东营凹陷油源特征分析

东营凹陷油气丰富，发育了古近系沙河街组三段、四段两套有效烃源岩。根据烃源岩及原油的地球化学特征分析，探讨凹陷内各油田的石油来源。将东营凹陷已发现石油划分为沙三型、沙四型及混合型，认为：南斜坡地区原油主要来源于沙四段烃源岩，凹陷中部及北部油田的原油主要源于沙三段或为沙三段、沙四段的混源油；凹陷周边油田的原油大多数来源于沙四上亚段烃源岩，大致呈环状分布于凹陷边部；凹陷中部油田的原油以沙三型为主。各供油洼陷生成的油气就近运移聚集，油气环绕生油洼陷呈环带状分布。图4表1参8

Relationship between source rock and oil accumulation in Dongying Sag

The Dongying Sag, which has two sets of source rocks including the fourth member (Es 4 ) and the third member (Es 3 ) of Shahejie Formation, is abundant in hydrocarbon. By analyzing the geochemical features, the oil sources of all oil pools in the sag are investigated, and divided into three types of sources: the Es 3 type, the Es 4 type and the mixed type,suggesting that the crude oils in the south slope mainly generated from the Es 4 source rocks, those in the central and the northern pools mainly generated from the Es 3 or from the mixture of the Es 3 and the Es 4 source rocks, those in the central area mainly belong to the Es 3 type, and those in the marginal pools distributed annularly around the sag mainly generated from the upper sub member of Es 4 source rocks. The hydrocarbons derived from the sub sags migrated and accumulated nearby, and are distributed round the sub sags.