营尔凹陷下白垩统油气勘探应避开高压水层

营尔凹陷下白垩统(K₁₎存在下沟组和赤金堡组2套源岩，目前它们已到成熟阶段。凹陷东侧长沙岭构造在下白垩统下沟组和赤金堡组储层中也发现油藏，但主要分布在高压水层的顶部及下部，而高压水层段存在良好的储层，并未发现油气。文章根据高压水层段的储层荧光特征，通过储层烃与源岩的对比，分析了下白垩统高压水层对油气运移的影响。研究结果表明：高压水层段，储层荧光弱，储层抽提物特征既不同于赤赤金堡组源岩，也不同于下构组源岩，为就近捕获的产物；高压水层未发生大规模的油气运移，其形成时间早于油气运移的时间。建议该区油气勘探目标的选择应避开高压水层，选择凹陷附近的圈闭、高压水层以下的层位。

Effects of High-pressure Water Zones to Hydrocarbon Migration in Lower Cretaceous of Ying'er Sag

The Lower Cretaceous Xiagou Formation and Chijinpu Formation are recognized to be source rocks in Ying'er sag and are mature at present. Oil accumulations have been discovered in the Lower Cretaceous Xiagou Formation and Chijinpu Formation reservoirs of Changshaling structure in the eastern sag. They are mainly distributed on the top or bottom of the high pressure water zones, but none of them have been discovered within the water zones, where high-quality reservoirs occur. The influences of the Lower Cretaceous high pressure water zones on hydrocarbon migration are studied through oil-source correlation based on the fluorescence analysis of the reservoirs in the high pressure water zones. The reservoirs in the high-pressure water zones are characterized by week fluorescence and the reservoir extracts are the products captured in-situ, with features neither the same with the Chijinpu Formation source rocks, nor the same with the Xiagou Formation source rocks. No large scale hydrocarbon migration has occurred in the high pressure water zones, though their formation was earlier than hydrocarbon migration. It is proposed that the high pressure water zones should be avoided when selecting exploration targets, while the horizons in the traps near the sag and under the high pressure water zones are favorable targets.