In recent years, the exploration of Dengying Formation in Anyue Gas Field has gradually shifted from the platform margin area to the platform area, and major breakthroughs have been made in the oil and gas exploration in the platform area. Taking Deng4 member of Longnvsi area in central Sichuan as an example, based on the latest geological data, oil testing results and seismic interpretation results, through analyzing the fault characteristics, fault formation period and its matching relationship with the karst transformation period, further clarify whether the fault has an impact on the karst transformation of the reservoir, and the research results point out the direction for finding high-quality reservoirs in Longnvsi area in Tainan.

In view of the imprecise sedimentary facies division, unclear favorable rock assemblage and undefined favorable exploration area of Jurassic Da′anzhai Member in Central Sichuan, a study was conducted on the rock type, sedimentary facies type, sedimentary facies distribution, sedimentary model, rock assemblage and favorable exploration area in the study area by the core description of three fully cored wells and the observation results of six field profiles in combination with thin slice identification, logging interpretation and organic geochemical analysis methods. The study results show that Rock was divided into 10 types. The sedimentary facies was divided into 3 subfacies（shore lake, shallow lake and fairly deep lake） and 10 microfacies（including fairly deep lake mud, organic bank and gravity flow）. Gongshanmio-Lianchi-Yingshan line is the sedimentary center developed in a fairly deep lake environment, and three rock assemblage types（C, D and E） were identified. Nanchong-Quxian-Yilong line was circularly developed in a shallow lake environment, and three rock assemblage types（A, B and F） were identified. The study results were applied from conventional tight oil to shale oil exploration. According to the TOC, porosity, permeability, fracturing effect and other evaluation indicators, it was considered that Type A rock assemblage was a favorable combination for tight oil carbonate rock exploration under the matching of fractures and cracks, and Type F was the most favorable combination for shale oil exploration, which was mainly distributed in the shallow lake facies at Sub-member 1 to Sub-member 2a of Da′anzhai Member. The study results are of great significance for shale oil exploration in the future.

The Lower Jurassic Da’anzhai Member in the Sichuan Basin is one of the important distribution series of strata of shale oil and gas （tight oil and gas）,but its drilling and test results are worse,so it is in urgent need to research the geological characteristics of favorable intervals and select the favorable exploration areas.Based on field outcrop,core,logging,and geophysical data,this paper studies the geological characteristic of the Da’anzhai Member shale oil and gas,analyzes the control factors of shale oil and gas enrichment,and selects the favorable exploration areas.And the following research results are obtained.First,the Da’anzhai Member is a set of mixed strata of shell limestone and black shale.The shale mineral is mainly composed of clay,followed by quartz and calcite,with a small amount of feldspar and pyrite,and the content of brittle minerals is medium.Second,the pore type is mainly inorganic pore,with a small number of organic pores,and multi-scale fractures such as shell edge fracture and joint fracture are developed.The physical properties decrease with the increase of shell content.Third,the abundance of organic matter in shale is moderate to good with average TOC of 1.34%.The organic matter is mainly of mixed type with a small amount of sapropel type and humic type.R o averages 1.11%,the degree of thermal evolution is low in the south and high in the north,and it is overall in the stage of maturity to high maturity.The oil content is moderate with chloroform asphalt"A"content averaging 0.26%.Fourth,the average S 1 value of pyrolysis free hydrocarbons is 1.27 mg/g,and the average OSI is 84.35mg/g.The lower limit of hydrocarbon source for shale oil and gas enrichment is TOC＞1.5% and R o ＞0.9%.The hydrocarbon expulsion efficiency is lower vertically,and the sections with higher oil content index （OSI＞100 mg/g） are mainly distributed in the middle of thick shale.Fifth,the movable oil saturation is generally less than 20%.Due to the influence of texture fractures and shale bedding fractures,the oil mobility in the samples of limestone interbedded with shale and shale with interbedded limestone is better than that in limestone and shale.In conclusion,the Da’anzhai Member shale has great potential in shale oil and gas exploration and development,high hydrocarbon generation quality,multi-scale fractures,and high formation pressure are the key factors for the enrichment and high production of shale oil and gas in the basin,and the favorable exploration areas are mainly distributed in the Santai-Yilong and Nanchong areas of central Sichuan Basin.

The siliceous rocks are commonly developed in the upper sub-section of the Fourth Member, Sinian Dengying Formation, Anyue Gasfield in central Sichuan, and their influence on reservoir karstification is still unclear, so it is necessary to conduct a corresponding study. For this reason, based on lithology, logging response characteristics, the cores and slices were described in details through observations, the study of the influence of siliceous rocks on reservoir karstification in the upper sub-section of the Fourth Member, Dengying Formation, in Longnyusi Area of Central Sichuan was carried out using basic characteristics of siliceous rocks, reservoir comparison diagram and siliceous plan, and the results show that The siliceous rocks in the study area are mainly algal laminated siliceous rocks, pure siliceous rocks and dolomitic siliceous rocks; the siliceous bed is divided into 2 sections in the upper sub-section of the Fourth Member, Dengying Formation, and the reservoirs above and below the siliceous bed are in good conditions, and the thickness of the siliceous rocks can be seen on the plane to be thinned to the northeast as well as to the southeast; the siliceous rocks are fractured by the Tongwan movement and suffer from dissolution enlargement, which cannot block the karst fluid infiltration; the fault cutting through the siliceous bed has no effect on the stimulation of the karst reservoirs. Therefore, siliceous rocks have less effect on the reservoir karstification. The research results have laid a foundation for finding favorable areas for reservoir development in the Longnyusi area within the platform.

Based on the fine seismic data interpretation result,combining the field sections and indoor thin-section observation,we study the depositional facies distribution characteristics,by analyzing the main rock types,paleontology,geochemical and seismic characteristics.On the basis of biological（chip） limestone,siliceous rocks and reef limestone development rule of the lithofacies and seismic stratigraphic structures and stratigraphic thickness variation characteristics,we find out that Maokou Formation has developed sedimentary facies of the open sea platform,marginal-platform shoals and slope-basin,summarize four kinds of sedimentary facies association,open sea platform with patch reefs,open sea platform with shaoal patch,the marginal-platform shoals and calcareous-siliceous basins.Land clarify the vertical evolution of sedimentary facies and plane distribution rule.The results show that the high-energy marginal-platform shoals present banding development in the Jiange-Yuanba-Longgang Area.The biological（chip） limestone develops the intercrystalline denudation pore,intergranular dissolved pore and biogenic body cavity pore,which is a high quality reservoir development zone with good phy sical properties.Maokou Formation（Member 4） in the western Sichuan trough and Guangyuan-Wangcang trough area sedimentary siliceous rock and mudstone is the high quality source rocks,the excellent sedimentary environment providing a favorable conditions for hydrocarbon accumulation oil source and reservoir.

通过岩心薄片鉴定、扫描电镜观察、X射线衍射分析与TOC含量检测等技术,精细划分了川中地区侏罗系大安寨段页岩岩相类型,并对各岩相的储集空间类型、物性和含气性等特征进行了分析,确认了优势岩相,并结合岩相与沉积相的纵向发育特征,指出了优势开发层段.研究结果表明:①川中地区大安寨段页岩储集空间以与黏土矿物相关孔隙和颗粒边缘孔为主,孔隙度为0.31％～8.55％,平均为3.97％;渗透率为0.001～12.185 mD,平均为0.659 mD;气的质量体积一般高于1.0 m3/t,其分布特征与孔隙度具有高度一致性.②研究区大安寨段页岩岩相可划分为6个大类13个小类,其中中高有机碳含量的介壳灰质黏土质页岩岩相有机质丰度、脆性矿物含量、孔隙度和含气量均最高,为最具优势的岩相,中高有机碳含量的粉砂质黏土质页岩岩相其次,中高有机碳含量的黏土质页岩岩相虽然其有机质丰度较高,但裂缝欠发育,具有一定的地质勘探潜力.③研究区大安寨段优势岩相主要分布在大二亚段的半深湖亚相,这也是有利的勘探方向.

针对拐子湖凹陷勘探程度较低、有效烃源岩分布及控制因素不明确的问题,运用有机地球化学、沉积层序及构造演化分析方法,对温1井烃源岩特征及主控因素展开研究.研究结果表明:研究区烃源岩有机质丰度整体较低,受沉积层序、构造综合影响,高位体系域有利于有机质富集;有机质类型为腐泥腐殖型和腐殖型;有机质热演化程度差异较大,富泥质岩类的发育可促进早期的热演化进程,构造的后期抬升使局部生烃时间大幅缩短,故有机质成熟度从未成熟至高成熟均有分布;烃源岩展布受断裂及沉积演化控制明显.该研究可为拐子湖凹陷北部下一步勘探提供参考.

近年来,四川盆地震旦系灯影组的油气勘探开发不断深入推进,川北地区作为后续勘探接替区,其灯影组储层的相关研究亟待进行.综合川北地区灯影组的地层、岩石及矿物特征,采用分析化验等手段揭示其储层特征,结果表明:灯二段、灯四段为川北地区灯影组储层发育层段,颗粒粘连白云岩、叠层状微生物白云岩和粉晶白云岩为主要储集岩类,次生溶孔、溶洞为主要储集空间;灯影组储层类型多样,发育孔-洞型、孔隙型、孔隙-裂缝型及溶洞型储层,以孔隙-裂缝型储层质量最佳.储层发育特征表明:滩丘沉积是灯影组储层发育的物质基础,后期岩溶改造是储层发育的关键;灯二段滩丘厚度相对更大,而储层物性相比灯四段较差.基于宏观储层演化和微观孔隙特征,建立了川北地区灯影组2种储层发育模式:灯二段以表生岩溶为储层发育的主控因素,见有不同期次白云石胶结和上覆地层细粒沉积物充填;灯四段以埋藏溶蚀为储层发育的主控因素,存在广泛的重结晶造成的溶蚀、溶蚀流体中硅质组分对孔隙的充填、以及溶蚀孔隙中沥青对储层的保护.依据不同的岩溶模式,可预测灯二段、灯四段有利储层的发育位置:在潜流带与滩丘沉积体叠加的部位,灯二段储层发育最佳;自顶部向下,自台缘向台内,灯四段储层质量逐渐下降.

依据野外及钻井岩心的宏观、微观特征,结合相应的地化资料,对川北地区灯影组灯二段的储层特征及主要控制因素进行了较为详细的研究.研究认为,其储集岩主要为颗粒粘连白云岩、藻叠层白云岩和白云质岩溶角砾岩,储集空间以次生成因的藻粘连格架 溶孔、顺层溶孔—溶洞—溶缝和穿层葡萄花边溶洞最为常见,储层类型多为孔洞型,常规物性具有低孔—低渗特征;颗粒粘连滩和藻丘为区内优质储层的发育提供物质基础,压实—压溶和多期胶结作用是原生孔隙消失的基本原因,桐湾运动工幕导致的表生岩溶作用是储层形成的关键.颗粒粘连滩、藻丘与表生岩溶水平潜流带的叠加使其储层主要分布在灯二段的中部.该研究结果可为川北地区震旦系灯影组油气勘探提供依据.

During the exploration of the south central Sichuan Basin,the fine-medium grained dolostones of Lower Permian Qixia Formation was found as good reservoir rocks.Industrial gas flows were obtained in numbers of development wells, which reveals great potentiality of the gas exploration.For the further prediction of dolomite reservoir distribution characteristics in central and southern regions, speeding up the next exploration and development of the study area, the genesis of dolomite reservoir is studied through the application of reservoir lithology recognition, carbon and oxygen isotope, fluid inclusion, cathodoluminescence and rare earth elements analysis in this study.The results show that, in the Qixia Formation,the dolostones formed without associated gypsum or other evaporites; the reservoir rocks are mainly gray fine-medium grained dolostones, which spread mainly in the Qier Group.According to a series of reservoir rock analysis, the δ13C content is 4.03 ~4.77‰; the paleosalinity varies among 131.74~133.39; the homogenization temperatures of fluid inclusions are among 110 ~180 ℃; the cathodeluminescence is fairly weak, and the dolomitic matrix reflects purple red light, while the saddle dolomite filled in the vugs absorbs all the light; the distribution tend of light rare earth elements and heavy ones are consistent with the protolith.Overall, in this study it is believed that the Qier Group dolomites were formed during the burial stage,while saddle dolomites filled in the vugs and fractures were formed due to a hydrothermal cause.

This paper mainly studies the grain bank of the Lower Cambrian Lower Longwangmiao Formation in eastern Sichuan Basin.Based on the field outcrops,drilling and logging data,cores and thin sections,the paper studies the characteristics,distribution and the major controlling factors of grain bank of the Lower Cambrian Lower Longwangmiao Formation.The grain dolostone and grain limestone fall into two main rock types of grain bank in the research area.Sandsized intraclast is the main type of intraclasts,and oolite as well as gravel-sized intraclast follow in order.There are three upward shallowing and granularity coarsening sequences,including lagoon-grain bank-lagoon,lagoon-grain bank-platform interior flat and interact bank sea-grain bank-interact bank sea.Each vertical sequence is commonly no more than 2m.Tin banks are superimposed vertically in a relatively small scale,showing a good inheritance.In horizontal aspects,the grain banks are small in scale and poor in continuity.In plane,the grain banks are mainly patched shoals and distributed on the cores and wings of submarine highlands in the direction of northeast.The research of major controlling factors shows that the development characteristics and superimposed pattern of grain bank in Longwangmiao Formation are determined by the relative sea-level change and that the palaeogeomorphology determines the lateral continuity and planar distribution.Comparative research shows that the paleogeomorphology,developed around the large depression areas around the lagoon,is a favorable area for the grain beach reservoirs.Besides,the grain beach reservoirs are mainly distributed in the upper part of the Lower Longwangmiao Formation as well as in the central and upper part of Upper Longwangmiao Formation in eastern Sichuan Basin.

与不整合面相关的碳酸盐岩古岩溶储层普遍发育,在我国的含油气盆地勘探中具有重要地位.靖边气田的勘探成果表明,鄂尔多斯盆地奥陶系顶部碳酸盐岩风化壳岩溶古地貌不仅是下古生界天然气聚集成藏的主要控制因素,而且对岩溶储层发育具有重要的控制作用[1].

四川盆地中三叠统雷口坡组是盆地内主要的产气层系之一,目前已发现中坝、卧龙河、龙岗、磨溪等气田.川中雷口坡组主要由一套浅灰—褐灰色中—厚层块状的白云岩、膏岩和石灰岩不等厚互层组成,从下至上分为四段,界线清晰,其中雷一段又分为两个亚段,雷四段分为三个亚段(图1).20世纪50年代开始,Moody (1959)、North(1985)、Schreiber(1988)等人先后在其专著中论述过油气和膏盐岩的关系,许靖华(1985)、王东旭(2005)、彭文绪(2008)等人也认为,膏岩不仅利于油气的保存,也利于下部岩层形成异常高压而产生裂缝,还能产生有机酸使下部地层形成较好的次生孔隙[1,2],在一定程度上促进油气储层的形成.但由于印支运动的影响,雷口坡组顶部发生了不同程度的剥蚀[3,4],这给宏微观研究带来了一定困难.

川中龙岗地区中三叠统雷四3亚段气藏无统一的气水界面,复杂的气水关系制约着气田后期的开发.在分析地球化学特征基础上,通过对研究区气、水分布规律研究,发现气藏的形成主要受储集层非均质性、沉积相、构造位置、断层及裂缝发育程度、保存条件等因素控制.对龙岗地区天然气组成和碳同位素特征分析,认为上覆须家河组为雷口坡组气藏主要的气源层;颗粒滩亚相储集层物性较好,在一定生烃强度下,天然气充注程度较高;气层、气水层、含气水层以孤立状构造圈闭为主;构造位置对气水分异作用明显;研究区断层及裂缝发育,为气藏提供了主要的输导体系及储集空间;上覆须家河组底部泥岩及雷口坡组膏盐岩层构成良好的盖层条件.

Good reservoirs are developed in the Middle Triassic Leikoupo-43 Formation in Longgang-Yingshan area of central Sichuan basin.There exist rich oil and gas resources in granular dolomite,suggesting good exploration prospect.Through macro-and micro-observation of thin sections and rocks from more than ten wells in combination with geochemical characteristics,the authors made a detailed investigation into diagenetic types and characteristics and examined the relationship between the diagenesis and the evolution of reservoir space.The findings show that the diagenetic evolution process of reservoir in the Middle Triassic Leikoupo-43 Formation in Longgang-Yingshan area of central Sichuan basin was complex,and during this process various diagenetic actions were developed,with the reservoir quality being clearly affected by the diagenesis.The compaction and pressure solution,multiphase cementation and multiphase packing action resulted in substantial reduction of intergranular pores and intercrystalline pores.The mixed water dolomitization,the supergene and burial dissolution and the tectonic disruption constituted the keys to the formation of high quality reservoir and the generation of massive intergranular dissolution pores,intragranular dissolution pores,intercrystalline dissolved pores and eroded fissures,which have now became the main oil and gas reservoir space.

四川盆地中部龙岗-营山地区中三叠统雷口坡组雷四3亚段储层发育较好,在颗粒型白云岩中显示丰富的油气,具有良好的勘探前景.通过对研究区30余口钻井岩心、薄片的宏观及微观观察,结合地球化学特征,对成岩作用类型及特征进行较详细的研究,探讨了成岩作用与储集空间演化的关系.研究发现区内雷四3亚段储层成岩演化过程复杂,各种成岩作用发育,储层质量的好坏受成岩作用影响明显.压实压溶作用、多期胶结作用以及多期充填作用导致粒间孔、晶间孔大幅度减少；混合水白云石化作用、表生期和埋藏期溶蚀作用以及构造破裂作用是优质储层形成的关键,形成了大量的粒间溶孔、粒内溶孔、晶间溶孔和溶蚀缝,成为现今该层段的主要储集空间.

A shallow marine carbonate rock sequence with shale and evaporate developed in the Lower Triassic Feixianguan Formation in northeastern Sichuan Province.The edge of carbonate platform commonly developed some oolitic banks,which are dolomitized.The Feixianguan Formation which are formed by oolitic bank dolostone is the most important gas reservoir in northeastern Sichuan Province. Some researchers considered them as the origin of mixing for fresh water and sea water,the others make up them into model for dolomitization by seepage-reflux.The Feixianguan oolitic bank dolostone included stable isotopic oxygen composition of -6.73‰～-3.65‰(PDB)(-10.81‰ in Luojiazhai area),the average is -4.89‰(PDB),stable isotopic carbon composition of +0.57‰～+3.00‰(PDB),for matrix and vug-filling saddle dolomite and bright dolomite cement,stable isotopic strontium composition of 0.70735～0.70800 for 87Sr/86Sr rate.These data about oolitic bank dolostone indicate that the dolomitization was formed in the buried condition.After measuring fluid inclusion homogenization temperature,dolomitization temperature and isotopic oxygen of dolomite are known,and then the isotopic oxygen composition of dolomitizing fluid can be calculated(δ18Odol-δ18Owater=[3.2×106 T -2]-1.5,from Friedman and O'Neil (1977)). The average is about +4‰ (SMOW).According to the positive covariance between fluid isotopic oxygen and carbon composition and fluid salinity during evaporation of seawater,fluid δD can be calculated.It is about +25‰(SMOW).The measurement of fluid inclusion salinity suggest that dolomitizing fluid is a brines,which is about several times of seawater.Dolomitizing temperature changes from 90 ℃ to 130 ℃.As far as our knowledge goes,stable isotopic O and C composition of the Lower Triassic oolitic bank dolostone is similar to these of the uppermost Permian reef dolostone.Therefore,it is possible that their dolomitizing fluids are identified source.However,the reason for this conclusion needs to be perfected in the future.

Based on macroscopic and microscopic features of outcrop sections and drilling cores of the Lei-4 member of Leikoupo formation of Middle Triassic in northern Sichuan basin,combined with the conventional petrophysical data,this paper studies in detail the basic features of the reservoir space types,lithologic and petrophysical properties,space distribution,as well as the main controlling factors.The reservoir is mainly distributed in Lei-4(3) sub-member of the Leikoupo formation,with lithology of grain dolostone,next to crystalline dolostone.The intergranular,intragranular and intercrystal dissolved pores are mainly reservoir space,cracks as the main space of percolation.The reservoir formation and evolution are mainly affected by sedimentary facies and diagenesis,among which intra-platform patch beach is the most favorable facies for developing reservoirs,and supergene karstification and burial dissolution give rise to the main storage spaces.

Based on core observation, thin section analysis, well logging data, the characteristics and controlling factors of reef reservoir of Changxing Formation in Wenquanjing and adjacent Huanglongchang and Wubaiti area of northeastern Sichuan were studied in detail. The result shows that the main reservoir rocks are fine-medium crystalline dolomite, clay-powder crystalline dolomite, medium-coarse crystalline dolomite and reef limestone（dolomite）, among which the fine-medium crystalline dolomite is the best. The physical property is poor, generally with porosity less than 2% and permeability less than 1.0 mD. The main reservoir spaces mainly are secondary intercrystal pores and intercrystal dissolved pores and intergranular dissolved pore, followed by small caves, and fractures developed locally. The pore structure has the characteristics of low porosity and small throat. The main reservoir type is porosity type, and fracture-porosity type is developed locally. The reservoir in the study area is mainly of type Ⅲ, and typeⅠand Ⅱ are rare. The reservoir formation and evolution are mainly affected by sedimentation, diagenesis and tectonism. Sedimentation is the foundation of reservoir formation, diagenesis is the key factor to improve the reservoir, and tectonism provides conditions for reservoir improvement.

There is a set of lacustrine facies carbonate rocks 20-60m in thickness in the lower part of 1st Member of Eogene Shahejie Formation in the Huanghua depression.There exist rich oil and gas resources in biological limestone,oolitic(dolomite) limestone and micrite dolomite,suggesting good exploration prospects.Through macro-and micro-observation of thin sections and rocks from more than 10 wells in combination with geochemical characteristics,the authors made a detailed investigation into diagenetic types and characteristics and examined the relationship between the diagenesis and the evolution of reservoir space.The results show that the diagenetic evolutionary process of carbonate rocks in the lower part of 1st Member of Shahejie Formation was very complex and characterized by a variety of diagenetic types,and that the reservoir quality was obviously affected by the diagenetic process.The compaction and pressure solution action and the multi-stage calcite and dolomite cementation resulted in drastic reduction of intergranular holes,biological coelomopores and framework holes.The mixed water dolomitization and the syngenetic-penecontemporaneous and burial dissolution constitute the keys to the formation of high quality reservoir,with the formation of massive intercrystal pores,intercrystal dissolution pores,intragranular dissolution pores,moldic pores,biological coelomopores,intergranular dissolution pores and corroded fissures,which have now become the main oil and gas accumulation space.