CN-122016589-A - Method, device, electronic equipment, storable medium and computer program product for calculating irreducible water saturation of tight sandstone reservoir

CN122016589ACN 122016589 ACN122016589 ACN 122016589ACN-122016589-A

Abstract

The invention relates to the technical field of oil and gas reservoir damage evaluation, in particular to a method and a device for calculating the irreducible water saturation of a tight sandstone reservoir, electronic equipment, a storable medium and a computer program product. The method comprises the steps of obtaining a pore distribution curve of a compact sandstone sample, determining capillary bound water content of different pressure differences of a compact sandstone reservoir based on the pore distribution curve of the compact sandstone sample, analyzing all rocks and clay minerals of the compact sandstone sample to obtain clay bound water content of the compact sandstone reservoir, and obtaining the saturation of the compact sandstone reservoir bound water based on the capillary bound water content and the clay bound water content. The method rapidly and accurately analyzes the irreducible water saturation qualitatively and quantitatively by establishing the relation between the absolute content, the pore distribution, the stress distribution and the interfacial tension of the clay mineral and the irreducible water saturation.

Inventors

LI WENZHE
ZENG JI
LUO ZHILIN
WANG YANG
ZHONG BO
YANG RUOYU

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20241112

Claims (12)

1. A method for calculating the irreducible water saturation of a tight sandstone reservoir, wherein the method comprises, Obtaining a pore distribution curve of a compact sandstone sample; Determining capillary bound water content of different pressure differences of a tight sandstone reservoir based on the pore distribution curve of the tight sandstone sample; Analyzing all rocks and clay minerals of the compact sandstone sample to obtain the clay bound water content of the compact sandstone reservoir; and obtaining the compact sandstone reservoir irreducible water saturation based on the capillary irreducible water content and the clay irreducible water content.
2. The method for calculating the irreducible water saturation of a tight sandstone reservoir according to claim 1, wherein the method for obtaining the pore distribution curve of the tight sandstone sample comprises a constant-speed mercury porosimetry, a high-pressure mercury porosimetry, a nuclear magnetic method or a nuclear magnetic-mercury porosimetry method.
3. The method of calculating the capillary bound water saturation of a tight sandstone reservoir according to claim 1, wherein determining the capillary bound water content of the tight sandstone reservoir based on the pore distribution curve of the tight sandstone sample comprises: Determining a relationship between the percent pore and the pore radius based on the pore distribution curve of the dense sandstone sample; obtaining the minimum pore radius and calculating the corresponding capillary pressure according to the relation between the pore percentage content and the pore radius; And obtaining capillary bound water content of the tight sandstone reservoir under different production pressure differences according to the minimum pore radius corresponding to the capillary pressure.
4. A method of calculating the irreducible water saturation of a tight sandstone reservoir according to claim 3, wherein the capillary pressure corresponding to the minimum pore radius is calculated as follows: Where r min is the minimum pore radius, σ 1 , 2 is the surface tension of the fluid, θ is the contact angle of the fluid with the sample, and P c is the capillary pressure.
5. The method of calculating the capillary bound water saturation of a tight sandstone reservoir according to claim 3 or 4, wherein the calculation formula of the capillary bound water content of the tight sandstone reservoir is as follows: Wherein S tw is capillary bound water content, V p is total porosity, and V i is volume corresponding to different pore sizes.
6. The method of calculating the irreducible water saturation of a tight sandstone reservoir according to claim 1, wherein the analyzing the tight sandstone sample for the whole rock and clay minerals to obtain the irreducible water content of the tight sandstone reservoir comprises: Analyzing all rock and clay minerals of the compact sandstone sample to determine absolute contents of clay minerals of illite, montmorillonite, chlorite and kaolinite; and calculating the absolute content of the illite, montmorillonite, chlorite and kaolinite clay minerals to obtain the clay bound water content of the tight sandstone reservoir.
7. The method of calculating the irreducible water saturation of a tight sandstone reservoir according to claim 6, wherein the calculation formula of the clay irreducible water content of the tight sandstone reservoir is: In the formula, The water absorption coefficient of the clay is a montmorillonite water absorption coefficient, b is an illite water absorption coefficient, c is a chlorite water absorption coefficient, d is a kaolinite water absorption coefficient, M Mongolian mask is a montmorillonite absolute content, M Yiyi (Chinese character) is an illite absolute content, M Green, green is a chlorite absolute content, M High height is a kaolinite absolute content, and M Total (S) is the total mass of the sample.
8. The method of calculating the irreducible water saturation of a tight sandstone reservoir according to claim 1, wherein the calculation formula of the irreducible water saturation of the tight sandstone reservoir is: Wherein S w is the bound water content; the water content is the clay bound water content, and S tw is the capillary bound water content.
9. A device for calculating the irreducible water saturation of a tight sandstone reservoir, wherein the device comprises, The first acquisition unit is used for acquiring a pore distribution curve of the compact sandstone sample; the determining unit is used for determining capillary bound water content of the tight sandstone reservoir under different pressure differences based on the pore distribution curve of the tight sandstone sample; the second acquisition unit is used for carrying out all-rock and clay mineral analysis on the compact sandstone sample to acquire the clay bound water content of the compact sandstone reservoir; And a third acquisition unit for acquiring the compact sandstone reservoir irreducible water saturation based on the capillary irreducible water content and the clay irreducible water content.
10. An electronic device comprising at least one processor and at least one memory, said memory being in data connection with said processor, wherein, The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-8.
11. A computer-storable medium, characterized in that it has stored thereon computer instructions which, when executed by a processor, particularly perform the steps of the method according to any of claims 1-8.
12. A computer program product comprising computer instructions which, when executed by a processor, particularly performs the steps of the method according to any one of claims 1-8.

Description

Method, device, electronic equipment, storable medium and computer program product for calculating irreducible water saturation of tight sandstone reservoir Technical Field The invention relates to the technical field of oil and gas reservoir damage evaluation, in particular to a method and a device for calculating the irreducible water saturation of a tight sandstone reservoir, electronic equipment, a storable medium and a computer program product. Background Compact sandstone reservoirs often need to be subjected to fracturing modification due to the characteristics of poor physical properties, thin throat, strong heterogeneity and the like. Along with the development of production, the production pressure difference is increased, so that the engineering problem of water production and gas production is easy to occur, and the root cause is that the reservoir is not subjected to fine evaluation, mainly the saturation of the irreducible water is not clear, and the gas-water distribution and occurrence state of the reservoir are not clear. The irreducible water saturation can well perform tight sandstone reservoir oil-gas evaluation, reserve calculation and productivity prediction, so that the irreducible water saturation is very important, if the irreducible water saturation cannot be clearly determined, the productivity is reduced, and if the irreducible water saturation is heavy, the gas well is flooded. Centrifugation, nuclear magnetic, mercury porosimetry, semi-permeable baffle, and closed core saturation experiments are representative irreducible water saturation measurements. The centrifugal method has high requirements on centrifugal speed and balance time, otherwise, the error is larger, the nuclear magnetic method has the advantages of being greatly influenced by the displacement method, the mercury-pressing method has the advantages of being quick, efficient and relatively low in cost, the rock sample cannot be reused, the actual difference between measured fluid and stratum is larger, the semi-permeable partition method is close to the wetting condition of an actual oil reservoir, the measuring time is longer, loose cores cannot be measured, and the closed core saturation experimental method has the characteristics of being high in accuracy, high in cost, long in period, small in data and the like. Bound water is typically deposited on the reservoir surface, at the corners of the pores and in the microcapillaries, and is subject to both capillary and viscous forces. The related research shows that the irreducible water saturation has a certain positive correlation with capillary force and the mass fraction of clay minerals (kaolinite, illite, montmorillonite and Meng Jianceng). The capillary force and the clay mineral content can be measured under laboratory conditions, so that the capillary curve and clay mineral-based irreducible water saturation calculation method has the advantages of low cost, short time consumption and high accuracy. Disclosure of Invention In order to solve the problems, the invention provides a method, a device, an electronic device, a storable medium and a computer program product for calculating the irreducible water saturation of a tight sandstone reservoir, which provide the following technical scheme: In a first aspect of the invention, there is provided a method of calculating irreducible water saturation in a tight sandstone reservoir, the method comprising, Obtaining a pore distribution curve of a compact sandstone sample; Determining capillary bound water content of different pressure differences of a tight sandstone reservoir based on the pore distribution curve of the tight sandstone sample; Analyzing all rocks and clay minerals of the compact sandstone sample to obtain the clay bound water content of the compact sandstone reservoir; and obtaining the compact sandstone reservoir irreducible water saturation based on the capillary irreducible water content and the clay irreducible water content. Preferably, the pore distribution curve of the compact sandstone sample is obtained by a constant-speed mercury porosimetry, a high-pressure mercury porosimetry, a nuclear magnetic method or a nuclear magnetic-mercury porosimetry combined method. Preferably, determining the capillary bound water content of the tight sandstone reservoir based on the pore distribution curve of the tight sandstone sample comprises: Determining a relationship between the percent pore and the pore radius based on the pore distribution curve of the dense sandstone sample; obtaining the minimum pore radius and calculating the corresponding capillary pressure according to the relation between the pore percentage content and the pore radius; And obtaining capillary bound water content of the tight sandstone reservoir under different production pressure differences according to the minimum pore radius corresponding to the capillary pressure. Preferably, the capillary pressure corresponding to the