用于薄层油气藏的聚丙烯酰胺全悬浮压裂液

Polyacrylamide Full Suspension Fracturing Fluid System Using in Thin-layer Oil and Gas Reservoir

基于薄层油气资源开发中控制缝高和低排量的需求,以丙烯酰胺(AM)、丙烯酸(AA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)、2-丙烯酰胺基乙基溴化铵(DAMAB)、烷基酚聚氧乙烯醚(NP-10)等为原料,通过水溶液自由基胶束聚合法合成聚丙烯酰胺嵌段共聚物(PMASD)。采用荧光分光光度计、流变仪和扫描电子显微镜研究了PMASD的临界缔合浓度、黏弹性和微观结构;同时,研究了PMASD压裂液的静态、动态携砂性能,并与聚丙烯酰胺滑溜水进行对比;最后,将PMASD压裂液进行了现场应用。结果表明,PMASD压裂液存在胶束结构,临界缔合浓度为0.127%。PMASD压裂液体系表现出较好的黏弹性,线性黏弹区范围为0.01~1.00 Pa,疏水缔合后强度大,抗剪切能力强。在低排量(20 L/min)的注入过程中,PMASD压裂液形成的网络结构呈无规则分布,具有很高的结构强度,可以有效携带支撑剂。PMASD压裂液的静态和动态携砂性能均较好。在砂液体积比为12%的实验条件下,PMASD质量分数≥0.25%(黏度为147 m Pa·s)时,在常温及80℃下均表现出较好的悬浮及携砂能力。相较于聚丙烯酰胺滑溜水,PMASD压裂液的携砂效果同比提高160%。在江苏油田X5-X井现场应用中,以2 m3/min的排量泵入PMASD压裂液,日产液由1.4 t增至6.5 t,日产油由0.6 t增至4.2 t,增产效果明显。全悬浮压裂液PMASD体系能满足薄层油气资源在低施工排量下有效携砂的压裂改造需求。

Based on the demand of controlling fracture height and low displacement in the development of thin-layer oil and gas resources,polyacrylamide block copolymer(PMASD)was synthesized by aqueous solution free radical micelle polymerization,using acrylamide(AM),acrylic acid(AA),2-acrylamide-2-methylpropanesulfonic acid(AMPS),2-acrylamidoethylammonium bromide(DAMAB)and alkylphenol polyoxyethylene ether(NP-10)as raw materials.The critical association concentration,viscoelasticity and microstructure of PMASD were studied by fluorescence spectrophotometer,rheometer and scanning electron microscope.At the same time,the static and dynamic sand carrying properties of PMASD fracturing fluid were studied,and then the results were compared with that of polyacrylamide slick water.Finally,the PMASD fracturing fluid was applied in the field.The results showed that the PMASD fracturing fluid had a micelle structure.The critical association concentration was 0.127%.The PMASD fracturing fluid system showed good viscoelasticity.The linear viscoelastic range was 0.01—1.00 Pa.After hydrophobic association,the strength was large,meanwhile,the shear resistance was strong.In the injection process of low displacement(20 L/min),the network structure formed by PMASD fracturing fluid was irregularly distributed and had high structural strength,which could effectively carry proppant.The static and dynamic sand carrying performance of PMASD fracturing fluid was good.Under the experimental condition of 12%sand liquid volume ratio,when the mass fraction of PMASD was equal or greater than 0.25%(147 mPa·s),it showed good suspension and sand carrying capacity at room temperature and 80℃.Compared with polyacrylamide slick water,the sand carrying effect of PMASD fracturing fluid increased by 160%.In the field application of X5-X well in Jiangsu oilfield,PMASD fracturing fluid was pumped at a displacement of 2 m3/min.The daily liquid production increased from 1.4 t to 6.5 t,meanwhile,the daily oil production increased from 0.6 t to 4.2 t.The effect of increasing production was obvious.The full suspension fracturing fluid PMASD system could meet the needs of effective sand-carrying fracturing of thin-layer oil and gas resources under low construction displacement.