元坝气田超深水平井防漏型乳化酸解卡技术

New Technology for Stuck Drill Pipe Using Mud Loss-Proof Emulsified Acid Implemented in a Ultra-Deep Horizontal Well in the Yuanba Gas Field

元坝气田水平井在钻进长兴组地层时常发生卡钻事故,采用常规泡酸易井漏且无法解卡。为解决该问题,在深入分析卡钻原因的基础上,研究了超深水平井防漏型乳化酸解卡技术。其基本思路是:利用乳化酸的缓速原理使酸液返至卡点位置,配合使用惰性堵漏材料来减缓形成漏失通道后的漏失速度,增长酸液与基岩的反应时间从而达到解卡的目的。通过室内试验形成了一套防漏型乳化酸配方,试验表明,该乳化酸与长兴组岩屑以及滤饼的酸溶率能分别达到50%和40%;酸液中的堵漏材料能有效提高封堵效果,封堵率达到99%;同时,乳化酸具有较好的缓速酸性能,破乳温度可达到140℃。该乳化酸在YB205-1井长兴组地层压差卡钻中进行了试用,成功解决了卡钻问题。研究表明,防漏型乳化酸能解决高渗碳酸盐岩超深水平井中的压差卡钻问题。

Stuck drill pipe during the drilling of horizontal wells has become a common problem in the Changxing Formation of the Yuanba Gas Field .Conventional foamed acids are prone to lost circulation and cannot eliminate the risk of stuck drillpipe .In order to solve the problem of stuck drillpipes during horizon‐tal drilling ,a new technology using mud loss‐proof emulsified acid was tried in an ultra‐deep horizontal well after being developed by means of an in‐depth analysis of the cause .For the basic stuck drillpipe freeing principle ,it is important to recognize that acid fluids can return to stuck point by retarding of emulsified acids and inert circulation lost materials can be used to reduce mud loss rate so as to increase time of reac‐tion between acid fluids and base rock to release stuck drillpipe .A mud loss‐proof emulsified acid formula has been developed through laboratory tests .Test results show that the emulsified acid can achieve an acid solubility of 50% in cuttings and 40% in mud cakes of the Changxing Formation ;circulation lost materials of acid fluid system can effectively improve plugging effects with a plugging ratio up to 99% .Further ,the emulsified acid system achieved good retarded acid performance and its demulsification temperature can be as high as 140degrees .The emulsified acid has been successfully used in drillpipe stuck due to differential pressure in the Changxing Formation in Well YB 205‐1 .According to research results ,mud loss‐proof emul‐sified acid can solve differential pressure which causes drillpipe to get stuck in ultra‐deep horizontal wells in highly permeable carbonate rocks .