抗盐聚合物乳液的性能与现场应用

Performance and Field Application of Salt-resistant Polymer Emulsion

针对常规滑溜水减阻剂在高温、高矿化度下性能严重下降的问题,研制了免混配抗盐聚合物乳液为减阻剂,并开展聚合物乳液配方优选研究。通过室内实验研究了清水和玛18水配制压裂液的流变性、黏弹性、降阻性能、破胶性能及对岩心伤害情况,并进行了现场应用。研究表明:质量分数为0.05%~1.2%的抗盐聚合物乳液,在高矿化度(21 159.88 mg/L)下黏度保持率在32.5%~62.5%之间,质量分数在0.2%~0.5%之间时能达到低矿化度下质量分数为0.1%~0.2%的压裂液体系性能,且流体的弹性模量占主导地位。抗盐聚合物乳液降阻率比常规聚合物乳液高4百分点以上。压裂液破乳液的表面张力小于28 mN/m、与煤油间的界面张力不高于2 mN/m,残渣含量低于50 mg/L,对岩心伤害较低。现场应用时采用聚合物浓度阶梯式增加的思路,砂浓度在30~270 kg/m^(3)时,聚合物质量分数范围应在0.15%~0.2%,砂浓度在300~360 kg/m^(3)时,聚合物质量分数范围应在0.2%~0.35%。进一步优化聚合物质量分数为0.15~0.35%,施工时降阻率可达到85%左右,试验井投产后效果较好,为玛湖油田水平井有效使用聚合物压裂液体系提供一种合理技术方案。

In view of the problem that the performance of conventional slip-water drag reducer is seriously decreased at high temperature and high salinity,a no-miscible salt-resistant polymer emulsion was developed as a drag reducer.It is necessary to carry out research on the optimization of polymer emulsion formula.Rheology,viscoelasticity,resistance reduction,gel breaking properties,core damage of fracturing fluid prepared with clean water and Ma 18 water were tested in laboratory and field application was carried out.The results showed that,when the concentration of salt-resistant polymer emulsion was 0.05%—1.2%,the viscosity retention rate was between 32.5%—62.5%at high salinity of 21159.88 mg/L,and the performance of the fracture liquid system at the concentration of 0.2%—0.5%could be similar to that at the concentration of 0.1%—0.2%at low salinity,and the elastic modulus of the system was dominant.The resistance reduction rate of the system was more than 4%higher than that of conventional polymer emulsion.The surface tension of the gel-breaking fluid was less than 28 mN/m,and the interfacial tension with kerosene was less than 2 mN/m,and the residue content was less than 50 mg/L.The damage of gel-breaking fluid to core was less.In field application,the idea of stepping polymer concentration increase was adopted,and it was obtained that when the sand concentration was 30—270 kg/m^(3),the mass fraction of polymer fracturing fluid should be 0.15%—0.2%;when the sand concentration was 300—360 kg/m^(3),the mass fraction of polymer fracturing fluid should be 0.2%—0.35%.The mass fraction of polymer fracturing fluid was further optimized to be 0.15%—0.35%,and the resistance reduction rate could reach up to about 85%during construction.After the test well was put into operation,the effect was good,which provided a reasonable technical scheme for the effective use of polymer fracturing liquid system in horizontal wells of Mahu oilfield.