渤海上第三系油藏形成特征及规律分析

Pool forming characteristics and regularity of the Upper Tertiary reservoirs in Bohai Bay

渤海地区上第三系勘探近年获得巨大突破 ,相继发现了蓬莱 19 3、曹妃甸 11 1、渤中 2 5 1等亿吨级大油田 ,找到了超过十亿吨的石油地质储量。利用该区歧南构造带、沙南构造带、沙垒田凸起等实际资料 ,分析这些油田勘探的成功经验及一些钻探失利的教训 ,总结出两类主要构造的成藏特征及规律 :①凹陷内上第三系断鼻、断块、断背斜构造的圈闭形成条件、次级断层发育程度、地层与断层组合关系等 ,是此类构造能否成藏的关键 ,其油藏具有油层薄、丰度低、油质轻的特点 ;②凸起上继承性披覆背斜油气富集程度高 ,油气运移条件好 ,后期断层的破坏是影响其油气富集的主要因素 ,其油藏特点是油层厚、丰度高、油质重。

In recent years, a big breakthrough of oil exploration in the Upper Tertiary was made in Bohai Bay, resulting in the discovered OOIP reaching 10 9t. The successful and unsuccessful experiences of oil exploration in the Upper Tertiary are analyzed based on the practical data from Qinan terrace zone, Shadongnan structural zone, Shaleitian uplift and the other oil pools in the Upper Tertiary of Bohai Bay. The oil pool forming characteristics and regularity of the two major types of structures are summarized:(1) The trap formation conditions, the density of the second-order faults and the combination of the strata and the fault of the faulted nose, faulted block and faulted anticline in the Upper Tertiary developed in the sag are the essential elements to oil pool formation. This kind of oil pool is characterized by thin oil layer, lower richness and light oil;(2) Oil and gas enrichment is high in the drape anticlines developed in the uplift. But the distruction of faults, which was active in the late stage, is the essential influencing factor to this oil enrichment. The structures have favorable pathways for oil migration. The oil pools formed here are characterized by thick oil layer, high richness and heavy oil.