彭阳地区延长组长3油藏类型及其控制因素分析

Analysis of Reservoir Types and Controlling Factors of Yanchang Formation Chang3 Oil Reservoirs in Pengyang Region

通过对彭阳地区延长组长3油藏类型及控制因素分析，认为其主要存在两种油藏类型，即岩性油藏与构造-岩性油藏。岩性油藏主要受沉积、物性因素控制，构造-岩性油藏主要受沉积、小型鼻隆构造双重控制。油气来源主要为东南部新发现的长7烃源岩，长3期发育的三角洲平原分流河道砂体是重要的储集体，但砂体物性非均质性较强，因此油藏主要集中在物性相对较好的砂体当中。彭阳地区构造复杂多样，由西向东发育多排小型鼻隆构造，其与物性较好的分流河道砂体形成了有利的构造-岩性圈闭．对该区长3油藏具有一定的控制作用．因此，延长组长3油藏下一步重点应在物性较好的砂体主带、鼻隆高部位进行勘探部署。

Through analyzing the types of the Yanchang Formation Chang3 oil reservoirs and their controlling factors in Pengyang region, Southern Ningxia, it is considered that there are two types of reservoirs, that is, lithologic oil reservoirs and structural- lithologic oil reservoirs. The lithologic oil reservoirs are controlled by sedimentary and physical property factors, while the structural- lithologic oil reservoirs are mainly controlled by both sedimentary and small nose-uplift structures. The oil/gas sources come mainly from the Chang7 source rock that was newly discovered in southeastern of Pengyang region. The distributary channel sands of the deltaic plain that developed in the Chang3 stage are important reservoir bodies, but with strong heterogeneity of physical property. So the oil accumulates mainly in the sand-bodies with better properties. The structures in Pengyang are very complicated. Multi-rows of small nose-uplift structures developed from west to east in the area. They and the good-properly distributary channel sands form an advantageous structural-lithologic trap, which control to a certain extent the Chang3 oil reservoirs in the region. It is suggested that for the Chang3 reservoirs the next step exploration should focus on the main sand-body zones with preferable physical properties, and on the higher positions of the nose-lift structures.