塔里木盆地台盆区奥陶系低丰度烃源岩排烃特征及有效性评价

发布时间：2018-03-29 05:30

本文选题：塔里木台盆区　切入点：低丰度　出处：《中国石油大学(北京)》2016年博士论文

【摘要】：截止2013年,塔里木盆地台盆区取得了许多有目共睹的勘探成效,然而,针对台盆区海相油气的来源厘定还存在问题,主要表现为:目前已经识别出两套高丰度(TOC0.5%)海相烃源岩,包括寒武系-下奥陶统和中-上奥陶统,但何者为主长期以来存在争议;同时,以高丰度烃源岩贡献为基础的资源评价结果与最新勘探实践不匹配,存在预测资源量偏小的问题,造成这些问题的根源是未将低丰度烃源岩的贡献列入考虑范围。低丰度可以分为两种类型,一种是古高今低,生排烃作用导致现今丰度很低,这类低丰度烃源岩是有利于油气成藏的;另一种是古时候丰度就极低,发生排烃作用微弱或无法发生排烃作用,这一类低丰度烃源岩对油气成藏贡献不大。如何区分这两种类型低丰度烃源岩,判识有效低丰度烃源岩并评价对油气成藏贡献,是目前急需解决的问题。本次研究选取塔里木盆地奥陶系低丰度烃源岩作为研究对象,根据排烃门限理论,计算了典型低丰度中上奥陶统岩石的实际含烃量与烃源岩排烃门限残留烃量的关系,区分了塔里木盆地台盆区奥陶系低丰度“已排烃/未排烃”两类烃源岩,对比了“已排烃/未排烃”两类低丰度源岩地化特征,并结合测井、地质等综合分析,从生烃母质类型与分布、有机质富集与保存等多方面入手,揭示了已排烃低丰度烃源岩的成因机制是,在稳定的生态系统内,富氢的浮游藻类或疑源类作为生烃母质,有机质在良好的还原环境下保存。在此基础上,通过对已排低丰度碳酸盐岩烃源岩的主控因素分析,采用多元线性逐步回归方法,建立了地化综合判别指标Ig定量预测和评价有效低丰度烃源岩模型,模型与源岩的生烃潜力、TOC、成熟度、S2/S1、S2五个因素相关;根据已排低丰度碳酸盐岩烃源岩的测井响应,采用多元非线性拟合方法,建立了测井综合判别指标Iw定量预测和评价有效低丰度烃源岩的模型,模型与GR、RD、U/TH相关。将上述判别标准和定量预测方法在塔中地区应用,计算了有效低丰度源岩的排烃量,并评价了有效低丰度源岩相对贡献,预测了台盆区最有利层位和区域。研究结果表明,塔中地区中上奥陶统有效低丰度源岩排烃量为40.9×108t,相对贡献为18%;塔里木盆地台盆区最有利层位是一间房组,有效低丰度源岩体积占地层体积的23.46%,其次是良里塔格组和吐木休克组;最有利区域位于塔北隆起及南部斜坡,排烃量为163.6×108t。
[Abstract]:As of 2013, the Tai-basin area of the Tarim Basin has achieved many obvious exploration results. However, there are still problems in determining the source of marine oil and gas in the Tai-basin area, mainly as follows: at present, two sets of high-abundance TOC0.5) marine source rocks have been identified. Including Cambrian-Lower Ordovician and Middle-Upper Ordovician, but which is the main one has been disputed for a long time, and the results of resource evaluation based on the contribution of high-abundance hydrocarbon source rock do not match with the latest exploration practice. There are the problems of small predictive resources, which are caused by the failure to take the contribution of low abundance source rocks into consideration. Low abundance can be divided into two types, one is ancient high and low, and hydrocarbon generation and expulsion cause the present abundance is very low. This type of low-abundance source rock is conducive to hydrocarbon accumulation; the other is that the abundance of hydrocarbon is very low in ancient times, and hydrocarbon expulsion is weak or unable to occur. This kind of low abundance source rocks have little contribution to hydrocarbon accumulation. How to distinguish these two types of low abundance source rocks, identify effective low abundance source rocks and evaluate their contribution to oil and gas accumulation, This study selects Ordovician low abundance source rock in Tarim Basin as the object of study, according to the theory of hydrocarbon expulsion threshold, The relationship between the actual hydrocarbon content and the hydrocarbon expulsion threshold of source rock is calculated, and two types of hydrocarbon source rocks with low abundance of Ordovician in Tarim Basin are distinguished. In this paper, the geochemistry characteristics of two types of low abundance source rocks are compared, and combined with the comprehensive analysis of logging and geology, the types and distribution of hydrocarbon source material, the enrichment and preservation of organic matter, and so on, are discussed. It is revealed that the genetic mechanism of the hydrocarbon expulsion low abundance source rocks is that, in a stable ecosystem, hydrocarbon-rich phytoplankton or suspected source materials are used as source materials for hydrocarbon generation, and organic matter is preserved in a good reductive environment. Based on the analysis of the main controlling factors of carbonate source rocks with low abundance, and the multivariate linear stepwise regression method, a quantitative prediction and evaluation model of effective low abundance hydrocarbon source rocks was established by using the geochemistry comprehensive discriminant index Ig. The model is related to five factors of hydrocarbon generation potential of source rocks: TOC, maturity and S _ 2 / S _ 1 / S _ 2. According to the logging response of carbonate source rocks with low abundance, the multivariate nonlinear fitting method is used. A model for quantitative prediction and evaluation of effective low abundance source rocks by logging comprehensive discriminant index Iw is established. The model is related to GRRDU / TH. Applying the above criteria and quantitative prediction methods to the Tazhong area, the hydrocarbon expulsion of effective low abundance source rocks is calculated. The relative contribution of effective low abundance source rocks is evaluated and the most favorable horizon and region in the platform basin area are predicted. The effective low abundance source rocks of middle and upper Ordovician in Tazhong area are 40.9 脳 10 ~ 8t, and the relative contribution is 180.The most favorable horizon in the platform basin area of Tarim Basin is the Yijianfang formation, the effective low-abundance source rock covers 23.46% of the volume of the strata, the Lianglitag formation and the Tumu shock formation are the next. The most favorable area is located in the northern Tarim uplift and the southern slope with a hydrocarbon expulsion capacity of 163.6 脳 10 ~ (8) t.
【学位授予单位】：中国石油大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P618.13

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