济阳坳陷生烃洼陷沉降类型及其油气地质意义

Settlement Types of Hydrocarbon-Generating Sag in the Jiyang Depression and their Geologic Significance for Hydrocarbon Accumulations

为明确生烃洼陷对含油气凹陷的油气地质意义,以渤海湾盆地济阳坳陷为例,基于控洼断层活动速率、不同层系沉积速率、埋藏史与剥蚀厚度等特征,将生烃洼陷划分为早期沉降型、继承沉降型与晚期沉降型3类,对比分析了不同类型洼陷的生烃特征及其与油气成藏的关系。研究表明:不同沉降类型洼陷在生烃量、生烃强度与生烃面积等方面差异明显,其生烃能力可划分为A、B、C、D 4个级别,其中,早期沉降型洼陷生烃能力较弱,继承沉降型洼陷生烃能力普遍较强,晚期沉降型洼陷生烃能力受洼陷规模、烃源岩质量等因素影响较大;洼陷的生烃能力决定了含油气凹陷的富集程度,影响了油气初次运移的动力条件,油气多围绕A、B类洼陷呈环带状展布;生烃洼陷沉降类型控制了含油气凹陷的成藏时间与期次。该研究丰富了陆相断陷盆地油气成藏理论,对东部盆地油气勘探实践具有一定的指导意义。

To determine geologic significance of hydrocarbon-generating sag to hydrocarbon-bearing sags, the Jiy- ang Depression in the Bohai Bay Basin has been studied. With consideration to intensities of sag-control faulting ac- tivities, sedimentary velocities of various formations, burial history, denudation thicknesses and various other fea- tures, hydroearbon-generating sags can be classified into three categories： early-stage settlement, inherited settle- mcnt and late-stage settlement. In addition, hydrocarbon-generating features of sags of various types and their rela- tionship with hydrocarbon aceumulation have been reviewed. Research results show thet~ are significant differenees in volumes, intensity and areas of hydrocarbon-generating of sags with different settlement types. Their hydrocarbon -generating capacities can be classified into four categories, namely A, B, C and l）. To be more specific, sags of early-stage settlement type have relatively low hydrocarbon-generating capacities, whereas sags of inherited settle- ment type have ~latively high hydrocarbon-generating capacities. At the same time, hydrocarbon-generating ea- paeities of sags of late-stage settlement type are significantly affected by scales of such sags, quality of source rocks and various other factors ; Generally speaking, hydrocarbon-generating capaeities of sags may determine enrichment of hydrocarbon-bearing sags, and eventually may affeet dynanfic conditions for primary migration of hydroearhons. Majority of hydroearhons may distributed in rings around Type A and Type B sags; In fact, settlement types of hy- drocarbon-generating sags may control reservoir-formation times and periods in hydrocarbon-bearing sags. Relevant research results may enrich theories related to hydrocarbon aeeumulation in continental faulting basins and may pro- vide necessary references for oil-gas exploration in basins in eastern parts.