摘要
为探索吐哈盆地煤系地层煤岩气成藏模式,开辟吐哈盆地天然气勘探新领域,按照地质要求,对柯柯亚构造带侏罗系J2x煤层进行密闭保形取心。柯柯亚地区为山前构造,地应力集中,煤层胶结性差、割理和裂隙发育等特点,极易破碎,加上取心钻井过程中的钻具涡动、水力冲蚀、井眼坍塌、卡钻、工具损坏等因素对取心收获率造成的负面影响,KX1H井前期平均取心收获率仅31.14%。文章针对该问题对本地区J_(2)x煤层取心关键技术进行了研究和集成,通过确定取心安全钻进时间规避井塌卡钻风险、优化钻具结构及钻井参数有效地缓解了钻具涡动和水力冲刷对取心收获率的影响、提高取心工具强度保障了工具在高地应力挤压地层的安全、优选取心钻头有效缓解了水力对松散煤心进入取心筒前的冲刷,形成了一套适合深层煤岩密闭取心的关键技术。现场应用效果显著,除去一筒岩心因钻遇破碎断层导致收获率较低(50%)外,其余取心收获率均达到100%,为其它山前构造煤层取心钻井提供了较好借鉴作用。
To investigate coalbed gas accumulation patterns in coal-bearing strata of the Tuha Basin and pioneer new frontiers in natural gas exploration,pressure-retained and shape-preserved coring operations were conducted on the Jurassic J_(2)x coal seams in the Kekeya structural zone,according to geological requirements.The Kekeya area,characterized by a piedmont tectonic setting with concentrated crustal stress,exhibits poorly cemented coal seams featuring well-developed cleats and fractures,rendering them highly fragile.Multiple factors including bottom hole assembly(BHA)whirl,hydraulic erosion,wellbore collapse,pipe sticking,and tool failures during coring operations significantly compromised core recovery rates,with several prior attempts yielding 0%recovery.This study focused on developing and integrating key technologies to enhance J_(2)x coal seam coring efficiency.Critical achievements include:1)Establishing safe coring time windows to mitigate collapse-induced sticking risks;2)Optimize the combination of drilling tools and drilling parameters to effectively reduce BHA whirl and fluid erosion impacts;3)Enhancing tool strength to ensure operational safety in high-stress formations;4)Selecting specialized coring bits to minimize hydraulic scouring of friable coal cores prior to barrel entry.Field applications demonstrated remarkable improvements in core recovery rates,successfully completing the pressure retained coring mission.These advancements provide fundamental geological data support while offering valuable technical references for coal seam coring operations in piedmont tectonic settings across other oilfields.
作者
周翔宇
张克明
宋权
苏涛
李云志
张永磊
ZHOU Xiangyu;ZHANG Keming;SONG Quan;SU Tao;LI Yunzhi;ZHANG Yonglei(CNPC Xibu Drilling Engineering Co.,Ltd.,Karamay,Xinjiang 834000,China)
出处
《钻采工艺》
北大核心
2025年第3期92-100,共9页
Drilling & Production Technology
基金
新型油气国家重大专项“新疆地区中低煤阶煤岩气高效开发技术与集成示范”之课题“新疆地区煤系地层复杂地质条件优快钻完井研究”(编号:2024ZD1406003)。
关键词
煤岩气
煤层气
山前构造
柯柯亚
密闭取心
地应力
应力坍塌
取心工具
coal-rock gas
coalbed methane
piedmont structure
Kekoya
coal seam coring
ground stress
stress collapse
coring tool
