弱凝胶调驱技术在海1块普通稠油油藏的应用

Application of weak gel flooding technology in ordinary heavy oil reservoir of Hai-1 block

海1块为注水开发普通稠油油藏,目前已进入高含水、高采出程度阶段,长期水驱开发使储层非均质性加剧,油藏依靠常规注水技术难以大幅度提高采收率。针对上述开发矛盾,分析了弱凝胶调驱提高采收率技术的原理并开展了海1块普通稠油油藏弱凝胶调驱可行性研究,按照"封、调、驱、洗"一体化思路对调驱体系及注入参数进行优化设计:第一段前置段塞选择有机铬凝胶与体膨颗粒复配组成高强度复合凝胶体系对高渗透层及大孔道进行封堵,注入量0.01 PV;第二段主段塞选择中等强度有机铬弱凝胶体系用于调整纵向吸水剖面,同时改善平面油水流度比,扩大波及体积,注入量0.14 PV;第三段驱油段塞选择一定浓度的驱油剂用于降低油水界面张力,进一步提高驱油效率,注入量0.05 PV。室内物理模拟及先导试验结果表明,三段塞调驱体系能有效封堵大孔道,改善平面油水流度比,提高水驱波及体积,大幅度改善海1块水驱后期开发效果,对同类油藏具有一定借鉴意义。

Hai-1 block is a waterflooding ordinary heavy oil reservoir. At present, it has entered the high water cut and high recov- ery percent stage. Long-term water flooding intensified the heterogeneity of the reservoir. It is difficult for some reservoirs which re- ly on conventional waterflooding to significantly increase oil recovery. In view of the aforementioned development contradictions, this paper analyzed the principle of weak gel flooding to increase oil recovery and studied the feasibility of weak gel flooding in Hai-1 block ordinary heavy oil reservoir. Based on the integration of ＂seal, adjust, flood and wash＂, this paper conducted the opti- mal design. The first slug, pre-slug, selected organic chromium gel with the pre-gelled swellable particle to compose high strength composite gel system for high permeable layer and large pore plugging with the injection volume of 0.01 PV. The second slug, main slug, selected medium strength organic chromium weak gel system to adjust the vertical water injection profile, meanwhile, im- proved the plane oil-water mobility ratio and swept volume with the injection volume of 0.14 PV. The third slug, flooding slug, se- lected certain concentration of displacing agent to reduce the oil-water interfacial tension and for the further improvements of oil displacement efficiency with the injection volume of 0.05 PV. Results of the laboratory physical simulation and pilot test showed that the slug control and oil displacement system can effectively block large pores and improve the plane oil flow ratio and water flooding swept volume. It also greatly improved the later development effects after water flooding in Hal- 1 block. This application gives certain reference to the similar reservoirs.