Numerical Simulation of Oil-Water Two-Phase Flow in Low Permeability Tight Reservoirs Based on Weighted Least Squares Meshless Method
Xin Liu1,*, Kai Yan2, Bo Fang3, Xiaoyu Sun3, Daqiang Feng4, Li Yin5
1
School of GeoSciences, Yangtze University, Wuhan, 430100, China
2
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Southwest Petroleum University), Chengdu, 610000,
China
3
Downhole Service Company, Petro China Qinghai Oilfield Company, Haixi, 817000, China
4
Research Institute of Drilling and Production Technology, Petro China Qinghai Oilfield Company, Dunhuang, 736200, China
5
PetroChina Qinghai Oilfield Company The Third Oil Plant, Dunhuang, 736200, China
*
Corresponding Author: Xin Liu. Email: liuxinup8023@163.com
Fluid Dynamics & Materials Processing https://doi.org/10.32604/fdmp.2024.047922
Received 22 November 2023; Accepted 22 February 2024; Published online 21 March 2024
Abstract
In response to the complex characteristics of actual low-permeability tight reservoirs, this study develops a meshless-based numerical simulation method for oil-water two-phase flow in these reservoirs, considering complex
boundary shapes. Utilizing radial basis function point interpolation, the method approximates shape functions
for unknown functions within the nodal influence domain. The shape functions constructed by the aforementioned meshless interpolation method have δ-function properties, which facilitate the handling of essential aspects
like the controlled bottom-hole flow pressure in horizontal wells. Moreover, the meshless method offers greater
flexibility and freedom compared to grid cell discretization, making it simpler to discretize complex geometries. A
variational principle for the flow control equation group is introduced using a weighted least squares meshless
method, and the pressure distribution is solved implicitly. Example results demonstrate that the computational
outcomes of the meshless point cloud model, which has a relatively small degree of freedom, are in close agreement with those of the Discrete Fracture Model (DFM) employing refined grid partitioning, with pressure calculation accuracy exceeding 98.2%. Compared to high-resolution grid-based computational methods, the meshless
method can achieve a better balance between computational efficiency and accuracy. Additionally, the impact of
fracture half-length on the productivity of horizontal wells is discussed. The results indicate that increasing the
fracture half-length is an effective strategy for enhancing production from the perspective of cumulative oil
production.
Keywords
Weighted least squares method; meshless method; numerical simulation of low permeability tight reservoirs; oil-water two-phase flow; fracture half-length
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