高渗疏松砂岩油藏聚合物驱提高采收率可行性研究

FEASIBILITY STUDY ON POLYMER FLOODING FOR UNCONSOLIDATED SAND RESERVOIRS WITH HIGH PERMEABILITY TO IMPROVE RECOVERY FACTOR

聚合物驱技术能够加快海上油田的采油速度,进而提高采收率。通过采用自制的填砂模型模拟海上油田高渗疏松砂岩油藏,选用缔合型聚合物NsAP和常用的HPAM进行可行性研究。研究结果表明:在注入过程中,由于NsAP溶液特殊的物理网络结构,使NsAP在孔隙介质中的吸附滞留不同于HPAM;其分子间的缔合作用,使其在孔隙介质中具有较好的抗剪切性;从而表现出了NsAP溶液的注入压力、阻力系数、残余阻力系数和粘度保留率均比HPAM溶液高。NsAP在高渗疏松砂岩油藏条件下,具有较好的降低水相渗透率能力,并能在油层深部建立较理想的流动阻力,扩大驱替流体在疏松砂岩中的波及体积。因此,利用缔合型聚合物作为驱替介质,有望成为提高海上油田采收率方法之一。

With self-made sand-filling model to simulate the unconsolidated sand reservoirs with high permeability in offshore oilfields,the feasibility study is conducted for the associated polymer NsAP and the conventional polymer HPAM.The study results show in the injection process,the absorbance and holdup of NsAP in the porous medium are different from that of HPAM since the NsAP solution has special physical network structure.The NsAP solution has strong shearing resistance in the porous medium because of the action of its intermolecular association.Therefore,the injection pressure,resistance coefficient,residual resistance factor and retention rate of the NsAP solution are all higher than that of HPAM solution.Under the conditions of the unconsolidated sand reservoirs with high permeability,NsAP can decrease the water phase permeability better,establish the flow resistance deeply within the reservoir,and expand the sweep volume of the driving fluid in the unconsolidated sand rocks.Taking the associated polymer as the driving medium may become one of the methods to improve the recovery factor of offshore oilfields.