元坝气田须家河组地层氮气钻井适应性研究

Adaptability research of nitrogen drilling in Xujiahe Formation, Yuanba Gas Field

 胡大梁 朱化蜀 郭治良

 中国石化西南油气分公司工程技术研究院，四川 德阳 618000

 Engineering Technology Research Institute, Southwest Oil and Gas Company, SINOPEC, Deyang 618000, China

 元坝气田是国内埋藏最深的海相大气田，其主力气藏长兴组埋深接近7 000 m。在上部，陆相地层采用气体钻井，海相地层采用复合钻井，提速效果显著。但是，深部的陆相须家河组地层岩性致密、硬度高，机械钻速低，是制约元坝气田钻井提速的瓶颈。针对这一问题，先后探索了多种钻井工艺，但提速效果有限。在普光、龙岗成功应用氮气钻井的基础上，开展了元坝须家河组氮气钻井提速潜力分析，从地层压力特征、井壁稳定性和地层产气量、出水量以及经济性等方面论证了氮气钻井在须家河组的适应性。研究表明，元坝气田须家河组属于高压、低产地层，测试基本不产水，大部分井段的岩石内聚力大于气体钻井临界值，井壁稳定性较好，氮气钻井预计可提速6倍以上，具有巨大的提速潜力和经济效益。建议选择适当的井位开展氮气钻井试验，为元坝钻井提速提供新的技术手段。

 Yuanba Gas Field is rich in natural gas with the main formation buried nearly 7,000 m.　The air drilling and compound drilling technology are applied in terrestrial and marine strata respectively which improve the rate of penetration greatly. But Xujiahe Formation is buried deeply and the geological conditions are quite complicated such as high density and hardness, strong heterogeneity, which lead to low penetration rate and long drilling period. Several drilling techniques such as impregnated bit with high speed turbo and downhole motor, PDC bit with high torque motor are tested but the ROP are lower than Pugang and Longgang. In order to improve the ROP, the paper analyzed the speed increasing potential of nitrogen drilling, formation pressure, wellbore stability, gas and water production rate. The result shows that Xujiahe Formation is suitable for nitrogen drilling because of the formation characteristics with high pressure, low production of gas and water, good wellbore stability. The ROP may be improved six times with nitrogen drilling which should be tested in the suitable area.

10.6056/dkyqt201505027