Release:
2018, Vol. 4. №3About the authors:
Alexander A. Pyatkov, Postgraduate Student, Department of Mechanics of Multiphase Systems, University of Tyumen; Laboratory Assistant with Higher Education, Tyumen Branch of Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences; Researcher, Uni-CONCORD (Tyumen); pyatkovi80@mail.ruAbstract:
A significant number of the world's known reserves of hydrocarbons are found in fields that are more or less fractured. Despite the fact that the fractures have a small relative volume, due to their high conductivity, they have a significant effect on the hydrocarbon production process. The development of such deposits is often difficult and sometimes ineffective. Earlier works according to the data of 56 deposits with the presence of fracturing, snow the range of change in the oil recovery factor from 10% to 70%. In this paper, we studied the features of a two-phase flow in fractured-porous reservoirs for stationary and non-stationary waterflooding using a discrete model network model. The dependence of the oil production dynamics on the duration of the water injection cycles, the parameters and the position of the fracture relative to the wells was investigated. The investigations were carried on a model, in which there were one or more fracture with different lengths and orientations relative to the wells. A numerical experiment is conducted using proprietary reservoir simulator with the capability to model the fluid motion in conditions of non-isothermal processes and a solitary long cracks in the formation. In the simulation used unstructured grid (Voronoi polygons). In this case the grid inside the fractures was rectangular. At the core of the simulator is a mathematical model of filtration “black oil”.
As a result of the performed research, it is shown that in the case of stationary waterflooding, the presence of fracturing in the reservoir leads to a rapid breakthrough of water to production wells and to a reduction in the oil recovery factor. Non-stationary waterflooding makes it possible to increase oil production. At the same time, a non-stationary cyclic waterflooding in a homogeneous reservoir does not lead to a significant increase in oil recovery. The degree of effectiveness of the cyclic waterflooding strongly depends on the permeability and on the orientation of the fractures relative to the wells. The presence of a strong effect from the non-stationary waterflooding of the reservoir may serve as one of the signs of the presence of fractures in the reservoir.
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