烃源岩层中异常高压研究——以渤海湾盆地东营凹陷古近系为例

异常高压对油气成藏具有重要作用。渤海湾盆地东营凹陷古近系沙三、沙四段烃源岩普遍存在异常高压,泥岩的欠压实作用和生烃作用是异常高压产生的主要因素,异常高压的高值区与暗色泥岩厚度大的地区有较好的对应关系。现今异常高压主要分布在2700~3500 m的深度范围,随着深度的增加,异常高压范围增大。应用异常高压研究成藏作用时,要考虑异常高压的时代性。烃源岩中现今异常高压对油藏的保存具有积极的作用,是未来油源灶;古异常高压对排烃是有效的,油气的主要富集区位于大规模生烃后的古异常低压区。

STUDY OF THE ABNORMAL HIGH-PRESSURE IN HYDROCARBON SOURCE ROCKS-TAKING PALEOGENE IN THE DONGYING SAG, THE BOHAI BAY BASIN AS AN EXAMPLE

The abnormal high-pressure is very important to oil and gas accumulation.There is abnormal high-pressure in the 3rd and 4th member of Shahejie Formation of Paleogene all over the Dongying Sag,the Bohai Bay Basin.The main factors that lead to the pressure are under-compaction and hydrocarbon generation in the source rocks.The overpressure area is well corresponding with the thickness of source rocks.The present abnormal high-pressure is mainly distributed at a depth range 2 700 m to 3 500 m,and the range becomes bigger with increasing of the buried depth.Times of abnormal high-pressure should be considered when applying abnormal high-pressure to hydrocarbon accumulation.The present abnormal high-pressure in the source rocks has an active effect on the saving of oil and gas and it is oil source kitchen in future.The ancient abnormal high-pressure took an active part in the hydrocarbon migration in the source rocks and there is the main accumulation area of oil and gas.The main oil-gas enriched zones are located in the abnormal high-pressure after hydrocarbon generation in large scale.