| Reservoir simulation is a vital link in coalbed methane (CBM) development project, and itskey technology and difficulty are the solutions to the governing equations of the CBM migration.The discretization of the equations and meshing of the reservoir determine the computationalcomplexity and the solution precision. Conventionally, numerical approaches like finitedifferential method (PDM) or finite element method (FEM) are the extensively employedmethods, and their solving ideas are "discretization"(the abstract of physical phenomena)--"continuum"(the macro governing equations)--"discretization"(the discrete differentialequations). In this dissertation, the authors involve the Lattice Boltzmann Method (LBM), aparticle method which has been extensively employed in the computational fluid dynamics, intothe solutions of the governing equations of the CBM migration.According to the coal reservoir characteristics, borrowing the idea of a reservoir meshingmethod from the conventional reservoir simulation, we involved an unstructured grid namelyperpendicular bisection (PEBI) grid in the CBM reservoir meshing to establish the solving lattice.Then, combined with the features of LBM, the finite volume LBM (FVLBM) method wasproposed based on PEBI grid. Considering the CBM migration laws and the LBM features,2Dunsteady-state diffusion model and single component single-phase seepage model for CBMdiffusion and flow are established and programmed respectively. Consequencely, the diffusionprocess was simulated in a2D stochastic porous medium model which generated by a porositycontrolled stochastic growth method--Quartet Structure Generation Set (QSGS). And wellinterference of the vertical well-group drainage was simulated as well. Under the premise ofmaximizing the drainage area of each single well while making full use of well interference’sacceleration for promote the CBM recovery, the optimal well spacing in the study area was fixedvia the simulations and in combination with the CBM productions resulted from the conventionalnumerical simulation software CMG. |
