In recent years,continuous breakthroughs have been achieved in exploring the Carboniferous volcanic hydrocarbon reservoirs in the periphery of the Western Well Pen-1 Sag within the central Junggar Basin.However,challenges such as the strong heterogeneity of volcanic reservoirs,complex genesis of high-quality reservoirs,and the unclear reservoir distribution patterns have significantly increased the costs of hydrocarbon exploration and development.To address these issues,we systematically characterize the lithology and lithofacies of volcanic rocks,as well as reservoir space types and their distribution patterns,using multiple techniques including petrology,geochemistry,micro-computed tomography(micro-CT),well logging,and seismic surveys.Through paleogeomorphic reconstruction and tectonic evolution analysis,we determine the durations of weathering and denudation and explore how tectonic movements,together with the intensities of weathering and leaching,control reservoir occurrence.In combination with differences in lithology,structure,and the intensity of weathering and leaching across various areas,we establish a developmental model for large-scale,high-quality volcanic reservoirs.The results indicate that the volcanic rocks in the study area are dominated by effusive phase(that is,basaltic,andesitic,dacitic,and rhyolitic types)and the pyroclastic flow sub-phase of explosive phase(i.e.,resulting in volcanic breccia lavas and welded tuffs).The spatiotemporal distribution of the lithology and lithofacies is governed by multi-stage eruption events.The reservoir spaces are dominated by secondary pores and fracture systems,with tectonic fractures and intergranular dissolution pores representing high proportions.The reservoirs exhibit significant differences in vertical zoning.For instance,the Mobei Uplift,located on a structural slope,preserves a complete four-layered structure consisting of clay zone,leaching zone,disintegration zone,and parent rock zone.In contrast,the Shixi Uplift,located at a structural high during the uplifting and denudation stage,experienced the denudation and transport of the clay zone.Weathering and leaching are key geological processes in the formation of weathered crustal reservoirs.A duration of sustained weathering and denudation of approximately 40 Ma is identified as the critical threshold for significant improvement in reservoir physical properties.Pronounced improvements in physical properties are observed in volcanic breccias,basalts,and andesites as these lithologies are more sensitive to weathering and dissolution.The Hercynian to Indosinian tectonic movements significantly improve the storage capacity of interior reservoirs through fracture reactivation,leading to the formation of a dual-layered reservoir structure comprising weathered crustal and interior reservoirs.Preferential lithologies for this reservoir type include dacites,rhyolites,and volcanic breccias.Accordingly,a volcanic reservoir developmental model proposed is characterized by a material basis comprising favorable lithologies and lithofacies,along with the dual control of supergene weathering and tectonic evolution.The superimposed zones of the Hercynian-Indosinian tectonically active areas and areas subjected to long-term weathering(>40 Ma)are identified as key targets for future exploration of high-quality volcanic reservoirs.

Constrained by the geological burial history of Cretaceous Qingshuihe Formation in the southern margin of Junggar Basin, the diagenetic physical simulation experiment was carried out with the low-mature sandstone samples taken from the outcrop area. Then, coupling with the regional geological data, the reformation of reservoirs with different diagenetic intensities by microfractures and the significance of microfractures for development of high-quality reservoirs were discussed. The results show that the large-scale microfractures were formed in the stage of late rapid deep burial, roughly equivalent to the period when organic acids were filled. The microfractures created good conditions for migration of oil and gas in deep and ultra-deep clastic rocks, and also enabled the transport of organic acids to the reservoirs for ensuing the late continuous dissolution of cements and particles. The existence of matrix pores and microfractures in the reservoirs before the rapid deep burial determined how the microfractures formed during rapid deep burial improved the reservoir quality. If matrix pores and microfractures were more developed and the cementation degree was lower before the rapid deep burial, the microfractures would be more developed and the dissolution degree would be higher during the late rapid deep burial, and so the reservoir quality would be improved more greatly, which can increase the reservoir permeability by up to 55%. If cementation was very strong, but matrix pores were not developed and microfractures existed locally before the rapid deep burial, the microfractures would also be more developed during the late rapid deep burial, which can increase the reservoir permeability by 43%. If cementation was strong, matrix pores were absent, and microfractures were not developed, limited microfractures would be formed during the late rapid deep burial, which can increase the reservoir permeability by only 16%. Formation of large-scale microfractures during late rapid deep burial and promotion of such microfractures to the dissolution of organic acids are considered as key diagenetic factors for the development of deep and ultra-deep high-quality reservoirs.

The Qingshuihe Formation in the western section of the southern margin of the Junggar Basin has excellent oil and gas exploration prospects. The systematic study of its diagenesis characteristics and pore evolution process will provide guidance for the later fine exploration and evaluation of oil and gas. Therefore, based on the analysis of ordinary thin sections, cast thin sections, whole rock X-ray diffraction, grain size, scanning electron microscopy, carbon and oxygen isotopes of carbonate cements and fluid inclusions, the diagenesis characteristics and pore evolution process of the Qingshuihe Formation in the western section of the southern margin of the Junggar Basin were systematically studied, and the differences of reservoir pore evolution process between different diagenetic facies were further discussed. The study shows that: (1)The reservoir of the Qingshuihe Formation in the studied area is dominated by glutenite. The content of rock debris is high, with an average of 65.97%, mainly tuff rock debris. The cement is mainly calcite. The average porosity of the reservoir is 6.2%, and the average permeability is 7.45×10-3 μm2. It is generally a tight reservoir of low porosity and low permeability, but high-quality reservoirs are still developed locally; (2)The reservoir burial mode of the Qingshuihe Formation in the southern margin of the Junggar Basin is characterized by long-term shallow burial and late rapid deep burial, and can be further divided into four evolutionary stages: long-term shallow burial, tectonic uplift to near surface, normal deep burial, and rapid deep burial. The diagenetic evolution of the reservoir was in early diagenetic stage A in the long-term shallow burial, tectonic uplift to near surface, and normal deep burial stages, while in the rapid deep burial stage, the reservoir was in early diagenetic stage B to middle diagenetic stage A; (3)The reservoir of the Qingshuihe Formation can be divided into four typical diagenetic facies types, namely, strong compaction facies, calcareous/iron argillaceous strong cementation facies, tuffaceous filling weak dissolution facies, and weak compaction pore development facies. The pore evolution model of the clastic rock reservoir of the Qingshuihe Formation in the southern margin of the Junggar Basin was established based on the constraints of diagenetic facies. The weak compaction pore development facies are high-quality reservoir diagenetic facies, followed by tuffaceous filling weak dissolution facies.

为研究准噶尔盆地东部石炭系优质火山岩发育规律,通过野外踏勘、岩心观察、铸体薄片鉴定、孔渗分析、测井及地震分析方法研究了火山岩储层特征及分布.结果表明:石炭系火山岩主要岩性岩相以溢流相安山岩、爆发相凝灰岩为主,其次为溢流相玄武岩、爆发相火山角砾岩;火山岩储层中气孔+溶蚀孔和溶蚀孔+裂缝型孔隙为有利的孔隙组合类型,溢流相玄武岩、安山岩和爆发相火山角砾岩储层物性最好,为优质储层发育岩性;优质火山岩储层发育受火山喷发环境、岩性岩相及后期构造改造综合控制,火山岩喷发环境决定了储集空间的发育程度与规模,水上喷发环境造成火山岩原生气孔较为发育,后期淋滤溶蚀改造较为强烈,因此水上喷发环境的火山岩储集性能要好于水下喷发环境;石炭系火山活动具有沿断裂呈串珠-中心式分布的特征,受到构造活动影响,靠近断裂的储层发育有大量的裂缝,对火山物性的改善至关重要,靠近断裂还可沟通烃源岩与储层,为后期有机酸溶蚀创造有利条件.可见准噶尔盆地东部石炭系火山岩油气勘探潜力巨大,火山岩储层中靠近断裂的水上近火山口爆发相和水下近火山口侵出相是最有利储层发育带,有利的火山岩区带主要分布在准噶尔盆地东部滴西地区、五彩湾地区和东部大井地区.

The Lower Wuerhe Formation in Mahu 1 well area of Junggar Basin is rich in oil and gas resources, which are rich in zeolite cements. In this paper, based on core observation and scanning electron microscope data, we clarified that there are four types of zeolite minerals, mainly turbidite, followed by zeolite, and occasionally zeolite and clinoptilolite. Based on the data of X-ray diffraction, physical properties and thin sections, there are two genetic modes of zeolite minerals in this area: cementation and volcanic erosion. For the first time, the prediction model of zeolite content was established by the method of multiple regression, and the plane distribution map of the content of turbidized zeolite in the target strata in the study area was established. The study found that zeolite mainly distributed in the conglomerate size in fine conglomerate and small conglomerate, and the microfacies mainly distributed in the front zone of fan delta.

以准噶尔盆地南缘四棵树凹陷下白垩统清水河组辫状河三角洲碎屑岩为研究对象,采用岩心观察、岩石薄片观察、扫描电镜和压汞实验等方法分析成岩作用特征;根据岩心成岩相测井响应关系,进行测井成岩相识别和储层评价.结果表明:四棵树凹陷清水河组主要发育长石岩屑砂岩和岩屑砂岩,储集空间类型丰富,非均质性较强,既存在粗孔喉、连通性较好的粒间孔隙,为储层主要储集空间类型,也存在细微孔喉、低渗透率的粒内溶孔和粒间溶孔,属于特低孔—特低渗、超低孔—超低渗储层.研究区识别4类成岩相,其中强压实致密相多见蚀变凝灰质充填,发育于河道边缘薄层砂岩;钙质(铁泥质)致密胶结相集中发育于河道主体厚层砂岩的顶底部,孔喉结构较差;凝灰质致密充填相发育于分布最广的弱动力环境,粒间杂基多而物性差;欠压实溶蚀相主要发育于水下分流河道,排替压力较低、孔隙结构最好.自然伽马、声波时差、密度、中子测井及电阻率多元统计结果平均判识率达80.6％.该结果为取心井测井成岩相的研究和优质储层发育规律的认识、有利储层发育带的评价和优选提供支持.

为了揭示准噶尔盆地玛湖凹陷下三叠统百口泉组砂砾岩储层孔隙结构特征与成因,本文首先明确沉积相和岩相类型,其次,开展光学显微镜和扫描电镜岩矿鉴定,并对全岩粉末和黏土矿物提取物进行X射线衍射(XRD)分析,确定矿物成分;最后,开展岩石物性和压汞测试,分析岩石孔隙和喉道特征.研究结果表明:研究区百口泉组沉积于浅水粗碎屑扇三角洲体系,储集层主要分布于块状含泥砾岩(Gm)、块状和叠瓦状砾岩(Gcm?Gci)、颗粒支撑的砂质细砾岩(Gcs)和水下分支河道交错层理砂岩(St)4大类岩相中;各岩相孔隙均以钾长石溶蚀形成的次生孔为主,原生孔仅在泥质质量分数低的Gcs和St岩相发育;孔隙间喉道主要由微裂缝和起连通作用的长石溶孔组成;不同岩相的孔隙结构差异显著,Gcs和St岩相的喉道半径(最大半径分别为20μm和27μm)整体大于Gm和Gcm?Gci岩相的喉道半径(最大半径分别为6μm和3μm);沉积作用奠定了砂砾岩孔隙结构的演化基础;发育于扇三角洲前缘Gcs和St岩相经过水下河道的不断淘洗,泥质质量分数显著降低,导致其初始孔喉半径大于扇三角洲平原至前缘Gm和Gcm?Gci岩相的孔喉半径;在成岩过程中,机械压实整体破坏了各岩相部分初始连通喉道,而钾长石的溶蚀则对各岩相孔隙连通性的改善有差异性影响;微弱的钾长石溶蚀只能产生半径小于2μm的微小喉道,对孔隙连通性的改善有限;而在油气输导断层上盘上倾方向的Gcs和St岩相中,在早侏罗世和早白垩世酸性含油气流体充注的促进下,强烈的钾长石(质量分数低于5％时)溶蚀导致微小孔喉连通,形成半径为2～20μm的较大孔喉,显著增大了流体渗流通道,是这2种优势岩相半径较大孔喉形成的主要原因,同时,钾长石溶蚀沉淀的高岭石堵塞了部分连通喉道.总体而言,扇三角洲前缘优势岩相Gcs和St的叠置沉积区叠加成岩过程中钾长石的强烈溶蚀,形成了百口泉组优质孔隙结构发育区,也导致百口泉组优质储层发育.

形成环境是影响火山岩储层发育的重要因素之一,准确判别火山岩形成环境对指导火山岩油气勘探具有重要的支撑作用.通过对准噶尔盆地东部石炭系火山岩宏观微观岩石学和地球化学特征分析,发现可以从岩石学相标志、古生物学相标志和地球化学相标志判别火山岩形成环境,陆上与水下环境形成的火山岩发育不同的岩性组合和宏观微观结构构造特征,腕足类等各种海相化石都是水下环境火山岩的典型标志.在地球化学方面,可以利用氧化系数(OX)等无机地球化学参数和甲藻甾烷、三环萜烷、正构烷烃等有机地球化学参数判断火山岩的形成环境.不同形成环境对火山岩储层储集性能影响差异显著,陆上火山岩储集空间组合更丰富,原生储集空间更大,且淋滤溶蚀改造作用对储集性能的改善更显著,其储集性能好于水下火山岩.该研究结果总结了不同形成环境火山岩的判别标志及对储层储集性能影响机理,为火山岩储层岩石成因环境分析及岩相古地理研究提供了依据.

The continuous breakthrough of deep and ultra-deep hydrocarbon exploration in China has attracted more and more attention. High-quality reservoir prediction is becoming one of the hotspots in deep and ultra-deep hydrocarbon exploration. Burial history, formation pressure and reservoir characteristics of the Qingshuihe Formation in the southern margin of Junggar Basin, China, were studied using thin section, scanning electron microscope, X-ray diffraction, stable isotopic testing of core samples, and homogenization temperature testing of fluid inclusion to explore the influence of burial history on the diagenetic process and reservoirs quality. Studies show that the Qingshuihe Formation went through four stages of the burial process after deposition, which successively consists of a long-term shallow burial stage, tectonic uplift stage, normal continuous deep burial stage and short-term rapid deep burial stage. The early long-term shallow burial and tectonic uplift stages not only can alleviate the strength of compaction, but also can maintain an open geochemical system in the reservoirs for a long time, which promotes the dissolution of intergranular volcanic ash by meteoric freshwater leaching and provide more secondary dissolution pores. The late short-term rapid deep burial process contributed to the development of overpressure, which effectively inhibits the destruction of primary pores resulted from compaction. Moreover, overpressure promotes the development of microfractures in the reservoirs, which can improve the permeability of the reservoirs and enhance the dissolution effect of organic acid. This study clarified the effect of burial style on the development of high-quality reservoirs by revealing the influence of burial process on diagenesis such as compaction, cementation and dissolution. It deepens the understanding of the development law of deep and ultra-deep high-quality clastic rock reservoirs, and also provides a new idea for the prediction of deep high-quality clastic rock reservoirs.

沸石类胶结物是准噶尔盆地西北缘玛南地区二叠系乌尔禾组发育的一种特殊胶结物类型.通过岩心观察、薄片鉴定、扫描电镜分析与岩石组分统计,明确了玛南地区乌尔禾组沸石胶结物的矿物特征、空间分布、成因机理与成储机制.研究区乌尔禾组主要发育浊沸石与片沸石,其中片沸石分为两期,早期富铁,晚期贫铁.研究区沸石胶结物的空间分布规律并不明显,仅在垂向上,从乌尔禾组到百口泉组,浊沸石与片沸石含量具有逐渐降低的趋势.沸石类胶结物的形成主要受控于母岩中凝灰岩砾石组分,中酸性火山岩砾石不利于浊沸石的形成,其他火山岩砾石与沸石的形成无明显关系,浊沸石大量发育的次生溶蚀孔隙是研究区油气赋存的主要储集空间类型.沸石类胶结物的沉淀与溶蚀可以简化为两阶段成岩作用过程,早期正常成岩胶结形成各类沸石胶结物,晚期深部成岩流体上涌,对储层进行溶蚀与改造,深部流体改造是成储的关键阶段.

陆梁油田L9井区西山窑组J2 x1油藏自21世纪初探明,但鉴于对油水层识别不清,导致后期投产井相继失利.为此,利用岩心观察、薄片鉴定、X衍射、岩电分析等资料,结合测井、试油试采动态等数据,对L9井区西山窑组油藏低对比度油层开展原因分析及识别方法研究.研究表明,岩性是影响该区物性、含油性、泥质含量、孔喉特征差异的根本因素.鉴于此,利用分岩性重新拟定了孔隙度、阿尔奇公式参数,并建立了分岩性识别低对比度油层的模型.结果表明分岩性识别低对比度油层解释结论与试油试采符合率达到94％,因此该方法在低对比度油层识别中具有较好的实用价值.

玛湖凹陷玛18井区多口井在百口泉组富泥储集层中试油获得高产,这与富泥段含油性差的传统认识相矛盾.为了探究富泥储集层收缩孔形成机理及其对储集层的影响,采用微米CT扫描实验技术和数字岩心计算方法对富泥储集层的三维孔隙结构开展研究,结果表明发育收缩孔的样品渗透率远高于不发育收缩孔的样品渗透率;采用原位电子探针技术对百口泉组泥质杂基的成分进行分析,结果表明高钾硅贫铁镁的泥质杂基在向云母类矿物转化过程中形成收缩孔;结合孔隙含量、孔隙度、渗透率和试油产量的多参数分析表明,收缩孔发育的富泥储集层段的孔隙度和渗透率并未因泥质含量增加而减小,反而呈现出增加的趋势;综合沉积相分析,玛18井区富泥储集层沉积环境为水下分流河道,广泛发育的收缩孔降低了泥质堵塞溶孔进而破坏储集层物性的程度.综合分析认为,高钾硅贫铁镁的泥质杂基在向云母类矿物转化时形成了收缩孔,收缩孔既扩充了岩石储集空间又沟通了其他类型的孔隙,进而改善富泥储集层的储渗能力,有利的沉积环境、优质的岩性和储集空间独特配置是富泥储集层成为优质储集层乃至获得高产的原因,其中,收缩孔的改造作用是关键因素.基于以上认识,利用测井图版识别出经过收缩孔改造的富泥储集层,试油效果良好,为玛湖地区挖潜增效提供了新的思路和方向.

The Triassic Baikouquan Formation in Mahu slope area,Junggar Basin,attracted much attention of the reservoir sedimentologist.The difference of physical property in the sandy conglomerate reservoir is obvious,but its control mechanism has not been clear.According to the difference of fluid property,the rock facies are divided into four types:Traction current sandy conglomerate facies (TCSCF),pebbly sandstone facies,sandstone facies and gravity flow sandy conglomerate facies (GFSCF).During burial,compaction effect in the GFSCF is sooner and stronger than that in the TCSCF.And in the process of continuous deep burial,porosity in the GFSCF is not decreasing significantly,but the permeability begins increasing.These show there are micro-cracks beginning to produce in GFSCF.The difference of the compaction effect cause that type of reservoir space in the TCSCF is mainly dominated by primary intergranular pores,and secondary pores and micro-cracks is the main reservoir space in the GFSCF.Finally,the physical property of the TCSCF is obviously better than that of the GFSCF,the former is the effective reservoir in the formation.

准噶尔盆地东道海子凹陷油气资源十分丰富,构造背景有利,开展优质储层的预测能够有效地指导井位优选,实现油气新发现.复杂成岩作用的改造决定了岩石物性和孔隙结构的演化,利用岩石薄片、铸体薄片、扫描电镜、X射线衍射等微观实验分析技术对东道海子凹陷北斜坡上二叠统梧桐沟组进行成岩作用研究,划分成岩阶段,并定量计算各阶段孔隙的改变量,明确孔隙度降低的主要影响因素.研究结果认为:①梧桐沟组成岩作用主要包括压实作用、胶结作用、交代作用及后期的溶蚀作用,目前主要处于中成岩A期;②压实减孔是梧桐沟组孔隙度损失的主要原因,平均减少23.59％,胶结作用所损失的孔隙度平均为3.30％,溶蚀作用较弱,平均增加孔隙度为2.36％;③叠后相干能量梯度属性方法裂缝预测认为梧桐沟组裂缝发育区与构造断裂特征有相关性;④有利储层受岩性、构造作用、成岩作用共同控制,滴南8井扇三角洲前缘断块群为有利储层发育区.该研究成果对该区下一步的勘探开发工作具有指向作用.

It is important to acknowledge reservoir-forming conditions and accumulation model,which are helpful for selecting and evaluating favorable exploration areas.Based on the drilling,logging,seismic and analysis assay data,reser-voir forming conditions in middle Jurassic Toutunhe formation of Fudong slope area in east of Junggar basin are re-searched,which shows the second member of Toutunhe formation has effective conditions to form large oil and gas reser-voirs.Through detailed analyse of existing oil and gas reservoir,main controlling factors of oil and gas reservoirs in study area are sedimentary system,abnormal pressure,and Faults.Above all,the second member of Toutunhe formation is the most favorable stratigraphic for exploration.

对南八仙油气田的油气地球化学特征及成藏进行分析,该区侏罗系油藏的原油具有姥植比高,碳同位素重,铷马蜡烷含量低的特点,油气源对比结果表明油气同源,均来源于下侏罗统烃源岩,油气成藏时间为E3-N1和N2.

The wide-spread sandstone in Xujiahe Fomation of the Upper Triassic,Sichuan Foreland Basin,is one of the most important exploration strata.With the exploration development of the gasfield,it needs to clarify the predominant factors that control the widespread sandstone developing to guide the further exploration and production. To elucidate the depositional mechanism and spacial arrangement of the the widespread sandstone,the sedimentary physical simulation method was adopted to transform the original geological conditions into physical model,on base of investigating the evolution of tectonic,ancient landform and sedimentary system,and so on.And the simulation parameters were taken into consideration and designed to study the mechanism of widespread sandstone through the simulation of flume experiment technology.Three provenances were designed in the experiment to incarnate the characteristics of sedimentary systems during different stages and at different locations under the multi-source conditions.Six intervals were simulated to playback the sedimentary characteristics,by conducting the experiment which was designed referring to principle of simulation and natrural model method.The main controlling factors of widespread sandstone were concluded,by designed such as simulation parameters,such as flow,sediment flux,gradient,subsidence and lake level et al.Some preliminary conclusions are obtained as follows： 1.Under the gradual slope conditions,it is in the shallow area-at the depth of 2.3 cm,slope of 4 that distributary channels migrated frequently,where the area water passed became larger gradually.And so did the area where sandbody deposited and was retransformd,which was benefit for widespread sandstone developing.The sandbodies were universally thin and homogeneous.And the width-thickness ratio of the deltas is grater than 98∶1. 2.In the experiment,when the flux was 4.35 l/s and sediment content was 9.5 g/s,the channels branched and sandbodies moved forward.While was 0.49 l/s and 0.4 g/s,single channel developed and sandbodies were eroded.So the flux and sediment content of different water consociation helped widespread sandstone development. 3.With tectonic subsidence and accommodation extending,the sand sediment developed to sandbodies of certain scale. 4.With frequent changes of the lake level,sandbodies of each stage expanded to different directions in the plane and overriding in vertical.Besides,the lobes combinated laterally,widespread sandstone was easily developed. 5.In the experiment,convergence of 3 sources showed explain of the development of widespread sandstone.During 6th depositional stage,the lake level rised in ascending order： 10cm-12cm-14cm-16 cm-18cm,when the sandbodies deposited continuously towards the source regions.When the lake level dropped from 18cm to 12cm,the accommodation decreased,the sediment carried by rivers deposited in low-lying location and former sandbodies were reformed obviously,which was benefit to widespread sandstone. In the depositional process,the channels bifurcated into distributary channels and lateral migrated continuously.The sandbody prograted and retrogradated vertically by fluctuation of lake level and assembled in horizontal and vertical direction.Then widespread sandstone developed.

The upper Triassic Xujiahe Formation in Sichuan Basin had the characteristics of wide distribution of sandbodies,big thickness of sediments,growth of multi-sources,big changes of the multi-source sediments and various periods of sediments.To represent the results of large scale of the sediments,a physical model was especially designed for the multi-sources in Xujiahe Formation.Because the features of different sources,different times and different positions were needed for simulation experiments,in the model design,3 sources were designed and six formations were simulated.Similitude principle combined with naturalness simulation principle was used for model design to present the real sedimentation characters.By using the similitude principle,the similitude correlation was established between the primary type and model for determining the boundary and designing the source features,settling the volume of flexible floor and the changes of the lake level.The hydrodynamic parameters were simulated for the experiment by naturalness simulation principle.The experimental parameters are repeatedly adjusted and validated by test-bed experiment and experiences,and the physical quantities required for experimental model are eventually determined.

The Late Triassic Western Sichuan Foreland Basin was the outcome that the fold-thrust belts developed in the front zone of orogenic belt thrust toward the Western Sichuan Area,it was due to the western edge of Yangtze plate occurring subduction to the west and colliding with the arc(land) land or another plate,it belonged to peripheral foreland basin.It was experienced complicated evolutionary process that the tectonic environment was transformed from extension to compression and deposited huge thickness of Xujiahe Formation that continental deposition was dominated,the unique sedimentary filling characteristics were established in the plane and in vertical direction.In the plane the difference of sharp subsidence caused by intensive Longmenshan thrust of orogenic belt and low amplitude steady subsidence of orogenic belt makes the differentiation of steep slope filling in the front of thrust belt and gently slope filling in Cratonic margin.And in the vertical direction,the structural movement has the episodic features alternating between active period and static period,the basin is filled with shore-shallow lake fine deposition of Member 1,3,5 of Xujiahe Formation and heavy-bedded and blanket sand of Member 2,4,6 of Xujiahe Formation.The alternated fillers of mudstone and sand are created by sandwich type source reservoir caprock.