, and converting the first gas content into second gas content of the rock under ideal condition. The method and the device can consider the influence of the temperature on the gas content of the natural gas, namely improve the accuracy of the determined second gas content.

Inventors

MA JIANYING
YANG YUQI
ZHOU KEJIA
ZHAO JUN
YU CHUNYONG
WANG CHANGLI
MENG LINA
CHEN SHUANGQING
LIU HONGZHOU
DONG YUEQI

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241104

Claims (10)

1. A method for determining the natural gas content in rock, the method comprising: determining the relative molecular mass of natural gas in the rock; Determining a rock density and a total porosity of the rock, determining a total void space per unit mass of the rock based on the rock density and the total porosity; Determining the stratum water density of an oil field where the rock is located and the stratum depth of the oil field, and determining the first stratum pressure of the oil field stratum in a normal pressure state of the stratum depth of the oil field based on the stratum water density and the stratum depth, wherein the normal pressure state is a state that the temperature is a first preset temperature and the pressure is a first preset pressure; Determining a second formation pressure of the rock in a standard state based on the first formation pressure and the formation coefficient of the oilfield formation, wherein the standard state is a state in which the temperature is the first preset temperature and the pressure is the second preset pressure; determining a first density of natural gas of the rock in a standard state based on the second formation pressure, the volume fraction of each component in the rock, and the density of other components than the natural gas; Determining a first gas content of the rock in a standard state based on the relative molecular mass of the natural gas, the first density, the volume fraction of the natural gas in the rock, the total void space, and the volume of the natural gas fraction per mole; and converting the first gas content into a second gas content of the rock in an ideal state, wherein the ideal state is a state that the temperature is a second preset temperature and the pressure is the second preset pressure.
2. The method according to claim 1, wherein the method further comprises: Determining a second density of natural gas of the rock at normal pressure based on the first formation pressure, the volume fraction of each component in the rock, and the density of other components than the natural gas; determining a second number of moles of the natural gas at atmospheric conditions based on the relative molecular mass of the natural gas, the second density, the volumetric ratio of the natural gas in the rock, and the total void space; and determining a third gas content of the rock under normal pressure based on the second mole number and the volume occupied by the natural gas per mole number.
3. The method of claim 1, wherein the determining a total void space per unit mass of the rock based on the rock density and the total porosity comprises: Based on the rock density and the total porosity, determining a total void space per unit mass of the rock by the following formula one: Equation one: wherein V represents the total pore space of the rock, m represents the unit rock mass, ρ Rock represents the rock density, the Indicating the total porosity.
4. The method of claim 1, wherein the determining the first gas content of the rock at the standard condition based on the relative molecular mass of the natural gas, the first density, the volume fraction of the natural gas in the rock, the total void space, and the volume fraction of natural gas per mole comprises: Based on the relative molecular mass of the natural gas, the first density, the volumetric ratio of the natural gas in the rock, and the total void space, a first number of moles of the natural gas in a standard state is determined by the following equation two: Formula II, n Standard of ＝B Natural gas *ρ1 Natural gas V1/M Determining a first gas content of the rock in a standard state based on the first mole number and the volume occupied by natural gas per mole number by the following formula three; formula III Q Standard of ＝n Standard of V2 Wherein n Standard of represents a first mole number, B Natural gas represents a relative molecular mass of the natural gas, ρ1 Natural gas represents the first density, V1 represents a volume fraction of the natural gas in the rock, M represents the total pore space, Q Standard of represents the first gas content, and V2 represents a volume occupied by the natural gas per mole number.
5. The method of claim 1, wherein said converting said first gas content to a second gas content of said rock at an ideal condition comprises: Based on a first temperature of the rock in a standard state, a second temperature of the rock in an ideal state, and the first gas content, the first gas content is converted into a second gas content of the rock in an ideal state by the following formula four: Formula four, t1/v3=t2/V4 Wherein T1 represents the first temperature, T2 represents the second temperature, V3 represents the first gas content, and V4 represents the second gas content.
6. The method of claim 1, wherein each component in the rock comprises natural gas, crude oil, and formation water; the determining a first density of natural gas for the rock at a standard condition based on the second formation pressure, the volume fractions of the individual components in the rock, and the densities of other components than the natural gas, comprising: Determining a first density of natural gas of the rock in a standard state based on the second formation pressure, the volume fraction of natural gas, the volume fraction of crude oil, the volume fraction of formation water, the density of crude oil, and the formation water density by the following formula five: Formula five P Standard of ＝(B Natural gas ρ1 Natural gas +B Crude oil ρ Crude oil +B Formation water ρ Formation water ) g Δh Wherein P Standard of represents the second formation pressure, B Natural gas represents the volume ratio of natural gas, ρ1 Natural gas represents the first density of natural gas, B Crude oil represents the volume ratio of crude oil, ρ Crude oil represents the density of crude oil, B Formation water represents the volume ratio of formation water, ρ Formation water represents the formation water density, g represents the gravity coefficient, and Δh represents the formation depth.
7. A device for determining the natural gas content in rock, the device comprising: A first determination module for determining the relative molecular mass of natural gas in the rock; A second determination module for determining a rock density and a total porosity of the rock, determining a total void space per unit mass of the rock based on the rock density and the total porosity; The third determining module is used for determining the stratum water density of the oil field where the rock is located and the stratum depth of the oil field, and determining the first stratum pressure of the stratum of the oil field in a normal pressure state of the stratum depth of the oil field based on the stratum water density and the stratum depth, wherein the normal pressure state is a state that the temperature is a first preset temperature, and the pressure is a first preset pressure; A fourth determining module, configured to determine a second formation pressure of the rock in a standard state based on the first formation pressure and a formation coefficient of the oilfield formation, where the standard state is a state in which a temperature is the first preset temperature and a pressure is a second preset pressure; a fifth determination module for determining a first density of natural gas of the rock in a standard state based on the second formation pressure, a volume fraction of each component in the rock, and a density of other components than the natural gas; a sixth determination module for determining a first gas content of the rock in a standard state based on a relative molecular mass of the natural gas, the first density, a volume fraction of the natural gas in the rock, the total void space, and a volume fraction of natural gas per mole; The conversion module is used for converting the first gas content into a second gas content of the rock in an ideal state, wherein the ideal state is a state that the temperature is a second preset temperature and the pressure is the second preset pressure.
8. A computer device, characterized in that it comprises a processor and a memory, in which at least one program code is stored, which is loaded and executed by the processor to carry out the method of determining the natural gas content in rock according to any one of claims 1 to 6.
9. A computer readable storage medium, characterized in that at least one program code is stored in the storage medium, which is loaded and executed by a processor to implement a method of determining the natural gas content in rock according to any one of claims 1 to 6.
10. A computer program product, characterized in that the product stores at least one program code for execution by a processor for implementing a method of determining the natural gas content in rock according to any one of claims 1 to 6.

Description

Method, device, equipment and storage medium for determining natural gas content in rock Technical Field The application relates to the technical field of petroleum and natural gas exploitation, in particular to a method, a device, equipment and a storage medium for determining the content of natural gas in rock. Background Rocks, particularly those with voids, cracks and vugs, are rich in natural gas and the natural gas content of the rock is an important parameter for natural gas resource evaluation and preference of the beneficial zone. The natural gas content in the rock refers to the volume of 1 ton of natural gas in the rock under the conditions of 101.325kPa and 25 ℃. Therefore, how to determine the natural gas content in rock is an important point in the industry. Disclosure of Invention The embodiment of the application provides a method, a device, equipment and a storage medium for determining the content of natural gas in rock, which can consider the influence of temperature on the content of the natural gas, namely improve the accuracy of the determined second content of the natural gas. The technical scheme is as follows: In one aspect, a method for determining natural gas content in rock is provided, the method comprising: determining the relative molecular mass of natural gas in the rock; Determining a rock density and a total porosity of the rock, determining a total void space per unit mass of the rock based on the rock density and the total porosity; Determining the stratum water density of an oil field where the rock is located and the stratum depth of the oil field, and determining the first stratum pressure of the oil field stratum in a normal pressure state of the stratum depth of the oil field based on the stratum water density and the stratum depth, wherein the normal pressure state is a state that the temperature is a first preset temperature and the pressure is a first preset pressure; Determining a second formation pressure of the rock in a standard state based on the first formation pressure and the formation coefficient of the oilfield formation, wherein the standard state is a state in which the temperature is the first preset temperature and the pressure is the second preset pressure; determining a first density of natural gas of the rock in a standard state based on the second formation pressure, the volume fraction of each component in the rock, and the density of other components than the natural gas; Determining a first gas content of the rock in a standard state based on the relative molecular mass of the natural gas, the first density, the volume fraction of the natural gas in the rock, the total void space, and the volume of the natural gas fraction per mole; and converting the first gas content into a second gas content of the rock in an ideal state, wherein the ideal state is a state that the temperature is a second preset temperature and the pressure is the second preset pressure. In one possible implementation, the method further includes: Determining a second density of natural gas of the rock at normal pressure based on the first formation pressure, the volume fraction of each component in the rock, and the density of other components than the natural gas; determining a second number of moles of the natural gas at atmospheric conditions based on the relative molecular mass of the natural gas, the second density, the volumetric ratio of the natural gas in the rock, and the total void space; and determining a third gas content of the rock under normal pressure based on the second mole number and the volume occupied by the natural gas per mole number. In another possible implementation, the determining the total void space per unit mass of the rock based on the rock density and the total porosity includes: Based on the rock density and the total porosity, determining a total void space per unit mass of the rock by the following formula one: Equation one: wherein V represents the total pore space of the rock, m represents the unit rock mass, ρ Rock represents the rock density, the Indicating the total porosity. In another possible implementation, the determining the first gas content of the rock in the standard state based on the relative molecular mass of the natural gas, the first density, the volume fraction of the natural gas in the rock, the total void space, and the volume of the natural gas fraction per mole number includes: Based on the relative molecular mass of the natural gas, the first density, the volumetric ratio of the natural gas in the rock, and the total void space, a first number of moles of the natural gas in a standard state is determined by the following equation two: Formula II, n Standard of ＝B Natural gas *ρ1 Natural gas V1/M Determining a first gas content of the rock in a standard state based on the first mole number and the volume occupied by natural gas per mole number by the following formula three; formula III Q Standard of ＝n Stand