近期吐哈盆地风险探井沁探1井、预探井吉7H井在台北凹陷下侏罗统三工河组获得重要发现，实现了吐哈盆地洼陷区岩性油气藏勘探的重大突破，展现了吐哈盆地“下洼进源”勘探的良好前景。基于新钻井取得的地质认识，系统梳理和总结了洼陷区岩性油气藏有利成藏条件，指出下一步勘探方向。研究表明：①台北凹陷侏罗系水西沟群发育八道湾组、三工河组、西山窑组3套烃源岩，新钻井揭示出三工河组不仅发育区域性盖层，也是优质烃源岩，重新评价显示台北凹陷水西沟群生烃潜力大；②下侏罗统三工河组是洼陷区勘探主力目的层，发育辫状河三角洲沉积体系，洼陷区砂体发育，在次生溶蚀和构造裂缝作用下，5 000 m以深仍发育有效储层；③台北凹陷下侏罗统存在葡东、红北、陵北、丘东和疙北五大岩性油气藏有利区带，勘探潜力大，是吐哈盆地未来勘探的重要方向。

Recently， risk exploration Well Qintan1 and exploration Well Ji7H in the Turpan-Hami Basin have made important discoveries in the Lower Jurassic Sangonghe Formation in Taibei Sag. The two wells realized a major breakthrough in lithologic oil and gas reservoir exploration in depression area， and showed a good prospect of “lower depression source” exploration in Turpan-Hami Basin. Based on the two wells， the favorable conditions of lithologic reservoir formation in the sag area are systematically summarized， and the directions of further exploration are specified. The results show that： （1） Three sets of source rocks， namely Badaowan Formation， Sangonghe Formation and Xishanyao Formation， are developed in Shuixigou Group of Jurassic in Taipei Sag. The new drilling reveals that Sangonghe Formation is not only a regional caprock， but also a high-quality source rock. The source rock re-evaluation shows that Shuixigou Group in Taipei Sag has great hydrocarbon generation potential. （2） Sangonghe Formation of Lower Jurassic is the main target layer for exploration in the depression area. Braided river delta sediments are developed. Sandbodies are developed in the depression area. Due to secondary dissolution and structural fractures， effective reservoirs are still developed at a depth of more than 5 000 m. （3） There are five favorable zones of rock reservoirs in the Lower Jurassic of Taibei Sag： Pudong， Hongbei， Lingbei， Qiudong and Gebei， which have great exploration potential and are an important direction of future exploration in Turpan-Hami Basin.

吐哈盆地台北凹陷丘东洼陷有多口井在中—下侏罗统水西沟群三工河组获得了高产油气流,展现了洼陷区深层的源内致密砂岩具有良好的油气勘探前景。为明确丘东洼陷水西沟群致密砂岩的油气地质条件,整体评价吐哈盆地水西沟群的勘探前景,基于新钻井取得的钻探认识,系统梳理和总结了丘东洼陷的有利成藏条件,指明了下一步的勘探方向。①丘东洼陷经历了多期构造运动,发育南部斜坡、中部洼陷、北部斜坡3个构造带,其中,中部洼陷区构造稳定,有利于多期叠合盆地的油气保存。②丘东洼陷水西沟群发育八道湾组、西山窑组2套煤系烃源岩和三工河组湖相泥质烃源岩,其干酪根类型以Ⅱ₂—Ⅲ型为主,处于成熟演化阶段。③丘东洼陷水西沟群发育南、北双向辫状河三角洲沉积体系,洼陷区砂体发育,且受有利相带、溶蚀作用、超压、裂缝等因素控制,在5 000 m以下仍发育有效储层。④整体分析台北凹陷水西沟群致密砂岩气的勘探潜力,其内3个洼陷(胜北洼陷、丘东洼陷、小草湖洼陷)均具备大面积煤系烃源岩与辫状河三角洲前缘砂体叠置发育的条件;可在三工河组优选出葡东、红北、陵北、丘东、疙北5个主力扇体,有利勘探面积为1090 km²,评价的天然气资源量为5.29×10¹²m³,石油资源量为5.2×10⁸t,资源潜力大,展现了吐哈盆地凹陷区具有良好的勘探前景。

A number of wells in Qiudong subsag of Taibei sag of Tuha Basin have obtained high-yield oil and gas flow in Sangonghe Formation of the Middle-Lower Jurassic Shuixigou Group, showing a good hydrocarbon exploration prospect of the deep intra-source tight sandstone in the subsag area. To make clear the petroleum geological conditions of tight sandstone from Shuixigou Group in Qiudong subsag and comprehensively evaluate the exploration prospects of Shuixigou Group in Tuha Basin, based on the drilling knowledge obtained from new boreholes, this paper systematically summarizes the favorable accumulation conditions of Qiudong subsag, and points out the next exploration direction. (1)Qiudong subsag suffered from multiple tectonic movements and developed three tectonic zones, namely southern slope, central subsag, and northern slope. Among them, the central subsag was tectonically stable, which was conducive to hydrocarbon preservation in the multi-stage superimposed basin. (2)Shuixigou Group in Qiudong subsag developed two sets of coal-measure source rocks in Badaowan Formation and Xishanyao Formation respectively, as well as lacustrine argillaceous source rocks in Sangonghe Formation. The dominant kerogen types were Ⅱ₂—Ⅲ and in mature evolution stage. (3)Shuixigou Group in Qiudong subsag developed bidirectional braided river delta sedimentary system to the south and north. The sand-bodies in the subsag area developed well and effective reservoirs developed even below 5 000 m under the control of such factors as favorable facies, dissolution, overpressure, and fractures. (4)By comprehensively analyzing the exploration potential of tight sandstone gas from Shuixigou Group in Taibei sag, it showed that the superposition of large coal-measure source rocks and braided river delta front sand-bodies were developed in all three subsags (Shengbei subsag, Qiudong subsag and Xiaocaohu subsag). Five main fan bodies, namely Pudong, Hongbei, Lingbei, Qiudong, and Gebei, can be selected from Sangonghe Formation with the favorable exploration area of 1 090 km², evaluated natural gas resource of 5.29×10¹²m³, and petroleum resource of 5.2×10⁸t. The great resource potential shows that the sag area in Tuha Basin has a good exploration prospect.

致密砂岩气已成为全球非常规天然气勘探的重点之一。中国致密砂岩气分布范围广，目前已在鄂尔多斯和四川等盆地实现了规模开发；致密砂岩气藏主要有低缓斜坡型、背斜构造型和深部凹陷型3种类型，其基本地质特征表现为以煤系源岩为主，生烃强度高，具有持续充注的气源条件；致密砂岩与烃源岩紧密相邻，大面积接触，以近距离垂向运移成藏为主；源储有效配置形成致密砂岩气大气区，局部富集。中国致密砂岩气的有利勘探面积约为32×10⁴km²，可采资源量达(8~11)×10¹²m³，目前中国致密砂岩气勘探开发技术已较成熟，具备加快发展的条件，在中国未来天然气发展中必将发挥重要作用。

<p>Tight sandstone gas has become a focus of the global unconventional natural gas exploration.It is widely distributed in China.Until recently, Ordos and Sichuan basins have achieved the large-scale exploitation.Tight sandstone gas in China has mainly three types, including slop type, structure type and depression type.The tight sandstone reservoirs are mainly sourced by coal-measure rocks, and charged continually.The widespread source rocks and reservoirs interbed.Therefore, the gas can migrate vertically from source to adjacent reservoir.The intimate contact of source and reservoir forms the large-scale gas-bearing area, with&ldquo;sweet spots&rdquo; locally enrichment.The favorable exploration area of tight sand gas in China is 3.2&times;10⁵ km²，with recoverable resources about(8～11)&times;10¹²m³.Currently, China has comparatively mature technology of the exploration and development of tight sandstone gas, having the conditions of accelerating the developing pace.Therefore, tight sandstone gas will play an important role in the future natural gas development in China.</p>

中国自&ldquo;十一五&rdquo;以来大力发展致密砂岩气，目前已成为仅次于美国、加拿大的致密砂岩气生产大国，同时众多地质学者对中国复杂地质条件下致密砂岩气成藏机理不断创新研究取得了重要进展，进入建立新类型致密砂岩气成藏理论阶段。通过对早期致密气相关成藏理论解析、典型气藏解剖及实验模拟等综合研究，认为中国现今发现的致密砂岩气具有克拉通大面积致密砂岩气、前陆背斜构造致密砂岩气和断陷深层致密砂砾岩气3种成藏机制。克拉通大面积致密砂岩气以近距离孔缝网状输导、储盖双重阻挡、大面积聚集为主，而后两者以断裂孔缝输导、优质盖层封盖、断块&mdash;岩性或背斜构造控藏为主。三者相同点为致密砂岩储层与烃源岩层紧密接触、储层致密、甜点富集；差异点主要为输导条件、封盖机制、运聚特征等。中国致密砂岩气地质资源量达36.54&times;10¹⁶m³，其中克拉通大面积致密砂岩气地质资源量占83.2%，为30.4&times;10¹⁶m³，四川盆地须家河组、鄂尔多斯上古生界是该类型现实的重点勘探区带；前陆背斜构造致密砂岩气和断陷深层致密砂砾岩气资源相对较少，库车白垩系深层、吐哈台北侏罗系、准南侏罗系与松辽盆地深层是有利勘探区带。&nbsp;

Since the elevenfifth plan,tight sand gas got vigorous development in China.Its production is only lower than that of the US and Canada.Aiming at the special geological condition of china,geologists have made new progresses in the theory of tight sand gas.With the indepth exploration,the accumulation theory was constantly improved.Through the analysis of early tight gas reservoir theory,anatomy of typical gas reservoir and experiments simulation etc.,it is thought that there are three main accumulation mechanisms,including the largescale tight sandstone type,the anticline structure compact sandstone type and the block tight sandstone type.Their similarities are the tight sands contacting closely with source rocks,the tight sand and the enriched sweet spot.Their differences are shown in the conducting conditions,capping mechanism,migration and accumulation characteristics etc.The characteristics of largescale tight sandstone are near distance seam hole mesh conducting,reservoir and seal double block and large scale gathered.The latter two are with fracture aperture conducting,high quality sealing cover,block or anticline tectonic control play.China's geological resource of tight sandstone gas is 36.54 trillion cubic meters.The study of the theory,exploration and development technology of largescale of tight sandstone gas are more mature,with geological resource of 30.4 trillion cubic meters.It has the basis and potential for accelerating development.Sichuan Xujiahe Formation and Upper Palaeozoic of Ordos Basin are the realistic key exploration zones.Jurassic of Kuqa northern section,Taibei sag of TurpanHami Basin and the south of Junggar Basin are the next favorable exploration zones.

Turpan-Hami Basin has abundant tight sandstone gas resources. In the early exploration, only small-scale oil and gas reservoirs such as Baka, Wenjisang and Mideng were discovered in positive structural belts in the peripheral Taibei Sag. Based on the comprehensive analysisof source rocks, sedimentary systems, reservoir conditions and source rock–reservoir–cap rock assemblages, the accumulation pattern of tight sandstone oil and gas reservoir is established interior of source rocks in Taibei Sag. The study result shows that two types of high-qualitysource rocks are developed in Shuixigou Group in Taibei Sag, namely the coal measure source rock of Badaowan Formation, mudstone ofSangonghe Formation and coal measure source rock of the second member of Xishanyao Formation, with high TOC, good organic matter type,mature stage of thermal evolution, and widely developed in the sag; Multiple reservoir–cap rock assemblages are formed in the second and firstmembers of Xishanyao Formation, as well as Sangonghe and Badaowan Formations. The sandstone deposits are widespread in the sag supplied by sufficient sediment sources from five braided river deltas in the west, north and south directions. The source rocks generate large-volume hydrocarbon and serve as the regional cap rocks to form multi-layer “sandwiched” type source rock–reservoir– cap rock assemblage; The sag has the favorable geological conditions for forming large-area tight sandstone gas reservoirs interior of source rocks, such as stable negative structures, good preservation conditions, high formation pressure and high maturity of source rocks. A horizontal well Ji7H was drilled based on the idea of “interior of source rock, marching towards deep sag and drilling horizontal well”, and high yield oil and gas flows of 40.37 m³/d and 51283 m³/d were obtained after fracturing by open flow with 7 mm choke. The tight sandstone condensate gas reservoir interior of source rocks supports to discover a new field of exploration and open up the prelude to the second exploration in Turpan-Hami Basin.

吐哈盆地早期围绕中—浅层正向构造带的常规油气藏进行勘探,在新层系、新领域和新类型油气勘探方面的研究比较薄弱。近年来,立足整体研究,基于重力-磁法-电法、地震、钻井及分析测试资料,开展了新一轮盆地级全层系构造精细解释、烃源岩评价、沉积与储层特征刻画、油气成藏富集规律研究,形成的主要认识如下:①吐哈盆地经历了海西期—印支期、燕山期和喜马拉雅期3期构造运动,发育基底断层、滑脱断层和山前逆冲断层3类断层,控制着不同时期、不同构造单元的展布及隆-坳格局;②盆地内发育石炭系海相—海陆过渡相、二叠系湖相、三叠系湖相和侏罗系湖相/煤系4套烃源岩,有效提升了油气资源潜力;③盆地内发育石炭系碳酸盐岩、二叠系—侏罗系碎屑岩和煤岩3类储层;④除常规油气外,盆地内还发育致密砂岩油气、深部煤层气等新的油气类型;⑤综合评价优选出侏罗系致密砂岩油气藏、深部煤层气藏、山前冲断掩伏带大构造区油气藏、斜坡区二叠系—三叠系岩性地层油气藏、盆地西缘冲断带二叠系—三叠系构造岩性油气藏、台南凹陷石炭系海相油气藏6个勘探新领域,聚焦17个有利油气勘探方向,根据认识程度、勘探研究进展的不同,按照战略展开、战略突破和战略准备3个层次勘探部署,以期实现油气勘探新突破。

The early exploration mainly focused on conventional hydrocarbon reservoirs in the middle-shallow positive tectonic zone in Tuha Basin. However, there is little research on explorations in new strata, new fields, and new types of oil-gas resources. In recent years, based on the synthetic research as well as gravity-magnetic-electrical method, seismic, drilling, and test data, a new round of efforts have been made on basin-level full-stratum fine structural interpretation, source rock evaluation, sedimentary and reservoir characterization, as well as investigations of hydrocarbon accumulation and enrichment regularities. The main understandings obtained are as follows. (1) The Tuha Basin underwent three tectonic movements of Hercynian-Indosinian, Yanshan, and Himalayan, by which basement faults, detachment faults, and piedmont thrust faults are developed, and have been controlling the distribution and uplift-depression pattern of different tectonic units in different periods. (2) The basin has developed four sets of source rocks with the Carboniferous marine and marine-continental transitional facies, Permian lacustrine facies, Triassic lacustrine facies, and Jurassic lacustrine facies/coal series, which have effectively enhanced the potential of oil-gas resources. (3) Three types of reservoirs are developed in the basin, i.e., Carboniferous carbonate rock, Permian-Jurassic clastic rock, and coal rock. (4) In addition to conventional oil and gas, new types of oil and gas such as tight sandstone oil and gas and deep coalbed methane are also detected in the basin. (5) Through comprehensive evaluation, six new exploration areas were selected, including Jurassic tight sandstone gas reservoirs, deep coalbed methane reservoirs, reservoirs in the large tectonic area of the piedmont overthrust belt, Permian-Triassic lithologic-stratigraphic reservoirs in the slope area, Permian-Triassic tectonic-lithologic reservoirs in the thrust belt at the western margin of the basin, and Carboniferous marine hydrocarbon reservoirs in Tainan sag, focusing on 17 favorable oil-gas exploration directions. Based on the different degree of understanding and research progress in hydrocarbon exploration, the exploration work is carried out at three levels, i.e., strategic deployment, strategic breakthrough, and strategic preparation, so as to find new breakthroughs in oil-gas prospecting.

Based on the systematic study of petroleum geological condition, such as source-reservoir-cap assemblage and reservoir-forming pattern in Turpan-Hami Basin, it is considered that the source rocks are mainly coal-bearing source rocks of Jurassic Xishanyao Formation and Badaowan Formation, and lacustrine source rocks of Permian Taodonggou Group. These two sets of source rocks with high hydrocarbon-generating intensity are located in the main subsidence area of Taipei Sag, and have the source conditions for forming large-scale oil field. Of the three sets of reservoirs, Jurassic reservoirs are mainly coarse sandstone of braided river delta distributary channels, the reservoirs of Permian Wutonggou Formation and Triassic Karamay Formation are mainly sandstone and conglomerate of the subaqueous distributary channels in the fan delta and braided river delta front. According to main factors controlling hydrocarbon accumulation, four types of accumulation patterns are classified in Jurassic: forward differentiation, reverse differentiation, vertical differentiation and mixed pattern. The Permian hydrocarbons accumulate in pattern of lateral long-distance and trapping in paleoslope. The Triassic hydrocarbons accumulate in pattern of vertical migration and self-generation and self-storaging in source rocks. By using analogy, statistics, genesis and Delphi weighting method, it is calculated out that the amounts of conventional petroleum resources and the remaining resources are 10.09×108 t and 6.07×108 t, respectively. Through evaluating geological conditions, predicting remaining resource distribution, three exploration directions and favorable target areas of Shanshan arc play, Lukeqin-honglian play and western arc play are proposed.

为进一步明确吐哈盆地下侏罗统致密砂岩气藏特征与勘探方向，开展了吐哈盆地下侏罗统致密砂岩气藏类型、成藏特征、有利勘探方向评价研究。认为吐哈盆地下侏罗统致密砂岩气藏分为背斜构造型、构造—岩性复合型和动力圈闭型3类，构造—岩性复合型致密砂岩气藏主要分布于胜北生气中心及周缘，储集砂体主要为湖底扇砂砾岩和三角洲前缘砂体，综合评价为II类储层，是勘探最有利的气藏类型。研究结果表明：①湖底扇砂砾岩、三角洲前缘细砂岩与构造匹配形成构造—岩性复合型致密砂岩气藏，砂砾岩、粗砂岩的抗压实能力优于细砂岩，粗粒度砂体的储集物性优于细粒砂体；②吐哈盆地下侏罗统致密砂岩气资源量为2 400×10⁸m³，胜北洼陷是最有利生气中心，勘探潜力大；③三工河组储层可分为4类，位于胜北生气中心的胜北洼陷南部斜坡带、胜北洼陷洼中隆起区、鄯善弧形带三工河组储层主要为Ⅱ类、Ⅲ类储层，是致密砂岩气的主要勘探有利区。

In order to further clarify the characteristics and exploration directions of the Lower Jurassic tight sandstone gas reservoirs in the Turpan-Hami Basin， the evaluation research on the types， accumulation characteristics， and favorable exploration directions of the Lower Jurassic tight sandstone gas reservoirs in the Turpan-Hami Basin has been carried out. It is believed that the Lower Jurassic tight sandstone gas reservoirs in the Turpan-Hami Basin can be divided into three types：Anticline structure type， structure-lithology compound type and dynamic trap type. The structure-lithology compound type tight sandstone gas reservoirs are mainly distributed in the Shengbei gas generation center. And the periphery， the reservoir sandbodies are mainly sublacustrine fan glutenite and delta front sandbodies， comprehensively evaluated as Type II reservoirs， and are the most favorable gas reservoir type for exploration. The research results show that： （1） The sublacustrine fan glutenite and fine sandstone at the delta front match the structure to form a structure-lithological compound tight sandstone gas reservoir. The compaction resistance of glutenite and coarse sandstone is better than that of fine sandstone and coarse-grained sand. The reservoir properties of the sand body are better than those of fine-grained sand bodies. （2） The Lower Jurassic tight sandstone gas resources in the Turpan-Hami Basin are 2 400×10⁸ m³， and the Shengbei subsag is the most favorable gas generating center with great exploration potential. （3） The reservoirs of the Sangonghe Formation can be divided into four types. The reservoirs of the Sangonghe Formation in the southern slope zone of the Shengbei Sag， the central uplift area of the Shengbei Sag， and the Shanshan， which are mainly Type II， are the main favorable targets for exploration of tight sandstone gas.

丘东洼陷是吐哈盆地致密砂岩气勘探开发的重点地区。通过致密砂岩气、煤系烃源岩的地球化学实验等分析，研究了丘东洼陷中下侏罗统致密砂岩气地球化学特征、成因类型、主力气源类型与分布等。结果表明：丘东洼陷致密砂岩气以烃类气体为主，含量为56.8%～97.2%，非烃气体主要为N₂；天然气干燥系数（C₁/C_1-5）为0.79～0.89，全部为湿气；天然气均为热成因气，温吉桑地区致密砂岩气为煤型气，照壁山&mdash;红旗坎地区为混合成因气，鄯勒地区为混合气和油型气，柯柯亚地区为混合气和煤型气；丘东洼陷北部地区致密砂岩气成烃母质中含有一定量的腐泥组分，南部温吉桑地区生气母质以偏腐殖型有机质为主；依据烃源岩有机质生物来源构成与沉积环境等指标参数，将研究区中下侏罗统泥岩分为A、B、C、D &nbsp;4种类型。精细气源对比表明，致密砂岩气烃源岩以煤系泥岩为主，煤岩不是主要的气源岩。有效泥质烃源岩发育区是寻找致密砂岩气&ldquo;甜点&rdquo;的重要方向。

柯柯亚地区中-下侏罗统水西沟群致密砂岩气资源丰富，对其储层&ldquo;甜点&rdquo;类型和成因的研究可为吐哈盆地乃至其他地区致密砂岩气的勘探开发提供借鉴。通过物性统计、岩心观察、薄片分析、裂缝统计、测井解释和产量对比等研究，认为吐哈盆地柯柯亚地区水西沟群致密砂岩气发育孔隙型和裂缝型2种&ldquo;甜点&rdquo;类型。在沉积微相、矿物组成、地层水研究及盆地埋藏史、盆地演化史模拟的基础上，指出特定的沉积微相（水下分流河道和河口坝）、相对较弱的压实作用和相对较强的溶蚀作用是孔隙型&ldquo;甜点&rdquo;形成的主要原因，而强烈的构造抬升运动和储层所处的特殊构造位置是裂缝型&ldquo;甜点&rdquo;发育的主控因素。综合研究认为，吐哈盆地孔隙型和裂缝型&ldquo;甜点&rdquo;是沉积、成岩和构造运动等多种因素共同作用的结果。

<p>The Lower-Middle Jurassic Shuixigou Group in the Kekeya area is rich in gas resources of tight sandstone reservoirs, analysis of their reservoir &ldquo;sweet spot&rdquo; types and genesis is of certain reference significance in the tight sandstone gas exploration & development in the Turpan-Hami Basin and other areas. By contrast of porosity and permeability, core observation, thin-section analysis, fracture statistics, log interpretation and production feature comparison, we summed up &ldquo;sweet spot&rdquo; reservoirs developed in the Shuixigou Group of the Kekeya area as two &ldquo;sweet spot&rdquo; types, i.e. the pored and fractured. Based on analyses of sedimentary microfacies, mineral compositions, formation water and simulations of basin burial history and basin evolution history, we concluded that specific sedimentary microfacies, relatively weak compaction and relatively strong dissolution are chief reasons of forming pored &ldquo;sweet spot&rdquo; reservoirs, while strong tectonic movement and local special tectonic locations control development of fractured &ldquo;sweet spots&rdquo; reservoirs. This comprehensive study showed that in the Turpan-Hami Basin, the formation of pored and fractured &ldquo;sweet spot&rdquo; reservoirs is a consequent result caused by interaction of deposition, diagenesis and tectonism.</p>

Tight sandstone gas and shale gas are currently two major unconventional hydrocarbon resources, which will be the significant resources for replacing the conventional oil and gas in next 10 to 20 years. Despite the understanding of geological property, or the technology of exploration and development, tight sandstone gas will be easily realized than shale gas in the next 10 years. However, precise prediction of favorable reservoir space has become a bottleneck for current tight sandstone gas exploration and development. Clarifying the deposition-diagenesis genetic mechanism of tight sandstone reservoir is the key to solve this problem. According to the research on the typical tight sandstone gas fields in China and data analysis abroad, tight sandstone generally deposited under weak hydrodynamic stability and relatively low depositional rate that much developed in coal-bearing（thin bed interbedded） strata of the transitional environments or deltas. Hence, these depositional mechanisms facilitate the requirement of forming tight sandstone. Continuous compaction during early diagenetic stage is the main process for their tight nature. The complex burial history under low geothermal gradients which were caused by multi-cycle movements of basin is the sufficient condition for forming tight sandstone reservoirs. Therefore, abnormal pressure zones in multi-cycle pre-Tertiary basins with low geothermal are the favorable area for exploring tight sandstone gas. The sandstones with thin interbedded coal-bearing strata in delta front are primary exploration and development intervals. Heterogeneity characteristics of tight sandstone play an important role on reservoir exploring and evaluating. The effect of microscopic pore structure change on permeability should be studied for evaluating pay reservoirs property. &ldquo;Permeability blind area&rdquo; and abnormal pressure data were employed for evaluating quality of reservoir. On the basis of this idea, we proposed six prospective areas for tight sandstone exploration and development in China in future.

通过岩心观察并综合利用普通薄片、铸体薄片、阴极发光、扫描电镜和压汞等资料，对克深气田巴什基奇克组致密砂岩储层的岩石学、物性及孔隙结构特征、成岩作用、成岩矿物、所处成岩阶段和成岩演化序列等特征进行了研究。结果表明：储层经历压实、胶结、溶蚀和破裂等成岩作用，现今正处于中成岩A期。根据成岩作用类型和强度、成岩矿物及其对储层物性的影响将储层划分为压实致密、碳酸盐胶结、伊/蒙混层充填、不稳定组分溶蚀和成岩微裂缝5种成岩相。选取声波时差、电阻率、自然伽马、密度和中子等测井曲线，通过岩心薄片资料刻度测井归纳了不同成岩相的测井响应特征，由此建立了各成岩相的测井识别准则。并对克深区块各井的测井资料进行了处理，得到了各单井成岩相剖面展布特征，结合试气资料表明，成岩微裂缝相常与构造裂缝伴生因而含气性最好，而在无裂缝的叠加作用时，不稳定组分溶蚀相含气性最好，压实致密、碳酸盐胶结和伊/蒙混层充填相则对应干层。通过成岩相的深入分析是进行致密砂岩气储层综合评价和有利发育区带预测的重要方法。

The lithology characteristics,reservoir property and pore structure,diagenesis,diagenetic minerals,diagenetic environment,diagenetic stage and diagenetic evolution sequence of Bashijiqike Formation tight sandstone reservoirs are studied by making full use of normal thin sections,casting thin sections,cathode luminescence,scanning electron microscope analysis data and mercury injection test data.The results show the reservoirs have experienced diagenesis such as compaction,cementation,corrosion and fracturing.It is now in the phase A of middle diagenetic stage.Then five types of diagenetic facies are divided based on type and intensity of diagenesis,diagenetic minerals and their effect on the reservoir quality.They are: tight compaction facies;,carbonate cemented facies,mixed-layer illite-smectite filling facies,diagenetic micro-fracture facies and corrosion of unstable components facies.According to the various well logging response characteristics of different types of diagenetic facies,five normal logging curves which are sensitive to the diagenetic facies are chosen to characterize the diagenetic facies.They are: neutron logging (CNL),density logging (DEN),acoustic slowness (AC),natural gamma ray (GR),array induction log (M2R2).Thus we can set up the logging recognition model and standard of diagenetic facies.Actual log data of wells in Keshen area were processed using this method,and the diagenetic facies of Bashijiqike Formation reservoir in this well is figured out on the vertical profile.When the logging recognition results of diagenetic facies of Bashijiqike Formation are corresponded with the actual gas test data,it is found that the diagenetic micro-fracture facies are always coexisting with tectonic fractures.When there are no tectonic fractures,the gas bearing property of the layer with the corrosion of unstable component facies is the best,while the diagenetic facies such as tight compaction facies,carbonate cemented facies and mixed-layer illite-smectite filling facies correspond to the dry layers.It is an effective way to comprehensively evaluate the reservoir and predict the sweet spot of tight gas sandstones by analyzing the diagenetic facies.

川西复合前陆盆地自晚三叠世以来经历了多次构造转换与沉积迁移,多期次、多边界活动的构造背景造成了沉积物源的多源性以及沉积体系的多样性和叠合性。上三叠统至侏罗系碎屑岩储层平均孔隙度<10 %,平均渗透率<0.1 mD,纳米级孔喉占主体,是典型的低孔低渗致密&mdash;超致密砂岩储层。储层分布范围从中浅层至深层,纵向上多层系不同类型储层复合叠置,平面上多套储层大面积叠合连片分布,呈现明显的叠合性和广覆性。储层在岩石组分、储集空间类型、物性特征、孔隙结构特征、成藏物性下限等方面具有极强的纵、横向非均质性。储层形成演化具有多阶段性,各个层系或层段均可形成规模有效储层。储层总体表现出&quot;物源、沉积-成岩、构造-断层&quot;控储的特征,同时不同层段有利储层发育的关键因素有所差别。根据岩石类型、沉积相、定量成岩相以及构造、断层特征等研究成果,可以对有利储层的分布进行综合定量预测。

The composite foreland basin in western Sichuan has undergone multiple tectonic conversions and sedimentary migrations since Late Triassic. Such tectonic settings with multi-phase and multi-boundary activities resulted in multiple sedimentary provenances as well as the diversity and superimposition of sedimentary system. The Upper Triassic-Jurassic clastic reservoirs are typical low-porosity and low-permeability tight to ultra-tight sandstone reservoirs with average porosity lower than 10 % and average permeability less than 0.1 mD, dominated by nanometer pore-throat. The reservoirs are distributed from mid-shallow layers to deep layers. Different types of multi-layer reservoirs are composite and superimposed vertically, while multiple sets of reservoirs were widely superimposed with laterally continuous distribution, presenting significant superimposition and extensive coverage. The reservoirs show extremely strong vertical and lateral heterogeneity in terms of rock components, pore space types, petrophysical properties, pore structure characteristics, petrophysical lower limit for reservoir formation, and etc. The reservoir formation and evolution occurred in multiple phases, and continuous effective reservoirs could be formed in each bed series or horizon. Generally, reservoirs present the reservoir-controlled characteristics of "provenance, sedimentation-diagenesis and structure-fault". Meanwhile, there are different key factors for favorable reservoir development in various horizons. The distribution of favorable reservoirs can be comprehensively and quantitatively predicted on the basis of rock types, sedimentary facies, quantitative diagenetic facies, fault characteristics and other research results.