我国西部地区超深井钻井取心技术

Coring technology in ultra-deep wells in West China

超深井取心收获率的高低受地层岩性、取心工具及工艺技术措施等因素影响很大。针对我国西部地区超深井段钻井取心地层可钻性差,研磨性强,井温高,循环压力高,井底沉砂造成堵心,井深复杂情况多且判断困难、地层裂缝发育、取心工具失稳等方面的难点,根据超深井取心的实践,总结了在该区超深井取心作业中涉及取心前准备、下钻、树心及取心钻进、割心、起钻等各个环节的技术措施,介绍了塔深1、元坝3、于奇6等3口井在超深井段取心工具选择、取心措施制订、取心层位岩性确定、钻具组合优选、钻井参数优化、提高岩心收获率等方面所取得的经验;进而提出旨在提高我国西部地区超深井段取心收获率的建议:①优选取心工具和取心钻头;②制订具有针对性的技术措施;③选用动力工具进行取心等。

Core recovery in ultradeep wells is greatly influenced by formation lithology,coring tools,and coring techniques,so deep coring in ultra-deep wells in West China has to meet the challenges of poor drillability,high abrasiveness,high temperature,high circulating pressure,core jamming due to sand settling at the hole bottom,highly developed fractures,instable coring tools,and uncertain and unexpected downhole problems.Herein based on field practices,some technical measures are summarized including hole preparation,tripping in and out,core making,coring and drilling,and core cutting.Coring operations in several ultra-deep wells such as Tashen 1,Yuanba 3,Yuqi 6,etc.are introduced,regarding the determination of coring tools,coring procedures,lithology of coring interval,optimal BHA and coring parameters,and core recovery improvement measures.And finally some suggestions are made on how to select optimal coring tools and bits,make specific coring plans,and adopt downhole motors to perform coring.