吉木萨尔页岩油藏超长水平井水平段长度界限研究

页岩油气开发实践表明,较长的水平段有利于提高单井控制储量与经济效益。与美国相比,中国页岩油气埋藏深度相当,但水平井的水平段长度差距较大。优化钻井技术、提高水平井水平段长度已成为现阶段中国非常规油气藏水平井钻井技术难题之一。以吉木萨尔页岩油藏超长水平井为例,分析了制约水平段长度的关键因素,包括额定泵压、钻井液安全密度窗口、钻柱和套管屈曲等,推导了水平井管柱摩阻-扭矩计算模型。基于吉木萨尔页岩油藏JHW00421井地质条件和现有钻井设备工艺参数,优化了井眼轨迹与钻具组合,研究了避免钻柱与套管屈曲的技术条件,制订了水平段长度为3 500 m的钻井技术方案,该井最终完钻井深为5 830 m,水平段长度为3 100 m,达到钻井方案设计要求。该项技术为页岩油藏超长水平井的实施提供了技术参考。

Lateral Length Limit of Ultra-long Horizontal Well in Jimsar Shale Oil Reservoir

Shale oil and gas development practices have shown that longer lateral length of horizontal well is favorable to enhance single-well controlled reserve and economic benefits. Comparing with the reservoir properties in the United States, the shale oil and gas reservoir burial depth in China is similar, but the lateral length of horizontal well is quite shorter. Drilling technology optimization and enhancing lateral length of horizontal well have become one of the technical difficulties in the unconventional hydrocarbon reservoirs in China at present. The key constraints for lateral length were analyzed by taking the ultra-long horizontal well in Jimsar shale oil reservoir as an example, including rated pump pressure, drilling fluid safety density window, drill string and casing buckling, etc. In addition, a pipe string friction-torque calculation model was derived for horizontal well. The wellbore trajectory and drilling tool combination were optimized and the technical conditions for avoiding drill-string and case buckling were researched based on the geology conditions of Well JHW00421 in Jimsar shale oil reservoir and the technical parameters of available drilling equipment. A drilling program was developed for a horizontal well with 3 500 m lateral length. The final measured depth of this well is 5 830 m and the lateral length is 3 100 m, which meet the drilling program design. This technology could provide certain technical reference for the implementation of ultra-long horizontal well in shale oil reservoir.