东营凹陷古近系超高压成因及其特征

东营凹陷古近系存在 3 类超高压地层。根据“综合压实曲线”和“压力正演模拟”,确定欠压实和生烃作用是泥岩超高压的成因。“接触传递”使与超高压泥岩呈接触关系的Ⅰ类砂岩产生超高压,Ⅱ类超高压砂岩则是“连通传递”的结果。沙三中亚段较深井段泥岩发育弱超高压,沙三下亚段压力增强到中超高压,沙四段发育强超高压。泥岩超高压平面上以沉积中心为超高压中心,向盆地边缘超高压强度减弱,呈“环状分布”;浅层砂岩（埋深小于 3 000 m）极少发育超高压,只分布在部分断裂带、不整合面附近,砂岩超高压强度大于泥岩;3 000 m 以下,泥岩超高压强度大于砂岩。

Overpressure Genesis and Differential Characteristics of Paleogene in Dongying Sag

There exist three types of over-pressured formations of Paleogene in Dongying sag. The undercompaction and hydrocarbon generation are the genetic mechanism of mudstone overpressure, according to the synthetic compaction curve and pressure forward modeling. The contact transmission leads to the overpressure of type-I sandstone contacting over-pressured mudstone, while the connecting transmission is the cause of forming overpressure of type-II sandstone. It is shown that weak overpressure occurs in mudstone in deeper well interval of Middle Sha-3 member, middle overpressure in Lower Sha-3 member and high overpressure in Sha-4 member. The mudstone pressure center depends on the sedimentary center, so the intensity of overpressure is decreasing toward the basin margin and distributed circularly. There is little overpressure in shallow sandstone less than 3 000 m in depth, except for its part distribution near the fault zone and unconformity, and the overpressure intensity of the sandstone is greater than that of the mudstone. In depth of over 3 000 m, such an intensity of the sandstone is smaller than that of the mudstone.