The Method of Analytic Calculation of Initial and Ultimate Pressure Gradients to Flow for Low-Permeability Reservoirs

Abstract

Recently, all over the world, hydrocarbon fuel reserves are deteriorating rapidly. The number of fields with hard-to-recover reserves is growing, the largest part of which are low-permeability reservoirs. In addition to problems with the development of this type of collectors, there is a difficulty in building hydrodynamic models of fields. All hydrodynamic simulators are based on the linear law of Darcy flow, so it is difficult to correctly adapt this model to the history of development, because this kind of objects has witnessed a nonlinear filtration. The construction of the hydrodynamic model is carried out in the simulator. Therefore, to adapt the model, it is necessary to select the parameters of the filtration medium, which are often far from the real studies of collectors. Tempest MORE of ROXAR, in which there is a possibility of modeling a nonlinear filtration for high-viscosity oil by “locking a gradient filter and a multiplier on the flow”. The former limits the well drainage area, and the latter reduces the fluid filtration rate multiple times. In the presented paper, the possibility of using this method to adapt the model for low-permeability reservoirs is described. Analytical methods for determining these critical pressure gradients are presented. Critical pressure gradients were analytically determined by using analytical methods following the example of the V. N. Vinogradova oil field with a low-permeability reservoir.