非常规油藏多功能滑溜水体系研究与应用

Research and application of multifunctional slick-water system in unconventional reservoirs

非常规油藏压裂使用的常规滑溜水存在溶解缓慢、携砂性能差、抗盐能力弱及对温度敏感等问题。针对以上问题,笔者自主研发由0.1%~0.6%可变黏减阻剂与0.2%纳米乳液组成的多功能滑溜水体系,该滑溜水体系溶解速度快,90 s基本溶解完成;0.1%的减阻剂滑溜水减阻率可达74.84%;使用中不需要添加交联剂可实现变黏携砂;对一价离子与二价离子均有很高耐受性,可使用返排液配液;在-30~40℃环境中放置后,减阻剂乳液仍可正常使用。滑溜水进入地层破胶后,对页岩、砂岩储层岩心的渗吸驱油率为71.25%~74.16%。经现场应用,压裂成功率100%,施工中砂密度最高为540~550 kg/m^(3),减阻率超过77%,压后两井日产油9.8~14.4 m^(3),证明多功能滑溜水体系具有驱油增效的特点。

Conventional slickwater used in unconventional reservoir fracturing has problems such as slow dissolution,poor sand carrying capacity,low salt resistance,and temperature sensitivity.In the light of the above problems,a multifunctional slick-water system consisting of 0.1%-0.6%variable viscosity drag reducer and0.2%nano emulsion was developed independently.The dissolution rate of the slick-water system was fast,and the dissolution was basically completed in 90 s.The drag reduction rate of low stick slip water could reach74.84%.It could realize the change of viscosity and carrying sand without adding cross-linking agent.Moreover,it had high tolerance to both monovalent ion and divalent ion and could use flow back fluid to match liquid.After being placed in an environment of-30-40℃,the drag-reducing agent emulsion could still be used normally.At the same time,after slick-water entered the formation,the gel fluid could play the function of oil displacement,and had stable and efficient oil displacement efficiency.The imbibition displacement rate of shale and sandstone reservoir cores was 71.25%-74.16%.After field application,the fracturing success rate was100%,the highest sand concentration was 540-550 kg/m^(3),the drag reduction rate was above 77%,which proved the characteristics of multi-functional slick-water flooding and oil efficiency enhancement.