碳酸盐烃源岩排烃模拟模型及应用——以鄂尔多斯盆地奥陶系马家沟组为例

MODELING MODEL FOR HYDROCARBON EXPULSION IN CARBONATE SOURCE ROCKS AND ITS APLICATION IN PRACTICE: EXAMPLE FROM THE MAJIAGOU FORMATION OF ORDOVICIAN IN ORDOS BASIN

陈义才 沈忠民 黄泽光 李延军 郭秀英 吕强 张军 石晓英

Chen Yicai Shen Zhongmin Huang Zeguang Li Yanjun Guo Xiuying L? Qiang Zhang Jun Shi Xiaoying

碳酸盐烃源岩由于胶结作用发育,固结成岩较早,所以,其排烃作用并非一定以压实作用为主,而是多种作用互存。不同的演化阶段排烃方式各异,在高过成熟阶段以微裂缝排烃和分子扩散为主。以一维地质模型为基础,根据生、排烃质量守恒原理可以定量建立扩散排烃和微裂缝排烃的数学模型。鄂尔多斯盆地奥陶系马家沟组依此模型进行的模拟结果表明:马家沟组在早二叠世末进入生烃门限,三叠纪末达到生油高峰,早白垩世开始进入过熟干气阶段;现今累计排烃率为 60%～80%,其中,压实排烃、扩散排烃和微裂缝排烃占主导地位,水溶相排烃只占很小比例。

With well development of cementation, carbonate hydrocarbon source rocks would be consolidated into rocks quite earlier, therefore, compaction effect is not merely chief one instead of multi-effects existence in hydrocarbon expulsion. Different evolution stages with various ways of hydrocarbon expulsion, in the higher-over maturation stage, micro-fissure hydrocarbon expulsion and molecular diffusion are believed to play a chief role. A mathematical model of diffusively hydrocarbon expulsion and micro-fissure hydrocarbon expulsion can be established quantitatively in line with the principle of mass conservation of hydrocarbon generation and expulsion on the basis of one dimensional geological model. Modeling results from this model indicate that Majiagou Formation in the Ordovician in Ordos basin had entered hydrocarbon generation threshold by the end of the earlier Permian and reached the peak of hydrocarbon generation in the Triassic, and began getting into the over saturation-dry stage in the earlier Cretaceous; Accumulative total hydrocarbon expulsion rate is 60%-80%, of which compactively hydrocarbon expulsion, diffusively hydrocarbon expulsion and micro fissure hydrocarbon expulsion are predominant whereas water soluble facies hydrocarbon expulsion occupies a small proportion.

10.11743/ogg20020301