低效热采/水驱稠油转化学降黏复合驱技术

Chemical viscosity reduction compound flooding technology for low-efficiency thermal recovery/water flooding heavy oil reservoirs

胜利油区稠油油藏开发以热采吞吐和水驱为主,热采中,稠油油汽比逐轮次下降,井间剩余油难以有效动用,钻新井不经济;水驱中,稠油油水流度比大,吨油操作成本增加,经济效益变差,采收率不足20%。“十三五”以来,为了提高低效稠油开发效果,立足多级调驱、化学降黏改善流度,提高采收率,确立了加合增效均衡驱替技术思路。从稠油致黏机理研究出发,深化了降黏剂的解聚、乳化等作用机制研究,开展了多级调驱、防膨及气体增溶等与化学降黏相结合的加合增效复合机理研究,研发了低聚型降黏驱油剂、黏弹性乳化调驱剂和双重功能泡沫调驱剂等关键化学剂,完善了方案优化决策调控技术,从而形成了以“强调驱、强降黏、强防膨、强活性、强增溶”为核心的稠油化学降黏复合驱技术。该技术有别于常规稀油的聚合物“二元”、“三元”复合驱以及普通稠油化学驱等技术,已成功推广应用到多轮次吞吐后、敏感性及高温高盐水驱等多种类型稠油油藏,覆盖地质储量1500×10^(4) t,预计提高采收率8%以上,有效支撑了低效稠油油藏的变革性效益开发。

The development of heavy oil reservoirs in Shengli Oilfield is dominated by thermal huff and puff and water flood⁃ing.The oil-to-steam ratio decreases by rounds and the remaining oil between wells is difficult to produce effectively in thermal recovery heavy reservoirs;it is not economical to drill new wells.The oil-to-water mobility ratio is high and the op⁃erating cost per ton of oil increases in water flooding heavy oil reservoirs,worsening the economic benefit and leading to a recovery factor of less than 20%.Since“The thirteenth Five-Year Plan Period in 2016-2020”,the technical idea of addi⁃tive,synergistic,and balanced displacement was devised to improve the development effect of low-efficiency heavy oil res⁃ervoirs and enhance mobility and oil recovery through multi-stage profile control and chemical viscosity reduction.Accord⁃ing to the study of viscosity mechanism of heavy oil,the research on depolymerization and emulsification mechanisms of vis⁃cosity reducer was deepened,and the compound mechanisms with chemical viscosity reduction were investigated,such as multi-stage profile control and flooding,anti-swelling,and gas solubilization.Key chemical agents such as oligomeric vis⁃cosity reducer and viscoelastic emulsification profile control and flooding agents and dual-function foaming agents were de⁃veloped,and the decision-making and control technology for scheme optimization was improved,thus forming the com⁃pound flooding technology of heavy-oil chemical viscosity reduction with“strong profile control and flooding,viscosity re⁃duction,anti-swelling,activity,and solubilization”as the core.Different from the“binary”and the“ternary”polymer flooding of conventional thin oil and the chemical flooding of common heavy oil,this technology has been successfully pro⁃moted and applied to various types of heavy oil reservoirs,such as those after multi-round huff and puff,sensitive,and high-temperature high-salinity water-drive ones,covering a geological reserve of 15 million tons.It is expected to increase the recovery factor by more than 8%,which effectively supports the transformational and beneficial development of low-effi⁃ciency heavy oil reservoirs.