海中凹陷涠洲组烃源岩特征及潜力分析

以钻井资料、烃源岩测试结果为基础，结合TSM盆地模拟技术，开展海中凹陷涠洲组烃源岩特征及资源潜力研究。渐新世，海中凹陷湖盆继承性发育，形成涠洲组烃源岩。涠洲组暗色泥岩有机质丰度中等，有机质类型以腐殖型（Ⅱ₂型）为主；其中洼槽带涠四段烃源岩在中中新世以后进入成熟热演化阶段，开始大量生烃，是海中凹陷涠洲组主要烃源岩层。作为目前海中凹陷钻井相对完整揭示的烃源岩层系，涠洲组地质资源量达到81.49×106 t油当量；有效烃源岩主要分布于凹陷洼槽带，生烃中心位于3号断裂下降盘。中石化探区内，3号断裂下降盘紧邻生烃中心，是探区内涠洲组源岩条件最有利的区域，应作为下步勘探工作首选突破区带。

Characteristics and Potential Analysis of Source Rocks of Weizhou Formation in Haizhong Sag

Based on the drilling data and experimental results of source rocks, combined with the TSM basin modeling technology, this paper studies the characteristics and potential of source rocks of Weizhou Formation in Haizhong Sag. In Oligocene, the lake basin of Haizhong Sag developed successively, source rocks in Weizhou Formation were deposited. The dark mudstone of Weizhou Formation has medium abundance of organic matter, and the organic matter type is mainly humic type (II₂). Source rocks of the fourth member of Weizhou Formation in the sag belt reached the mature thermal evolution stage after the Middle Miocene, and began to generate a large amount of hydrocarbons, which is the main source rock for Weizhou Formation in Haizhong Sag. As a relatively complete source rock series revealed by drilling in Haizhong Sag, the geological resource of Weizhou Formation is 81.49×106 t oil equivalent. The effective source rocks are mainly distributed in the sag belt, and the hydrocarbon generation center is located in the downthrown block of Fault 3. In the SINOPEC chemical exploration area, the downthrown block of Fault 3 is close to the hydrocarbon generation center, which is the most favorable area for the source rock conditions of Weizhou Formation, which should be the preferred breakthrough area for the next exploration work.