摘要
针对威远区块页岩气水平井水平段长、套管居中度不高、油基钻井液与水泥浆兼容性差、驱替顶替效率不高、后期大型压裂易造成环空窜气等难点,通过合理安放扶正器保证套管居中、优化前置液技术、采用塑性水泥浆体系等几个方面提出了技术对策。下套管前认真通井,清洁净化井眼,采用套管"抬头"技术,斜井段以下采用旋流刚性扶正器和整体式弹性扶正器交叉使用的方式,可以保证套管居中度在72%以上。冲刷隔离液削弱油膜的结构力和内聚力,达到较好冲刷效果;具有一定黏度的加重隔离液有效隔开油基钻井液和水泥浆。通过加入特制塑性剂材料提高水泥石形变能力,达到固井及压裂的要求。现场应用表明,该技术提高了水泥环的封固质量,为今后该地区页岩气水平井固井提供了技术支撑。
Because drilling horizontal wells for development of shale gas in Weiyuan block have some features,including long horizontal section,low degree of casing centralizing,poor compatibility of oil based drilling fluids and cement slurry,low displacement efficiency of slurry,easy to cause the annular gas channeling by late large scale fracturing,etc.,the technical countermeasures have been put forward,such as install centrilizers properly to keep the casing centering,optimize the pad fluids,adopt the plastic cement slurry system,etc. Before running casing,drifting must be done seriously to clean the wellbore,and combined with the technique of heaving lower casing end,installing swirl rigid centralizers and intergral elastic centralizers alternately below the inclined well section to guarantee the casing centering above 72%. The spacer can flush and weaken the structural force and cohesive force of the oil film to obtain better flushing results,and weighted spacer with a certain viscosity may separate the oil based drilling fluids and cement slurry. By adding the specific plastic material,the deformation capacity of set cement can be improved to meet the requirement of cementing and fracturing. Field application showed that the technology has improved the isolating quality of cement sheath,which can provide the technical support for cementing of shale gas wells in the area in the future.
出处
《非常规油气》
2016年第6期108-112,共5页
Unconventional Oil & Gas
关键词
威远区块
油基钻井液
页岩气
固井
Weiyuan block
oil based drilling fluids
shale gas
cementing
