Optimization of Sensitive Technical Parameters of Water Alternating Gas Injection Displacement Based on Multi-indicator Orthogonal Design

Abstract

In view of a series of comprehensive problems such as the limited space of conventional water displacement, the low-pressure maintenance level, and the greater contradiction during the high water cut period of 64-20 sub-block, the development potential of its conversion medium with carbon dioxide was evaluated. After determining that water alternating gas injection displacement was the dominant development method in the target area, the sensitive parameters were optimized based on multi-indicator orthogonal design, numerical simulation and comprehensive scoring. The research results show that the use of water alternating gas injection displacement in the high water cut period could better maintain the formation pressure and greatly increase the recovery percent. It has a large application potential in the target area and the final optimal parameters are as follows: gas injection time is 20 years, cycle is 8 months, velocity is 1 × 104 m3/d, gas-water ratio is 1 : 1 and bottom hole flowing pressure is 13 MPa. And the technical parameters of velocity and cycle have the most important contribution to the displacement effect during the high water cut period in the earlier period.