长宁页岩气开发井气体钻井技术研究

RESEARCH ON GAS DRILLING TECHNOLOGY IN CHANGNING SHALEGAS FIELD

长宁地区部分井区表层溶洞、裂缝发育,全区中下部韩家店、石牛栏地层岩性致密,可钻性差。前期开发井采用常规钻井液方式在表层段钻井易发生恶性井漏,在韩家店、石牛栏井段钻井机械钻速低、钻井周期长。通过在上述地层开展气体钻井可行性分析,优化气体钻井方案,最终成功在本区开发井应用气体钻井技术,表层平均单井漏失量由2 000 m^3降至0 m^3,韩家店~石牛栏平均机械钻速由3.1 m/h提高至7.31 m/h,该段钻井时间由18 d降低至4.5 d,2014年累计节约钻井成本1 500万元以上,达到了治漏、提速、降本的效果。

The surface formations of some blocks in Changning shale gas field have many well developed water-eroded caves and fractures,and the lower formations named Hanjiadian and Shiniulan in Changning shale gas field have dense lithology with poor drillability. In the early time,malignant lost was often encountered when drilled the surface formations with conventional mud in the development wells,and with low drilling speed,long drilling period when drilled the Hanjiadian and Shiniulan formations. Through the feasibility analysis of gas drilling for the formations mentioned above,optimizing the gas drilling program,then gas drilling was successfully carried out in the development well of Changning shale gas field. The average single well loss in the surface formation had been decreased from2816 m^3 to 0 m^3,ROP was increased from 3. 1m/h to 7. 31m/h in Hanjiadian and Shiniulan formations,and drilling period was decreased from 18 days to 4. 5days in this interval. The drilling cost was saved more than 15 millions,and the effect of decreasing leakage and increasing ROP was achieved.