Analysis of hydrogeolgical characteristics and water environmental impact pathway of typical shale gas exploration and development zones in Sichuan Basin,China

Studying the influence of shale gas exploration and development on groundwater environment is the basis of guiding water environment protection in the process of shale gas exploration and development. Groundwater environmental pollution is concealed, complex and persistent. Once it is difficult to control the pollution, the current commercial shale gas development zones in Sichuan Basin that are mostly located in karst areas and highly sensitive to groundwater will be vulnerable to the impact of shale gas exploration and development. Based on the hydrogeological conditions of shale gas exploration and development area and combined with engineering analysis of exploration and development, various risk pathways that may affect the groundwater environment during process of shale gas exploration, mining well construction, mining operations and other stages were identified in this paper. Some existing risk pathways were proved by verification of typical areas and should not be ignored. Based on the actual situation of typical areas, the countermeasures of groundwater environmental protection in the process of shale gas exploration and development in karst areas were discussed. It is believed that the ground-water environment can be better protected by strengthening administration, research and application of new technologies, precise design, hydrogeological conditions, and research and feedback of groundwater environmental protection.     

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.     

四川盆地五峰-龙马溪组页岩储层非均质性特征

通过对比焦石坝、长宁和威远气田五峰-龙马溪组页岩产层段的岩矿、物性、含气性以及可压裂性等地质参数及其纵向变化规律,综合分析了页岩储层的平面和纵向非均质性及其对“甜点”优选和储层改造的影响。研究表明,纵向非均质特征在不同地区具有总体一致性：石英含量、有机碳含量和含气量均呈现下高上低的基本趋势;底部深水陆棚沉积层段普遍具有高有机碳含量、高脆性、高孔隙度和高含气量的特征,一系列属性参数的相互耦合和匹配决定了五峰组-鲁丹阶成为“甜点”的主要发育层段。平面非均质特征主要表现为储层品质以及“甜点”发育层段和厚度的区域差异：长宁和威远地区的钙质含量明显高于焦石坝地区,发育钙质硅质混合页岩相;焦石坝地区的水平应力差明显低于长宁和威远地区,且天然裂缝更为发育;长宁和焦石坝地区的“甜点层”发育于五峰-鲁丹阶下部,而威远地区的“甜点层”则发育于鲁丹阶-埃隆阶中部。页岩储层的非均质性决定了“甜点”的分布范围、发育层段和厚度;矿物组成、天然裂缝、岩石力学参数和地应力场的空间变化是进行压裂设计的重要依据。     

四川盆地长芯1井下志留统龙马溪组页岩气储层特征研究

四川盆地东南部地区长宁构造长芯1井下志留统龙马溪组泥(页)岩,厚度约147m.该套泥(页)岩组合以纹层状泥(页)岩、纹层状含灰质泥(页)岩、纹层状粉砂质泥(页)岩为主,见钙质结核及黄铁矿条带.龙马溪组底部30m以富有机质的黑色纹层状泥(页)岩为主,其石英、长石和黄铁矿总量平均51.9％,粘土矿物含量平均24.7％,方解石和白云石含量平均23.4％,与美国典型页岩储层有相似性.总有机碳含量底部为3.9％ ～6.7％,上部为1.0％ ～2.1％.龙马溪组页岩岩心平均孔隙度为5.68％,平均渗透率为5.96×10-3 μm2,与孔隙度成明显正相关.扫描电镜下龙马溪组泥(页)岩微孔隙主要包括矿物晶间(溶)孔、晶间隙、晶内孔,有机质内微孔和微裂缝等.根据压汞分析,泥(页)岩孔喉中值半径最大为33nm,平均为10nm.研究表明,长芯1井龙马溪组海相页岩气储层微孔隙发育的受控因素有岩性、成岩演化程度和有机质发育特征等.富有机质泥(页)岩的物性好于粉砂质泥(页)岩和钙质泥(页)岩;成岩阶段晚期,矿物组合发生变化,蒙脱石向伊利石转变,形成新的微孔隙,增加了储层孔隙度;TOC是控制龙马溪组页岩气储层的主要内在因素,也是提供页岩气储存空间的重要物质.     

Source identification of methane in groundwater in shale gas development areas: A critical review of the state of the art,prospects, and future challenges

Shale gas exploration and development carry the risk of causing groundwater contamination and enhancing the greenhouse effect through methane leakage. Identifying the source of abnormal methane in groundwater of shale gas development areas is becoming a research hotspot in the fields of groundwater and climate change. This paper reviews the traditional methodology in identifying sources of methane and its deficiency in groundwater application. Then potential and advantages of using noble gases were discussed on how to overcome these limitations of the traditional method. Finally, based on noble gas, the current application status and future challenges of methane source identification in groundwater were analyzed. It can be summarized as:(1) due to chemical and/or microbial processes in the aquifer system, the traditional methodology for methane source identification, which utilizes molecular and isotopic compositions of hydrocarbon gas, has multiple interpretationsand large uncertainties;(2) the non-reactive nature and well-characterized isotopic compositions of noble gases in the atmosphere, hydrosphere, and crust, make noble gases ideal indicators of the sources of methane in groundwater. Moreover, the mechanism of formation and release of crustal noble gas prevent shale gas signatures from being interfered with by natural gas;(3) the key scientific tasks surrounding the use of noble gases for methane source identification include quantitatively separating the components of atmosphere-derived, mantle-derived, and crust-derived noble gases from the bulk noble gases in groundwater. It quantifies the solubility fractionation of noble gases induced by water-gas interaction during methane migration to the aquifer. The application of noble gases can bring a new perspective to tracing the source of methane in groundwater and is of great significance to the protection of groundwater quality in shale gas development areas and mitigation of climate change.     

贵州下石炭统旧司组页岩气地质特征及有利区优选

贵州下石炭统旧司组作为页岩气新区新层系勘探重点,近年来虽开展了大量的页岩气地质调查工作,但勘探效果甚微。本文在大量露头、钻井和测试分析资料的基础上,对其页岩空间展布特征、地球化学特征、页岩气储集特征和含气性特征进行详细分析,发现旧司组主要沉积于台盆和泻湖环境,黔西南地区干酪根类型主要为Ⅱ1和Ⅱ2型,在黔南地区主要为Ⅰ型,TOC主要分布于1%～2%。Ro值主要分布于1%～2.5%,区内热液矿物或温泉的影响不具区域性。页岩中石英含量多＞40%。旧司组下段页岩孔隙以宏孔为主,上段页岩孔隙呈中、宏孔并存。孔隙度主要分布2.0%～10.0%,储集性能中等。黔南地区目标层含气性良好,以吸附气为主。黔西南地区目标层以游离气为主,其含气性受断裂和目标层所处应力状态控制。在此分析基础上,结合勘探实践经验,采用综合信息叠合法初步优选出：望谟-紫云-罗甸、罗甸-克度和蟠龙-勺米3个有利勘探区,有利区面积约为1 448 km²。     

中国页岩气勘探开发的关键要点与初期产能特征

中国页岩气产业近几年已取得了明显进展。上扬子区下古生界海相地层产能效果显著,四川盆地侏罗系陆相、鄂尔多斯盆地三叠系陆相地层页岩气也实现了突破,此外,在西北地区侏罗系陆相、南方中扬子区上古生界海陆过渡相、东部断陷盆地古近系陆相地层都取得了重要进展。总结了优质页岩气资源区产层涉及的地球化学和沉积特点等关键指标,根据压力系数、TOC、成熟度（Ro）、孔隙度、含气性、含气饱和度、脆性矿物含量、黑色页岩层厚度8个指标参数建立了一种图像判别方法,以快速判断地下页岩气储层是否会产气,且产气层潜力能否达到工业气流（水平井工艺下）。认识到有机纳米孔隙内的有机质具有“接力成气”形成天然气的机理,有机孔隙随有机质成熟度（Ro）先升后减,识别出Ro值在2.60%～2.80%区间为孔隙有利发育带,同时也是最佳生气窗口,该层段地层是页岩气勘探的最佳窗口。物质相态转化可为页岩气排出提供有效动力,页岩气勘探中有机孔隙最佳成熟度窗口Ro值在1.35%～3.00%区间。认识到生油岩生成的石油总量有40%～60%的液态烃滞留在源岩中,为后期裂解成气提供了丰富的物质基础。认为页岩油气的“革命”既是勘探技术的突破,也是开采技术的革命,能提高储气层泄气面积的水平井段多级规模压裂是提高产能的关键,这些都延伸和推广了传统石油地质学理论的内涵和外延,拓展了油气勘探领域的发展潜力。分析了我国页岩气产区部分气井的初期产能和开采潜力特征,认为中国虽在海相地层获得了部分区块的商业性开发,但大部分区域仍待开发中准确评估,页岩气资源开发的关键技术还需提升。对中国部分页岩气产区经济效益情况进行了概要推断分析,认为中国页岩气只在个别地区获得了有价值的商业气流,总体上还处于开发起步阶段,要达到大规模商业开采尚需时日。     

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.     

四川盆地侏罗系大安寨段湖相页岩油气基本特征及勘探方向

[研究目的]证实四川盆地中部地区大安寨段具备良好的页岩油气勘探潜力.[研究方法]本文通过岩心、薄片、扫描电镜、全岩X射线衍射、有机地球化学、三轴应力实验、核磁共振测试等方法分析了大一三亚段页岩油气形成条件及富集因素.[研究结果]结果表明:大一三亚段泥页岩具湖相混合层系、分布广、厚度大、储集空间类型多、物性条件较好、生烃...     

四川盆地东部地区下志留统龙马溪组页岩储层特征

四川盆地是中国西南部重要的含油气盆地,在东部和南部地区下志留统龙马溪组页岩广泛发育。在川东南、鄂西渝东地区的勘探井中志留系具有良好的气显示。研究区龙马溪组厚65~516m,底部为一套海侵沉积的富含笔石的黑色页岩,龙马溪组向上和向东砂质和钙质含量增加,演变为浅水陆棚沉积。龙马溪组主要由层状-非层状泥/页岩、白云质粉砂岩、层状钙质泥/页岩、泥质粉砂岩、层状-非层状粉砂质泥/页岩、粉-细粒砂岩、钙质结核、富含有机质非层状页岩8种岩相组成。总有机碳含量(TOC)为0.2%~6.7%。有机质以II型干酪根为主,Ro为2.4%~3.6%。页岩中石英矿物含量在2%~93%,主要呈纹层状或分散状分布,主要为陆源碎屑外源成因。龙马溪组页岩岩心孔隙度为0.58%~0.67%,渗透率为0.01×10^-3μm²~0.93×10^-3μm²。扫描电镜下龙马溪组页岩微孔隙度为2%左右,主要包括晶间孔和粒内孔,孔隙直径为100nm~50μm。页岩储层的形成机理主要为有利矿物组合、成岩作用和有机质热裂解作用。龙马溪组与美国Barnett页岩具有一定差异,主要表现在龙马溪组页岩埋藏较深、热演化程度较高、含气量较低、储层较致密、以陆源成因石英为主。对于评价下志留统龙马溪组页岩气勘探前景而言,今后须重点加强针对龙马溪组底部黑色硅质岩系石英成因、成熟度、埋藏史、含气量等方面的研究,以及进行详细的古地貌和古环境恢复。     

准噶尔盆地南缘页岩气形成条件与有利区预测

通过对准噶尔盆地南缘泥页岩分布情况、厚度、面积、总有机碳含量、热演化程度、有机质类型、矿物岩石成分等因素的分析,确定了准噶尔盆地南缘侏罗系八道湾组、三工河组和西山窑组、二叠系芦草沟组、红雁池组以及石炭系是页岩气发育的有利层位。经过对有利层位的页岩气富集条件分析,并利用镜质体反射率(Ro)等值线、泥岩厚度等值线和总有机碳含量(TOC)等值线进行叠加的分析方法,最终确定霍玛吐背斜带西北缘、沙湾凹陷和莫南凸起三者过渡区域的侏罗纪地层,阜康凹陷与阜康断裂带过渡区域的侏罗纪地层,柴窝堡坳陷达坂城凹陷和永丰凹陷二叠纪地层埋藏较浅处,以及齐古断褶带石炭纪地层埋藏较浅处等4处为页岩的有利发育区。     

宁夏六盘山盆地白垩系马东山组页岩气地质特征与勘探潜力分析

以六盘山盆地固页1井白垩系马东山组泥页岩为研究对象,通过野外观察、岩心编录、岩石热解、X衍射、干酪根元素分析、等温吸附等手段,对六盘山盆地固页1井白垩系马东山组页岩气勘探潜力进行评价。结果表明:(1)六盘山盆地白垩系马东山组具有丰富的荧光、油迹、沥青等油气显示,并见200余米的暗色泥页岩、油页岩层位。(2)马东山组泥页岩有机质类型为Ⅱ～Ⅲ型;65%样品TOC大于1.0%,37.2%的样品TOC大于2.0%;50%样品Ro大于0.8%,T_(max)处于435～445℃,处于低成熟—成熟阶段,属生物成因气与热成因气混合气。(3)马东山组泥页岩具黏土矿物低,长石类和碳酸盐类矿物含量高的特征,碳酸盐类矿物均值达38.2%,长石类含量均值24.4%,石英含量均值17.2%,黏土含量均值仅为13.2%;符合页岩气压裂施工的黏土含量小于30%,脆性矿物含量大于40%标准。其黏土组成以伊利石和伊/蒙间层为主,均值含量分别达69%、26.1%。(4)马东山组泥页岩有效孔隙度介于0.117%～1.268%;渗透率0.0009～0.0042 m D,属低孔低渗储层。马东山组泥页岩具有较强的储气能力,其最大甲烷吸附能力介于0.96～4.6 m~3/t,均值2.29 m~3/t。(5)对比延安组页岩地质、地化参数,认为六盘山盆地白垩系马东山组泥页岩层位具备较好的页岩气勘探潜力,可以作为良好的页岩气层位进行进一步工作,其成果将对河西走廊白垩系非常规油气层位勘探具有借鉴意义。     

四川盆地龙马溪组页岩气储层石英类型与特征

为了解页岩气储层石英类型和特征,以四川盆地龙马溪组页岩为研究对象,对样品进行了薄片观察、氩离子抛光-场发射环境扫描电镜观察、能谱分析、X-射线衍射分析、有机碳含量测试。结果表明,龙马溪组页岩石英含量在23%～83%之间,平均值为52%。根据成因,可分为5类:陆源碎屑石英、生物骨骼相关石英、沉积期-成岩早期混合石英、成岩期自生石英和裂缝中石英脉。石英含量与有机碳含量成正相关,其中有机石英在还原环境下能更好地指示有机质的发育情况。有机石英是指保留有软体并演化成干酪根的生物骨骼石英、交代生物骨架石英和与沥青伴生石英。与沥青伴生石英堆积在页岩原生孔隙中,降低了储层的孔隙度,但在一定程度上抑制了后期成岩作用,为沥青的充注保留了空间,且石英与沥青之间发育的缝隙与有机孔一起形成连通的孔隙网络。     

四川盆地下侏罗统自流井组陆相页岩油气地质特征

四川盆地下侏罗统自流井组发育东岳庙段和大安寨段两套富有机质页岩层系,主要为湖泊相的页岩夹粉砂岩、介壳灰岩。基于页岩、介壳灰岩和粉砂岩之间的组合特征,自流井组共识别出3类7种页岩岩相组合类型。页岩有机质丰度中等,有机质类型以Ⅱ1、Ⅱ2型为主,热演化程度中等,油气共存。页岩储集空间既有无机孔,也有有机质孔,局部发育微裂缝。自流井组页岩中无机矿物与有机质、有机质与有机质孔的配置关系控制着页岩源—储配置的有效性,在较高的演化程度下,随着TOC的增大有机质孔隙度增大,页岩的源—储配置关系变好。刚性矿物稳定支撑格架下保存的固体沥青个体大,内部有机质孔数量多、孔径大;黏土矿物不稳定支撑格架下保存的沥青呈长条形,内部的有机质孔孔径较小。基于页岩层系不同岩性源—储耦合条件评价结果,页岩的源—储耦合条件明显优于夹层,源—储耦合条件好的优质页岩层段是页岩油气的甜点层段,其中黏土质页岩最好,介壳灰质页岩、粉砂质页岩为次;介壳灰岩和粉砂岩夹层不具备烃源条件且储集条件差,只能与相邻的富有机质页岩形成近源聚集体系。     

鄂尔多斯盆地东南部延长组长7段陆相页岩气地质特征及勘探潜力评价

提要：鄂尔多斯盆地为大型富含油气盆地,发育本溪组、山西组、延长组长7段、长9段等多套页岩层系,具备页岩气形成的基本地质条件。为查明鄂尔多斯盆地东南部延长组长7段页岩气的勘探潜力,本文利用有机地球化学和岩石学分析、含气量测试、等温吸附曲线测定等多种手段,分析了延长组长7段页岩的基本地质、地化及含气性特征。在此基础上,对长7段页岩气勘探潜力进行了初步评价。结果表明,长7段陆相页岩埋深和厚度适中、有机质类型以Ⅰ、Ⅱ型为主,有机质丰度和脆性矿物含量高,含气量可达1.25~6.45 ml/g。与北美地区典型页岩相比,研究区长7段页岩有机质类型、有机碳含量类似,粘土矿物含量和长石含量偏高,碳酸盐和石英含量偏少,有机质成熟度偏低。研究区内延长组长7段页岩气资源勘探潜力巨大,资源量为1 528.409亿m3,可作为常规油气勘探的重要补充,志丹—甘泉一线西南部为页岩气勘探的有利目标。     

重庆涪陵页岩气勘查开发区环境地质调查进展

紧密结合国家非常规能源勘探开发的重大战略,聚焦重庆涪陵页岩气勘查开发区环境地质调查工作,总结了研究区岩溶发育特征与分布规律,评价了涪陵页岩气开发区区域水资源量和地下水质量.在此基础上,收集分析国内外资料,梳理了页岩气勘查开发所引发的6类环境(地质)问题及勘查、钻井、压裂、开采、闭井等5个阶段需关注的地质环境问题或风险等,其中涪陵页岩气勘查开发区主要诱发水土污染、地质灾害和大气污染等环境(地质)问题;基本识别了2种地下水污染模式、3种污染类型及可能的地下水污染风险途径;初步确定了涪陵页岩气勘查开发区污染指示性特征因子,并形成了页岩气勘查开发区地质环境影响评价指标体系,可指导页岩气勘查开发的环境地质调查.该研究为页岩气国家新型清洁能源的绿色开发和开发区生态文明建设提供支撑.     

重庆涪陵页岩气勘查开发区环境地质调查进展

紧密结合国家非常规能源勘探开发的重大战略,聚焦重庆涪陵页岩气勘查开发区环境地质调查工作,总结了研究区岩溶发育特征与分布规律,评价了涪陵页岩气开发区区域水资源量和地下水质量。在此基础上,收集分析国内外资料,梳理了页岩气勘查开发所引发的6类环境(地质)问题及勘查、钻井、压裂、开采、闭井等5个阶段需关注的地质环境问题或风险等,其中涪陵页岩气勘查开发区主要诱发水土污染、地质灾害和大气污染等环境(地质)问题; 基本识别了2种地下水污染模式、3种污染类型及可能的地下水污染风险途径; 初步确定了涪陵页岩气勘查开发区污染指示性特征因子,并形成了页岩气勘查开发区地质环境影响评价指标体系,可指导页岩气勘查开发的环境地质调查。该研究为页岩气国家新型清洁能源的绿色开发和开发区生态文明建设提供支撑。     

宣广盆地中二叠世栖霞组层序地层特征及页岩气勘探前景

对宣广盆地中二叠世栖霞组进行层序地层学分析,结合栖霞组富有机质页(泥)岩有机地球化学特征,评价页岩气勘探前景。研究表明:区内栖霞组可分为3个三级层序;每个层序划分出海侵体系域、凝缩段和高水位体系域,代表了一次相对较大的海平面升降旋回。富有机质页(泥)岩主要分布于凝缩段、凝缩段与海侵体系域或高水位体系域的转换过渡层段。栖霞组富有机质页(泥)岩厚8~35 m,TOC值0.77％~9.49％,有机质成熟度为1.428％,脆性矿物(石英、长石)相对富集,具有良好的脆性和可压性,页岩气成藏条件良好,特别是栖霞组五段具有巨大的资源潜力。     

柴达木盆地东部石炭系页岩气储层渗流特征研究

页岩气是一种潜在资源量巨大的非常规天然气资源,页岩气藏具有多尺度的孔渗结构及多种渗流形态,研究页岩气藏储渗特征能够为页岩气的勘探开发提供理论支撑。该研究选取了柴达木盆地东部石炭系克鲁克组与怀头他拉组的页岩钻井岩心共5个样品,应用氩离子抛光扫描电镜实验与孔径分布测试(包括压汞法、氮气吸附法、二氧化碳吸附法)对页岩的孔隙结构特征进行定性定量测试。基于页岩气质量流量渗流模型,给出页岩表观渗透率与平均压力的关系。通过甲烷渗流模拟实验测定页岩的表观渗透率。从表观渗透率随平均压力的变化特征出发,分析页岩储层中的气体渗流规律。研究结果表明：页岩气的渗流形态包括滑脱流、扩散流及达西流。在低压情况下,渗透率低的页岩中以扩散流为主,其次为滑脱流。随渗透率的增大,渗流主要形式转变为滑脱流。当压力大于2 MPa时渗流形态以达西流为主,滑脱与扩散行为不明显。研究区内页岩微孔与中孔发育较多,达西渗透率与大孔的孔隙体积相关性较大,扩散流对表观渗透率的贡献与50 nm以下的孔隙孔体积比例有一定的相关性。低压下扩散流对表观渗透率的贡献较大,扩散流是一种非常重要的页岩气运移形式。     

页岩气资源潜力与勘探开发前景

页岩气为近年来在北美地区广泛勘探开发的天然气新目标,在全球非常规油气勘探开发中异军突起,成为突破最晚、近期发展最快的非常规天然气资源。依据北美地区页岩气勘探开发的历程和全球页岩气勘探开发的进展,阐述了全球页岩气勘探开发的基本态势和页岩气5个方面的典型特征,分析了全球页岩气的资源潜力与分布特征,预测中国页岩气资源潜力约100×1012m3,指出页岩气的成功勘探开发是近10年来油气地质理论与工程技术取得的最激动人心的重大成就,页岩气资源潜力丰富,实现全面开发将带来一场全球的能源革命。最后,提出了4点加快中国页岩气发展的建议。