Frac plug multistage fracturing technology is one of the main unconventional reservoir stimulation technologies. The fully dissolvable frac plug is a more efficient staged fracturing tool in compare with the fast-drilling frac plug. One of the most important advantages by using dissolvable frac plug is that the milling-out operation conducted in traditional plug is no more necessary, which significantly reduces the costs and risks of plug removal.

Weiyuan shale gas field is located in the southwest of China, most platforms have three-six horizontal wells. The blocking and sticking problems often happened due to the casing deformation or accumulation of sand in the wellbore. In this paper, the main technical challenges of fully dissolvable frac plug technology are analyzed. The field application of well A is described, including frac plug selection, field operation, the solutions under different blocking and sticking scenarios, sand flushing operation and problem analysis, etc.

The blocking and sticking problems happened in the process of tool string delivery. Then, corresponding solutions are prepared for the blocking and sticking problems before using the dissolvable plugs. Twenty-two fully dissolvable frac plugs and twenty-three fracturing balls were used in well A to complete twenty-three stages of fracturing. Field application results show that the fully dissolvable frac plug for multistage fracturing technology completes the reservoir stimulation safely and efficiently. The technology could meet the demands for pressure bearing performance and dissolving property.

This paper offers a case study that describes the application of fully dissolvable frac plug technology in long horizontal well of shale gas. It also provides an experience and reference case for engineers to develop other fracturing wells in unconventional reservoir.

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