元坝超深含硫气井测试事故分析与预防措施

Testing accident analysis and preventive measures for ultra-deep sulfur-bearing gas wells in Yuanba Gas Field

曹阳 贾宝 熊昕东 乔治国

CAO Yang JIA Bao XIONG Xindong QIAO Zhiguo

中国石化西南油气分公司工程技术研究院，四川德阳　618000 中国石化西南石油局井下作业公司，四川德阳　618000

Engineering Technology Institute of Sinopec Southwest Oil & Gas Company, Deyang 618000, China

元坝气田长兴组气藏埋深7 000 m左右，井底温度高达157 ℃，作业工况及井下条件复杂，测试难度大、风险高，测试时面临管柱埋卡、脱落、工具失效等问题。针对现场大量事故案例，在理论分析和现场试验基础上研究出各类事故相应的预防措施。压井工艺由直接压井改为循环隔离液后再压井，并对钻井液进行优化，解决了钻井液分相、沉淀等问题，降低了管柱埋卡事故率；优化施工水力参数，消除了工具被刺蚀风险；对RTTS封隔器中心管和水力锚锚爪进行改进，避免了封隔器中心管断裂，同时提高了封隔器坐封稳定性；合理控制油管入井次数减少了油管脱落风险。以上措施在YB205等10余口井中成功应用，有效降低了元坝气田测试事故率，为同类井作业提供借鉴。

With a burial depth of approximate 7 000 m, and as high as 157 ℃of downhole temperature, the gas reservoir in Changxing Formation in Yuanba gas field is of complex working condition and downhole geological condition, so the testing is hard to carry out, where high risks such as string being buried, stuck or falling off and malfunction of tools may occur. Based on theory analysis and field test, corresponding preventive measures for various accidents have been made by means of analyzing a large number of onsite accident cases. Well kill was enabled after seal liquid circulation in stead of traditional direct well kill; furthermore, the drilling fluid was optimized. In this way, drilling fluid parvafacies and precipitation and other problems were solved, and the string was less likely to be buried and stuck; construction hydraulic parameters were optimized to eliminate the risk that tools might be punctured or corroded; RTTS packer central tube and hydraulic anchor jaws were improved to avoid the fracture of packer central tube while improving the stability of packer setting; the reasonable control of the frequency of oil tube running reduced the risk of oil tube falling off. The above measures have been successfully applied in over 10 wells including well YB205, which effectively reduced accident rate in Yuanba gas field testing. They can be used as reference in well operation of the same kind.