玛湖凹陷上乌尔禾组强敏感油藏CO_(2)同步吞吐试验

Simultaneous CO_(2)Huff⁃n⁃Puff Test in Highly Sensitive Reservoirs in Upper Wuerhe Formation,Mahu Sag

为探索玛湖凹陷强敏感致密砾岩油藏水平井压裂后高效开发提高采收率技术,在玛湖1井区开展注CO_(2)同步吞吐试验。结果表明:CO_(2)同步吞吐可提高强敏感致密砾岩油藏采收率,驱油机理主要是萃取、混相、竞争吸附、膨胀驱替等;裂缝沟通是导致气窜的主要原因,通过现场调控,实现井组与气窜井同步焖井,保证现场实施效果;试验井组受压裂液浸泡导致黏土矿物水化膨胀,造成喉道封堵,渗流能力减弱,影响了CO_(2)波及范围,导致阶段换油率较低。CO_(2)同步吞吐试验取得了较好的增油效果,试验井组阶段增油量为3983 t,换油率为0.36,该试验为强敏感致密砾岩油藏水平井压裂后提高采收率提供了技术思路及矿场经验。

In order to explore the post⁃fracturing EOR technologies for efficient development of highly sensitive tight conglomerate oil reser⁃voirs in horizontal wells in the Mahu sag,a simultaneous CO_(2)huff⁃n⁃puff test was carried out in the Mahu 1 well block.The results show that simultaneous CO_(2)huff⁃n⁃puff can enhance oil recovery of highly sensitive tight conglomerate reservoirs,and its oil displacement mech⁃anisms mainly include extraction,miscibility,competitive adsorption,and expansive displacement.Fracture communication is the main cause of gas channeling.Through field regulation and control,synchronous soaking of well groups and gas channeling wells was achieved,ensuring the field implementation effect.Soaked by fracturing fluid,the clay minerals in the tested well group hydrate and expand,causing pore throat blockage,which affects CO_(2)swept range and results in a low interim oil exchange ratio.The simultaneous CO_(2)huff⁃n⁃puff test achieved favorable stimulation effects,with an interim oil increment of 3,983 tons and an oil exchange ratio of 0.36 in the tested well group.This test provides technical ideas and field experience for horizontal wells in enhancing oil recovery of highly sensitive tight conglomerate reservoirs after fracturing.