Organization
Development and Construction Department of Yuanba Gasfield, Southwest Oil &
Gas Company, SINOPEC, Langzhong 637400, China
摘要
元坝气田长兴组气藏储量巨大，但由于气藏埋深接近7 000 m，面临多压力系统、井底高温高压、高含硫化氢等诸多技术难题。元坝12-1H 井作为第1 口实施开窗侧钻的开发井，钻井过程中遇到开窗点超深、地层可钻性差、超深井测量信号传输困难、地层温度高等技术难点。根据目标靶点结合实钻井眼轨迹，优化井眼轨道设计方案，优选开窗点位置，避开套管接箍和复杂层位，采用卡瓦坐封式斜向器+ 硬地层专用铣锥进行开窗作业，选择适合小井眼和耐高温的无线随钻仪器和螺杆钻具，优化调整钻具组合，形成了适用于元坝超深井的开窗侧钻钻井技术。该井自6 330 m 处开窗，开窗时间26 h，侧钻至井深6 955 m 完钻，最大井斜62.4°，全角变化率控制在16（ °）/100 m以内，侧钻总进尺625 m，钻遇各类气层88.6 m，保证了地质目标的实现， 为同类井的施工提供了较强的技术支撑。
Abstract
The gas reservoir in Changxing Group of Yuanba Gasfield is very huge. Owing to the fact that the gas reservoir is buried about 7 000 m underground, many technical difficulties such as multi-pressure system, high bottom hole temperature, high bottom hole pressure and high bottom hole hydrogen sulfide content are encountered. In the course of drilling of Well Yuanba 12-1H as the first development well to which the window sidetracking technology is applied, the technical difficulties such as ultra-deep window opening point, low drillabillity of formation, and difficult transmission of measurement signal in ultra-deep well and high temperature of formation have been encountered. On the basis of the target and actual wellbore trajectory, the wellbore trajectory design program has been optimized, the position of window opening point has been properly selected, the collar of casing and complicated formation have been avoided, the slip packer whipstock and special milling cone for hard formation have been used to carry out the window opening operation, the temperature-resistant wireless MWD tools and screw drill tools which are suitable for small wellbore have been selected, the combination of drilling tools have been optimized and adjusted, and the window sidetracking drilling technology suitable for ultra-deep well Yuanba has been formed. As for the well, the window is opened from the location of which the depth is 6 330 m, the window open time is 26 h, the sidetracking is completed at the depth of 6 955 m, the maximum hole deviationinclination is 62.4 °, the whole-angle change rate is controlled as lower than 16 (°)/100 m, the total sidetracking footage is 625 m, and the depth of various gas pools encountered is 88.6 m, all of which guarantee the achievement of geological objective, and provide the relatively strong technical support for operation in similar wells.
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