枯竭油气藏型储气库老井再利用可行性分析

Feasibility Analysis on the Reuse of Gas Storage Old Wells in Depleted Oil and Gas Reservoirs

D储气库建设在国家级湿地内,该地区建设新井几无可能,为保证储气库产能建设,需将区块内原油气藏老井纳入储气库注采井网,因此对老井的再利用可行性分析十分必要。将D储气库老井建井数据和生产套管腐蚀壁厚检测数据相结合,提出了一套老井再利用可行性分析流程,对3口老井完整性、生产套管的剩余强度开展了可靠性评价。结果表明:原油气藏采气井B-53井井口设施虽完善,但该井井身结构不符合储气库注采井要求,无技术套管作为第二道安全屏障,同时生产套管剩余强度不满足储气库强度需求,应关井封堵或改造;原油藏注气井TZ-1井、TZ-2井整体符合储气库生产要求,可进行注采井再利用,但二开套管鞋以上缺少水泥环,需对环空补挤水泥,并建立定期检测制度。最后,根据B-53井实际情况,提出了2套老井改造方案:一是封堵储层改为观测井,二是重新钻进改造为水平(定向)注采井。

D gas storage is built in the national wetland,so it is almost impossible to build new wells in this area.In order to ensure the construction of gas storage capacity,it is necessary to transform and utilize the old wells in the block,so it is necessary to analyze the feasibility of reusing the old wells.In this paper,the old well construction data and production casing corrosion wall thickness detection data of D gas storage are combined to put forward a set of old well reuse feasibility analysis process.The reliability evaluation of the integrity of three old wells and the residual strength of production casing is carried out,and the feasibility of old well reuse is analyzed.The results show that although the wellhead facilities of B-53 well are perfect,the wellbore structure does not meet the requirements of gas storage injection production well.There is no technical casing as the second safety barrier,and the residual strength of production casing does not meet the strength requirements of gas storage,so the well should be shut in or reformed.Wells TZ-1 and TZ-2 meet the production requirements of gas storage,and can be reused for injection production wells.However,there is no cement sheath barrier above casing shoe,so it is necessary to establish a regular inspection system for wellhead facilities and casing wall thickness.At the same time,according to the actual situation of well B-53,two sets of transformation methods are put forward.One is to plug the reservoir into observation well,the other is to transform it into horizontal(directional)injection production well.This paper can provide guidance for the feasibility evaluation and reuse of old wells in depleted oil and gas reservoirs.