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东营凹陷沙四段和沙三段普遍存在异常高压,泥岩声波时差对超压具有很好的响应关系,超压段均对应异常高的声波时差值,而且泥岩声波时差随着岩石颗粒垂直有效应力的减小而增加.利用东营凹陷丰富的测井、测试和地质资料综合分析超压成因,在确定超压泥岩和砂岩均属于正常压实的基础之上,提出生油作用为超压的主要成因机制.主要证据有:(1)超压泥岩不具有异常低密度特征;(2)超压段泥岩密度与岩石颗粒垂直有效应力缺少线形关系;(3)东营凹陷超压砂岩不具有异常高的原生孔隙度和地温梯度;(4)超压顶界面深度范围为2 000～3 000m,随着烃源岩埋深的增加而增大,所对应的成熟度Ro(%)为0.50%～0.75%,温度大约为87～123℃;(5)超压烃源岩现今仍具有很强的生油能力;(6)超压带内钙质泥岩的存在使超压具有很好的压封闭条件;(7)烃源岩中发育大量的裂缝;(8)超压储层主要为油层或者油水同层,水层很少.东营凹陷砂岩超压主要是由烃源岩中排出的高压流体运移至储层中而发生超压传递造成的.
Abnormal pressure is common in Sha 4 and Sha 3 of Dongying depression, and the acoustic jet lag of mudstone has a good response to overpressure. The overpressure zone corresponds to the abnormally high acoustic jet lag, and the acoustic jet lag of mudstone changes with the vertical effective stress of rock particles .According to the comprehensive logging, testing and geologic data analysis of overpressure in Dongying Sag, it is concluded that overpressured mudstone and sandstone belong to the normal compaction, and the main role of overgap in oil generation is proposed The main evidences are as follows: (1) overpressured mudstone does not have abnormally low density features; (2) mudstone density in overpressured zone lacks linear relationship with vertical effective stress of rock particles; (3) overpressured sandstone in Dongying Sag does not have abnormally high (4) The depth of overpressure top interface ranged from 2 000 m to 3 000 m, with the increase of buried depth of source rock, the corresponding maturity Ro (%) was 0.50% -0.75 %, And the temperature is about 87-123 ℃. (5) Overpressured source rocks still have strong oil generation capability now. (6) The existence of calcareous mudstone in overpressure zone makes the overpressure have good pressure seal conditions ; (7) a large number of fractures are developed in source rocks; and (8) overpressured reservoirs are the major ones For the oil layer or the same layer, there are few water layers.The sandstone overpressure in Dongying sag is mainly caused by the overpressure transfer caused by the high pressure fluid discharged from the source rocks into the reservoir.