Non-darcy Flow Numerical Simulation for Low-permeability Reservoirs (SPE 154890)

With further progress of oilfields' development all over the world, more and more low permeability reservoirs are being put in production. However, fluid flow in low permeability porous media deviates from the classic Darcy's law and instead conforms to the one of non-Darcy seepage. Most mature commercial numerical simulation softwares may cause error in simulating development performance of low permeability reservoirs. So a non-Darcy seepage numerical simulation software has been developed. In this paper, non-Darcy seepage mathematical model was proposed. In addition, on the basis of practical field and laboratory experiment data, an ideal model of five-spot well pattern was also established. Under the same reservoir condition, the non-Darcy simulation, conventional Darcy simulation and the simulation of threshold pressure gradient were conducted. The comprehensive comparison and analysis of the simulation results of Darcy flow, threshold pressure gradient flow and non-Darcy flow were provided. Research shows that compared to the results of Darcy flow, when considering non-Darcy flow, the oil production is low, and production decline is rapid; the fluid flow in reservoir consumes more driving energy which reduces the water flooding efficiency. Darcy flow model overstates the reservoir flow capability, and threshold pressure gradient flow model overstates the reservoir flow resistance. In the low permeability reservoirs, non-Darcy seepage dominates in a large scale of formation and the non-Darcy simulation result shows excellent agreement with the production data. Therefore taking the non-Darcy seepage into account is more suitable to reflect the percolation mechanism and development performance of low permeability reservoirs. This numerical simulation method has been applied successfully in Shengli oilfields.