Acidizing Technology for Deep Penetration in Main Fault Zone of Shunbei Oil and Gas Field

Due to fractures developed in the carbonate reservoirs of main fault zones in the Shunbei Oil and Gas Field, the well wall is prone to sloughing and falling frequently during drilling, and the cuttings in ultra-deep horizontal well have very difficult flow back, along with serious leakage in some wells. The cuttings accumulation and serious leakage cause the payzone to be blocked heavily, and this blockage cannot be removed by conventional acidizing technologies. In fact, they experience great difficulty in keeping stable production. In order to solve the problem, the team developed a working hypothesis and then tested it. The low-viscosity and quick reaction acid was used in near the wellbore to create wormholes by rapid diffusion penetrating damage zone, while large amount of high-viscosity acid was injected to far wellbore zone to create high-conductivity channels. On this basis, a deep penetration acidizing technology in the main fault zone was developed, featuring “plug removal near wellbore and channeling far from wellbore”. This technology has been applied to 6 wells, resulting in cumulative oil increment of 16.06×10⁴ t, which shows great acidizing effects and resolves the problems of payzone blocking near and far from the wellbore. Field application results showed that the technology could effectively solve the blocking problems of main fault zone in Shunbei oil and gas field, and provide a reference for acidizing and plug removal of similar carbonate reservoirs at home and abroad.