Enrichment model and major controlling factors of below-source tight oil in Lower Cretaceous Fuyu reservoirs in northern Songliao Basin,NE China

Based on the geochemical,seismic,logging and drilling data,the Fuyu reservoirs of the Lower Cretaceous Quantou Formation in northern Songliao Basin are systematically studied in terms of the geological characteristics,the tight oil enrichment model and its major controlling factors.First,the Quantou Formation is overlaid by high-quality source rocks of the Upper Cretaceous Qingshankou Formation,with the development of nose structure around sag and the broad and continuous distribution of sand bodies.The reservoirs are tight on the whole.Second,the configuration of multiple elements,such as high-quality source rocks,reservoir rocks,fault,overpressure and structure,controls the tight oil enrichment in the Fuyu reservoirs.The source-reservoir combination controls the tight oil distribution pattern.The pressure difference between source and reservoir drives the charging of tight oil.The fault-sandbody transport system determines the migration and accumulation of oil and gas.The positive structure is the favorable place for tight oil enrichment,and the fault-horst zone is the key part of syncline area for tight oil exploration.Third,based on the source-reservoir relationship,transport mode,accumulation dynamics and other elements,three tight oil enrichment models are recognized in the Fuyu reservoirs:(1)vertical or lateral migration of hydrocarbon from source rocks to adjacent reservoir rocks,that is,driven by overpressure,hydrocarbon generated is migrated vertically or laterally to and accumulates in the adjacent reservoir rocks;(2)transport of hydrocarbon through faults between separated source and reservoirs,that is,driven by overpressure,hydrocarbon migrates downward through faults to the sandbodies that are separated from the source rocks;and(3)migration of hydrocarbon through faults and sandbodies between separated source and reservoirs,that is,driven by overpressure,hydrocarbon migrates downwards through faults to the reservoir rocks that are separated from the source rocks,and then migrates laterally through sandbodies.Fourth,the differences in oil source conditions,charging drive,fault distribution,sandbody and reservoir physical properties cause the differential enrichment of tight oil in the Fuyu reservoirs.Comprehensive analysis suggests that the Fuyu reservoir in the Qijia-Gulong Sag has good conditions for tight oil enrichment and has been less explored,and it is an important new zone for tight oil exploration in the future.

Controlling factors of high-quality volcanic reservoirs of Yingcheng Formation in the Songnan gas field

Predicting high-quality volcanic reservoirs is one of the key issues for oil and gas exploration in the Songnan gas field.Core,seismic,and measurement data were used to study the lithologies,facies,reservoir porosity,and reservoir types of the volcanic rocks in the Songnan gas field.The primary controlling factors and characteristics of the high-quality volcanic reservoirs of the Yingcheng Formation in the Songnan gas field were investigated,including the volcanic eruptive stage,edifice,edifice facies,cooling unit,lithology,facies,and diagenesis.Stages with more volatile content can form more high-quality reservoirs.The effusive rhyolite,explosive tuff,and tuff lava that formed in the crater,near-crater,and proximal facies and in the high-volatility cooling units of large acidic-lava volcanic edifices are the most favorable locations for the development of the high-quality reservoirs in the Songnan gas field.Diagenesis dissolution,which is controlled by tectonic action,can increase the size of secondary pores in reservoirs.Studying the controlling factors of the high-quality reservoirs can provide a theoretical basis for the prediction and analysis of high-quality volcanic reservoirs.

Geological characteristics and high production control factors of shale gas reservoirs in Silurian Longmaxi Formation, southern Sichuan Basin, SW China

Marine shale gas resources have great potential in the south of the Sichuan Basin in China.At present,the high-quality shale gas resources at depth of 2000–3500 m are under effective development,and strategic breakthroughs have been made in deeper shale gas resources at depth of 3500–4500 m.To promote the effective production of shale gas in this area,this study examines key factors controlling high shale gas production and presents the next exploration direction in the southern Sichuan Basin based on summarizing the geological understandings from the Lower Silurian Longmaxi Formation shale gas exploration combined with the latest results of geological evaluation.The results show that:(1)The relative sea depth in marine shelf sedimentary environment controls the development and distribution of reservoirs.In the relatively deep water area in deep-water shelf,grade-I reservoirs with a larger continuous thickness develop.The relative depth of sea in marine shelf sedimentary environment can be determined by redox conditions.The research shows that the uranium to thorium mass ratio greater than 1.25 indicates relatively deep water in anoxic reduction environment,and the uranium to thorium mass ratio of 0.75–1.25 indicates semi-deep water in weak reduction and weak oxidation environment,and the uranium to thorium mass ratio less than 0.75 indicates relatively shallow water in strong oxidation environment.(2)The propped fractures in shale reservoirs subject to fracturing treatment are generally 10–12 m high,if grade-I reservoirs are more than 10 m in continuous thickness,then all the propped section would be high-quality reserves;in this case,the longer the continuous thickness of penetrated grade-I reservoirs,the higher the production will be.(3)The shale gas reservoirs at 3500–4500 m depth in southern Sichuan are characterized by high formation pressure,high pressure coefficient,well preserved pores,good pore structure and high proportion of free gas,making them the most favorable new field for shale gas exploration;and the pressure coefficient greater than 1.2 is a necessary condition for shale gas wells to obtain high production.(4)High production wells in the deep shale gas reservoirs are those in areas where Long11-Long13 sub-beds are more than 10 m thick,with 1500 m long horizontal section,grade-I reservoirs penetration rate of over 90%,and fractured by dense cutting+high intensity sand injection+large displacement+large liquid volume.(5)The relatively deep-water area in the deep-water shelf and the area at depth of 3500–4500 m well overlap in the southern Sichuan,and the overlapping area is the most favorable shale gas exploration and development zones in the southern Sichuan in the future.With advancement in theory and technology,annual shale gas production in the southern Sichuan is expected to reach 450×108 m3.

Physical property characteristics of Yanchang Formation reservoir in the southwest of Ordos Basin and their controlling fac-tors： taking Chang 3 and Chang 4 ＋ 5 reservoirs in Longdong area as an example

分析鄂尔多斯盆地西南部陇东地区延长组储层物性特征及其控制因素，发现沉积和成岩控制储层物性。沉积微相带不同，储层物性就不同；成岩作用中压实-压溶作用、胶结作用对储层物性具有破坏作用，溶蚀作用是储层物性改善的关键因素。沉积微相带是控制油气藏储层展布的内在因素，成岩作用是储层形成过程中控制物性演化的外部因素。

Characteristics of Shale Reservoir and Sweet Spot Identification of the Lower Cambrian Niutitang Formation in Northwestern Hunan Province, China

The accumulation and productivity of shale gas are mainly controlled by the characteristics of shale reservoirs;study of these characteristics forms the basis for the shale gas exploitation of the Lower Cambrian Niutitang Formation(Fm),Southern China.In this study,core observation and lithology study were conducted along with X-ray diffraction(XRD)and electronic scanning microscopy(SEM)examinations and liquid nitrogen(N2)adsorption/desorption and CH4 isothermal adsorption experiments for several exploration wells in northwestern Hunan Province,China.The results show that one or two intervals with high-quality source rocks(TOC>2 wt%)were deposited in the deep-shelf facies.The source rocks,which were mainly composed of carbonaceous shales and siliceous shales,had high quartz contents(>40 wt%)and low clay mineral(<30 wt%,mainly illites)and carbonate mineral(<20 wt%)contents.The SEM observations and liquid nitrogen(N2)adsorption/desorption experiments showed that the shale is tight,and nanoscale pores and microscale fractures are well developed.BJH volume(VBJH)of shale ranged from 2.144×10^-3 to 20.07×10^-3 cm^3/g,with an average of 11.752×10^-3 cm3/g.Pores mainly consisted of opened and interconnected mesopores(2–50 nm in diameter)or macropores(>50 nm in diameter).The shale reservoir has strong adsorption capacity for CH4.The Langmuir volume(VL)varied from 1.63 to 7.39 cm^3/g,with an average of 3.95 cm^3/g.The characteristics of shale reservoir are controlled by several factors:(1)A deep muddy continental shelf is the most favorable environment for the development of shale reservoirs,which is controlled by the development of basic materials.(2)The storage capacity of the shale reservoir is positively related to the TOC contents and plastic minerals and negatively related to cement minerals.(3)High maturity or overmaturity leads to the growth of organic pores and microfractures,thereby improving the reservoir storage capacity.It can be deduced that the high percentage of residual gas in Niutitang Fm results from the strong reservoir storage capacity of adsorbed gas.Two layers of sweet spots with strong storage capacity of free gas,and they are characterized by the relatively high TOC contents ranging from 4 wt%to 8 wt%.

Reservoir Characteristics and Controlling Factors of Silurian Lower Kepingtage Formation in Tahe Area, Tarim Basin, NW China

With the breakthrough of exploration in Well TP16-1, the lower Kepingtage Formation becomes a key target for petroleum exploration of deep clastic reservoir in Tahe area. In this paper we focused on the research of the reservoir characteristics and its controlling factors in two sub-member formations（S1k11 and S1k13）. Based on X-ray diffraction, conventional physical properties data（porosity and permeability） and reservoir storage space data（casting thin section and scanning electron microscope）, we determined that the S1k1 Formation belongs to extra-low porosity and permeability reservoir, although the upper S1k13 Formation shows relative better physical characteristic than the lower S1k11 Formation. The development of storage space in the study area is controlled by sedimentary microfacies, diagenesis process. Reservoirs in S1k1 Formation are mainly located in channel（S1k11 sandstones） and sand flat（S1k13 sandstones）. The sand flat sediments with a more coarse grain size compared with the channel. In diagenesis, compaction is the major controlling factor for reducing the porosity, followed by cementation. Dissolution of diagenesis is the major controlling factor in enhancing the reservoir porosities. Compared with channel（S1k11） sandstones, sand flat sandstones（S1k13） have better reservoir quality for its weaker compaction, cementation and stronger dissolution. On the basis of sedimentary characteristics（grain size and subfacies）, physical property（porosity and permeability） and reservoir storage space, we divide the S1k1 reservoir into three categories（I, II and III）. Type I reservoir is high quality reservoir. It is mainly distributed in the south area of S1k11 and S1k13 reservoir. Type II is moderate reservoir. It is located in the middle of S1k11 reservoir and in the north of S1k13 reservoir. Type III is the poor reservoir. It is only located in the north of S1k11 reservoir.

Controlling Factors and Accumulation Model of Hydrocarbon Reservoirs in the Upper Cretaceous Yogou Formation, Koulele Area, Termit Basin, Niger

Based on the sedimentary and tectonic background of the Termit Basin, this paper focuses on the Upper Cretaceous Yogou Formation and uses organic geochemistry, logging, oil testing and seismic data to analyze the primary control factors of the hydrocarbon accumulation and establish corresponding model in order to predict favorable exploration target zones of hydrocarbon reservoirs. This study demonstrates that the Upper Cretaceous Yogou Formation is a self-generation and self-accumulation type reservoir. The Yogou Formation hydrocarbon reservoirs in the Koulele area are controlled by four factors：（1） the source rock is controlled by a wide range of YS1-YS2 marine shale,（2） the sandstone reservoir is controlled by the YS3 underwater distributary channel and storm dunes,（3） migration of hydrocarbons is controlled by faults and the regional monocline structure, and（4） the accumulation of hydrocarbons is controlled by lateral seal. The structures in the western Koulele area are primarily reverse fault-blocks with large throws, and the structures in the east are dominantly fault-blocks with small throws（co-rotating and reverse） and a fault-nose. In the western Koulele area, where the facies are dominated by storm dunes on a larger scale, it is easier to form lithologic reservoirs of sandstone lens. In the eastern Koulele area, high-quality channel sandstone reservoirs, fault-blocks with small throws, and the monocline structure benefit for the formation of updip pinch out lithologic traps, fault lithologic reservoirs and fault-nose structural reservoirs. Future exploration targets should be focused in the western storm dunes zone and eastern distributary channel sand zone with small fault-blocks.

准噶尔盆地中拐凸起东斜坡上乌尔禾组常规—致密油藏主控因素及成藏模式

准噶尔盆地中拐凸起东斜坡上乌尔禾组油气资源丰富,是效益勘探及建产的重要领域。应用测录井、生产测试及岩心分析化验资料,研究中拐凸起东斜坡上乌尔禾组储层特征,明确储层差异性的主控因素,建立中拐凸起东斜坡常规—致密油藏序次分布的成藏模式。结果表明:自北部向南部,研究区逐步由常规油藏转化为致密油藏,沉积作用是造成储层差异性的物质基础,控制储层岩性及原始物性,压实作用和浊沸石胶结作用加剧储层常规—致密差异演化;研究区成岩相带划分为泥质充填带、贫泥—弱胶结带、浊沸石胶结带和强压实—弱溶蚀带4种相带,其中贫泥—弱胶结带为有利储层发育带。该结果为研究区致密油藏勘探提供指导。

窄河道型致密砂岩储层特征及主控因素——以天府气田金华区块沙溪庙组为例

四川盆地天府气田金华区块沙溪庙组发育典型的窄河道型致密砂岩储层,具有低孔、低渗特征。基于详实的野外及岩心观察,结合薄片、扫描电镜及CT、核磁等分析测试,通过储层沉积微相、孔隙结构、成岩作用综合研究,阐明了储层发育主控因素。研究表明:1)天府气田沙二段沉积相以泛滥平原陆上河流相为主,河道微相储层物性最佳,河道窄而细,常呈北东—南西向展布;2)储层岩石类型主要为岩屑长石砂岩,石英体积分数由下向上有明显增加趋势,孔隙类型以残余原生粒间孔为主,其次为粒内溶孔;3)孔隙结构表现为低孔喉、低分选、强非均质性特征,根据压汞参数,储层类型可细分为3类;4)影响储层的主要成岩作用为胶结和溶蚀,胶结作用具有破坏和保护双重影响,既可通过方解石胶结减孔,又可通过绿泥石环边胶结抑制压实,“富长石”背景下的长石溶蚀作用有效改善了储层。研究认为,天府气田金华区块优质的高能窄河道砂体、中浅埋藏残余的规模原生孔隙、叠加绿泥石环边抗压实及长石规模溶蚀作用改善储层,三者共同形成“窄河道非连续甜点”的成储模式。该典型模式的建立为天府气田的可持续开发提供了重要的理论支撑。

柴达木盆地干柴沟地区古近系下干柴沟组上段页岩层系优势岩相及其控储因素

柴达木盆地干柴沟地区页岩油勘探近年获得重要突破,研究高原咸化湖盆岩相与储层特征对甜点识别具有重要意义。通过岩心和薄片观察、全岩矿物组成和原位微量元素分布测试、大面积视域扫描拼接成像、高压压汞与氮气吸附实验以及一维核磁共振分析,判识了岩相类型,系统研究了页岩储集性和含油性差异,提出了优势岩相和控储主因。研究结果表明:研究区储层有块状灰云岩(碳酸盐矿物含量>70%)、层状灰云岩(碳酸盐矿物含量50%~70%)、纹层状混积岩(碳酸盐矿物含量10%~50%)和断续状水平层理混积岩(碳酸盐矿物含量10%~50%)4种岩相。块状灰云岩和层状灰云岩孔隙以晶间孔为主,储集空间大且连通性好,孔隙中含油指数高,为优势岩相;纹层状混积岩基质孔隙发育较差,纹层密集发育的混积岩渗透性较好;断续状水平层理混积岩孔、缝不发育,储集性较差。优势岩相成储过程受3方面因素控制:①碳酸盐矿物组构决定宏孔发育程度;②陆源长英质细粒沉积物和黏土矿物含量控制比表面吸附性;③纹层发育程度最终改善储层渗透性能。

四川盆地东部上石炭统黄龙组规模储层形成主控因素与发育模式

石炭系黄龙组是四川盆地东部地区(以下简称川东地区)重要的天然气产层之一,石炭系储层是控制气藏发育的关键因素。为了深入评价川东地区黄龙组储层,拓展勘探新领域,寻找接替区,在前人研究的基础上,应用大量钻井、岩心、露头和分析化验等资料,系统研究了黄龙组储层发育的主控因素和发育模式,并预测规模储层的展布。研究结果表明:(1)黄龙组储集岩主要为颗粒白云岩、角砾白云岩和晶粒白云岩,储集空间主要为晶间孔/晶间溶孔、粒间溶孔/粒内溶孔、溶洞和裂缝,颗粒滩为有利储集体,裂缝-溶蚀孔洞型储层质量好;(2)储层发育主要受乐山—龙女寺古隆起和开江古隆起、沉积作用及成岩作用的共同控制,古隆起控制颗粒滩分布和准同生期成岩作用,是规模成储的基础,准同生期白云石化作用、层间岩溶和风化壳岩溶作用的叠加是形成规模储层的关键,喜马拉雅构造运动产生大量构造裂缝,提高了储层的渗滤性和规模性;(3)一定厚度和较大面积的Ⅰ—Ⅲ类储层可形成规模储层区,对5个规模储层发育区进行了评价,已发现气藏主要分布在这5个区域的背斜构造部位。结论认为,川东地区石炭系仍有较大的天然气勘探开发潜力,向斜区发育大面积的规模储层,是下一步天然气增储上产的重要方向。

川东北元坝地区上三叠统须家河组天然裂缝发育特征与主控因素

川东北元坝地区上三叠统须家河组致密砂岩储层物性较差,天然裂缝的发育改善了储层物性。天然裂缝是主要的储集空间和渗流通道,对天然气的运移、成藏和高产有着重要的影响。本文根据地表露头、岩心、薄片和成像测井等资料,对元坝地区须家河组天然裂缝成因类型及发育特征进行研究,并分析控制天然裂缝发育的主控因素。结果表明,研究区主要发育构造成因的低角度和高角度剪切裂缝,主要方位为NW-SE(300°±10°)和NEE-SWW(70°±5°)向,有效性好;裂缝充填程度较低,有效性好。构造部位、岩性和岩层厚度为影响裂缝发育的主要因素。鼻状构造部位及断层上升盘距离断层面400 m以内、垂直断距在60~120 m之间、北西向断层延伸线拐点附近为裂缝发育的有利部位,有利于天然气高产;中细粒石英砂岩和细粒长石岩屑砂岩中裂缝最为发育;高能量环境规模砂体(高石英含量,低泥质含量)更有利于裂缝发育;裂缝发育程度与岩层厚度呈明显的负相关关系,当岩层厚度小于1 m时,裂缝密度大,发育程度高。

川中龙女寺地区中二叠统茅口组储层特征及其主控因素

近年来,川中龙女寺地区JT1井和MX145井等多口钻井在中二叠统茅口组获得高产工业气流,展现出茅口组良好的勘探开发潜力,但由于储层特征及其发育主控因素不清楚,严重制约了龙女寺地区茅口组进一步的油气勘探。以川中龙女寺地区茅口组储层为对象,开展储层岩性、物性和孔喉结构等地质特征及地球化学特征研究,提出了川中龙女寺地区中二叠统茅口组优质储层主控因素。研究结果表明:(1)龙女寺地区茅口组储层岩性为白云岩及灰岩2类,晶粒白云岩、角砾白云岩和颗粒灰岩为主要储层岩石类型。白云岩储层可划分为3大类、6个亚类,灰岩储层可划分为4大类、5个亚类。(2)晶间孔、非选择性溶孔和溶洞为茅口组储层主要储集空间类型,裂缝-孔洞型储层的构造-溶蚀缝、洞体系储集空间大,分布广泛且连通性好,为有利储层。(3)茅口组储层具有“沉积作用-白云石化作用构建骨架,岩溶作用-构造作用叠加改造”的形成与发育模式。沉积作用、白云石化作用和构造作用是优质储层的主要控制因素,角砾白云岩为优质储集岩。

川中蓬莱气区龙王庙组储层特征及其与磨溪—高石梯地区对比

川中蓬莱气区下寒武统龙王庙组钻遇良好碳酸盐岩储层,天然气显示好,成为继川中地区安岳大气田后龙王庙组重点勘探区之一,但储层发育规律不明制约了勘探部署。基于最新的钻井及分析测试等资料,系统分析了蓬莱气区龙王庙组储层特征及主控因素。研究认为,蓬莱气区龙王庙组具有陆源碎屑与碳酸盐混合沉积背景,储层主要分布在龙王庙组中上部;储集岩石类型主要为(残余)颗粒白云岩和结晶白云岩;储集空间类型主要为粒间溶孔、粒内溶孔、晶间溶孔及微裂缝;以低孔低渗储层为主,储层厚度主要介于10~42 m之间。储层发育受控于层序地层、岩性及成岩作用等,进积型准层序组和准层序中上部的(残余)颗粒白云岩和结晶白云岩是储层发育主要部位,大气淡水溶蚀、油气溶蚀作用及破裂作用是核心建设性成岩作用。对比安岳大气田主体区磨溪—高石梯地区,认为储层主控因素相近,主要受颗粒白云岩、溶蚀作用、破裂作用等控制,但蓬莱气区龙王庙组储层具有灰质含量高、陆源碎屑含量多、准同生期暴露弱等特点,寻找准同生期暴露的高能颗粒白云岩和细晶白云岩及表生岩溶改造的白云岩是蓬莱气区重点关注的储层目标。

鄂尔多斯盆地环江地区长8_(1)亚段东西部储层对比研究

鄂尔多斯盆地环江地区三叠系延长组长8_(1)亚段东西部储层储集性能差异明显,造成环江地区东西部油藏富集规律不同。通过岩心观察、测井曲线对比、岩石薄片鉴定以及压汞曲线分析等方法,厘清了环江地区三叠系延长组长8_(1)亚段东西部储层基本特征,进而分析了研究区储层致密成因和东西部储层差异主控因素。结果显示:①环江地区长8_(1)亚段东西部储层以岩屑长石砂岩和长石岩屑砂岩为主,粒度西部粗于东部,储集空间类型以剩余原生粒间孔为主,次生长石溶孔次之,填隙物含量较高;②东西部物性差异明显,西部山城罗山川地区孔隙度和渗透率分别为10.71%、6.44 mD,发育低孔特低渗储层,有相当一部分地区能达到中孔低渗,东部大巴咀涝池口至洪德以东地区孔隙度和渗透率分别为5.63%、0.13 mD,基本为特低孔超低渗致密储层;③物源供给、沉积作用和古地形是研究区西部储层物性好于东部的先天地质因素,其中沉积作用和古地形控制着储层砂体厚度和空间展布等宏观特征,物源供给影响储层沉积岩石粒度大小分布和填隙物分布等微观特征。成岩作用是降低研究区东西部储层整体物性的关键因素。

松辽盆地北部下白垩统扶余油层源下致密油富集模式及主控因素

基于地球化学、地震、测井和钻井等资料,对松辽盆地北部下白垩统泉头组扶余油层地质特征、致密油富集主控因素及富集模式等进行系统分析。研究表明:①泉头组上覆上白垩统青山口组优质烃源岩,环凹鼻状构造发育,沉积砂体大面积连续分布,储层整体致密;②优质烃源岩、储层、断裂、超压和构造等多要素配置联合控制扶余油层致密油富集。源储匹配关系控制致密油分布格局;源储压差为致密油富集提供充注动力;断砂输导体系决定油气运移和富集;正向构造是致密油富集的有利场所,断垒带是向斜区致密油勘探重点突破区带;③基于源储关系、输导方式、富集动力等要素建立扶余油层致密油3种富集模式,一是源储对接油气垂向或侧向直排式:“源储紧邻、超压驱动、油气垂向倒灌或源储侧向对接运聚”;二是源储分离断裂输导式:“源储分离、超压驱动、断裂输导,油气通过断层向下运移到砂体富集”;三是源储分离断砂匹配式:“源储分离、超压驱动、断裂输导、砂体调整、油气下排后通过砂体侧向运移富集”;④油源条件、充注动力、断裂分布、砂体以及储层物性等方面的差异性造成扶余油层致密油的差异富集,齐家—古龙凹陷扶余油层具有较好富集条件,勘探程度低,是未来致密油探索重要新区带。

延安气田上古生界山西组致密砂岩储层微观特征及主控因素

延安气田主力气层上古生界山西组储层非均质性较强,物性较差,属于典型的致密砂岩气藏,勘探有利区预测及气藏开采难度较大。为明确储层低孔低渗成因及发育主控因素,通过岩心薄片、扫描电镜、全岩X衍射等多种实验分析,按塑性颗粒含量差异性,将山西组致密砂岩划分为5种岩石相,以相控指导建模,应用三维地质建模软件进行岩石相随机建模。结果表明:沉积相、水动力条件及成岩作用共同影响砂岩孔隙的发育及储集性能;塑性物质机械压实是造成储层物性差的根本原因;纯石英砂岩与富石英低塑性颗粒岩屑砂岩孔隙发育、物性较好,为有效储层,其主要发育于水动力较强的水下分流河道与河口坝微相的中下部。通过岩石相建模能更好地认识岩石相三维空间分布规律,提高有效储层分布预测精度,对延安气田精细开采具有指导意义。

柴西南区岩性油气藏地质特征及控制因素

近年来,柴达木盆地在咸化湖相滩坝砂中发现了多个“小而肥”的岩性油气藏。为了拓展岩性油气勘探规模、发现新的目标及区带,支撑油田规模增储上产,利用岩心、测井和地震资料,开展岩性油气藏成藏条件综合分析。通过解剖已发现岩性油气藏特征,明确控制因素,指出了岩性油气藏勘探接替领域。结果表明,柴西南区具备形成岩性油气藏的四大有利条件:一是发育继承性的七个泉—红柳泉、砂西—跃进、扎哈泉—乌南三大稳定的古斜坡,利于油气聚集成藏;二是临近红狮和扎哈泉两个生烃中心,油源条件优越;三是咸化湖盆发育大型辫状河三角洲、广覆式分布的滨浅湖滩坝砂及藻席—灰云坪沉积,形成碎屑岩和碳酸盐岩两种互补型的储集体;四是发育多种疏导体系,纵向上可以形成多套含油层系。受古构造、沉积、成岩等多因素控制,柴西南区发育砂岩上倾尖灭型、砂岩透镜体型、物性封堵型和白云石化成岩圈闭四种类型岩性油气藏。岩性油气藏受古构造、优质源岩和有效储层三因素控制。古构造决定岩性圈闭的类型和油气运移方向;优质烃源岩控制岩性油气藏的分布及规模;有效储层控制岩性油气藏的富集。综合评价指出,辫状河三角洲前缘砂体是古近系下干柴沟组下段岩性勘探的有利区,主要分布在砂西、尕斯、乌南向盆内的倾末端;白云石化成岩圈闭是古近系下干柴沟组上段岩性勘探的有利区,主要分布在环红狮凹陷周缘;广覆式分布滩坝是新近系上干柴沟组、下油砂山组岩性油气藏勘探的有利区,主要分布在英雄岭、尕斯、扎哈泉、乌南等地区。这一认识支撑了切探2井、尕斯新层系等岩性勘探获得一系列重大突破,可为柴西南区岩性油气藏的下一步勘探提供指导。

鄂尔多斯盆地东南部长7段页岩油气富集主控因素

为明确鄂尔多斯盆地东南部长7段页岩油气富集主控因素,综合钻井、测井、岩心分析化验等资料,对研究区长7段页岩油气富集程度及其机理进行研究。页岩解析气量与烃源岩总有机碳含量呈正比,有机质含量控制页岩油气的总含量,有机质发育大量孔隙,页岩油气以吸附态和游离态赋存于有机孔隙中。储集层孔隙结构和孔隙度影响页岩油气的含量及赋存状态,吸附油气主要赋存于微孔中,游离油气主要赋存于中孔和大孔中,但中孔中游离气含量高于大孔,而孔隙度越大,页岩中油气绝对含量越高。砂岩夹层和富有机质页岩的配置关系控制着页岩油气的富集部位,根据粉砂岩、细砂岩与页岩的关系,延长组长7段页岩油气可划分为近源和源内2类,源内又可分为砂岩与页岩互层型、页岩夹砂岩型和页岩型;下伏于富有机质页岩中的砂体和透镜状砂体油气含量最高,其次是上覆于富有机质页岩的砂体和呈舌状或指状与富有机质页岩接触的砂体。