Multistage circuitous-temporary plugging fracturing technology for deep oil-gas reservoirs

Abstract

China is rich in deep oil and gas resources with buried depth of more than 3 500 m. To overcome the technical difficulties in the implementation of conventional temporary plugging technology for the staged fracturing of horizontal well of deep oil-gas reservoirs, such as the small net pressure of fractures and the limited pressure window, we propse a technical idea of multi-level circuitous temporary plugging of fracturing and then build a mathematical model and solve this model by Newton iterative method. On this basis, we conduct the substantive research work on the simulation and optimization of technical parameters, such as the timing of circuitous temporary plugging, the decrease of pump rates, etc. The research results show that circuitous temporary plugging can significantly improve the pressure window of fracturing construction and the net pressure of the main fracture, which is helpful to realize the diversion of the fractures of deep and ultra-deep oil-gas reservoir and greatly increase the reformed volume; multistage circuitous temporary plugging fracturing can further increase the fracturing pressure window and the net pressure of the main fracture based on single-level circuitous temporary plugging, which is conducive to achieving the complexity of the fractures of deep and ultra-deep oil-gas reservoir and the maximization of the reformed volume. And meanwhile remaining the cost of fracturing vehicles and other processes basically unchanged. The application results of test wells show that the production after fracturing can be increased by more than 30% compared with adjacent wells. Therefore, the multi-level circuitous temporary plugging technology provides important guiding significance and reference for improving the fracturing effect, exploitation level and economic benefits of deep-ultra-deep oil-gas reservoir.