利津洼陷古近系烃源岩异常高压计算方法与分布特征

东营凹陷利津洼陷古近系沙四段上亚段、沙三段下亚段和沙三段中亚段烃源岩中广泛发育异常高压.对其异常高压的成因进行分析,利用综合解释法建立了研究区80口已钻井的地层孔隙压力系数剖面；明确了沙四段上亚段、沙三段下亚段和沙三段中亚段的地层孔隙压力系数等值线分布,分析了利津洼陷烃源岩地层异常高压的分布特征.研究结果表明,综合解释法在计算由欠压实和生烃膨胀等多种成因共同作用形成的利津洼陷古近系烃源岩异常高压时的精度较高；研究区古近系烃源岩异常高压分布与洼陷形态一致,呈东北—西南向展布,在洼陷深陷区以高压和超高压为主,至洼陷边缘构造高部位逐渐呈辐射状降低至正常压力；洼陷中心的异常高压是烃源岩向洼陷边缘排烃的主要动力.

Calculation method and distribution features of abnormally high formation pressure in Paleogene source rocks, Lijin subsag

Abnormally high formation pressure commonly exists in formation upper Es4, lower Es3, middle Es3 source rocks of Paleogene, Lijin subsag, Shengli oilfield. The formation mechanisms of abnormally high pore pressure in Paleogene source rocks are analyzed herein. Also, the pore pressure profiles of 80 drilled exploration wells in this subsag are established by Comprehensive Explanation Method. Moreover, the pore pressure distribution features of source rocks are researched through drawing contour maps of formation upper Es4, lower Es3, middle Es3, respectively. The Comprehensive Explanation Method has a high precision in calculating abnormally high pore pressure of source rocks in Lijin subsag formed with combined action of under-compaction and hydrocarbon generation. The abnormally high pore pressure of Paleogene source rocks in Lijin subsag distributes with a trend from northeast to southwest.The pore pressure is high or ultra-high in the central region of Lijin subsag, and decreases to a normal level in the periphery area. The abnormally high formation pressure in the source rocks of Lijin subsag is the main force of hydrocarbon expulsion from the central subsag to the periphery area.