渤海湾盆地济阳坳陷孤北潜山下古生界油气来源及运移方向

Source and migration direction of hydrocarbon in Lower Paleozoic in Gubei buried hill, Jiyang Depression, Bohai Bay Basin

为明确渤海湾盆地济阳坳陷孤北潜山下古生界油气运聚特征,指出下步油气勘探方向,利用钻井、地震、分析化验等资料,对该区油气来源、输导体系及油气运聚方式进行了研究。孤北潜山下古生界油气来自渤南洼陷沙三段烃源岩,断层与下古生界风化壳是油气运移的主要通道。其中北东向断层与东西向盆倾断层活动时期与渤南洼陷生烃期一致,是油气运移的重要通道之一;下古生界潜山顶面风化壳厚度大,物性好,渗流能力强,可以作为油气远距离横向运移的良好输导层。原油主要充注方向为自西向东、自北向南,西排山与渤南洼陷通过孤西1号断层对接,渤南洼陷生成的油气可直接运移到西排山中聚集成藏;而对于中排山和东排山,油气首先沿埕东断层和孤北断层向东运移至潜山低部位,然后沿下古生界风化壳向高部位运聚成藏;同时中排山油气也可以沿东西向盆倾断层F或F走向运移进入东排山。西排山中部、中排山北部埕东断层上升盘及整个东排山是研究区下一步重点勘探区域。

In order to clarify the characteristics of oil and gas migration and accumulation in the Lower Paleozoic of the Gubei buried hill and guide the direction of further oil and gas exploration, the hydrocarbon generation, transportation, migration and accumulation were systematically studied based on the data of drilling, seismic and testing. The oil and gas in the Lower Paleozoic of the study area were mainly sourced from the third member of the Shahejie Formation in the Bonan Sag. Faults and the weathering crust of the Lower Paleozoic provided channels for oil and gas migration. The active period of NE trending faults and EW trending basin-dipping faults is consistent with the hydrocarbon generation period of the Bonan Sag, and is one of the important channels for oil and gas migration. The weathering crust on the top of the buried hills in the Lower Paleozoic has big thickness, good physical properties and strong seepage ability, which can be regarded as a good transport layer for long-distance lateral migration of oil and gas. Crude oil mainly migrated from west to east and north to south. The western buried hill and the Bonan subsag are connected by the Guxi No. 1 fault, and the oil and gas generated in the Bonan subsag can be directly migrated to the western buried hills. For the central and eastern buried hills, oil and gas first migrated eastward along the Chengdong and Gubei faults to the lower part of the buried hill, and then migrated and accumulated to the higher part along the Lower Paleozoic weathering crust. Meanwhile, the oil and gas in the central buried hill migrated into the eastern buried hill along the EW trending basin-dipping faults For F. The central part of the western buried hill, the rising wall of the Chengdong fault in the north of the central buried hill and the whole eastern buried hill area are key targets for further exploration in the study area.