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STP强凝胶调堵剂由聚丙烯酰胺、交联剂及延缓剂组成。其中,聚丙烯酰胺的相对分子量为4.00×106—7.00×106、水解度为17.6%;交联剂为Na2Cr2O7+NH4Cl氧化还原体系;延缓剂为加入乙二醇的乳酸/丙酸/乙酸有机酸复配体系。考察了pH值、温度、矿化度及延缓剂用量等因素对STP强凝胶成胶的影响。筛选出STP强凝胶成胶的最佳条件:pH值为5.2,温度为55 ℃、矿化度小于7 g/L。在此条件下调节延缓剂用量可控制成胶时间(12—144 h)。在由3支串联高渗透率岩心和3支串联低渗透率岩心并联而成的非均质模型上,对STP液典型配方进行深部调剖驱油模拟实验研究。结果表明,在水驱饱和油之后(合层采收率为24.3%),依次用调堵剂封堵第一、第二、第三高渗岩心后水驱,合层采收率分别达46.8%、62.2%和69.1%。由此可以得出,封堵深度越大,提高采收率的幅度越大;深部调剖可增加注水对低渗透层的波及程度,未成胶的调堵剂液通过高渗层时可驱替其中的残余油。
STP strong gel plugging agent by polyacrylamide, crosslinking agent and retardant composition. Among them, the relative molecular weight of polyacrylamide is 4.00 × 106-7.00 × 106, the degree of hydrolysis is 17.6%; the cross-linking agent is Na2Cr2O7 + NH4Cl redox system; the retardants are lactic acid / propionic acid / acetic acid organic acid with ethylene glycol Complex system. The effects of pH, temperature, salinity and amount of retardants on the gelation of STP strong gels were investigated. The optimal conditions for gelling strong gel of STP were screened out: the pH was 5.2, the temperature was 55 ℃ and the salinity was less than 7 g / L. Under this condition, the dosage of retarder can be adjusted to control the gelling time (12-144 h). On the heterogeneous model consisting of three parallel high permeability cores and three parallel low permeability cores in parallel, the typical formulation of STP solution was simulated by deep profile control and oil displacement simulation. The results show that after the water flooding saturated oil (combined recovery of 24.3%), followed by plugging agent plugging the first, second and third high permeability core water flooding, combined layer recovery of 46.8 %, 62.2% and 69.1%. It can be concluded that the deeper the plugging depth, the greater the rate of oil recovery; the deep profile control can increase the degree of water infiltration on the low permeability layer, the non-gelled plugging agent liquid can be displaced when passing through the high permeability layer Among the residual oil.