地温—地压场特征与油气分布的关系——以辽东湾地区为例

CHARACTERISTICS OF GEOTEMPERATURE-GEOPRESSURE FIELDS AND THEIR RELATIONSHIPS WITH DISTRIBUTION OF OIL AND GAS: TAKING LIAODONG BAY AS AN EXAMPLE

利用辽东湾地区70余口探井实测的静温静压数据以及地震地层压力预测的数据,对该地区地温场、地压场、地温—地压系统特征进行剖析,并探讨了它们与油气分布的关系。该地区目前已发现的大中型油气田多位于辽西低凸起高地温梯度区。辽东湾发育深、浅2个超压体系,浅层超压体系主要对应东三段,深层超压体系主要对应沙三段,油气藏主要位于超压区的边缘或常压区。深、浅2个超压体系在北、中、南部地区发育特征的差异控制油气分布层位的差异性,北部地区沙一、二段是最主要的含油层系,中、南部地区则以东二段为最主要的含油层系。辽东湾发育高压型复式温压系统,上下2套温压系统能量差较大,油气垂向运移动力强,趋向于在温压系统分界附近富集成藏。

The characteristics of the geotemperature field, geopressure field and geotemperature-geopressure system in Liaodong Bay are analyzed and their relationships with the distribution of oil and gas are discussed by using the geotemperature and geopressure data measured in 70 wells and the formation pressures data predicted through seismic survey in the study area. The current discovered large and medium oil and gas fields are concentrated on the low swell with high geothermal gradient in Liaoxi. Two overpressure systems, including a shallow one and a deep one, are developed in Liaodong Bay, with the shallow one corresponding to the Ed_3 member and the deeper overpressure system corresponding to the Es_3 member. The oil and gas reservoirs are mainly distributed on the edge of the overpressure zone or in the normal pressure zone. The differences in development characteristics of these two overpressure systems in the northern, central and southern parts of the study area have controlled the differences in the horizons of oil and gas distribution. In the northern part, Es_1 and Es_2 are the main oil-bearing formation, while in the central and southern part, Ed_2 is the main oil-bearing formation. Duplex geotemperature-geopressure systems with high pressure are developed in Liaodong Bay, and the energy contrast between the upper and lower pressure systems is large, thus hydrocarbons migrate very actively in vertical direction and tend to accumulate near the boundaries of the two systems.