Research on mechanisms of enhanced liquid for offshore heavy oil reservoirs based on deformation phase permeability curve

Author of the article:SHI Hongfu, XU Zhongbo, WANG Xinpeng

Author's Workplace：Bohai Petroleum Research Institute, CNOOC China Ltd., Tianjin Branch, Tianjin, 300459, China

Key Words：Common heavy oil; Mechanism of enhanced liquid; Microscopic; Network model; Sweep efficiency; Numerical simulation; Deformation phase permeability; History matching

Abstract：The Bohai heavy oilfield production shows a stable or even decreased water cut, increased recoverable reserves and improved oil recovery ratio after enhanced liquid. This phenomenon is not completely consistent with the existing mechanics of fluids in porous media, and results in poor history matching in numerical model. To address this issue, a network model was used to analyze the microscopic enhanced fluid mechanism and obtain a relative permeability curve(deformation phase permeability curve), reflecting the variation of the displacement pressure gradient to improve the accuracy of history matching and index prediction. Microscopic network simulation confirms that increasing the displacement pressure gradient expands the level and sweep range of available pore throats, while increasing the probability of piston displacement, thus improving the oil displacement efficiency. Field application shows that the use of “transformation relative permeability curve” can more accurately fit the production dynamics after enhanced liquid and guide the prediction for development index.