Research on Gas Drive Front Distribution of Storage in Oil Fields Based on Field Test Monitoring Inversion

The PG2 underground gas storage (UGS) is the first storage in oil fields which rebuilt a waterflooding reservoir. It is important to determine the gas injection front to improve the oil recovery and gas storage space utilization efficiency. Based on the pilot test of PG2 UGS, this paper carried out injection-production well test and production dynamic monitoring test, compared and analyzed the dynamic monitoring results before and after gas injection, and studied the distribution law of gas injection front under different technologies The results show that: (1) The formation pressure test results showed that 78% of wells in the test area responded to pressure, and the pressure diffusion rate is 3.8–11 m /d. (2) Tracer monitoring results showed that the main displacement direction was near the east-west direction, affecting the P25 well to the east and P12 well to the west, and the migration rate reached 3.6–6.8 m/d. (3) Combined with test results of formation pressure, tracer testing, production and absorption profile and saturation testing, the gas drive plane sweep is relatively uniform, and the well control zone plane sweep coefficient is 0.75. The longitudinal sweep range is small, and the longitudinal sweep coefficient is 0.3. The location of gas injection front is determined according to field test monitoring, which provides an optimization basis for the injection and production scheme design of subsequent PG2 UGS construction.