【作者】 霍秋立；

【导师】 卢双舫； 冯子辉；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2007， 博士

【摘要】 近年来随着松辽盆地深层天然气勘探步伐的加快,在徐家围子断陷深层火山岩和砾岩储层中均获得了重要突破,展现出松辽盆地天然气广阔的勘探前景。与此同时也出现了许多地质问题急需解决,本文针对徐家围子断陷深层源岩空间分布、源岩生烃潜力、天然气成因类型、混源天然气来源及天然气成藏时间等问题开展了研究工作。研究中除了采用先进的地球化学实验技术外,还针对存在问题开展了实验技术攻关,创新性地开发出了源岩吸附气制备方法、天然气微量重烃富集技术及混源天然气源岩贡献比例定量计算等新技术,其中混源天然气源岩贡献比例定量技术已获国家发明专利。采用这些新技术,并将地质与地球化学相结合,解决了实际地质问题,取得的成果和认识对下步深层天然气勘探有重要指导意义。对深层源岩分布和生烃潜力的研究直接关系到对该地区资源的认识和勘探决策。本次研究以实际钻井资料为基础,并结合沉积相等研究,确定了徐家围子断陷泉二段以下各地层中暗色泥岩的空间分布及煤层分布,指出沙河子组暗色泥岩厚度大,分布广,其次为火石岭组和营城组,登娄库组暗色泥岩则主要分布于徐家围子西部靠近古中央隆起带附近,厚度相对较小。在徐深1和升深2井及以东局部地区的沙河子组和火石岭组地层中还发育一定厚度的煤层。有机地球化学分析表明沙河子源岩有机质丰度高,除以III型干酪根主为外,还存在II型和I型干酪根,为好生气岩;火石岭组和营城组有机质丰度相对较高,属中—较好气源岩;登娄库组和泉头组一—二段源岩为差—中等气源岩。利用高温高压热模拟实验技术研究了沙河子组泥岩的生烃和原油的裂解成气过程,建立了适合本区的天然气甲烷碳同位素与源岩成熟度Ro关系方程,建立了源岩生烃模式和原油裂解生气模式。开展了深层天然气的组成、碳同位素及氢同位素地化特征研究,采用多种图版和指标对天然气成因类型进行了判别。指出徐家围子断陷深层天然气主要是以甲烷为主的干气,并存在有CO2气藏(如芳深9气藏),总体上天然气的碳同位素较重,在组分碳同位素系列上,除正系列外,还有较多的系列倒转及部分的负系列,反映出该地区天然气来源的复杂性。研究认为天然气出现倒转的原因可能是由于该地区存在多套的气源岩及源岩的成熟度较高所致。昌德地区天然气主要以煤型气为主,并可能混有无机成因气,升平-宋站地区天然气主要为煤型气,而兴城地区则主要为煤型气与油型气的混合气。采用天然气与源岩成熟关系方程、源岩吸附气与天然气甲烷碳同位素对比及混源天然气源岩贡献比例定量计算技术深入研究了徐家围子断陷天然气的来源,指出天然气主要来源于沙河子组源岩,但不同地区来源比例明显不同,天然气来源于不同源岩的贡献与源岩分布密切相关,在沙河子组源岩发育的兴城地区来自该源岩的贡献可达99%,而靠近古中央隆起带石炭—二叠系源岩发育区内则来自该套源岩的贡献较大,可达85%,同样主要来源于营城组的源岩的天然气也均分布于营城组源岩发育区内,由此推断松辽盆地深层天然气应主要以垂向运移为主,天然气藏的分布受源岩区的控制,有效气源岩的分布区也就是天然气的有利勘探区。利用源岩生、排烃史、天然气甲烷碳同位素分馏及储层包裹体分析技术并结合本区沉积埋藏史和热史综合研究了天然气的成藏时间。认为升平地区天然气的充注主要为一期,在泉头组沉积末期至青山口组沉积时期,时间大约在110Ma~90Ma。昌德地区天然气的充注成藏时间有两次,一次主要青山口组沉积初期到嫩江组开始沉积时期,另一次则在嫩江组沉积末期到明水组沉积时期,时间大约分别为82Ma~98Ma,75Ma~63Ma;兴城地区天然气充注成藏有两期,一期为青山口组沉积时期至姚家组沉积时期,另一期为嫩江组沉积中期至明水组沉积时期,时间大约分别为100Ma~90Ma和78Ma~68Ma。最后预测了徐东斜坡带及安达向斜区是天然气有利富集地区,莺山-双城断陷、古龙断陷、林甸-常家围子断陷中也具备了生成大量天然气的条件,这些地区也应是天然气下步勘探的有利地区。更多还原

【Abstract】 The breakthrough which were occurred mainly in volcanic and conglomeratic reservoirs demonstrated the great potential for deep gas exploration in the Xujiaweizi rift depression. With the exploration speeds up, more and more geological problems should be resolved rapidly. Some of problems about the distribution of source rocks, the potential hydrocarbon generative of source rock, the genetic type of natural gases, the contribution ratio of different source rocks to mixed natural gases reservoir and Timing for gas charge in reservoirs have studied in this paper. Not only the advanced geochemical experimental techniques have been used in our studying work ,but also we developed some new techniques and methods, for example the adsorbed gas preparation technique, the enriching method of light hydrocarbon in natural gases and experimental technique of natural gas contribution ratio of four layers source rocks. The last one was awarded national invention patent. Being used the new techniques and combining geology analysis, some new conclusions will play important roles in exploration in this area.The spatial distribution and hydrocarbon generation potential of source rocks determine the resource potential and exploration strategy. Based on the data of drilling and deposition phase the thickness and spatial distribution of source rocks has been described. The dark mudstones and coal beds in the Shahezi Formation occur in much wider geographic area, with dark mudstones ranging in thickness from rift depression 30m to 350 m and locally up to1000 m. the dark mudstones in Huoshiling Formation distributed mainly in middle of the rift depression, and its thickness is less than Shahezi Formation. The dark mudstones in Yingchengzi and Denglouku Formation distributed locally and its thickness is much thinner than in Shahezi and Hulshiling Formation. The geochemistry analysis data (Rock-Eval, TOC and solvent extraction yields) of source rocks indicate excellent gas generative potentials in Shahezi Formation, good to excellent gas generative potentials to Huoshiling and Yingcheng Formation and poor to good gas generative potentials to Denglouku and Quantou Formation. Maceral identified and hydrogen index values of the studied rocks indicate most gas-prone type III organic matter, but the organic source input in the some potential hydrocarbon source rocks from the Shahezi Formation may initially contain some aquatic organic matter. The high temperature and high pressure simulation experiment has been used to study the process of hydrocarbon generation in source rock in Shahezi Formation and the process of gas generation by oil cracking. Both the models of hydrocarbon generation of source rock and oil and the equation about relationship between methane carbon isotope and source rock maturity (Ro) have established.The characteristic of composition and carbon isotope and hydrogen isotope of natural gases in Xujiaweizi rift depression have been studied. Also the genetic type of natural gases in this area has been classified. The gases are generally dry (i.e. with little C2+ hydrocarbons), However, there are wells that produce CO2 rich gases (e.g. Xushen No.9 well). Theδ13C values of gases are generally heavier, and most of gases have positive or negative carbon isotope series, few of them show reversal carbon isotope series. The complication distribution of isotope series suggested that the natural gases in the reservoir may be either mixing of gases generated at different source rocks or high thermal maturity source rocks or contribution of abiogenic gases. Using the quantitative calculation technique of the contribution ratio of different source rocks to mixed gases, Calculated the contribution ratio of four layer source rocks to natural gas reservoir in Xujiaweizi rift depression. The result indicates that most of the gases in the Xujiaweizi rift depression were derived from source rocks in Shahezi Formation. But the contribution ratios of source rocks show clearly dependence on spatial distribution of different source rocks. For example, the contribution ratio of source rocks in Shahezi Formation to gas reservoir in its source rocks developing area is can be up to 99%. And in the palaeo-central uplift, which developing source rocks in C-P, the contribution ratio of C-P source rocks to gas reservoir can be up to 85%. Similarly, the same regularity is coincident to source rocks in Yingcheng Formation. So, it is can be concluded that gases in Xujaweizi rift depression should be migrate vertically to reservoirs. The distribution of gases reservoir are controlled by spatial distribution of source rock. The distribution areas of principal source rocks are also the most favorable exploration zone for deep natural gases.Timing for gas charge in reservoirs have been studied by three techniques, including the hydrocarbon generation and expulsion of source rocks, carbon isotope fractionation during natural gas generation from source rocks and fluid inclusions analysis. The 1-D basin modeling also be used to define the geologic age of gases charge in reservoirs. The results suggest the timing of the gas charge was around 110Ma~90Ma in Shengping area, 82Ma~98Ma and 75Ma~63Ma in Changde area, 100Ma~90Ma and 78Ma~68Ma in Xingcheng area. This is slightly latter than or at the same time as the main period of gas generation from main source rocks.Finally, in Xudong and Anda area there are thicker dark source rocks distributed, where are predicted to be favorable exploration zone for deep natural gases in Xujiaweizi rift depression. Yingshan-Shuangchun rift depression, Gulong rift depression and Lingdian-Changjiaweizi rift depression also have gases generation conditions, will be next favorable exploration zone in the future.更多还原