【作者】 李政；

【导师】 沈忠民；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2011， 硕士

【摘要】 以自给系统为特征的页岩气藏的勘探开发在北美获得了巨大成功,拓宽了天然气勘探的空间。北美勘探实践证明,页岩气形成的成熟度较宽,在烃源岩各个演化阶段均可成藏,在高演化阶段更为有利,页岩中有机碳含量、有机质类型、矿物组成、孔隙含水量、可诱导的裂缝发育程度等均与页岩气的产能密切相关,压裂技术和钻井技术在页岩气的有效开发中起着关键作用。中国东部陆相盆地广泛发育泥页岩,是否存在页岩气资源?这在我国是一个崭新的研究领域。本文选择在中国东部具有典型意义的东营凹陷进行研究,分析中国东部古近系湖相地层中存在页岩气资源的可能性。东营凹陷位于渤海湾盆地东南部,是渤海湾中、新生代裂谷盆地中的一个三级负向构造单元,面积5700km²。东营古湖盆在演化的过程中经历过多次湖侵和湖退旋回,在湖盆演化的断陷加速期（古近系沙河街组沙四晚期）和断陷鼎盛期（沙河街组沙三早期）发育两套重要的暗色泥页岩。其中沙四晚期（沙四上亚段）暗色泥岩厚度一般在250～350m左右,页岩厚度约40～120m,埋深在1576～5200m左右;沙三早期（沙三下亚段）暗色泥岩厚度一般在300m以上,最厚可达500m,页岩厚度150～200m,埋深在1500～4200左右,截止2009年底,东营凹陷有110口井在钻遇Es₃^下、Es₄^上段泥页岩时有油气显示,其中有8口井获工业油流。本文通过对大量地球化学、岩石矿物、测井、录井、地震资料的分析,认为东营凹陷古近系沙三下-沙四上亚段两套泥页岩厚度大、有机质丰度高、有机质类型好、有机质成熟度分布范围宽,与北美地区已发现页岩气系统地质地球化学参数具有一定的可比性,具备形成页岩气的物质基础;东营凹陷沙三下和沙四段上亚段泥页岩中普遍发育异常高压,各洼陷压力系数中心处压力系数均超过1.8（除博兴洼陷为1.5以外）,具有良好的泥页岩油气藏的压力环境,东营凹陷沙三下和沙四上亚段泥页岩全岩矿物组成具有较高石英和碳酸盐含量,粘土矿物含量低于50%,具有一定的脆性特征,且普遍发育微裂隙,利于页岩气的成功开采,与Haynesville页岩和Eagle Ford页岩具有一定的可比性。岩石物性分析表明,泥页岩发育段的孔隙度一般在3%～12%之间,渗透率在0.001～0.02mD。与美国几大页岩气系统对比发现,东营凹陷泥页岩具有较好的储集条件。在喜马拉雅运动作用下,东营凹陷在东营组末期（24.6～14Ma）发生整体抬升,并遭受剥蚀,对两套泥页岩孔隙结构的形成和生、排烃具有重要影响;东营凹陷湖相泥页岩气测资料的调查发现,钻至沙三下亚段、沙四上亚段二套泥页岩发育段的探井气测显示均表现为高异常,钻井过程中频繁发生井涌和井漏现象,预示着气体的存在;两套泥页岩罐顶气轻烃丰度（C₁-C₄）随埋深增加而增加,而重轻烃比值∑（C₅-C₇）/∑（C₁-C₄）较低,一般低于0.15,表明两套泥页岩罐顶气在3400m以下主要成分为气态烃;利用容积法对东营凹陷沙三下亚段和沙四上亚段泥页岩的含气量进行了计算,并与北美已发现页岩气系统地区气源岩的含气量进行对比,认为东营凹陷泥页岩的含气量与Barnett页岩和Haynesville页岩相当,高于其它页岩气系统的含气量。上述分析表明,该区存在页岩气资源潜力,中国东部古近系湖相泥页岩是值得关注的天然气勘探新领域。更多还原

【Abstract】 The history of exploration and production in North America shows shale gas can generate and accumulate in the source rocks with a wide rage of thermal maturity, especially in high thermal maturity. The production of shale gas is strongly affected by the total organic carbon content, organic type, mineral composition, moisture content of pores and the distribution of inducible crack. in the shale. Fracturing and drilling are the key technology for shale gas exploitation.Bohai Gulf Basin is a Mesozoic-Neozoic terrestrial rift basin in the east of China. Dongying Depression lies in the southeast of Bohai Gulf Basin with the area of 5700km². By the end of 2009, there are 110 exploratory wells have Oil &gas showings, 8 exploratory wells have industrial overflows in Dongying Depression.According to analysis of geochemical ,mineral, logging, drilling and seismogram data on palaeogene strata in Dongying Depression, t The shale of lower Es3 and upper Es4 in Palaeogene Lacustrine are the main source rocks in Dongying depression. The thickness of the dark mudstone of upper Es4 is about 250³50m, the thickness of shale is mainly from 40 to120m, the buried depth is about 1576⁴700m. The thickness of the dark mudstone of lower Es3 is commonly above 300m, with a maximum of 500m, the thickness of shale is 150²00m, and the buried depth is about 1,500-4,200m.According to the analysis of geochemical, mineral, logging, drilling and seismogram data on palaeogene strata in Dongying Depression, the shale of lower Es3 and upper Es4 is characterized by large thickness, high abundance of organic matter, favorable types and wide range of maturity（Ro=0.35～1.5%）. It has similar geological and geochemical characteristic comparing with North America and the material foundation generating shale gas.The abnormal high pressure occurs rather widely in the shale of lower Es3 and upper Es4 in Dongying depression. The maximum pressure coefficient in the center are more than 1.8 （except for Boxing sub-sag with pressure coefficient 1.5）, the shale in Dongying depression has favorable pressure environment. The shale in this area has high content of quartz and carbonate and its clay content is less than 50%. It is similar to Haynesville shale and Eagle Ford shale. The physical property analysis of the shale shows that, the porosity is about 3%～12% and the permeability is 0.001～0.02mD. Comparing with the discovered shale gas reserves in North America, the shale in Dongying depression has favorable reservoir properties. The gas logging analysis on the shale of lower Es3 and upper Es4 shows abnormal phenomena. Moreover, well kick and leak frequently occurred during well servicing. These indicate the existence of gas. The light hydrocarbon abundance of head space gases increase with depth, while the∑（C₅-C₇）/∑（C₁-C₄） value is low, usually less than 0.15, which shows that the head space gases of the shale under 3400m are mainly gas. According to the relation of light hydrocarbon composition of head space gases and gas-to-oil ratio to buried depth, the exploration of the shale reservoir in Dongying Depression should be concurrent exploration, when the buried depth is less than 3400m, the exploration should give priority to oil reservoir, as for the buried depth is more than 3400 meters, the exploration should consider the condensate hydrocarbon reservoirs and gas reservoirs primarily. The gas reserves of shale of lower Es3 and upper Es4 in Dongying Depression was estimated with volumetric analysis. Comparing with the discovered shale gas reserves in North America, the gas reserves of Dongying Depression corresponds to that of Barnett and Haynesville shale and is more than others. So it has potential to form shale gas reservoir and it will be a new field of natural gas exploration.更多还原