辽河西部凹陷油气运移特征及其影响因素

The characteristics of oil secondary migration and its affecting factors in the western Liaohe depression

辽河西部凹陷油气十分富集,油气藏类型复杂,油气相态多样发育,不同构造带油气运移特征存在差异。本文主要根据原油中咔唑类含氮化合物浓度和相关参数,以及储层流体包裹体的发育特征,结合油气相态及物性分布特征,探讨了辽河西部凹陷油气运移特征以及影响因素。研究表明,中央隆起带原油中咔唑类化合物浓度高、异构化参数变化小,油气包裹体主要呈线状分布,在切穿矿物加大边的裂隙中,油气运移通道以走滑形成的东西向雁列式或帚状断裂为主,运移动力主要为流体异常压力;斜坡带原油中咔唑类化合物浓度及其相关异构化参数变化明显,油气包裹体多分布在石英与长石颗粒次生加大边中,呈群体面状分布,显示较强荧光特征,油气主要由洼陷带至斜坡带以扇三角洲前缘分支河道指状砂体或辫状河道砂体为运移通道,以水动力与浮力推动,远源或近源运移成藏;陡坡带原油中咔唑类化合物总浓度以及异构化参数存在变化,以台安大洼断裂带或指状砂体为运移通道、以异常流体压力为动力近源运移成藏;古潜山原油咔唑类化合物总浓度低,参数变化明显,主要以不整合面或基底断裂为运移通道,以异常流体压力为动力近源运移成藏。油气运移聚集时间主要在东营期,自北往南油气成藏时间逐渐变晚,与沙三段、沙四段生烃期较为匹配。

In the western Liaohe depression,the oil and gas accumulation zones consisted of multiple phases and reservoir types are mainly caused by the hydrocarbon migrated pathways. Based on the analysis of the carbazoles and correlated parameters in non-hydrocarbons,and the oll fluid inclusions in reservoir, combined with the oil or gas distribution regularity, the secondary migrated characteristics and its effective factors have been researched. In central uplift zone, the concentrations of total carbazoles in oil samples are high and the correlated parameters change a little. The oil bearing fluid inclusions are characterized by irregular shape, strong fluorescent light and linear distribution in the micro factures of the quartzes. So,the oil and gas migrated paths are the EW direction en echelon faults under the movement of slipping and the migrated force were abnormal pore fluid pressure. In slope belts,the content of carbazoles and its parameters changed a lot. The oil bearing fluid inclusions are characterized by regular shapes, strong fluorescent light and planar distribution in the secondary edges of the quartzes. The oil migrated by the finger sand-bodies of fan delta front branch channels or braided streams and the migrated forces are hydrodynamic and buoyancy from the sags to the slope belts. In the steep slope belt,the content of carbazoles and its parameters changed. The oil migrated by the Taian-Dawa fault pressure. In belts or finger sand bodies and the migrated forces are abnormal pore fluid buried hills,the concentration of carbazoles and its parameters changed a lot. The oil migrated by the unconformable surfaces or foundational faults and the migrated force is mainly abnormal pore fluid pressure. The oil migrated stage is Dongying period and became later from the northeast to the southwest correlating with the generated hydrocarbon history.