柴达木盆地复杂深井安全钻井技术

Drilling Safety Technology for Complicated Deep Wells in Qaidam Basin

柴达木盆地钻探对象近年来逐渐向深层探索。超深井普遍存在压力系统复杂、地层岩性复杂、储层流体复杂、工程力学复杂等工程地质特征,钻井工程面临着设计优化难、施工风险大、钻井速度慢、工程质量控制难度大等技术问题。通过开展钻井工程方案优化、PDC钻头优选、超高温钻井液及高温水泥浆、高压盐水层安全钻井等研究,初步形成了柴达木盆地复杂深井安全钻井配套技术。现场应用6口井,均顺利完钻,平均井深为6286.6m,钻井周期达236.3d,平均机械钻速为3.15m/h,复杂时效为10.8%,较前期缩短45.6%。昆1-1井7310m井深完钻,创柴达木盆地最深钻井记录。

The drilling targets in Qaidam Basin have gradually extended into deep layers in recent years. Generally speaking, the ultradeep wells are geologically characterized in complex pressure systems, complex stratigraphical lithology, complex reservoir fluid and complex engineering mechanics. Drilling engineering faces some technological bottlenecks, such as difficult optimization of design,high operational risks, slow drilling speed, and difficulty for engineering quality control. A systematic technology for drilling safety of complicated deep wells in Qaidam Basin was developed thanks to optimization of the drilling engineering plan, optimization of PDC bit, research on ultra-high temperature drilling fluid and high-temperature drilling mud, and high-pressure salt-water layer drilling safety study. The technology was applied to six wells on the field, achieving good results for well completion. The well depth was 6286.6 meters on average and the drilling period reached 236.3 days. The average mechanical drilling speed was 3.15 m/h while the complex timeliness was 10.8 percent, 45.6 percent shorter than the initial stage. Drilling and completion of the 7310-meter-deep Kun 1-1Well set a record high for well depth in Qaidam Basin.