【作者】 薛海涛；

【导师】 卢双舫；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2004， 博士

【摘要】 我国碳酸盐岩沉积区分布面积广阔，碳酸盐岩烃源岩评价标准问题，事关油气勘探方向和投资力度，一直是石油地质、地球化学家所关心的焦点问题之一。我国碳酸盐岩烃源岩以高过成熟为主，这类烃源岩评价(尤其是气源岩评价)不仅不适宜直接采用国内已有泥质烃源岩的评价方法，也不能照搬国外较低成熟度碳酸盐岩烃源岩的评价方法。因此，本文从我国碳酸盐岩分布区的实际地质条件出发，建立了一套碳酸盐岩烃源岩评价方法，并提出了一套碳酸盐岩烃源岩有机质丰度评价标准。 传统的烃源岩评价主要以生烃评价为主，但由于所生成的油气只有从源岩中以游离相运移出来之后才能对油气藏的形成做出贡献。因此，对源岩排烃能力的评价比对其生烃能力的评价更具有指导油气勘探的实际意义。本文根据物质平衡法原理将比较棘手的排烃问题，分解成相对较易考察的生烃问题和残留、耗散烃的问题。 将油源岩、气源岩分别加以考虑。油源岩评价以排油量大小为标准(排油量=净油量-残留油量)，气源岩以排气量大小为标准(排气量=生气量-吸附气量-油溶气量-水溶气量-扩散气量)。 对评价中遇到的有机质生烃(有机质成油、成气、油成气)、源岩残留烃(岩石残留液态烃、岩石吸附天然气、油溶气、水溶气)、天然气扩散等问题进行了较为系统的研究，并以塔里木盆地地质参数为例，计算了不同地质条件下烃源岩的生油气量、残留液态烃量、吸附气量、油溶气量、水溶气量、扩散气量，进而根据物质平衡法计算出排油量、排气量。建立了不同厚度、不同生烃潜力、不同顶面埋深条件下烃源岩的有机质丰度理论下限、工业下限及分级评价标准。 具体的主要研究内容及成果如下： 1．首次提出以物质平衡原理为理论基础，以排烃量的有无和大小来对碳酸盐岩烃源岩进行分级评价的研究思路。使对烃源岩评价标准的确定从依靠纯经验过渡到依据定量计算，同时将油源岩、气源岩分开来进行评价。 2．首次以塔里木盆地为例建立了碳酸盐岩气源岩理论下限和工业下限评价标准。分别计算了不同地质条件下单位面积碳酸盐岩的生气量及源岩和围岩各种形式的残留和耗散气量(吸附气量、油溶气量、水溶气量、扩散气量)，进而根据物质平衡原理计算出源岩开始以游离相有效排气时所对应的有机碳含量，并将它作为该地质条件下气源岩的有机质丰度理论下限值。研究发现气源岩的丰度下限随源岩厚度的增加而减小；随成熟度的增加先减小后增加；随有机质类型(生烃潜力)的变好而减小；随上覆岩层剥蚀厚度的变化也有明显的改变。 3．首次基于排烃强度的大小确定了油源岩、气源岩分级评价标准，并计算了相应的有机质丰度界限值，绘制了塔里木盆地碳酸盐岩油源岩、气源岩有机质丰度分级评价图版。经过分析综合，归纳出我国碳酸盐岩沉积区(Ⅱ型有机质，成熟碳酸盐岩)油源岩、气源岩有机质丰度分级评价标准。油源岩各级别“非，潜效，差，中，好，很好”对应的TOC界限值为“0.25，0.4，0.55，0.8，1.5”；气源岩各级别对应的TOC界限值为“0.15，0.25，0.4，0.6，1.0”。 4．首次把实际扩散气量与最大扩散气量的概念区别开来，并分别进行计算。研究表明最大扩散气量可能是实际扩散气量的几倍甚至几十倍。以往用最大扩散气量来代替实际扩散气量的算法会过高的估计天然气的扩散损失量，给气源岩评价和气藏的资源评价带来较大的误差。 5．对油源岩的有机质丰度工业下限的研究表明，该值随油源岩厚度的增大而减小；随有机质生烃潜力的增大而减小。对于碳酸盐岩来说，生烃潜力小于200mg/g是不大可能成为油源岩的。摘要 6.设计了一套测徽岩石吸附天然气量的实验装置。并用这套装置对灰岩、泥岩、I型干酪根、If型干酪根等四种样品在不同温、压条件下对甲烷的吸附量进行了测定。从实验结果可以看出，泥岩的吸附量大于灰岩，二「酪根的吸附量远大于泥岩和灰岩;而且吸附量随温度的升高而降低，随压力的升高而增加。采川兰格缪尔模型来描述各样对甲烷的吸附，对模型进行标定，得到吸附模型。 7.应用自行设计的气体溶解度测定装置，做了气体在原油中的体积溶解度实验。研究发现，多组分天然气、甲烷和NZ、CO:在原油中的溶解度随着压力的增加而增大，但天然气、甲烷和N:增加的幅度越来越小，而co:增加的幅度越来越大。天然气、甲烷和CO:的溶解度随温度的升高而减小，N:的溶解度随温度的升高而增加。建立了气体在原油中的摩尔溶解度和气油比的理论方程。 8.在同时考察源岩中有机质因生、排烃而损失和无机质因成岩作用而失重的基础上，探讨了有机碳恢复系数及生烃潜力损失率的可能变化范围。结果表明，有机质生烃潜力和有机质丰度的变化主要取决于源岩的生、排烃效率，对性质偏差的有机质，有机质的实测丰度随演化程度的增高不降反升:而对位于高成熟阶段的优质有机质，有机碳的恢复系数可达2以上:随有机质类型变好和成熟度升高，生烃潜力损失率增高;一般情况下，有机质生烃潜力的恢复幅度比有机质丰度的恢复大得多。 9.利用目前国内外业己报道的有机质成油和油裂解成气的化学动力学模型，计?更多还原

【Abstract】 In China, sediment trap of carbonate rocks is large, oil generation from carbonate rocks has been the focus which geologists and geochemists are- concerned about. Most of carbonate source rocks in our country are high-maturity, over-maturity, therefore, neither does the existing assessment method of argillaceous source rocks in China fit for the evaluation of this sort of source rocks, nor can copy the foreign evaluation of lower maturity carbonate source rocks. Based on practical and geological conditions, this paper sets up a set of assessment method of carbonate source rocks, and puts forward a set of organic enrichment evaluation criterion of carbonate source rocks.Traditional evaluation of source rocks is mainly about hydrocarbon generation, only when the generated oil gas from source rocks is expelled in the form of separate phase, can it be useful for the form of pool. Therefore, the evaluation of hydrocarbon expelling capacity of source rocks is more practical for the instruction of oil gas exploration than that of hydrocarbon generation capacity. In this paper, based on the principle of material balance, divide the tough problem of expelling hydrocarbon into relatively and easily investigated problems of hydrocarbon generation, residual and diffusion hydrocarbon.Study oil source rocks and gas source rocks respectively. The evaluation of oil source rocks is based on magnitude of the expelling oil (expelling oil quantity=net oil quantity-residual oil quantity), and the evaluation of gas source rocks is based on magnitude of expelling gas (quantity of expelling gas= gas quantity of generation-adsorption-dissolving in oil-dissolving in water-diffusion).Systematically investigate the hydrocarbon generation of organic matter (oil and gas generation from organic matter and oil to gas), residual hydrocarbon of source rocks (residual liquid hydrocarbon of rocks, gas adsorption of rocks, gas dissolving in oil and gas dissolving in water) and gas diffusion etc. Take the conditions of Tarim as an example, calculate quantity of oil and gas generation, residual liquid hydrocarbon, gas adsorption, gas dissolving in oil, gas dissolving in water, and gas diffusion under different geologic conditions, then according to the principle of material balance, work out oil expelling and gas expelling quantity. Lastly establish theoretical, industrial threshold value of organic enrichment of source rocks and grading evaluation criterion under different source rocks thickness, hydrocarbon potential, superface depth conditions.The main content and achievements are listed as following:1. For the first time, put forward a new research approach which uses the principle of material balance as the theoretical basis, and make grading estimation of carbonate source rocks by the quantity of hydrocarbon expelling. As a result, establish the evaluation criterion of source rocks on the basis of quantitative calculation, instead of pure experience, then estimate oil source rocks and gas source rocks respectively.2. For the first time, take Tarim basin as an example to establish theoretical, industrial threshold value of organic enrichment of carbonate source rocks. Calculate gas quantity of generation, adsorption, dissolving in oil, dissolving in water, diffusion of unit area carbonate rocks at different geologic conditions.And then according to the material balance principle, figure out the corresponding organic carbon content when gas being started expelling from source rocks with separate phase. Regard it as the theoretical threshold value (TOCmjn) of gas source rocks at that same geologic condition. Based on the study, find that TOCmi,, decreases with the increasing source rocks thickness; decreases at first and then increases with the increasing maturity and decreases with the better organic-matter type.3. For the first time, set up grading estimating criterion of oil source rocks and gas source rocks with the hydrocarbon expelling intension. Figure out the corresponding organic carbon content threshold value, and更多还原