鄂尔多斯下古生界碳酸盐烃源岩评价与成烃特征

SOURCE ROCK EVALUATION AND CHARACTERISTICS OF HYDROCARBON GENERATION FROM LOWER PALEOZOIC CARBONATE IN ORDOS BASIN

李延钧 陈义才 杨远聪 吕强 张军 石晓英

Li Yanjun Chen Yicai Yang Yuancong Lu Qiang Zhang Jun Shi Xiaoying

在岩性、热解参数等原生性识别和碳酸盐烃源岩评价的基础上,经统计有机质丰度、类型、性质,确定有机质成熟度与演化阶段,进行综合评价与对比后,对研究区烃源岩的生烃能力作出了综合评价,认为原始生烃母质属Ⅰ—Ⅱ型,具有中等生烃强度的烃源岩特点,属较好烃源岩范畴,研究认为,鄂尔多斯下古生界碳酸盐烃源岩具有三段式四阶段的生烃演化特征,即以见R=0.65%、1.50%、2.25%划分为低成熟、成熟、高成熟三段式和热裂解气生成的第四阶段。第四阶段主要处于过成熟阶段,以残余干酪根的热裂解以生成高温甲烷干气为特征,马家沟组中下部和寒武系正处于这一成烃演化阶段。

Based on primary lithology, thermolysis parameter of Lower Paleozoic carbonate source rocks in Ordos Basin,the abundane,types and nature of organic matter in the source rocks are used to determine the maturity and evolution stages of organic matter and estimate hydrocarbon generation ability of the study area. It is considered the kerogen wasⅠ-Ⅱ types with middle-intensity hydrocarbon generation. It is emphasized that hydrocarbon generation of Lower Paleozoic carbonate source rocks can be divided into three phases including four stages, that is, low-maturation phase with R=0.65%;maturation phase with R=1.50% and high-maturation phase with R=2.25%, and the fourth stage of over-maturated pyrolysis gas stage. In this stage, residual kerogen was pyrolyzed and dry gas of high-temprature methan was generated. The source rocks of middle-lower parts of Majiagou Formation and the Cambrian System in the study area are of this stage.

10.11743/ogg19990418