Abstract:

Aiming at the problems of conventional temporary plugging materials in horizontal shale gas wells in Sichuan, such as insignificant increase in temporary plugging pressure, easy shedding under low pressure difference and poor plugging effect, long‑acting and short‑acting temporary plugging knots for perforation plugging were prepared. Their degradation performance and pressure‑bearing plugging performance were evaluated, the influence of injection method on plugging efficiency was explored, and a temporary plugging knot injection device was developed, thus forming a knot‑based temporary plugging fracturing technology for shale gas. The results show that in polymer slick‑water fracturing fluid at 90 ℃, the degradation rate of long‑acting temporary plugging knots is less than 10% within 83 h and more than 99% after 174 h, while that of short‑acting temporary plugging knots is less than 10% within 5 h and more than 99% after 24 h. Both types of temporary plugging knots exhibit static pressure‑bearing capacity higher than 50.0 MPa and dynamic plugging efficiency above 90%. The maximum single injection capacity of the device is 60 temporary plugging knots with a size of 18~20 mm, and the injection rate is adjustable from 1 to 60 knots per minute. Field tests were carried out in Well Ning‑A, a horizontal shale gas well, including 5 stages of inter‑stage temporary plugging and 6 stages of intra‑stage temporary plugging in casing‑deformed intervals. The average post‑plugging pressure increases were 9.0 MPa and 5.6 MPa, respectively. Field microseismic monitoring shows obvious differences in event points before and after temporary plugging, verifying the effectiveness of the proposed technology.

Key words: Fracturing, Temporary plugging knot, Segmented, Casing?deformed well, Shale gas, Horizontal well

摘要：

针对四川页岩气水平井采用常规暂堵材料封堵孔眼时暂堵压力涨幅不明显、低压差易脱落而导致封堵效果差等问题，制备了可封堵孔眼的长效和短效暂堵绳结，并对其降解性能、承压封堵性能进行了评价；探索了加入方式对其封堵效率的影响，并研制了暂堵绳结加入装置，形成了页岩气绳结暂堵压裂技术体系。结果表明，在温度为90 ℃的聚合物滑溜水压裂液中，长效暂堵绳结在83 h内的降解率小于10%，174 h后降解率大于99%，短效暂堵绳结在5 h内的降解率小于10%，24 h后降解率大于99%；两种暂堵绳结的静态承压能力均大于50.0 MPa，动态封堵率均在90%以上；加入装置单次最大加入量为18~20 mm的暂堵绳结60个，加入速率在1~60个/min内可调；该技术在页岩气水平井宁A井开展了套变段段间暂堵分段实验5段和段内暂堵实验6段，暂堵后平均压力升幅分别为9.0、5.6 MPa，现场微地震监测结果显示暂堵前后事件点差异明显，验证了技术的有效性。

关键词: 压裂, 暂堵绳结, 分段, 套变井, 页岩气, 水平井