大情字井地区青山口组泥岩超压发育特征及分布预测

Over-pressure development mudstone characteristics and distribution prediction of Qingshankou Formation in Daqingzi oil field

选定大情字井高台子油层青山口组青一、二段页岩油勘探的最有利区域,研究该区泥页岩层段大规模发育超压情况。依据岩心及测井资料、泥岩段声波时差与埋深关系和应用平衡深度法建立工区岩性图版,筛选出泥岩,依据计算对应深度的孔隙流体压力和超压系数来研究超压发育程度。结果表明:在工区内,超压在垂向上的分布具有明显的层控效应,作为烃源岩质量最好、有机碳含量最高的qn 1-Ⅰ、qn 2-Ⅴ小层超压最为发育;平面上,超压的分布受泥岩的分布及相带展布的控制,在泥岩较为发育的前三角洲亚相超压最为发育。超压特征研究可为大情字井地区青山口组泥页岩油有利富集区域、成藏模式、油气藏评价等研究提供依据。

This paper is concerned with an investigation into the large-scale over-pressure development of shale section to determine the most favorable area for shale oil exploration in Qingshankou Formation,Gaotaizi reservoir,Daqingzi well.The research building previous studies and the core and logging data involves developing the lithology map of the work area;screening out the mudstones;and calculating the pore fluid pressure and the over-pressure coefficient of the corresponding depth according to the relationship between the acoustic time difference of the mudstone section and the buried depth and by the balanced depth method to study the degree of over-pressure development.The results show that in the work area,the vertical distribution of over-pressure has an obvious stratabound effect,and the most developed over-pressure occurs in the small layer of qn 1-I,qn 2-V which is the best source rock with the highest quality and organic carbon content.In plane,the distribution of over-pressure is controlled by the distribution of mudstone and the distribution of facies belt,in the pre delta subfacies with relatively developed mudstone,over-pressure is most developed.The study of over-pressures could serve as a basis for identifying shale oil favorable enrichment area,reservoir forming model and reservoir evaluation of Qingshankou Formation in Daqingz well area.