| Popis: |
In this paper, semi-analytical model of waterflooding by parallel horizontal wells with transverse water-injection induced fractures has been reviewed for low-permeability reservoirs. The numerical experiments can be divided in following stages: equilibrium pressure of stable water-injection induced fracture existence estimation; evaluation of the critical equilibrium pressure of the injection-induced fractures and estimation of the conditions for the stable fracture growth; evaluation of the critical injection fluid rate for the stable fracture growth; prognosis of the fracture growth dynamics. The main idea of the proposed work is to obtain the conditions of the stable fracture existence. This situation is possible in the late stages of field development, when oil production is compensated by fluid injection, and the pressure distribution does not depend on time. Numerical modeling shows the existence of the critical fracture half-length and pressure, after which the equilibrium of injection-induced fractures becomes unstable. Before this critical fracture length is exceeded, the fracture growth can be controlled by bottomhole pressure and flow rate, since each subcritical length of the equilibrium existence of a fracture corresponds to its equilibrium pressure and flow rate. It is possible to control fracture growth before its unstable state, knowing this pressure and flow rate. The early fracture growth can be estimated by the analytical formula for the fracture half-length in the so-called Carter regime. These results were obtained for specific parameters of the development system, but can be scaled to another homothetic system. The developed model will help to understand the fundamentals of water-injection induced fracture initiation and poroelasticity, as well as develop methods that allow to control and regulate the growth of water-injection induced fractures. |
