Multi-stage Decoupling Preconditioning Solution Technology for Large-Scale Reservoir Simulation

In response to the complex seepage mechanism of unconventional oil and gas reservoirs, large-scale volume fracturing of multi-segment and multi-cluster horizontal wells, and differences in oil and gas pressure and saturation properties, which result in uneven distribution of eigenvalues, large value of conditions, and slow solving speed of nonlinear equation matrix, a multi-stage decoupling preconditioning solution technology was carried out on the Jacobian coefficient matrix of the oil and gas numerical discrete equation based on the implicit pressure explicit saturation method (IMPES) processing idea. Multi-grid method (AMG) + block based incomplete LU decomposition method (BILU0) are used to preprocess the Jacobian coefficient matrix in multiple stages, and the block based generalized minimum residual method (BGMRES) is used to solve the preconditioned nonlinear algebraic equations. The calculation result proves that compared with other single processing methods, this method effectively reduces the number of iterations for solving discrete equations while ensuring calculation accuracy, improves calculation speed, and has important application value for rapid formulation and decision-making optimization of oil and gas field development plans.