中国南方海相页岩气保存机理及模式

保存条件是控制页岩气富集和高产的关键因素,我国四川盆地五峰组—龙马溪组页岩气已实现了商业化开发,但受到保存条件的影响,页岩气富集差异性明显,对勘探开发目标优选提出了挑战。因此,深化中国南方海相页岩气保存机理及模式研究对扩大页岩气勘探开发成效、提高页岩气产量具有重要意义。本文以四川盆地及周缘地区五峰组—龙马溪组页岩为研究对象,应用盆地模拟、流体包裹体分析、覆压孔隙度和渗透率实验、页岩三轴岩石力学测试等技术方法,取得了3方面认识：(1)揭示了页岩气构造保存机理,构造演化控制了页岩微裂缝开启、游离气富集和地层超压发育,差异构造演化过程及强度控制了页岩气赋存状态及含气量,构造抬升开始晚、强度小对页岩气保存有利;(2)阐明了页岩气顶底板封闭机理为岩性和物性封闭,岩性致密、页岩厚度、微观孔隙结构是顶底板封闭的关键控制因素,页岩气自封闭机理为毛管力和分子间作用力封闭,受控于孔隙连通性和甲烷吸附作用;(3)基于埋深和构造变形强度,建立了海相页岩气正向构造高部位和负向构造低部位保存模式。正向构造页岩气保存受控于裂缝发育程度,埋深大于页岩破裂深度、背斜两翼夹角大于120°有利于页岩气保存,负向构造页岩气保...     

中国南方海相页岩气勘探理论：回顾与展望

自重庆涪陵焦石坝焦页1井实现我国南方海相页岩气勘探突破后，通过解剖和探索提出了复杂构造区海相页岩气“二元富集”规律的认识。通过“十三五”科技攻关的持续深化研究，进一步阐明了深水陆棚相优质页岩是页岩气“成烃控储”的基础和保存条件是页岩气富集高产的关键的深刻内涵。该套页岩浮游藻类与浮游硅质生物共生、繁盛，硅质生物骨屑的成岩多孔性有利于藻类所生成烃类的原位滞留和后期裂解形成有机孔隙的大量发育与保存，而顶底板封堵条件与后期构造运动强弱是页岩气富集保存的关键要素，揭示了海相页岩气“源储一体，早期滞留，原位富集，晚期改造”的富集保存机理，明确了复杂构造区海相页岩气勘探的目标与方向。深层、常压和陆相页岩气将是四川盆地及周缘页岩气勘探开发的重要接替领域，“十四五”期间四川盆地页岩气勘探将有望得到更大的快速发展。     

南方复杂地区页岩气差异富集机理及其关键技术

针对我国南方海相富有机质页岩时空非均质强、热演化程度高、构造演化历史复杂、页岩气具差异富集和保存条件多样等特点,采用多学科方法对南方五峰组-龙马溪组海相页岩气区进行精细解剖,形成了针对南方复杂地区海相高过成熟页岩气评价参数表征的多项关键技术.研究结果显示富泥硅质页岩和富泥/硅混合质页岩是五峰组-龙马溪组的优质岩相;页岩中孔和宏孔提供了主要的孔体积,微-纳米孔隙结构特征受页岩组分及其孔隙发育程度双重控制;页岩气富集演化具二高、三复杂特点（古温度高,热演化程度高,温压演化复杂,页岩气赋存方式复杂及保存条件复杂）.研究中所提出的页岩岩相表征和优选技术、多尺度储集空间全息表征技术、海相页岩复杂演化改造过程表征技术、初步形成的甜点评价参数体系表征方法可有效地应用于南方五峰组-龙马溪组海相页岩气评价.研究成果可为南方页岩气基础地质调查工程提供技术支撑.      

南方海相页岩气“二元富集”规律——四川盆地及周缘龙马溪组页岩气勘探实践认识

继JY1井龙马溪组页岩测试获得高产工业气流,实现南方海相页岩气的战略突破之后,近期焦石坝地区多口开发井获得高产天然气流,展现出四川盆地海相页岩气勘探的良好前景。通过对四川盆地及周缘多口井的岩性、有机地球化学、岩石矿物含量、物性、储集类型、微观孔隙结构特征、裂缝发育程度、含气量和气井产量、压力等钻探成果及分析测试资料进行深入解剖研究,探索并提出了复杂构造区海相页岩气"二元富集"规律,即:深水陆棚优质泥页岩发育是页岩气"成烃控储"的基础;良好的保存条件是页岩气"成藏控产"的关键。本文对中国南方海相页岩气的高效勘探开发具有重要的借鉴、指导意义。     

中国南方海相页岩气选区关键参数探讨

中国南方海相页岩具有热演化程度高和经历过多期构造运动等特征,基于多个页岩气区块的勘探开发实践,提出了以保存条件为核心、地质评价为重点,兼顾经济评价的页岩气有利区选区思路,筛选出了有机质含量、有机质成熟度和压力系数3项中国南方海相页岩气选区的关键评价指标。有机质含量是页岩气富集成藏的物质基础,在选区时应本着"高中找厚"的原则,即在TOC含量平均较高的页岩层段(系)寻找富有机质页岩连续厚度大的页岩层段;成熟度过高对页岩气的富集成藏有消极的影响,在选区时应本着"高中找低"的原则;压力系数可以直观反映页岩气的保存程度,压力系数越高,表明页岩气的保存程度越好,在选区时应本着"强中找高"的原则,即在强构造的地质背景下寻找压力系数高的区块。以湘西北牛蹄塘组页岩气的实际勘探情况为例,认为湘西北地区牛蹄塘组页岩气具有较好的勘探开发前景,但是成熟度过高和保存条件差(压力系数低)是影响湘西北地区页岩气富集与高产的主要潜在风险。     

四川盆地及周缘下古生界海相页岩气富集高产主控因素——以焦石坝地区五峰组—龙马溪组为例

利用钻井、地震及样品实验数据资料,首先对焦石坝地区五峰组—龙马溪组页岩气的形成条件进行了评价,然后探讨了四川盆地及周缘下古生界海相页岩气富集高产主控因素。研究认为:焦石坝地区五峰组—龙马溪组泥页岩具有厚度大、有机质丰度高、类型好、热演化程度较高、储集物性以及含气性好、以及良好保存条件和可压性等特点;四川盆地及周缘下古生界海相页岩气富集高产主控因素是富有机质泥页岩的发育程度、保存条件、天然裂缝的发育和泥页岩的可压裂性等,因为富有机质泥页岩的发育为页岩气的生成和储集提供了丰富的物质基础,良好的保存条件是页岩气富集的关键,天然裂缝和可压裂性是高产的重要保证。     

川东南地区五峰组-龙马溪组页岩气富集与高产控制因素

中美页岩气地质和地表条件的对比分析表明,中国南方海相页岩与北美典型页岩的主要评价指标相近,是页岩气勘探的主攻层系。其中,四川盆地及周缘地区是有利勘探地区。中国石油化工股份有限公司2006年以来,经历6年的研究与勘探探索,2012年在四川盆地涪陵焦石坝地区龙马溪组页岩气获得重大突破,发现了涪陵页岩气田,取得了中国页岩气的首个商业发现。五峰组-龙马溪组页岩气富集与高产的地质因素包括原始沉积条件和后期保存条件,台内坳陷控制优质页岩的形成分布,页岩厚度大、有机质含量高是页岩气选区的首要评价指标。保存条件影响页岩气的富集程度,四川盆地内部总体保存条件较好,有三叠系膏盐岩分布的地区保存条件好,页岩气层段压力系数高,页岩气富集程度高。在选区评价中,原始沉积条件和后期保存条件均有利的地区是页岩气勘探的有利区。通过对典型探井五峰组-龙马溪组页岩气富集条件的分析表明,有机质提供了页岩气富集的物质基础,有机质孔是页岩气富集的主要储集空间,层理(缝)是页岩气水平渗流的高效通道,高硅质含量具有良好的可压性,高压力系数指示页岩气富集程度高。有机质、有机质孔、层理(缝)、硅质含量和压力系数等表征页岩气富集与高产的5种关键参数具有成因联系和统计相关的特征,纵向上又具有"五性一体"的分布特征,从而决定了五峰组-龙马溪组下部富含有机质的优质页岩层段既可以富集页岩气,又有利于页岩气的开发,是开发页岩气的主要层段和水平井轨迹的关键目标层。     

涪陵页岩气田发现的启示与思考

位于四川盆地东缘焦石坝构造的涪陵页岩气田,已探明地质储量3 806×108 m3,是北美地区以外,首个实现商业开发的页岩气田。焦石坝构造是一个受北东向和南北向两组断裂体系控制形成的菱形断背斜,其特殊的构造背景对页岩气的富集具有重要控制作用。涪陵页岩气田的产层为五峰组-龙马溪组页岩,具有富有机质页岩厚度大、有机质丰度高、有机质热演化程度高、脆性矿物含量高、地层压力系数高、单井产量高、裂缝发育、烷烃碳同位素倒转等特点。3年的勘探开发表明,涪陵页岩气田普遍高产、稳产,证实为高产富集的页岩气田。本文通过对区域地质特征的解剖和对涪陵页岩气田基本特征的总结,结合前人对美国页岩气田的研究,提出了涪陵页岩气田发现的启示与思考。结论认为:首先,证实中国存在高产页岩气田,但富集因素与美国不同,正向构造和晚期区域走滑作用极为重要;其次,天然裂缝的发育是页岩气富集高产的关键;第三,几乎所有的商业性页岩气田都是地层超压;第四,讨论了页岩气的运移问题,认为页岩气通过短距离的运移传递,可以实现大范围的运移聚集;第五,提出基于商业回报和资源利用不同角度的考量,可能会影响生产方式的选择;第六,中国页岩气发展需要技术、思路创新和长远视角,必须重视深层海相、陆相和盆地外常压页岩气的研究。     

昭通太阳背斜山地浅层页岩气"三维封存体系"富集成藏模式

本文系统分析了太阳地区构造断裂系统、顶底板条件、沉积岩相、优质页岩展布、源储条件及富集高产规律,提出了"多场协同多元耦合"共同作用下太阳背斜区山地浅层页岩气"三维封存体系"富集成藏赋存模式,具有5个特征:①页岩储层上覆龙马溪组一段二亚段—石牛栏组厚层致密页岩和泥灰岩,下伏临湘组—宝塔组厚层致密瘤状灰岩,具有良好的封隔层条件,形成了封存体系的顶板和底板;②压扭应力背景下形成的断裂系统属于挤压性逆冲断层、压扭性走滑断层,断层的纵向封闭性好,有效地保护了优质页岩气藏;③断层两盘页岩气层对接岩性均为致密泥灰岩和灰岩,侧向封堵性防止了页岩气泄漏点出现,使得山地浅层页岩气仍具有连续型气藏特征;④前陆盆地"水体滞留+火山灰沉降"造就了"海洋漂浮生物繁盛+缺氧强还原"深水陆棚沉积环境,形成了"富碳、高硅、低黏、高脆"的优质烃源岩储集体,构建了"规模生烃、高效吸附富集"的页岩微纳米级储集孔隙空间;⑤页岩储层具有相对小的地应力和两向水平应力差,既利于在中低泵压下的储层压裂施工作业,又具备体积压裂打碎页岩形成复杂缝网和气井获得高产的关键要素.提出了复杂构造区山地浅层页岩气"多元富集高产"的规律性认识,即:前陆盆地深水缺氧强还原环境促使了"富碳、高硅、低黏"页岩储层发育(沉积成岩控制源储特征)、持续良好的三维封闭保存体系有效保护了富有机质页岩生烃留烃富烃和超压保孔(保存条件控制天然气藏)、页岩脆性与地应力以及水平应力差决定了体积压裂改造的难易程度并影响了人造页岩气藏的构建效果(应力可压性控制人造气藏)、Ⅰ类优质页岩气储层连续厚度和地层压力系数决定了页岩气禀赋的资源储量丰度与气井高产(烃储禀赋控制单井产量).研究成果对中国南方复杂构造区海相浅层页岩气的高效勘探开发具有重要的借鉴引领和指导意义.     

川东南南川地区构造变形与页岩气富集

南川地区自下古生界海相页岩成气以来,遭受了强烈的构造改造作用,致使页岩气富集规律复杂。为揭示南川地区中新生代构造变形对页岩气富集的制约,通过构造精细解析,以及对演化时序和页岩气富集主控因素的分析,构建了结构模式,恢复了中新生代构造演化过程,厘定了页岩气富集主控因素,进而分析了构造样式与页岩气富集模式的响应关系。研究表明,南川地区整体构造变形自东向西逐渐减弱,存在北段强烈冲断褶皱-断展-断滑、南段强烈冲断褶皱-断滑两种前展式结构模式。中燕山期,主体NE向构造发育,平桥、东胜构造形成,至中燕山期末期,受金佛山隆起以及南川-遵义断层的作用,南段发生构造叠加与改造,早期NE向构造演化为北倾单斜,并在南川-遵义断层东侧发育近南北向阳春沟背斜。受差异构造变形作用,北段断褶带发育背斜型富页岩气构造样式,外缘带为单斜型构造样式,而南段构造叠加带则发育单斜型和背斜型构造样式。页岩气整体保存条件受构造变形方式制约,北段页岩气保存条件由东向西逐渐变好,而南段页岩气保存条件较为复杂,其中北段的低角度单斜、宽缓背斜、较宽缓背斜3类构造样式为有利的页岩气富集构造。     

川东盆缘带龙马溪组关键保存要素对页岩气富集的控制作用

川东盆缘带是南方地区龙马溪组页岩气勘探的重点地区,已经在涪陵地区建成我国第一个页岩气大气田.研究区页岩气原始地质条件优越,但由于后期构造改造强烈,保存条件十分复杂,直接影响到页岩气的富集程度,除涪陵地区外的其他地区尚未取得产能建设的重大突破.笔者等利用钻井、野外、测井、地震及分析测试资料分析了研究区构造及演化特征、抬升...     

川滇黔邻区龙马溪组页岩气富集主控因素与勘探方向

中国的页岩气资源评价必须立足于中国主要陆块的地质条件与构造演化特点之上,对于不同层系、不同地区的页岩气选区评价,也必须抓住关键因素。川滇黔邻区的五峰组-龙马溪组富有机质页岩发育,但保存条件较渝东南地区更为复杂。印支期以来,该区经历了多期次构造应力场转换,断裂、褶皱发育,因此,建立针对性的页岩气选区评价参数体系是该区页岩气勘探走出困局的当务之急。本文在分析该区已有页岩气钻井成效的基础上,立足于扬子海相层系页岩气勘探应是基于保存条件的"连续型甜点区"的选区评价基本思路,结合前人研究成果,系统梳理出一套评价指标体系。该体系涵盖5大因素(区域盖层、直接盖层、底板条件、页岩层自身条件、构造改造强度)、4个等级、17个选区评价参数。另外,根据已有相关钻井数据,总结提出了5个页岩气层评价表征参数(含气量、孔隙度、电阻率、氮气组分含量和压力系数)。根据该指标体系,对川滇黔邻区的主要构造单元进行了梳理分析,优选出5个有利区,提出了各有利区的首选可能突破点。本研究对复杂构造区页岩气有利区带优选具有一定的指导意义。     

Distribution characteristics,exploration and development,geological theories research progress and exploration directions of shale gas in China

The shale gas resources in China have great potential and the geological resources of shale gas is over 100×10¹²m³,which includes about 20×10¹²m³ of recoverable resources.Organic-rich shales can be divided into three types according to their sedimentary environments,namely marine,marine-continental transitional,and continental shales,which are distributed in 13 stratigraphic systems from the Mesoproterozoic to the Cenozoic.The Sichuan Basin and its surrounding areas have the highest geological resources of shale gas,and the commercial development of shale gas has been achieved in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in these areas,with a shale gas production of up to 20×10⁹m³ in 2020.China has seen rapid shale gas exploration and development over the last five years,successively achieving breakthroughs and important findings in many areas and strata.The details are as follows.(1)Large-scale development of middle-shallow shale gas(burial depth:less than 3500 m)has been realized,with the productivity having rapidly increased;(2)breakthroughs have been constantly made in the development of deep shale gas(burial depth:3500-4500 m),and the ultradeep shale gas(burial depth:greater than 4500 m)is under testing;(3)breakthroughs have been made in the development of normal-pressure shale gas,and the assessment of the shale gas in complex tectonic areas is being accelerated;(4)shale gas has been frequently discovered in new areas and new strata,exhibiting a great prospect.Based on the exploration and development practice,three aspects of consensus have been gradually reached on the research progress in the geological theories of shale gas achieved in China.(1)in terms of deep-water fine-grained sediments,organic-rich shales are the base for the formation of shale gas;(2)in terms of high-quality reservoirs,the development of micro-nano organic matter-hosted pores serves as the core of shale gas accumulation;(3)in terms of preservation conditions,weak structural transformation,a moderate degree of thermal evolution,and a high pressure coefficient are the key to shale gas enrichment.As a type of important low-carbon fossil energy,shale gas will play an increasingly important role in achieving the strategic goals of peak carbon dioxide emissions and carbon neutrality.Based on the in-depth study of shale gas geological conditions and current exploration progress,three important directions for shale gas exploration in China in the next five years are put forward.     

中国南方海相页岩气超压机制及选区指标研究

在页岩气勘探开发选区的过程中,首先要寻找含气量较高的地区作为开发区块,含气量高的地区其资源丰度高,在同样的增产改造规模下单井EUR也较高,经济性也好。由于页岩含气量等于吸附气加上游离气,再加上溶解气,游离气、吸附气和溶解气都与压力系数关系密切。在美国开展页岩气地质选区过程中,由于地质条件稳定,认为超压对于页岩气田没有那么重要,正常压力、甚至欠压都可以实现开发,因此美国页岩气地质选区指标中没有压力系数的概念,并没有将超压作为一个关键指标。但是由于中国与北美地质成藏背景不同,北美页岩气主要位于环加拿大克拉通盆地,背景非常稳定,而我国是由多个地块拼接而成,构造复杂,同时页岩形成的时代较久,因此,我国与北美地质条件最大的差别为页岩成熟度高低和构造运动的强弱。因为我国海相成熟度高,导致孔隙压实,孔隙度降低;我国构造运动相对活跃,断裂发育,保存条件相对差。对于高成熟、低孔隙度的页岩,要达到同样的含气量需要较大的地层压力系数,这样单井最终可采储量才能达到经济极限,才能实现商业开发。我国南方分布有丰富的海相页岩气,具有厚度大、分布稳定的特点,普遍经历了高成熟演化和强烈地质构造运动。在油气生成过程中由于排烃作用的发生形成了广泛发育超低含水饱和度的特征,超低含水饱和度存在为形成超压富集区创造了条件,这种超压核心区是南方海相页岩气近期主要的勘探目标。扬子地区已经发现的超压页岩气田的增压机制主要包括构造抬升型增压、水热型增压、黏土矿物脱水型增压、生烃型增压。焦石坝海相页岩气田主要为构造型增压所形成的超压页岩气田,长宁页岩气田主要为生烃增压型页岩气田。页岩气选区指标应该是核心区/富集区优选指标,指标取值依据必须与超压气田地质特征参数匹配才有意义。北美地区页岩气地质选区需要考虑埋深、页岩厚度、TOC含量、含气量、硅质矿物含量。由于北美地质条件简单、成熟度适中,在低压、欠压条件下可实现商业化,但在高成熟、断裂发育背景下,地层压力系数尤其重要,应该考虑地层层压力系数。因此,本文认为页岩气地质选区中,除了考虑页岩埋深(1 500~4 500 m)、页岩厚度(>30 m)、总有机碳含量(>2%)、硅质矿物含量(>30%)等基本参数外,应把地层压力系数大于1.3以上作为我国南方海相页岩气选区的重要指标之一,才能体现我国南方海相页岩气特点,同时提高页岩气选区的准确性和科学性。     

Geological Conditions and Prospect Forecast of Shale Gas Formation in Qiangtang Basin,Qinghai-Tibet Plateau

The presence of shale gas has been confirmed in almost every marine shale distribution area in North America.Formation conditions of shale gas in China are the most favorable for marine,organic-rich shale as well.But there has been little research focusing on shale gas in Qiangtang Basin,Qinghai-Tibet Plateau,where a lot of Mesozoic marine shale formations developed.Based on the survey results of petroleum geology and comprehensive test analysis data for Qinghai-Tibet Plateau,for the first time,this paper discusses characteristics of sedimentary development,thickness distribution,geochemistry,reservoir and burial depth of organic-rich shale,and geological conditions for shale gas formation in Qiangtang Basin.There are four sets of marine shale strata in Qiangtang Basin including Upper Triassic Xiaochaka Formation （T3x）,Middle Jurassic Buqu Formation （J2b）,Xiali Formation （J2x） and Upper Jurassic Suowa Formation （J3s）,the sedimentary types of which are mainly bathyal-basin facies,open platform-platform margin slope facies,lagoon and tidal-fiat facies,as well as delta facies.By comparing it with the indicators of gas shale in the main U.S.basins,it was found that the four marine shale formations in Qiangtang Basin constitute a multi-layer distribution of organic-rich shale,featuring a high degree of thickness and low abundance of organic matter,high thermal evolution maturity,many kinds of brittle minerals,an equivalent content of quartz and clay minerals,a high content of feldspar and low porosity,which provide basic conditions for an accumulation of shale gas resources.Xiaochaka Formation shale is widely distributed,with big thickness and the best gas generating indicators.It is the main gas source layer.Xiali Formation shale is of intermediate thickness and coverage area,with relatively good gas generating indicators and moderate gas formation potential.Buqu Formation shale and Suowa Formation shale are of relatively large thickness,and covering a small area,with poor gas generating indicators,and limited gas formation potential.The shale gas geological resources and technically recoverable resources were estimated by using geologic analogy method,and the prospective areas and potentially favorable areas for Mesozoic marine shale gas in Qiangtang Basin are forecast and analyzed.It is relatively favorable in a tectonic setting and indication of oil and gas,shale maturity,sedimentary thickness and gypsum-salt beds,and in terms of mineral association for shale gas accumulation.But the challenge lies in overcoming the harsh natural conditions which contributes to great difficulties in ground engineering and exploration,and high exploration costs.     

三江盆地绥滨坳陷下白垩统陆相页岩油气形成的地质条件分析

绥滨坳陷是位于三江盆地西部的次一级构造单元,并且作为中国东北部地区唯一的中生界具有海相和海陆交互相沉积的、未获得常规油气突破的坳陷,对其进行非常规油气地质研究显得意义重大。其中中生界下白垩统穆棱组和城子河组的陆相富有机质含煤泥页岩是该地区最重要的两套主力烃源岩层系。通过分析绥滨坳陷下白垩统暗色泥页岩的分布情况、地球化学指标、页岩储层及含气性特征等因素,认为下白垩统两套富有机质泥页岩的分布面积较广泛(＞2 000 km²)、累积厚度大(＞1 000 m)、TOC含量高(＞1.3%)、受局部火山活动的影响,成熟度以成熟-过成熟为主(平均1.19%),有机质类型以Ⅲ和Ⅱ₂为主,有利于生气,且储层中石英、长石及碳酸盐等脆性矿物含量较高,易于后期压裂改造的实施。另外,多段泥页岩层段气测显示异常,表明了其良好的页岩气勘探潜力。并与美国和国内海、陆相产气页岩层的主要参数指标相比较,初步认为普阳-南大林子凹陷的北部及南部的东荣集贤一带为页岩气勘探的有利地区且以城子河组为最有利层段,而穆棱组次之,页岩油气资源潜力巨大。     

Geological Factors Controlling the Accumulation and High Yield of Marine-Facies Shale Gas: Case Study of the Wufeng-Longmaxi Formation in the Dingshan Area of Southeast Sichuan,China

The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research. In this study, the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated. Shale cores underwent laboratory testing, which included the evaluation of total organic carbon(TOC), vitrinite reflectance(Ro), whole-rock X-ray diffraction(XRD), pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM). Based on the results of natural gamma ray spectrum logging, conventional logging, imaging logging, and seismic coherence properties, the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively. The results showed that(1)layer No. 4(WF2-LM4) of the Wufeng-Longmaxi Formation has a Th/U ratio 2 and a Th/K ratio of 3.5–12. Graptolites and pyrite are relatively abundant in the shale core, indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2) The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen. There is a good correlation among TOC, Ro, gas content, and brittle minerals; the fracturing property(brittleness) is 57.3%. Organic and inorganic pores are moderately developed. A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3) The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects, and it is poorly preserved. The DY2 well is located far from the Qiyueshan Fault. Large faults are absent, and upward fractures in the Longmaxi Formation are poorly developed. The well is affected by low tectonic deformation intensity, and it is well preserved.(4) The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning. The thickness of the high-quality shale interval(WF2-LM4) is relatively small, which may be an important reason for the unstable production of shale gas thus far. Based on the systematic analysis of the geological factors controlling high-yield shale gas enrichment in the Dingshan area, and the comparative analysis with the surrounding typical exploration areas, the geological understanding of marine shale gas enrichment in southern China has been improved. Therefore, this study can provide a useful reference for shale gas exploration and further development.     

Exploration and research progress of shale gas in China

There are three types of shale gas resources in China. The resources are present in large amounts and are widely distributed. Marine facies, transitional facies and continental facies resources each account for a third. Based on resource distributions, there are many wells penetrated into the Sinian, Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian strata of the Yangtze plate and its periphery, the North China Craton and the Tarim Basin. Many years of exploration have indicated that the marine Silurian Longmaxi shale gas is widely distributed in south China and has been industrialized in its production in the Sichuan basin. The shale gas from the Cambrian Niutitang Formation and the Sinian Doushantuo Formation are important discoveries in Yichang, Hubei and Zhenba, Shanxi. There are also shale gas resources found within transitional facies and continental facies in different areas in China. The “two element enrichment theory” has been summarized during the exploration process of Silurian marine shale gas in the Sichuan Basin. In addition, horizontal drilling and fracturing technologies up to 3500 m in depth have been developed. Based on the understanding of shale gas accumulation in a complex tectonic zone outside the Sichuan basin, a preliminary summary of the formation of the “converse fault syncline control reservoir” and “paleo uplift control reservoir” model has been constructed. The dominant theory of “Trinity” shale gas enrichment and the high yield of the “deep water Lu Pengxiang sedimentary facies belt, structural preservation conditions and overpressure” is summarized. Guided by the above theories. Anye1 well in Guizhou and Eyangye1 well in Hubei were drilled. “Four storey” oil and shale gas is found in the Permian Qixia group, the Silurian Shiniulan Formation, the Longmaxi Formation and the Ordovician Baota Formation in Anye1 well. Good shale gas has been gound in the Cambrian Niutitang formation inian Doushantuo formation in Eyangye 1well. This paper aims to summarize and review the main progress, theoretical technology and problems of shale gas exploration and development in recent years in China, and predicts the future exploration and development direction for shale gas and possible exploration areas.     

沁水盆地煤系页岩气成藏模式分析

本次研究分析了石炭纪-二叠纪海陆过渡相泥页岩测试数据和地质资料,依据海陆过渡相泥页岩地球化学、储层物性、含气性等特征,探讨了海陆过渡相页岩气的成藏模式。在生气模式方面,海陆过渡相页岩气以自生为主,他生为辅,煤层作为补充气源,热演化进程方面要求低于海相泥页岩;在储气模式方面,海陆过渡相泥页岩储层更加致密,孔隙度更小,对游离气的存储能力相对较差;在吸附气存储方面,储层的最大吸附量受控于泥页岩有机质丰度;在保存模式方面,页岩气保存受泥页岩厚度、构造埋藏史、基本构造形态等多种因素的控制,且任一种不利控制因素可能破坏页岩气藏。