摘要
川东北罗家2井在第二次完井中发生套管破裂,引发严重井漏和井喷,井底的高压、高含硫化氢气体从破口处窜入地层,沿套管外质量差的水泥环上窜到断层处经裂缝上窜到地面,天然气和地层水在距井口1.2km的地方窜出地面,造成险情。为此,选用特种凝胶ZND进行堵漏。该特种凝胶ZND不同于一般的聚合物堵漏剂,它不需要交联,在地面配好后直接使用,特种凝胶在地面管线钻具水眼及环空中容易流动,而进入漏层后黏度迅速增加,流动阻力大,具有很强的黏弹性,可以占据漏层附近的漏失空间。特种凝胶ZND难以与地层水混合而被冲稀,如果被气体吹散,细小的颗粒不与地层水混合,可以在地层重新集结,形成结构。特种凝胶ZND在川东北罗家2井中的成功应用,验证了其处理恶性漏失的技术可行性。
A severe lost circulation and a blowout happened on the well Luojia-2 in the northeastern Sichuan basin,which were caused by the casing cracking during the secondary completion.The high-pressure and high-H2S-content natural gas fluxed into the formation through the casing crack and channeled up through the poor-quality cement sheath outside the casing to reach the fault where the gas flowed to the ground surface through the fracture.The point the natural gas and the formation water appeared at the ground was 1.2 km away from the wellhead.To control this dangerous scenario,a special gel ZND was selected for plugging.The ZND is different from the average polymer type of lost circulation material(LCM)additives,without requirement of crosslinking and it can be directly used after being prepared at the well site.This gel can easily flow through the pipes at the site,through the nozzles of the drilling tools and in the annulus.The viscosity of the gel will increase after entering the thief zone which results in high flow friction,so the gel will occupy the space near the thief zone.The gel will not mix with the formation water and so will not be diluted.Even if the ZND is dispersed by gas,since the minute particles will not mix with formation water,the particles will combine in the formation to form new structure.The successful application of ZND on the well Luojia-2 has proved the technical feasibility of ZND in controlling severe lost circulations.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2008年第6期81-82,85,共3页
Natural Gas Industry
基金
国家自然科学基金重大项目(编号:90610013)的资助
关键词
井漏
井喷
套管挤坏
特种凝胶
堵漏压井
lost circulation,well blowout,casing collapse,special gel,plugging and killing
