Minimum miscible pressure prediction method for CO2-crude oil system considering reservoir well spacing

Patent metadata

Field	Value
Publication number	US-12498361-B2
Application number	US-202519066174-A
Country	US
Kind code	B2
Filing date	Feb 28, 2025
Priority date	Mar 1, 2024
Publication date	Dec 16, 2025
Grant date	Dec 16, 2025

Abstract

A minimum miscible pressure prediction method for a CO 2 -crude oil system considering reservoir well spacing is provided, including: obtaining characteristic parameters of each component of crude oil; based on the characteristic parameters of each component of the crude oil, obtaining corresponding bubble point or dew point pressures, as well as corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents; based on the corresponding bubble point or dew point pressures, as well as the corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents, constructing a minimum miscible pressure prediction model for the CO 2 -crude oil system considering the reservoir well spacing; and based on the minimum miscible pressure prediction model for the CO 2 -crude oil system considering the reservoir well spacing, obtaining minimum miscible pressure values for the CO 2 -crude oil system under different reservoir well spacing.

First claim

What is claimed is:

1 . A minimum miscible pressure prediction method for a CO 2 -crude oil system considering reservoir well spacing, comprising following steps:
obtaining CO 2 -crude oil basic data, performing crude oil component splitting and crude oil saturation pressure fitting, and obtaining characteristic parameters of each component of crude oil; based on the characteristic parameters of each component of the crude oil, conducting multi-stage swelling experiments to obtain corresponding bubble point or dew point pressures, as well as corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents; based on the corresponding bubble point or dew point pressures, as well as the corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents, performing minimum miscible pressure prediction for the CO 2 -crude oil system considering the reservoir well spacing, and constructing a minimum miscible pressure prediction model for the CO 2 -crude oil system considering the reservoir well spacing; and based on the minimum miscible pressure prediction model for the CO 2 -crude oil system considering the reservoir well spacing, obtaining minimum miscible pressure values for the CO 2 -crude oil system under different reservoir well spacing; the characteristic parameters of each component of the crude oil include a sum of molar contents of methane and nitrogen, a sum of molar contents of ethane and butane, a sum of molar contents of pentane and the ethane, and a sum of molar masses of heptane and crude oil components with higher carbon numbers; wherein a method based on the characteristic parameters of each component of the crude oil, conducting the multi-stage swelling experiments to obtain the corresponding bubble point or dew point pressures, as well as the corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents comprises: cleaning a model of a slim tube of a preset length, injecting kerosene, and keeping constant to a reservoir temperature of 127 Celsius degree and an experimental pressure of 18 MPa; displacing the kerosene in the slim tube with formation crude oil at a speed of 0.2 milliliter per minute until 2 times a rock pore volume is displaced, and then measuring a produced gas-oil ratio and components of a sample at an outlet end of the slim tube; stopping displacement when the components are consistent with a formation crude oil sample; filling an intermediate container with CO 2 and keeping constant to the reservoir temperature and the experimental pressure; using an injection pump to displace a gas sample at a constant pressure 0.1 MPa higher than the experimental pressure; ending a displacement experiment after injecting a gas sample with 1.2 times the rock pore volume; during a displacement process, recording a produced oil and gas volume, a pump reading, an experimental pressure, and a back pressure every additional 0.1 times the rock pore volume injected; gradually increasing the experimental pressure until a recovery rate of the formation crude oil is higher than 90%; and changing a length of the model of the slim tube and repeating above experimental steps to obtain the corresponding bubble point or dew point pressures, as well as the corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents; a method based on the corresponding bubble point or dew point pressures, as well as the corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents, performing the minimum miscible pressure prediction for the CO 2 -crude oil system considering the reservoir well spacing comprises: inputting the corresponding bubble point or dew point pressures, as well as the corresponding oil-gas interfacial tension, oil phase and gas phase densities, and viscosities under different injected gas contents into data fitting software, and setting different types of data samples; selecting variable types and formulating a fitting mode based on the different types of data samples; selecting a fitting estimation method based on a data trend, setting a dependent variable and independent variables, and constructing a fitting model; and based on an iterative method, constructing the minimum miscible pressure prediction model for the carbon dioxide-crude oil system considering the reservoir well spacing for the dependent variable and the independent variables; wherein the different types of data samples comprise: the sum of the molar contents of the methane and the nitrogen, the sum of the molar contents of the ethane and the butane, the sum of the molar contents of the pentane and the ethane, the sum of the molar masses of the heptane and the crude oil components with higher carbon numbers, a slim tube experiment temperature, a slim tube length L, and a minimum miscible pressure obtained from a slim tube experiment; a method for constructing the fitting model is:

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Assignees

• Univ China Petroleum Beijing

Inventors

• Chen Hao
• Liu Xiliang
• Li Borui
• Li Yang
• Cheng Weiming
• Tian Xiaofeng
• Tan Xianhong
• Zhang Lijun
• Yang Renfeng
• Zuo Mingsheng
• Yang Baoxi
• Zhang Ruwei
• Lin Zhizhen
• Li Qiuting
• Qi Xinyu
• Luo Feng
• Yang Linxi
• Li Pengbo
• Liu Wen

Classifications

• G06F2119/14

  Force analysis or force optimisation, e.g. static or dynamic forces · CPC title

• G06F2113/08

  Fluids · CPC title

• G06Q50/02

  Agriculture; Fishing; Forestry; Mining · CPC title

• G01N33/2823 Primary

  Raw oil, drilling fluid or polyphasic mixtures · CPC title

• G06F30/28 Primary

  using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD] · CPC title