ZS区块提速提效钻完井技术优化与实践

ZS区块天然气储层岩性为流纹岩、凝灰岩、火山角砾岩，具有高硬度、高研磨性、强非均质性，裂缝发育，富含酸性流体等特性。邻井平均机械钻速低至1.49 m/h，平均钻井周期长达137.12 d，易发生井漏、套管腐蚀等问题，并且后期增产作业及开采过程中，水泥环密封失效，导致井口带压。通过“一趟钻”技术优化井身结构，优选与地层配伍性好的非平面齿钻头，优选油包水钻井液体系，根据储层特征优化完井方式，分析CO₂腐蚀影响因素选择套管，采用自修复水泥浆技术预防井口带压，实现平均钻井周期缩短至69.82 d，三开平均机械钻速3.11 m/h，较邻井提高108.5%，钻井过程中无井漏、井塌等复杂情况，固井后无环空带压问题。

Optimization and practice of drilling and completion technology on increasing of ROP and efficiency in ZS block

The gas reservoirs in ZS block is dominated by lithology of rhyolite, tuff and volcanic breccia and are characterized by high hardness and abrasiveness, strong heterogeneity, well- developed fractures and rich acidic fluids. In the offset well, the average ROP is 1.49 m/h, and the average drilling cycle is 137.12 d. Lost circulation and casing corrosion always occur. In addition, the cement ring seal fails during stimulation and production, resulting in wellhead pressure. The well structure was optimize through the technology of one-trip drilling. The non-planar tooth drill bits with good compatibility with the formation and the water-in-oil drilling fluid system were selected. The completion method was optimized according to the reservoir characteristics. The factors affecting CO₂ corrosion were analyzed to optimize the casing types. The self-repairing cement was used to prevent wellhead pressure. The average drilling cycle is reduced to 69.82 d. The average ROP in the third spud is 3.11 m/h, which is 108.5% higher than that of the offset well. There are no lost circulation during the drilling process and no annular pressure after cementing operation.