CN-121997786-A - Shale oil reservoir displacement effect prediction method, device, equipment and medium

CN121997786ACN 121997786 ACN121997786 ACN 121997786ACN-121997786-A

Abstract

The disclosure provides a method, a device, equipment and a medium for predicting a shale oil reservoir displacement effect, and belongs to the technical field of shale oil displacement. According to the method, the volume fraction and capillary pressure of each of three phases of carbon dioxide, oil and water are obtained, a shale oil pore scale carbon dioxide, oil and water three-phase displacement model is built through a phase field method, a simulation domain is drawn according to shale oil reservoir pore size distribution, grid division is conducted on the simulation domain, initial conditions and boundary conditions are set, displacement behaviors of nano-pore shale oil in a three-phase displacement mode are calculated, and three-phase displacement effects are predicted according to the displacement behaviors of the nano-pore shale oil in the three-phase displacement mode. Therefore, the three-phase displacement effect of shale oil can be predicted in a modeling mode aiming at the small-pore shale oil reservoir, the problem that the shale oil is difficult to develop under the condition of extremely low permeability and non-connectivity of pores is solved, and the efficiency of shale oil displacement development is further improved.

Inventors

WANG XIAOMEI
HE KUN
YANG CHUNLONG

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241104

Claims (10)

1. The method for predicting the displacement effect of the shale oil reservoir is characterized by comprising the following steps of: The volume fraction and capillary pressure of each of the three phases of carbon dioxide, oil and water are obtained, and a shale oil pore scale carbon dioxide, oil and water three-phase displacement model is constructed through a phase field method; drawing a simulation domain according to shale oil reservoir pore size distribution, performing grid division on the simulation domain, and setting initial conditions and boundary conditions; And calculating the displacement behavior of the nanopore shale oil in the three-phase displacement mode, and predicting the three-phase displacement effect according to the displacement behavior of the nanopore shale oil in the three-phase displacement mode.
2. The method of claim 1, wherein constructing a shale oil pore scale carbon dioxide, oil, water three-phase displacement model by a phase field method comprises: establishing a momentum conservation equation of the three-phase fluid of carbon dioxide, oil and water; wherein a conservation of momentum equation is established between the fluid velocity and density based on the fluid surface tension and the volumetric force.
3. The method of claim 2, wherein the flow rate of the three-phase fluid to be displaced in the same shale reservoir pore size is determined according to the conservation of momentum equation.
4. The method of claim 2, wherein constructing a shale oil pore scale carbon dioxide, oil, water three-phase displacement model by a phase field method comprises: The density of the three-phase mixture of carbon dioxide, oil and water is determined according to the volume fraction of each of the three phases of carbon dioxide, oil and water and the density of each phase.
5. The method of claim 4, wherein constructing a shale oil pore scale carbon dioxide, oil, water three-phase displacement model by a phase field method, further comprises: The viscosity of the three-phase mixture of carbon dioxide, oil and water is determined according to the volume fraction of each of the three phases and the viscosity of each phase.
6. The method of claim 5, wherein constructing a shale oil pore scale carbon dioxide, oil, water three-phase displacement model by a phase field method comprises: defining free energy of the three-phase displacement model as a function of phase field variables; Wherein the volume force is determined based on the interfacial surface tension coefficient of each phase, the additional free volume energy parameter, and the capillary parameter of each phase.
7. The method according to any one of claims 1 to 6, further comprising: determining chemical potential of each of three phases of carbon dioxide, oil and water according to the three-phase displacement model of the carbon dioxide, oil and water; The surface tension of the fluid force applied to the shale oil pores is calculated from the chemical potential.
8. A shale reservoir displacement effect prediction device, comprising: The model building unit is used for obtaining the volume fraction and capillary pressure of each of the three phases of carbon dioxide, oil and water and building a shale oil pore scale carbon dioxide, oil and water three-phase displacement model through a phase field method; the condition setting unit is used for drawing a simulation domain according to shale oil reservoir pore size distribution, carrying out grid division on the simulation domain and setting initial conditions and boundary conditions; The calculation prediction unit is used for calculating the displacement behavior of the nanopore shale oil in the three-phase displacement mode and predicting the three-phase displacement effect according to the displacement behavior of the nanopore shale oil in the three-phase displacement mode.
9. The electronic equipment is characterized by comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory are communicated with each other through the communication bus; a memory storing a computer program; A processor, when executing a program stored in a memory, implements the method for predicting a shale reservoir displacement effect according to any one of claims 1 to 7.
10. A computer readable storage medium, characterized in that a computer program is stored, which, when executed by a processor, implements the method of predicting a shale reservoir displacement effect of any one of claims 1 to 7.

Description

Shale oil reservoir displacement effect prediction method, device, equipment and medium Technical Field The disclosure belongs to the technical field of shale oil displacement, and particularly relates to a method, a device, equipment and a medium for predicting a shale oil reservoir displacement effect. Background Shale oil is used as an unconventional energy source with rich reserves, and effective development of shale oil is important to guarantee energy supply. However, the reservoir properties of shale oil vary greatly from conventional reservoirs. Shale reservoir pore scale space is very small, and mainly consists of nanopores. The transport behavior of fluids in nanopores is susceptible to pore wall surfaces due to the narrow flow channels in the nanopores. This results in greater difficulty in the effective exploitation of shale reservoirs than conventional reservoirs. In order to improve the recovery ratio of shale oil, in recent years, a carbon dioxide oil displacement technology has been widely focused and studied. By injecting carbon dioxide into the stratum, the viscosity of crude oil is effectively reduced, and the displacement efficiency is improved, so that the oil and gas yield is increased. In shale reservoirs, the existence of micro-pores makes three-phase flow and displacement behavior of CO 2-oil-water very complex, and influences the overall recovery efficiency. To achieve efficient development of shale oil reservoirs, elucidation of CO2 displacement mechanisms on the nanoscale is urgently needed. The core displacement experiment is difficult to develop due to the extremely low permeability and the non-connectivity of the pores. Therefore, the development of the prediction method for efficiently and accurately predicting the CO 2-oil-water three-phase displacement behavior in the shale oil micro-pores has important significance for improving the recovery ratio of the shale oil. Disclosure of Invention In view of the above problems, the disclosure provides a method, a device, equipment and a medium for predicting a shale oil reservoir displacement effect, which can predict a shale oil three-phase displacement effect by modeling a small-pore shale oil reservoir. The technical scheme provided by the disclosure is as follows: An aspect of an embodiment of the present disclosure provides a method for predicting a displacement effect of a shale oil reservoir, including: The volume fraction and capillary pressure of each of the three phases of carbon dioxide, oil and water are obtained, and a shale oil pore scale carbon dioxide, oil and water three-phase displacement model is constructed through a phase field method; drawing a simulation domain according to shale oil reservoir pore size distribution, performing grid division on the simulation domain, and setting initial conditions and boundary conditions; And calculating the displacement behavior of the nanopore shale oil in the three-phase displacement mode, and predicting the three-phase displacement effect according to the displacement behavior of the nanopore shale oil in the three-phase displacement mode. Further, the construction of the shale oil pore scale carbon dioxide, oil and water three-phase displacement model by a phase field method comprises the following steps: establishing a momentum conservation equation of the three-phase fluid of carbon dioxide, oil and water; wherein a conservation of momentum equation is established between the fluid velocity and density based on the fluid surface tension and the volumetric force. Further, determining the flow speed of the three-phase fluid for displacement in the aperture of the same shale oil reservoir according to the momentum conservation equation. Further, the construction of the shale oil pore scale carbon dioxide, oil and water three-phase displacement model by a phase field method comprises the following steps: The density of the three-phase mixture of carbon dioxide, oil and water is determined according to the volume fraction of each of the three phases of carbon dioxide, oil and water and the density of each phase. Further, the construction of the shale oil pore scale carbon dioxide, oil and water three-phase displacement model by a phase field method further comprises the following steps: The viscosity of the three-phase mixture of carbon dioxide, oil and water is determined according to the volume fraction of each of the three phases and the viscosity of each phase. Further, the construction of the shale oil pore scale carbon dioxide, oil and water three-phase displacement model by a phase field method comprises the following steps: defining free energy of the three-phase displacement model as a function of phase field variables; Wherein the volume force is determined based on the interfacial surface tension coefficient of each phase, the additional free volume energy parameter, and the capillary parameter of each phase. Further, the method further comprises: determining che