昆2井优快钻井及油气层保护技术

昆2井是一口位于柴北缘西段的昆特依凹陷潜伏Ⅰ号圈闭上的风险探井,设计井深为5950m。针对柴北缘深探井存在的主要技术难题,制定了昆2井的技术对策。通过对钻井设备的优选、井身结构的优化、钻头及钻具组合的优选、钻井参数及钻井液性能的优化、油气层保护技术的研究与应用,形成了一套适合于柴北缘的优快钻井技术,使昆2井的完钻井深达到5950m。与邻区的深探井平均水平相比,在井深增加888m、大尺寸井眼段更长的前提下,昆2井的钻井、完井周期分别缩短了98.75d、124.2d,钻机月速度增加了317m/台,平均机械钻速增加了0.82m/h。根据“理想充填新理论”,确定了保护油气层的最优复配暂堵方案,利用该方案所配制的钻井液其渗透率恢复值达到了87.5%以上,流变性能良好,滤失量低,对改善泥饼质量、增强井壁稳定性有明显的效果。

Techniques of Formation Protection and Optimal-fast Drilling of Well Kun-2

Technical countermeasures for well Kun-2 are drawn up to solve the key difficulties in deep exploration well in the northern marginal zone of Qaidam Basin. A suite of optimal and fast drilling techniques suitable to the northern marginal zone of the basin are developed on the basis of the optimization of drilling equipment, wellbore structure, drilling bits and tools assembly, as well as drilling parameters and properties of drilling fluid, and the research and application of oil-gas reservoir protection techniques. As a result, the completion drilling depth of well Kun-2 reaches 5,950 meters. As the well depth increases by 888 meters and the big-sized well hole gets longer, the cycles of drilling and well completion of well Kun-2 are reduced by 98.75 days and 124.2 days respectively, with the speed of each drilling rig increasing by 317 meters monthly and the average drilling rate increasing by 0.82m per hour. An optimal composite and temporarily blocked plan is established to protect the oil-gas reservoir. By applying this plan, a new kind of drilling fluid is made up, with its restorable permeability reaching more than 87.5 percent and having better fluidity and lower filtration loss, obviously improving mud-cake quality and enhancing sidewall stability.