济阳坳陷渤南洼陷沙河街组流体压力梯度特征及其油气地质意义

Fluid pressure gradient characteristics and petroleum geological significance in Shahejie Formation of Bonan Sag in Jiyang Depression

刘鹏 孟涛 闫法堂 李忠新 单程程

LIU Peng MENG Tao YAN Fatang LI Zhongxin SHAN Chengcheng

1. 中国石化 胜利油田分公司 勘探开发研究院, 山东 东营 257015; 2. 中国石化 胜利油田分公司 石油开发中心, 山东 东营 257099

1. Research Institute of Petroleum Exploration and Development, SINOPEC Shengli Oilfield Company, Dongying, Shandong 257015, China; 2. Petroleum Development Center, SINOPEC Shengli Oilfield Company, Dongying, Shandong 257099, China

流体压力梯度是剩余流体压力在空间和时间上的变化速率，可作为指示油气运移方向和聚集区的重要参数，具有重要的油气地质意义。以济阳坳陷渤南洼陷沙河街组为研究对象，基于钻井、测井、录井、地震及分析化验资料，综合运用多种技术方法，在古、今流体压力刻画基础上，表征了流体压力梯度的时空展布特征，分析了其受控因素并指出相关油气地质意义。结果表明：渤南洼陷重点层段的横向压力梯度远小于纵向压力梯度，横向压力梯度高值区主要围绕洼陷边缘呈环带状展布，纵向存在三大压力梯度高值段，纵向压力梯度高值段在平面上呈带状展布，分布范围较广；渤南洼陷主要成藏期始末的时间压力梯度高值区位于洼陷南西和北东区域，以生烃增压为主，其余区域为相对低值区，推测排烃泄压较为强烈；致密岩性层、断裂体系与高渗储集体发育是压力梯度形成与分布的主要控因，其中致密岩性层控制纵向压力梯度高值段，断裂体系控制横向压力梯度高值区与纵向压力梯度低值段，断层级别及活动性控制时间压力梯度大小，高渗储集体发育易形成横向压力梯度高值区和时间压力梯度低值区；空间压力梯度大小可指示油气的运移优势方向，时间压力梯度差异可指示页岩油与常规油各自的优势聚集区。

Fluid pressure gradient is the rate at which residual fluid pressure changes both spatially and temporally. It serves as an important parameter for indicating oil and gas migration pathways and accumulation zones, holding great geological significance. This paper focuses on the Shahejie Formation in the Bonan Sag of the Jiyang Depression. Based on drilling, logging, mud logging, seismic and geochemical analysis data, various technical methods were integrated to characterize the spatiotemporal distribution of fluid pressure gradients by mapping both paleo and present-day fluid pressures. Additionally, the controlling factors were analyzed, and their geological significance was discussed. The results show that the horizontal pressure gradient in key layers of the Bonan Sag is significantly lower than the vertical pressure gradient. High horizontal pressure gradient zones are mainly distributed in a ring-shaped pattern around the edge of the sag. There are three high vertical pressure gradient zones, forming elongated zones in a planar distribution with a broad spatial extent. High temporal pressure gradient zones at the beginning and end of the main hydrocarbon accumulation period in the Bonan Sag occur in the southwestern and northeastern regions of the sag, mainly driven by hydrocarbon generation pressurization, whereas the remaining areas exhibit relatively low values, suggesting intense hydrocarbon expulsion and pressure release. Tight lithological layers, fault systems, and the development of high-permeability reservoirs are the main controlling factors of the formation and distribution of pressure gradients. Among them, tight lithological layers control the high vertical pressure gradient zones, and fault systems control both high horizontal and low vertical pressure gradient zones. Fault order and activity influence the magnitude of temporal pressure gradients, and the development of high permeability reservoirs tends to result in high horizontal pressure gradient zones and low temporal pressure gradient zones. The magnitude of spatial pressure gradient indicates the preferred direction of oil and gas migration, while differences in temporal pressure gradients indicate the dominant accumulation zones for shale oil and conventional oil.

中国石化科技部项目“济阳坳陷太古界潜山油气成藏条件及目标评价”(P22034)和“济阳坳陷缓坡带稠油发育区潜力评价及目标优选”(P24018)联合资助。

https://doi.org/10.11781/sysydz2025020273