涠西南凹陷D次凹流二段优质烃源岩特征

Characteristics of High-quality Source Rock in Member Liu-2 of D Sub-sag in Wexinan Sag

杨鹏程 余学兵 张传运

YANG Pengcheng YU Xuebing ZHANG Chuanyun

中国石油化工股份有限公司上海海洋油气分公司勘探开发研究院, 上海 200120

Institute of Exploration and Development, SINOPEC Shanghai Offshore Oil & Gas Company, Shanghai 200120, China

涠西南凹陷D次凹流二段发育有机质丰度很高的层段，为了研究这些层段的分布及地球化学特征，首先基于烃源岩总有机碳（TOC）-氯仿沥青“A”的关系提出了该地区优质烃源岩的丰度下限（TOC=2%）；然后利用测井资料采用ΔlogR法计算了流二段烃源岩的TOC曲线，结果显示流二段烃源岩整体有机质丰度很高，达到优质烃源岩的标准，并在纵向上识别出上下两层丰度异常高的层段（TOC=10%）；利用流二段干酪根元素及岩石热解参数得到了优质烃源岩的有机质类型，主要为Ⅰ-Ⅱ1型；利用Ro及烃源岩可溶有机质演化等方法确定了该地区烃源岩生烃门限深度（2 600 m）和排烃门限深度（3 100 m），并探讨了典型井区烃源岩的热演化阶段；最后对优质烃源岩发育的成因进行了分析，认为藻类勃发提供的高古生产力和深湖相还原环境是优质烃源岩发育的有利因素。

The test results of samples demonstrate high-quality source rocks with abundant content of organic matters are developed in some intervals of Member Liu-2 of D sub-sag. In order to study the distribution of these intervals and their geochemical characteristics, the authors, firstly, determined TOC=2% is the lower limit of TOC for the high-quality source rocks based on the relationship of TOC versus "A". Secondly, the TOC curves of Liu-2 source rocks were fitted by ΔlogR method. The results indicate that the contents of organic materials are overall high and meet the standard of the high-quality source rock, and two intervals with abnormal high contents of TOC, up to 10%, were recognized. The kerogen types of high-quality source rocks classified by kerogen elements and rock pyrolysis parameters are type Ⅰ and Ⅱ1. Threshold depth of oil generation and expulsion were determined by Ro values and evolution characteristics of soluble organic matters, they are 2 600 m and 3 100 m, respectively. The authors also studied the genesis of high-quality source rocks, it is thought that the paleo-productivity derived from the algal blooming and reducing environments of deep lacustrine facies are main controlling factors.

https://doi.org/10.3969/j.issn.1008-2336.2017.01.001