基于对中国南方和美国页岩气地质特点的分析,探讨了中国式页岩气成藏富集主控因素及勘探开发的关键问题。中国式页岩气地质特点包括：构造演化阶段多,构造类型复杂,断裂发育,页岩层系连续分布面积小,寒武系、志留系两套主要页岩层系现今的热演化程度和埋深没有对应关系。通过对影响页岩气富集的主要因素（裂缝、构造类型、页岩气运移、含气量等）的分析和探讨,提出了中国式页岩气的富集机理：“沉积相带、保存条件”是控制页岩气成藏的主要因素,控制页岩气选区;“构造类型、构造作用”是控制页岩气富集的主要因素,控制甜点区的选择。中国页岩气勘探开发下一步攻关方向为：①与美国页岩气发展刚好相反,中国页岩气勘探开发要从超压区向常压区甚至低压区发展;②四川盆地内应从中深层向深层发展,开展埋深大于4 000 m页岩层系成藏富集机理,特别是水平井压裂工艺技术的攻关;③借鉴海相页岩气的勘探开发经验,推动海陆过渡相、陆相页岩气的发展。图4表3参33

By analyzing geological characteristics of shale gas in Southern China and the United States, main factors controlling the accumulation and key issues in the exploration and development of shale gas in China have been examined. The geological characteristics of shale gas in China include multi-stages of tectonic evolution, complex structure types, abundant faults, small continuous distribution area of shale formations, and no corresponding relationship between current thermal evolution degree and current burial depth of two main sets of shale formations (the Cambrian and Silurian). According to the analysis of the factors affecting shale gas enrichment such as fracture, tectonic type, shale gas migration, and gas content etc, the enrichment mechanisms of shale gas in China are: “sedimentary facies and preservation condition” are the main reservoir-controlling factors affecting the accumulation of shale gas, and “structure types and tectonism” are the main factors controlling the enrichment of shale gas in China; the former factors define shale gas plays, and the latter ones determine the position of sweet spots. The future research directions of shale gas in China are: firstly, contrary to the shale gas development in the United States, shale gas exploration and development in China should extend from the overpressure to normal pressure, and even low pressure areas; secondly, shale gas exploration in the Sichuan basin should extend from middle-deep to deep formations, studies should be done on the shale gas enrichment mechanism and accumulation models in formations more than 4 000 m deep, and horizontal well fracturing technology for these formations; thirdly, the development of transitional facies and continental facies shale gas should be brought along by drawing on exploration and development experience of marine shale gas.

页岩含气量评价对页岩气资源预测、储量计算、勘探开发规划具有重要的意义。解吸法是页岩含气量评价中应用非常广泛的一种直接测量方法。页岩气的解吸方法主要沿用了煤层气的技术，将岩心或岩屑封装于解吸罐后，测定解吸气和残留气，计算损失气，3部分的总和即页岩储层的含气量。经过多年的发展，解吸装置在不断改进，解吸数据分析方法一直在优化。目前已经发展了USBM法、多项式法、Smith-Williams法、下降曲线法、Amoco法等多种解吸数据处理方法。在实际应用中，温度等环境因素、损失时间、采用的拟合方法以及解吸装置本身都会对解吸结果产生明显的影响。由于页岩气的扩散机制和解吸过程与煤层气存在一定差异，简单沿用煤层气的方法与技术评价页岩含气量，可能存在明显的误差。未来的研究将致力于改进解吸装置，发展符合页岩气体解吸机理的数学模型，规范解吸方法，建立相关行业标准。

The evaluation of shale gas content has a great significance on resource prediction,reserve calculation,and exploration and development planning.Desorption method is one of the methods which is widely applied to the evaluation of shale gas content.The present shale gas desorption method has mainly followed coalbed methane technologies.After the core or cutting shale sample is sealed in the desorption canister,desorbed gas and residual gas are measured,and the lost gas is fitted using the measured data.Their sum is the total gas content.After years of development,desorption apparatuses as well as data analytical methods have been improved continuously.USBM method,polynomial method,Smith-Williams method,decline curve method and Amoco method have been successively developed to analyze desorption process.In actual applications,temperature and other environmental factors,lost time,fitting method and desorption apparatuses will influence the result of desorption.Due to the differences in diffusion mechanism and desorption process between shale gas and coalbed methane,evaluation of shale gas content based on methods from coalbed methane may lead to a significant error.Future research will target to improve desorption apparatuses,develop shale gas desorption models,standardize desorption methods as well as set up a relevant industry standard.

为了研究页岩气降压开采过程中吸附气解吸作用对基质表观物性（如有效孔隙半径、有效孔隙度、表观渗透率）及气体流动机制的影响,推导了吸附解吸作用下页岩基质孔隙有效半径和表观渗透率动态模型,建立了考虑吸附解吸影响基质表观物性和气体传输机制的页岩气渗流数学模型。采用有限体积法对模型进行求解,利用实验及矿场数据验证了模型的可靠性,最后应用该模型研究了页岩气开采过程中基质物性参数、气体流动机制变化特征以及吸附效应对页岩气开发的影响规律。研究结果表明,页岩气开采过程中基质孔隙有效半径、有效孔隙度和表观渗透率逐渐变大,体积压裂改造区域流动机制由滑脱流转变为过渡流;忽略吸附层影响将导致地质储量和产气量严重高估;随着吸附层厚度增加,累计产气量变化不大,但采收率逐渐降低。图12表1参25

The adsorption/desorption effects impact the petro-physical properties of matrix pores during gas depressurizing production, such as effective pore radius, effective porosity, apparent permeability, which will further impact the gas flow regime. In this paper, the dynamic models of effective pore radius and apparent permeability under the action of gas adsorption/desorption are derived. The mathematical model of shale gas flow is established considering the effects of adsorbed gas on apparent properties and gas flow regime. After that, the model is solved and validated using a finite volume method and experimental and field data. Finally, the variations of apparent parameters of matrix pores and gas flow regimes during gas production, and the influences of adsorption on gas production are demonstrated. The results show that the effective pore radius, porosity and apparent permeability increase during gas production; the gas flow regime in stimulated reservoir volume (SRV) changes from slip flow to transition flow; if the impacts of adsorbed gas on gas production is overlooked, both original gas in place (OGIP) and gas production will be significantly overestimated. The cumulative gas production changes slightly as the adsorption layer thickness increases, but the gas recovery factor decreases.

川南地区是中国页岩气勘探开发的热点地区，页岩气藏类型种类多、资料丰富。为总结该区基本地质特征及富集高产规律，利用大量地震、钻井、测井及分析化验等资料，从沉积作用、构造变形、保存条件等方面分析了页岩气藏关键地质因素，并剖析典型页岩气藏类型特征、富集条件差异及其勘探开发启示。研究表明：①沉积作用整体控制了五峰组—龙一₁亚段页岩地层厚度、储层品质与厚度；②构造变形对页岩气藏的影响体现在构造样式、埋深、地应力场、天然裂缝发育特征等方面；③页岩气藏保存条件受构造改造强度、沉积作用、埋深等多因素影响；④川南地区页岩气藏可分为斜坡型、向斜型、低陡背斜夹宽缓向斜型及箱状断背斜型等4种类型，不同类型气藏的地质特征、富集条件存在差异；⑤针对不同类型页岩气藏的地质与工程特征开展分析，并提供相应技术对策，有助于提高单井产量与页岩气产能建设。该研究成果丰富了四川盆地页岩气富集高产理论，为其他区域页岩气藏的规模效益开发提供了技术参考。

The southern Sichuan Basin is the hot spot of shale gas exploration and development in China， where there are many types of shale gas reservoirs and abundant data. In order to summarize the basic geological characteristics and laws of enrichment and high yield in that area， by using seismic， drilling， logging， testing data， we analyzed key geological factors of shale gas reservoir in the aspects of sedimentation， tectonic deformation， preservation conditions， and also analyzed characteristics， differences of enrichment condition and implications of typical shale gas reservoirs. The results show， （1）The sedimentary process controls the formation thickness， quality and thickness of reservoir in O₃ w-S₁ l^1-1； （2）The influence of tectonic deformation on shale gas reservoir reflects in structural style， burial depth， geostress field， characteristics of natural fracture； （3）The preservation conditions of shale gas reservoirs are affected by many factors such as the intensity of structural reconstruction， sedimentation and burial depth； （4）Shale gas reservoirs in southern Sichuan Basin can be divided into four types： type of slope， type of syncline， type of low-steep anticline with wide-gentle syncline and type of faulted anticline， while different types of gas reservoirs have different geological characteristics， enrichment conditions； （5）The geological and engineering characteristics of different types of shale gas reservoirs are analyzed and corresponding technical countermeasures are provided， which are helpful to improve the production of single well and the construction of shale gas production capacity. The research results enrich the theory of shale gas enrichment and high yield in Sichuan Basin， and provide technical reference for the large-scale and cost-efficient development of shale gas in other areas.

通过对焦石坝地区龙马溪组页岩岩心进行解吸以分析其气体组分和碳同位素组成，研究了四川盆地志留系龙马溪组页岩气碳同位素倒转现象。结果表明，解吸气相对井口气组分明显偏湿、碳同位素值明显偏重；各组分碳同位素值随解吸时间变重：不同样品δ¹³C₁值最大变重幅度12.3 ‰ ~23.9 ‰ ，而不同样品δ¹³C₂值最大变重幅度仅0.8 ‰ ~2.3 ‰ ，即甲烷碳同位素值相对重烃变化更明显，与前人页岩岩心解吸实验结果一致。研究结果认为：地层状态下页岩气可能并未发生碳同位素倒转，岩心解吸过程中观察到的δ¹³C₁值比δ¹³C₂值变化更明显，不是不同组分扩散速率差异造成，而主要是由于甲烷与乙烷处于不同解吸阶段导致，即乙烷处于其解吸早期阶段而甲烷处于其解吸较晚阶段；生产过程中吸附作用引起的烷烃气不同组分相态差异与所处解吸阶段差异可能是导致四川盆地龙马溪组页岩气碳同位素完全倒转的主要原因，但不能否认干酪根裂解气与原油裂解气的混合对页岩气碳同位素倒转做出的部分甚至大部分贡献。

<p>This study is focused on the carbon isotope reversal of shale gas in Silurian Longmaxi Formation, Sichuan Basin. Core desorption test is conducted on the shale in Longmaxi Formation, Jiaoshiba area, so as to analyze its gas components and carbon isotope compositions. The results indicate that the desorbed gas is obviously wetter than the wellhead gas in component, and the carbon isotope of the former is significantly heavier; the carbon isotope values of each component became greater with the increase of desorption time. In terms of different samples, the maximum variation of &delta;¹³C₁ value is from 12.3 &permil; to 23.9 &permil;, while that of &delta;¹³C₂ is only from 0.8 &permil; to 2.3 &permil;, i.e., the carbon isotope of methane presents more obvious variations than heavy hydrocarbon, which is consistent with the results of previous shale core desorption experiments. It is concluded that &delta;¹³C₁ value observed in core desorption process has more obvious variations than &delta;¹³C₂ value, which is not caused by the difference in diffusion rate, but mainly results from the differences in desorption stages, i.e., ethane is in its early desorption stage while methane in the late desorption stage. In the production process, the differences in the component phase of alkane hydrocarbon gas and those in desorption stage caused by adsorption-desorption process may be the major reasons for complete reversal of the carbon isotopes of shale gas in Longmaxi Formation, Sichuan Basin. However, it cannot be denied that the mixing of kerogen pyrolysis gas and crude oil cracking gas make a partial or even a major contribution to the reversal of carbon isotopes in shale gas.</p>

川东南地区上奥陶统五峰组_下志留统龙马溪组页岩为我国页岩气勘探开发的重要层位，在焦石坝、彭水、丁山、南川等地区都有重要发现。利用中国石化无锡石油地质研究所自主研发的快速现场解吸仪，对该地区典型页岩气井解吸气量、损失气量、总含气量、解吸气天然气组分和解吸气甲烷碳同位素（约30min取1样）进行测试。数据分析表明，上述数据对页岩气成藏机理、勘探开发有着重要的意义，主要表现在：①首样甲烷碳同位素值及特征可以预测页岩气富集层，为页岩气甜点层识别的有效方法；②总含气量和解吸天然气组分识别页岩气甜点层，为页岩气甜点层识别的最直接方法；③页岩气组分和碳同位素值联合判别页岩气成因类型，干酪根碳同位素特征和页岩气碳同位素特征可作为气源对比的有效手段；④页岩气组分特征可以判别该地区的保存条件，其对页岩气的散失程度研究具有指示意义；⑤损失气量和解吸气量及其关系能够反映出主要赋存方式的差异，对页岩气井不同阶段产气特征具有预测作用；⑥甲烷碳同位素值随解吸时间出现明显分馏效应，可以预测页岩气产气阶段及剩余气的含量。

The Uppermost Ordovician-Lower Silurian Wufeng-Longmaxi Formations in southeastern Sichuan Basin is the most important shale gas habitat in China,with a series of discoveries in Jiaoshiba,Pengshui,Dingshan and Nanchuan areas.In this paper,we present data obtained using a self-designed apparatus of onsite shale gas desorption for measuring the gas content,chemical and stable carbon isotope composition at 30 min interval,and discuss the implications of these data for shale gas accumulation and exploration.Carbon isotope value of the initial desorption gas of each shale sample proves valuable for sweet spot identification.The total content and composition of desorption gas provides vital information for estimating the total gas resource in place.Combination of shale gas composition and carbon isotope value could be used to distinguish gas genetic type and relationship to source kerogen.A semi-quantitative model is presented to use the onsite gas desorption data in the assessment of shale gas preservation conditions related to regional structural evolution,as well as the prediction of general trend as a function of production time.

长宁和焦石坝气田为2种不同类型的海相页岩气&ldquo;甜点&rdquo;区。针对两大刻度区开展了8项关键参数分析，揭示了两大&ldquo;甜点&rdquo;区的共性和差异，主要表现为:①2个气田均具有正向构造背景、富有机质页岩厚度大(>30m)、有机质丰度高(平均TOC>3%)、岩相组合有利(硅质页岩和钙质硅质页岩为主)、基质孔隙发育(孔隙度>4%)、气层压力高(压力系数>1.4)、单井产量高(水平井初试产量一般在10&times;10⁴m³/d以上)等地质特征，但在裂缝发育程度、孔隙类型和地应力方面存在差异;②长宁气田总体为层间缝发育、基质孔隙为主、两向应力差大(>10MPa)的高产气区，开发难度相对较大，在四川盆地承压区具有广泛代表性，可以成为盆地内向斜区和燕山&mdash;喜马拉雅期断褶区资源评价类比取值的重要参考对象；③焦石坝气田总体为特殊构造背景下的裂缝型页岩气藏，在四川盆地承压区具有特殊的构造背景、宏观网状缝和裂缝孔隙十分发育、两向地应力小(

<p>Changning and Jiaoshiba gas fields are two different types of marine shale gas &ldquo;sweet spot&rdquo;.Based on the analysis of eight key geologic parameters,the commonalities and differences between the two gas fields were uncovered in this paper as follows:(1)The two gas fields share the geologic characteristics including positive structural setting,great thickness of organic-rich shale(>30m),high organic matter abundance(average <em>TOC</em>>3%),favorable lithofacies association(dominated by siliceous shale and calcareous-siliceous shale),well-developed matrix pores(porosity>4%),high gas reservoir pressure(pressure coefficient>1.4),and excellent per well production(initial test production of horizontal well generally exceeds 100 000m³/d).However,they differ in development degree of fractures,pore types,and in-situ stress.(2)Changning gas field,characterized by well-developed interlaminated fractures,dominant matrix pores,and great difference between maximum and minimum horizontal in-situ stress(>10MPa),is a highly productive area with relatively great development difficulty.This gas field is broadly representative of the confined area in the Sichuan Basin,thus providing a significant reference for the resource assessment and analogy in syncline area and Yanshanian-Himalayan folding area within the basin.(3)Jiaoshiba gas field is a fractured shale gas reservoir in general,which features special structural setting,well-developed macro-netted fractures and fracture pores,small difference between maximum and minimum horizontal in-situ stress(<10MPa),great resource abundance,relatively less development difficulty,and high production.The basic geologic parameters of shale gas occurrence in this gas field can be used as a useful reference for the shale gas resource evaluation in some areas of east Sichuan.The study suggested that the Wufeng-Longmaxi shale gas reservoirs are of two distinct types:One with both matrix pores and fractures,and another with only matrix pores,providing two types of important calibrated area for shale gas resource evaluation.</p>

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&ldquo;五性一体&rdquo;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。

以四川盆地东南缘焦石坝构造龙马溪组页岩气田及邻区为例，探讨复杂构造区、高演化程度页岩层系成藏富集的关键控制因素。焦石坝构造为经历多期构造运动改造的断背斜；龙马溪组页岩热演化程度高，Ro值大于2.2%，下部发育厚35～45 m、TOC值大于2%的优质页岩层系；产层超压，地层压力系数为1.55，页岩气产量、压力稳定。构造类型、构造演化及地球化学分析表明，龙马溪组存在多期生烃和天然气运聚过程，两组断裂体系与龙马溪组底部滑脱层的共同作用控制网状裂缝形成和超压的保持，是页岩气富集高产的关键，龙马溪组封闭的箱状体系保证了气藏的动态平衡。焦石坝页岩气藏的高产富集模式为“阶梯运移、背斜汇聚、断-滑控缝、箱状成藏”；经历多期构造演化的复杂构造和高演化页岩层系发育区，要形成页岩气高产富集区，与常规气藏一样，需要有利的保存和构造条件。图7表4参24

The Silurian Longmaxi shale gas play in the Jiaoshiba structure in the southeast margin of the Sichuan Basin is studied to discuss the key control factors of shale gas enrichment in complex tectonic and high evolution zone. The Jiaoshiba structure is a faulted anticline which experienced multiphase tectonic movement. The Longmaxi Formation has high thermal evolution degree with Ro more than 2.2%, and has a 35-45 meters thick high-quality shale (TOC > 2%) in its lower part. The reservoir is overpressure with a pressure coefficient of 1.55, and the shale gas production and pressure are stable. Structure type, evolution and geochemical analysis show that there are several stages of hydrocarbon generation, migration and accumulation in the Longmaxi Formation. The joint action of two groups (two stages) of fault systems and the detachment surface at the bottom of the Longmaxi Formation controls the development of reticular cracks and overpressure preservation, and it is the key to the shale gas accumulation and high yield. The closed box system in the Longmaxi Formation ensures the gas reservoir dynamic balance. The model of high yield and enrichment of the Jiaoshiba shale gas play is “ladder migration, anticline accumulation, fault–slip plane controlling fractures, and box shape reservoir”. Like in conventional gas plays, good preservation and tectonic conditions are also required to form high yield shale plays in areas which have complex structures, experienced multi-stage tectonic movement, and have high evolution shale.

四川盆地东部盆缘JY1井龙马溪组页岩测试获得高产工业气流，经过长时间试采，压力、产量稳定，实现了南方复杂构造、高演化程度海相页岩气的战略突破。通过对JY1井构造、岩性与龙马溪组TOC、热演化程度及矿物含量特征的分析，结合区域地质资料，得到如下启示:①与北美地区不同，在多期构造演化和抬升剥蚀背景下，构造与保存条件是页岩气富集成藏的首要条件;②龙马溪组只有下部优质烃源岩才起到滑脱作用，多期层滑和构造作用形成的网状裂缝是页岩气富集高产的关键;③上奥陶统灰岩为龙马溪组页岩气的形成起到了良好的封隔作用;④与常规气藏不同，断裂和抬升的破坏作用对优质页岩层系的影响相对较弱，对南方广大地区页岩气的勘探具有示范意义。