东营凹陷古近系烃源岩超压特征及分布规律

统计分析1307口探井实测压力系数和83l口探井使用的钻井液密度数据，发现东营凹陷古近系沙三段、沙四段普遍存在异常超压，超压(压力系数1．1-1．5)主要出现在2100-3500m深度，强超压(压力系数大于1．5)主要出现在2800-3500m深度。东营凹陷沙三段、沙四段主力烃源岩超压平面分布具有北高南低、东高西低的总体特点，超压主要分布在洼陷带、断裂构造带和中央背斜带上。烃源岩压力系数等值线北部陡坡带比较密集，南部缓坡带相对稀疏。生油洼陷中心附近异常高压带的分布与生油洼陷基本一致，洼陷深陷区压力系数很大，向周围斜坡和构造高部位呈辐射状逐渐减小至正常，压力分布带与洼陷、边缘斜坡和构造较高部位的欠压实与压实带发育、分布规律的一致性很好。图3表l参9

The characteristics and distribution of abnormal pressure in the Paleogene source rocks of Dongying Sag

There are abnormally high pressures in the 3rd and 4th member of Shahejie Formation (Es 3 and Es 4 ) of the Paleogene over all the Dongying Sag, which are proved by the tested pressure data from 1307 wells and the data of drilling fluid density from 831 wells. Abnormally high pressure (coefficient of pressure is between 1.1 1.5) mainly occurs in the depth ranging from 2100 to 3500m, and the strong abnormally high pressure (coefficient of pressure over 1.5) exists in the interval between 2800m and 3500m deep. Abnormally high pressures strata are distributed in the central sag, the fault belt and the central anticline belt. The coefficient of pressure is higher in the northern slope belt than that in the southern slope belt. The highest pressure is distributed in the central sag and decreases forward to the slopes around the sag margins. The abnormal pressure distribution is well identical with under compaction formations.