克深2气田井筒堵塞机理及解堵工艺

Well blockage mechanism and blockage removal technology in Keshen 2 Gas Field

塔里木油田库车山前克深2气田76%的气井存在井筒堵塞问题,导致油压、产气量下降,甚至关井停产。现场采用连续油管冲砂取样得到井筒堵塞呈局部井段堵塞特征,采用“微观+宏观”分析方法得出堵塞物主要为碳酸钙结垢,并且存在“井周储层+井筒”复合堵塞情况。研发的“9%盐酸+1%氢氟酸”解堵液体系,溶垢能力94.42%,溶砂能力34.17%,对13 Cr油管的腐蚀速率满足行业标准要求;基于堵塞规律认识制定出以“油套是否连通”和“有无挤液通道”为主要考虑因素的4套解堵工艺,并将“井筒解堵”升级为“井筒-井周储层”系统解堵。截至2019年底,克深2气田共实施气井解堵作业14井次,有效率86%,解堵后单井平均油压由29.7 MPa上升至44.1 MPa,单井平均无阻流量由26.8×104 m3增加至123.3×104 m3,增产3.6倍,实现躺井、异常井的高效复产,为国内外与库车山前高压气田具有相同地质及井况条件的其他油田堵塞治理提供借鉴。

76%of the gas wells in Keshen 2 Gas Field in Kuqa foreland of Tarim Oilfield suffer well blockage,which leads to the decrease of tubing pressure and gas production rate and even shut down and off production.The on-site sandwash sampling by coiled tubing shows that well blockage mainly occurs in local hole sections.The“microscopic+macroscopic”analysis reveals that the stemming is mainly composed of calcium carbonate scale and there is complex blockage of“circumferential reservoir+well”.The developed blockage removal fluid system of“9%hydrochloric acid+1%hydrofluoric acid”has the scale dissolving capacity of 94.42%and the sand dissolving capacity of 34.17%and meets the requirement on the corrosion rate of 13 Cr tubing.Four sets of blockage removal technologies with“connection of tubing and casing?”and“existence of liquid injection pathway?”as the main considerations are prepared based on the cognitions on the blockage laws.In addition,the“well blockage removal”is upgraded to“well-circumferential reservoir”blockage removal.By the end of 2019,blockage removal operation of gas well had been performed 14 well times in Keshen 2 Gas Field,and its efficiency is 86%.After the operation,average single-well tubing pressure is increased from 29.7 MPa to 44.1 MPa,average single-well absolute open flow is increased from 26.8×104 m3 to 123.3×104 m3 and production rate is increased by 3.6 times.In this way,failed wells and abnormal wells are recovered efficiently.The research results provide the reference for the blockage treatment in other domestic and foreign oilfields with the same geological and well conditions as the high pressure gas field in Kuqa foreland.