深层长水平段页岩气井趾端压裂滑套的研制

为打破国外公司的技术垄断、解决国内深层长水平段页岩气井第一段储层改造面临的技术难题,在明确应用环境及施工要求的基础上,开展了结构设计、室内试验与评价、配套固井工艺研究,研制出了一种能够满足高温、高压固井及大排量压裂施工要求的趾端压裂滑套,并在四川盆地长宁—威远国家级页岩气示范区内的长宁H7-5井开展了现场试验。结果表明:(1)自主研发的趾端压裂滑套通过井口打压的方式打开,形成第一段压裂或泵送通道,可替代连续油管第一段射孔作业;(2)趾端压裂滑套采用内表面特殊涂层设计、内滑套上行开启结构以及压裂喷砂孔暂堵设计,可提高滑套在固井环境中的适应能力、降低固井水泥对滑套正常开启的影响;(3)趾端压裂滑套采用破裂盘破裂开启滑套的方式,可提高滑套的开启精度,保证在高温、高压条件下工具能够精确开启。结论认为,所研制的趾端压裂滑套现场工艺操作简单,工具性能稳定、可靠,开启精度高,各项指标均达到了页岩气水平井固井、压裂设计和施工的要求,提高了施工作业的效率,降低了作业的风险和成本,在深层长水平段页岩气井第一段储层改造中具有较好的推广应用前景,对于深层页岩气藏实现效益开发具有重要的现实意义。

Research and development of the toe fracturing sliding sleeve technology for deep-seated shale gas wells with long horizontal sections

For breaking the foreign technical monopoly and solve the technical problems in the first stage of reservoir stimulation in deep-seated shale gas wells with long horizontal sections in China, structural design, indoor experiment & evaluation and matching cementing technology study were conducted after the application environment and construction requirements were confirmed. Accordingly, a toe fracturing sliding sleeve which meets the requirements of high temperature and high pressure cementing and high flow-rate fracturing was developed and then tested on site at Well Changning H7-5 in the Changning–Weiyuan National Shale Gas Demonstration Area, Sichuan Basin. And the following research results were obtained. First, this independently developed toe fracturing sliding sleeve can be opened by applying pressure to the wellhead, and thus the passage for Stage I fracturing or pumping is formed to substitute the Stage I perforation of coiled tubing. Second, the toe fracturing sliding sleeve adopts the design of special inner surface coating, the upgoing opening structure of inner sliding sleeve and the temporary plugging design of frac sand jet orifice, which can improve the adaptability of the sleeve to cementing environment and reduce the effect of cement on the normal opening of the sleeve. Third, the opening of the toe fracturing sliding sleeve depends on the breaking of rupture disks, which can improve its opening accuracy and ensure its accurate opening at high temperature and high pressure (HTHP). In conclusion, this independently developed toe fracturing sliding sleeve is advantageous with stable and reliable performance, convenient operation and high opening accuracy, and its indicators all meet the design and construction requirements of cementing and fracturing of shale gas horizontal wells, so it can increase the construction efficiency and reduce construction risk and cost. Furthermore, it presents the promising prospect of popularization and application in Stage I reservoir stimulation of deep-seated shale gas wells with long horizontal sections. And it is also of great practical significance to the beneficial development of deep shale gas reservoirs.