延长区块陆相页岩水基钻井液性能优化评价

延长陆相页岩气资源量丰富，勘探开发处于早期研究阶段。储层地质情况复杂，水平井钻井时常发生井塌等事故，为保持井壁稳定常使用油基钻井液，而油基钻井液又面临环境保护和高成本等压力，为此，研制出页岩水基钻井液体系PSW-1。PSW-1钻井液用0.2%聚合物BOP、2.0%提切剂TQ-1和2.0%的润滑剂ORH-1进行处理，以改善其携屑能力和润滑性。PSW-1的动切力为10 Pa、静切力为4.5 Pa/10 Pa、润滑系数为0.07。经过在4口页岩气水平井的现场应用，PSW-1钻井液能有效地悬浮、携带岩屑，大幅降低钻进时的摩阻；失水量为2.0～2.8 mL，井径扩大率仅为6.34%，有效保持井壁稳定和井下安全。为低成本、高效开发延长陆相页岩气水平井提供技术支持。 

Performance Optimization of a Water Base Drilling Fluid for Continental Shale Gas Drilling in Block Yanchang

Abundant shale gas resource has been found in Yanchang, and the exploration and development of the resource is in research stage. The geology of the shale gas reservoirs is complex, and borehole collapse in horizontal drilling has always been a problem. The use of oil base mud to control borehole wall collapse has resulted in environment protection and high cost issues. To address these problems, a water base drilling fluid, PSW-1, was developed for shale gas drilling. The PSW-1 drilling fluid was treated with 0.2% BOP (a polymer), 2.0% gelling agent TQ-1, and 2.0% lubricant ORH-1 to improve its carrying capacity and lubricity. The properties of the PSW-1 are:YP=10 Pa, Gel strengths=4.5 Pa/10 Pa, and friction coefficient=0.07. Field test of PSW-1 on 4 wells demonstrates that it was able to effectively suspend and carry drilled solids, and showed excellent lubricity. The filter loss of the drilling fluid was 2.0-2.8 mL. Percent hole enlargement was only 6.34%. Borehole wall collapse was avoided, and downhole safety was ensured. The successful use of PSW-1 has provided technical support to the development of continental shale gas in block Yanchang.