东营凹陷梁家楼油田成藏模式再研究

Restudy of pool-forming pattern of Liangjialou oilfield in Dongying sag

张林晔 刘庆 张春荣 孔祥星 朱日房

Zhang Linye Liu Qing Zhang Chunrong Kong Xiangxing Zhu Rifang

前人研究认为,渤海湾盆地东营凹陷梁家楼油田是沙河街组三段中亚段泥岩生成的烃类直接排入其上紧邻的浊积砂砾岩形成的自生自储型油藏,然而东营凹陷烃源岩研究的最新成果并不支持上述结论。油源对比、油藏水化学特征、油藏压力等资料均表明,梁家楼油田南部区块油藏的油气主要源自沙河街组四段上亚段,多属超压油藏,油藏水以氯化钙型为主,为烃类首先沿沙河街组四段岩性疏导体系侧向运移再经断层垂向运移形成的下生上储型或自生自储型油藏;而中、北部区块源自沙河街组三段下亚段,属常压油藏,油藏水以碳酸氢钠型为主,为烃类沿油源断层直接垂向运移形成的下生上储型油藏。上述认识启示勘探人员对东营凹陷的沙河街组三段中亚段烃源岩进行重新评价,并重新认识近洼陷中心其他类似油藏的成藏模式和成藏过程。

Liangjialou oilfield in Dongying sag,Bohai Bay basin,was previously thought to be an"indigenously generating and accumulating"oil reservoir,i.e.hydrocarbons generated in the mudstones in the middle 3 member of Shahejie Formation have migrated upward into the adjacent turbidite glutinite.This view,however,is not supported by the latest achievements in hydrocarbon source rock studies in Dongying sag.Oil-to-source correlation,hydrochemical characteristics of oil reservoir and reservoir pressure show that oil reservoirs in southern Liangjialou oilfield,mostly characterized by superpressure and chloride-calcium type water,have been sourced by the upper 4 member of Shahejie Formation,i.e.hydrocarbons have firstly migrated laterally along the pathways in the rocks,and then migrated vertically upward through faults and become oil reservoirs either of "both generated and accumulated indigenously"or"generated below and accumulated above";while those in middle and northern Liangjialou oilfield,characterized by normal pressure and sodium bicarbonate water,hydrocarbons have been generated in the lower 3 member of Shahejie Formation, and then directly migrated vertically through faults in the source rock,so the oil reservoirs are of the type of "generated below and accumulated above". The knowledge enlightened us to reevaluate the source rocks in the middle 3 member of Shahejie Formation and restudy the pool-forming patterns in the similar pools around the center of the sag.

10.11743/ogg20040303