松辽盆地北部深层天然气富集主控因素研究

【作者】 田春志；

【导师】 卢双舫； 萧德铭；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2002， 博士

【摘要】 本文在调研了国内外天然气勘探理论与技术发展的基础上，针对松辽盆地深层天然气勘探所面临的基本理论问题，从天然气的特点出发，指出气源条件（生气量、生气强度、生气期）和保存条件（盖层、断层、天然气扩散）是决定天然气富集规模的主控因素，并重点对松辽盆地深层天然气在地质历史中的生成、扩散和保存进行了深入研究，为客观合理地获取深层天然气资源量奠定基础。 在气源条件研究中，以化学动力学理论为主线对天然气的生成过程和生成量进行了动态、定量评价。这一工作包括：为标定有机质成油、成气的化学动力学模型，设计进行了恒速升温热模拟实验；为标定油成气的化学动力学模型，设计进行了等温的油裂解成气的热模拟实验；为建立油中各族组分（饱和烃、芳烃、非烃、沥青质）成气的化学动力学模型，进行了恒温或恒速升温模拟实验。在上述实验基础上，建立了松辽盆地北部深层源岩有机质初次裂解成油、成气的化学动力学模型，为评价深层源岩于不同时期的生油量、生气量奠定了基础；建立了不同性质原油及原油中各族组分二次裂解成气的化学动力学模型，为动态评价油裂解过程的成气量和耗油量提供了理论依据和实用方法；对盆地深层源岩的地化特征进行了系统评价；考虑到深层源岩的成熟度较高，实测地化指标（残余有机碳、氢指数等）不能客观反映源岩有机质的原始丰度和原始生烃潜力。本文利用化学动力学模型计算的生烃率，建立并实现了通过逐步递推来恢复有机质的原始生烃潜力和原始有机碳。研究结果表明，松辽盆地北部深层恢复后的生烃潜力可达到恢复前的46倍，原始丰度可达到恢复前的2.2倍。在上述工作的基础上，对深层源岩的生烃剖面、生烃史、生烃强度、不同时期的生烃量及累积生烃量进行了系统评价，结果表明：松辽盆地北部深层现今净生油量为67.76×1O⁸t，排油量为43.99×1O⁸t，累计生气量为74.27×1O¹²m³，排气量为62.3×10¹²m³。 在天然气保存研究中，主要探讨了盖层封盖性与断层封闭性。在详细论述了松辽盆地北部深层天然气盖层宏观和微观发育特征的基础上，对研究区天然气的盖层封闭能力进行了综合评价，创造性地提出了利用天然气通过泥质岩盖层的渗滤速度综合评价盖层的方法。评价结果表明松辽盆地北部深层登娄库组盖层在古龙凹陷中心处为好的封盖区，肇州—肇源一双深4井一带为中等盖层分布区，其余地区皆为较好的封盖区，泉一、二段盖层在古龙断陷及长垣以东大部分地区为好的封盖区，中等封盖区主要分布于林甸和松基1井附近，泰康地区为差的封盖区，其余地区皆为较好的封盖区。断层的封闭性则利用砂泥对接概率方法和断面压力及断裂带泥质含量方法来进行评价的，用此方法全面评价了松辽盆地北部深层各个时期断层的侧向封闭性及垂向封闭性能，得到了令人满意的结果。 在天然气扩散研究中，为了获取地层条件下天然气扩散系数，本文选取17块不同物性的人造石英粉砂岩样品利用封闭式方法在0.2MPa和20℃条件下进行干、湿样条件下天然气的扩散实验，利用实验获得的干、湿样天然气扩散系数的倍数与孔隙度之间的关系，对实测天然气扩散系数进行饱和介质转换，利用修正后的爱因斯坦方程对实测天然气扩散系数进行温度校正。根据气源岩空间分布关系，利用系统论的思想，首次提出了天然气扩散系统概念，并划分出三套深层天然气扩散系统（sh+yc～d₂、d₂～q_n和sh+yc～q_n），并以此为基础估算了松辽盆地北部深层天然气扩散损失量。扩散总量为16.35×10¹²m³，深层源岩的累计生气量为74.27×10¹²m³，扩散量占总生气量的22.2％。沙河子组～营城组扩散总量为10.80×10¹²m³，占该组生气量的16.1％。登二段气源岩的扩散量为55.55×10¹²m³，占该段生气量的81.6％。 在以上工作基础上,对深层天然气源岩-盖层系统的时空配置进行了深入探讨。在天然气聚集系数的选取中综合考虑了构造运动、盖层条件、扩散作用及排气强度的影响，使深层天然气资源量计算更加合理可信。本次研究计算的深层天然气资源量为5650×1O⁸m³，同时，指出松辽盆地北部深层天然气成藏与分布的有利地区，主要分布于西部古龙断陷及其周围和东部徐家围子断陷及其周围。更多还原

【Abstract】 This paper, in accordance with the basis theoretical problems for natural gas exploration in deep-formation in the north of Songliao basin, according to the practical features, point out that gas source condition(gas-generating amount, gas-generating intensity, gsa-generating period) and reservation condition(cap rocks, faults, dissipation of natural gas) are main controlling factors determining accumulation of natural gas, and emphatically studied generation, dissipation and conservation of natural gas in geologic history to acquire objectively and rationally the resource amount of deep-formation natural gas on the basis of investigating the development of natural gas exploration theory and technology from home and abroad.In study of gas source condition, the quantitative dynamic evaluation of generation of natural gas and gas-generating amount are made on the basis of chemical dynamics. This work include: In order to demarcate chemical kinetic model inwhich organic matter generate oil and gas, constant velocity, rising temperature thermal modeling experiment is designed; In order to demarcate chemical kinetic model inwhich oil crack into gas, isothermic thermal modeling experiment inwhich oil crack into gas is designed ; In order to establish chemical kinetic model inwhich family constituents in oil (saturated hydrocarbon, arene, non-hydrocarbon,bitumen ) change into gas, isothermic or constant velocity jsothermal modeling experiment is designed. On the basis of above experiments, the chemical kinetic model inwhich organic matter of source rock of deep-formation in the north of Songliao basin primarily crack into oil or gas is established, which set up a basis for evaluating oil-generating amount, gas-generating amount of source rock of deep formation in different periods; set up the chemical kinetic model inwhich different qualities of oil and family constituents in oil secondarily cracked into gas, which provide theoretical foundation and practical methods for dynamic evaluation of gas-generating amount and oil-consuming amount in process of oil cracking. The geochemical features of source rocks in deep-formation of basins are systematically evaluated. Considered that the maturity of deep-formation source rocks is relative high and the practical tested geochemical index (remnant organic carbon, hydrogen index etc)can not objectively reflect the original abundance and original hydrocarbon-generating potential of organic matter in source rocks, original hydrocarbon-generating potential and original organic carbon of organic matter are restored from progressive recurrence using chemical kenetic models to calculate hydrocarbon-generating rate in this paper. The studied results illustrate that the restored hydrocarbon-generating potential of deep-formation in the north of Songliao basin is as 46 times as that of unrestored , and the original abundance is as 2.2 times as that of unrestored .On the basis of above studies, the hydrocarbon-generating profiles, hydrocarbon-generating history, hydrocarbon-generating intensity, hydrocarbon-generating amount in different periods and total up hydrocarbon-generating amount in deep-formation source rocks are systematically evaluated. The results illustrate that the present netoil-generating amount of deep-formation in the north of Songliao basin was calculated, being 67.76 X 10 t,oil-discharging amount 43.99 X 10 t , accumulative total gas-generating amount 74.27 X 10 m ,gas-discharging amount 62.30 X 10 m ,In study of conservation condition of natural gas , the sealing property of cap rocks and faults are discussed. On the basis of brilliant exposition of macroscupic and microscupic features of cap rocks of deep-formation natural gas in Songliao basin, the sealing capacity of cap rocks of natural gas in studied area is comprehensively evaluated, and creatively put forward a comprehensive cap rock-evaluating method using percolating velocity which natural gas pass though mudstone cap rocks. The evaluating results illustrate thatthe cap更多还原