川中—川西须家河组三段致密砂岩储集层分类及成因

四川盆地中部和西部(川中—川西)上三叠统须家河组岩石组分复杂、孔喉结构非均质强,含气和产能平面变化快,亟需明确储集层分类标准、发育机制及分布规律。以须家河组三段致密砂岩为对象,通过薄片、物性、压汞和核磁共振等实验,分析微观孔隙结构,建立储集层分类评价标准,揭示岩石组分、成岩作用对储集层类型的控制。研究表明,须三段发育微裂缝、原生粒间孔、残留粒间孔、溶蚀孔和晶间孔5类储集空间,粒间孔喉发育程度是决定储集层品质的关键;基于分形特征,将孔喉系统划分为5个区间,结合中大孔喉占比、主流喉道等参数,实现4类致密储集层的精细划分;I类储集层具有“弱压实强溶蚀”特征,高石英颗粒、低泥岩和碳酸盐岩岩屑、适量火山岩岩屑是形成的关键,Ⅱ类储集层具有“强压实强溶蚀”特征,较多杂基、低泥岩岩屑、高长石颗粒是形成的物质基础,Ⅲ类和Ⅳ类储集层均具有强胶结特征,其中Ⅲ类储集层中钙质岩屑含量高,方解石胶结发育,Ⅳ类储集层杂基减孔明显。研究成果可指导该区致密储集层形成机制研究,也为致密储集层分类和成因关联分析提供一定借鉴。

砂岩夹层储层分级评价及展布特征——以松辽盆地长岭凹陷大情字井地区青山口组一段为例

松辽盆地南部青山口组一段夹层型页岩油具有良好的勘探潜力,其夹层品质对含油性及产能影响大。然而,夹层物性呈现较强的非均质性,急需对夹层储层进行表征与描述,建立一套适合夹层储层的分级方案。通过场发射扫描电镜、高压压汞、核磁共振等实验对储层进行表征,基于压汞分形理论,建立适用于砂岩夹层的储层物性分级标准,结合测井资料对储层物性参数进行预测,进而刻画夹层优质储层平面展布。研究表明:根据源岩成熟度的差异,松辽盆地南部大情字井青一段可分为低熟区(R_(o)<1.0%,R_(o)为镜质体反射率)和中高熟源岩区(R_(o)>1.0%),夹层物性随烃源岩成熟度增大而变差。根据储层物性差异特征,分区块建立了夹层物性分级标准,将砂岩夹层分为Ⅰ—Ⅲ类和无效储层;由Ⅰ类储层到无效储层的大孔含量和中孔含量依次变少,储集空间由粒间孔、粒间溶蚀孔过渡至粒内溶蚀孔和晶间孔;压汞形态由弱平台型、缓直线型过渡至上凸状,储层含油性逐渐变差。优质夹层“甜点”主要沿着河口坝主体、水下分流河道等沉积微相分布,厚度自西南向东北方向减薄。研究成果为该区青山口组一段夹层型页岩油“甜点”优选提供重要支撑。

中国典型陆相盆地致密油成储界限与分级评价标准

基于松辽盆地下白垩统泉头组和上白垩统青山口组砂岩、准噶尔盆地玛湖地区下三叠统百口泉组砂砾岩和吉木萨尔凹陷二叠系芦草沟组混积岩等中国典型陆相盆地致密储集层微观孔喉表征结果,利用水膜厚度法、含油产状法、试油产能法、力学平衡法对致密油的理论下限、成藏下限、有效渗流下限和成储上限进行厘定;采用聚类分析法对比不同致密储集层孔喉结构差异,确定致密储集层分级界限,并分析与成储界限之间的关联。结果表明,致密储集层与常规储集层的分级界限对应物性上限,Ⅱ类与Ⅲ类致密储集层的分级界限对应有效渗流下限,Ⅲ类与Ⅳ类致密储集层的成储界限对应成藏下限,理论下限对应致密储集层和非储集层的界限。分级评价标准实际应用结果显示,致密油产量受控于致密储集层类型,Ⅰ类和Ⅱ类致密储集层是致密油高产的有利层段。图8表3参37。

准噶尔盆地吉木萨尔凹陷混积岩孔喉系统分类及控制因素

针对混积岩优质储集层成因复杂的难题,进行准噶尔盆地吉木萨尔凹陷二叠系芦草沟组混积岩孔喉系统、控制因素及流体可动性研究。结果表明,混积型储集层发育粒间孔喉系统(A型)、粒间-溶蚀-晶间混合孔喉系统(B型)、溶蚀孔喉系统(C型)、溶蚀-晶间混合孔喉系统(D型)和晶间孔喉系统(E型)5类。混积岩孔喉系统有3个主要主控因素:混积岩组分含量及排列方式、沉积环境和成岩作用。混积岩组分含量及排列方式控制孔喉系统类型及变化;沉积环境主要控制孔喉系统的宏观分布,近源、高能环境混积岩粗粒组分多,颗粒或互层型支撑,发育A型和B型孔喉;远源、中能环境混积岩过渡为云泥支撑,发育C型和D型孔喉;而远源、低能环境混积岩孔喉主要为E型和D型。压实和方解石胶结等成岩作用进一步破坏粒间、溶蚀孔喉占比。在砂泥混积时,孔喉系统类型为“A→B→C→D”变化,云砂混积时孔喉系统类型为“A→C→D→E”、或“B→D→E”变化,云泥混积时孔喉系统类型为“D→E”的变化,细节受偏砂粒、长石和白云石含量影响。其中,A型孔喉的物性及可动性最好,D型和E型最差;可动流体分布与支撑方式有关,云泥支撑型混积岩大孔可动优势不明显。研究成果为混积型储集层甜点评价及解释模型的合理构建提供了地质依据。图15表1参19。

海相高成熟页岩气储层孔隙连通关系——以彭水地区龙马溪组为例

孔隙连通关系影响着页岩气的渗流及产出程度,但对页岩连通关系的研究还相对薄弱。以彭水地区五峰—龙马溪组页岩气层为例,通过多种实验手段刻画页岩的连通孔隙组合类型,分析孔喉连通关系。研究发现,页岩储层发育有机孔相互连通、有机孔—微裂缝连通、有机孔—黏土孔连通和黏土孔—晶间孔连通4类组合关系。以有机孔相互连通组合为主的富有机质页岩,符合短导管状孔喉组合模式,孔喉比最小;而以有机孔—黏土孔相互连通组合为主的中、贫有机质页岩,为短导管和树形孔隙复合模式,孔喉比较大。当TOC(有机碳含量)/黏土矿物含量比值减小时,树形孔隙比例增多,孔喉比也会变小。小孔喉比和高含量的有机孔相互连通孔隙组合,有利于减弱压裂液滞留产生的水锁伤害。

吉木萨尔凹陷芦草沟组页岩油录井响应及“甜点”快速评价技术

混积型页岩油岩性复杂、矿物类型多、“甜点”横向变化快,常规测井对岩性、物性及含油性响应不敏感,而核磁测井需要岩石物理实验标定,解释周期长,尚缺乏有效的现场“甜点”快速评价技术。针对上述问题,以准噶尔盆地吉木萨尔凹陷芦草沟组页岩油储层为例,以核磁测井解释为依据,研究气测、碳酸盐矿物、钻时等录井资料对混积型页岩油岩性、物性和含油性的响应特征,明确内在联系,优选敏感参数,实现页岩油储层参数和“甜点”的快速评价。研究表明:混积型页岩油岩性、物性及含油饱和度在录井资料上均有明显响应,其中,碳酸盐含量和白云石占比能有效反映粉砂岩、云质粉砂岩、砂屑白云岩、泥晶白云岩和云质灰岩等主要岩性,碳酸盐含量、全烃/钻时对孔隙度反映敏感,碳酸盐含量、湿度比和全烃对含油饱和度敏感。基于录井敏感参数的孔隙度和含油饱和度解释模型,精度可达71.0%,与核磁测井相比,Ⅰ类油层“甜点”识别率超90%,能够实现随钻过程中页岩油“甜点”的快速准确评价。研究成果对提高混积型页岩油水平井“甜点”钻遇率及降本增效有指导意义。

高—过成熟陆相断陷盆地页岩与海相页岩储层特征对比——以徐家围子断陷沙河子组和四川盆地龙马溪组为例

我国陆相断陷盆地含气页岩发育广泛,以往主要作为气源岩研究,对其储集性及影响因素的研究较少,亟须开展相应研究来明确陆相断陷盆地页岩储层发育主控因素。选取松辽盆地徐家围子断陷沙河子组与四川盆地龙马溪组页岩,利用有机地化、全岩分析、扫描电镜、低温氮气吸附和核磁共振等实验,对比研究高—过熟陆相断陷盆地和海相含气页岩储层特征差异并探讨主控因素。研究表明:沙河子组页岩形成环境多样,有机质类型以Ⅲ型(腐殖型)为主,黏土矿物含量高,胶结石英发育,黏土相关孔和石英粒间孔为主要孔隙类型,比表面积小但孔径大,储层发育受压实作用、黏土矿物转化和煤层发育的控制;龙马溪组页岩形成于陆棚环境,有机质类型以I型(腐泥型)为主,有机质丰度高,生物成因石英含量高,有机孔和黏土相关孔为主要孔隙类型,有机质类型和成熟度主控孔隙发育。整体上,沙河子组页岩储层发育条件稍差于龙马溪组,但平原沼泽微相页岩紧邻煤层发育,自生胶结石英发育、伊蒙混层比例高,储层有机质丰度高、可压性好、孔体积和比表面积较大、孔隙发育较好,可作为潜在有利目标开展进一步评价研究。

海相页岩气储层孔隙表征、分类及贡献

以渝东南彭水地区五峰组-龙马溪组页岩气为例,开展低温二氧化碳吸附(LTCA)、氮气吸附(LTNA)、核磁共振(NMR)、压汞、扫描电镜以及氦测孔隙度等孔隙表征实验,全面刻画页岩孔隙结构,建立全孔径表征及分类方法,研究它们在页岩气赋存和渗流等方面的差异贡献。结果表明,氦测孔体积最大;其次为LTNA和NMR,两者分别在刻画较小孔(<10nm)和较大孔方面优势明显,联合二者可表征页岩全孔径分布。全孔径分布揭示页岩气孔隙分布范围宽,但70%孔体积集中在孔径小于25 nm。结合分形特征,以5,25和100 nm为界,将其划分为微孔、小孔、中孔和大孔。微孔、小孔和中孔主要受有机质含量和粘土矿物含量的影响;此外,中孔还受粒内溶蚀孔的影响,而大孔主要由粒间孔和粘土层间缝构成。微孔和小孔分别为页岩吸附气、游离气提供主要场所;小孔和中孔相互连接,为页岩气在基质中渗流提供通道。研究成果对页岩气储层分类、渗流机理认识等具有指导意义。

吉木萨尔凹陷芦草沟组混积型页岩油可动性实验

为确定吉木萨尔凹陷芦草沟组页岩油藏储集层孔喉结构及其原油可动性,利用薄片、扫描电镜、高压压汞等划分储集层;通过驱替与核磁共振联测实验,开展页岩油可动性评价,揭示可动油占比、孔径变化规律及其控制因素,建立页岩油可动性定量评价模型。芦草沟组发育粒间孔型、粒间-溶蚀-晶间孔型、溶蚀孔型、溶蚀-晶间孔型和晶间孔型5类储集空间。粒间孔型发育在粉—细砂岩相和砂质白云岩相中,可动性最好;溶蚀孔型主要发育在白云质粉砂岩相中,可动性中等;其他类型主要发育在泥岩相、泥质白云岩相和石灰质砂岩相中,可动性稍差。厘定页岩油可动孔喉下限为20 nm,可动性明显提高的孔喉界限为60 nm和150 nm,试油产能与之对应较好。页岩油赋存特征和孔喉结构共同影响页岩油可动性,粉—细砂岩相和白云质粉砂岩相的孔喉及页岩油赋存均最佳,为芦草沟组页岩油最有利开发岩相。

渝东南地区龙马溪组页岩储层非均质性控制因素

非均质性是页岩储层内在的、固有的属性,根据测量尺度和方法的不同可进步划分为微观和宏观非均质性。微观非均质性主要是指借助于实验手段所测量的页岩储层微—纳米尺度的非均质性,例如孔隙大小、分布、连通性等,而宏观非均质性般表现为厘米及以上尺度,主要依赖于地震、测井和岩心观察等手段。尽管前人已经对页岩储层岩相、含气性、沉积环境、孔隙结构等宏微观性质开展了研究(王玉满等,2016).

联合高压压汞和核磁共振分类评价致密砂岩储层--以鄂尔多斯盆地临兴区块为例

致密砂岩气藏储层的孔渗关系通常都较差,沿用常规的储层分类方案难以满足该类储层分类评价的需要。为此,以鄂尔多斯盆地东缘临兴区块二叠系致密砂岩气藏为例,借助高压压汞、核磁共振和扫描电镜等多种手段,刻画致密砂岩储层微观结构,研究微观结构参数对宏观物性的控制作用,进而在此基础上开展致密砂岩储层分类评价。研究结果表明:(1)核磁共振能够识别不同大小的孔隙分布,高压压汞能够反映储层的孔喉配置关系及渗流能力;(2)两种手段刻画结果吻合较好,随T2谱右峰比例的增加,进汞曲线呈现下凹形、孔喉半径增大,孔隙类型由粒内溶蚀孔和晶间孔逐渐过渡为粒间孔和粒间溶蚀孔,储层品质变好;(3)微观孔隙结构控制储层物性及流体可动性,大孔的孔隙度和有效孔隙度的相关性最佳,大孔孔隙度可用于评价致密砂岩的储集能力;(4)高压压汞获得的孔喉半径R15与孔隙度、渗透率相关性最佳,可用于评价致密砂岩的渗流能力;(5)综合大孔孔隙度和R15将临兴区块致密砂岩储层分为4类,分类结果与现场试气结果吻合度较高。结论认为,高压压汞和核磁共振两种方法相结合,能够有效识别反映致密砂岩储集能力和渗流能力的关键参数,提高储层分类的可靠性和完整性;通过优选反映储集能力和渗流能力的关键参数,可以指导致密砂岩储层的分类评价。

致密气充注聚集机理及数理模型

致密气的气-水分布和产出非均质性虽已从实验和地质观察角度总结了相应认识规律,但一直缺少定量的数理模型揭示其聚集机理。从驱替-核磁物理模拟、考虑物质平衡和力学平衡的数值模拟以及实际地质观察3方面论证致密气充注聚集机理,结果显示致密气充注聚集时会在源-储界面附近优先形成含气饱和度稳定带,气源不足时,从源-储界面起,依次形成含气饱和度降低带和未充注带。源岩条件越好,排气量越多、超压越大,致密储集层含气饱和度稳定带和降低带越厚,整体含气饱和度越高;源岩条件有限时,致密储集层条件越好,孔渗越高、孔喉越大,含气饱和度稳定带和降低带厚度越薄,但含气饱和度高。致密气“甜点”有利层段发育在靠近源岩的优质储集层中,对应含气饱和度稳定带。基于数理模型的数值模拟结果很好地吻合了驱替-核磁物理模拟结果,并合理解释了松辽盆地徐家围子断陷深层和鄂尔多斯盆地临兴—皇甫致密气区的气-水分布和产出规律。

Investigation of mechanical properties of bedded shale by nanoindentation tests: A case study on Lower Silurian Longmaxi Formation of Youyang area in southeast Chongqing, China

The mechanical properties such as Young's modulus, hardness and fracture toughness of Lower Silurian Longmaxi shale samples from Youyang area in southeast Chongqing, China were investigated using dot matrix nanoindentation measurements. With the help of field emission scanning electron microscope(FESEM) and energy dispersive X-ray fluorescence spectroscopy(EDS), the indentation morphology and mineral composition in indentation area were quantitatively analyzed. According to mechanical strength classification, a micromechanical model with three components was introduced and the Mori-Tanaka model was used to upscale mechanical parameters from nano-scale to centimeter-size scale, which were further compared with uniaxial compression results. The experimental results show that there is a positive linear correlation between Young's modulus and hardness and between the Young's modulus and the fracture toughness under nano-scale; the Young's modulus, hardness and fracture toughness perpendicular to the bedding are slightly lower than those parallel with the bedding. According to data statistics, the mechanical properties at the nano-scale follow Weibull distribution feature and the dispersion degree of hardness results is the highest, which is mainly due to shale anisotropy and nanoindentation projection uncertainty. Comparing the results from nanoindentation test, with those from upscaling model and uniaxial compression test shows that the mechanical parameters at the nano-scale are higher than those from upscaling model and uniaxial compression test, which proves mechanical parameters at different scales have differences. It's because the larger the core, the more pores and internal weakness it contains, the less accurate the interpreted results of mechanical parameters will be.

Tight gas charging and accumulation mechanisms and mathematical model

The gas-water distribution and production heterogeneity of tight gas reservoirs have been summarized from experimental and geological observations, but the charging and accumulation mechanisms have not been examined quantitatively by mathematical model. The tight gas charging and accumulation mechanisms were revealed from a combination of physical simulation of nuclear magnetic resonance coupling displacement, numerical simulation considering material and mechanical equilibria, as well as actual geological observation. The results show that gas migrates into tight rocks to preferentially form a gas saturation stabilization zone near the source-reservoir interface. When the gas source is insufficient, gas saturation reduction zone and uncharged zone are formed in sequence from the source-reservoir interface. The better the source rock conditions with more gas expulsion volume and higher overpressure, the thicker the gas saturation stabilization and reduction zones, and the higher the overall gas saturation. When the source rock conditions are limited, the better the tight reservoir conditions with higher porosity and permeability as well as larger pore throat, the thinner the gas saturation stabilization and reduction zones, but the gas saturation is high. The sweet spot of tight gas is developed in the high-quality reservoir near the source rock, which often corresponds to the gas saturation stabilization zone. The numerical simulation results by mathematical model agree well with the physical simulation results by nuclear magnetic resonance coupling displacement, and reasonably explain the gas-water distribution and production pattern of deep reservoirs in the Xujiaweizi fault depression of the Songliao Basin and tight gas reservoirs in the Linxing-Huangfu area of the Ordos Basin.

Lower Limits and Grading Evaluation Criteria of Source Rocks and Reservoirs of Tight Oil and Gas

1 Introduction The importance of the unconventional petroleum is increasingly prominent, with the rising demand of oil and gas in the economic and social development and the gradual consumption and depletion of conventional oil and gas resources. Compared with the shale and coal-bed gas reservoir, tight reservoir has better fracturing capability.

Present Situation of Core Mercury Injection Technology of Unconventional Oil and Gas Reservoir

Unconventional oil and gas step into a new area of global oil and gas exploration due to the success of the development of shale gas of America.

Limits and grading evaluation criteria of tight oil reservoirs in typical continental basins of China

Based on the microscopic pore-throat characterization of typical continental tight reservoirs in China,such as sandstone of Cretaceous Qingshankou and Quantou formations in Songliao Basin,NE China sandy conglomerate of Baikouquan Formation in Mahu area and hybrid rock of Lucaogou Formation in Jimusaer sag of Junggar Basin,NE China the theoretical lower limit,oil accumulation lower limit,effective flow lower limit and the upper limit of tight oil reservoirs were defined by water film thickness method,oil bearing occurrence method,oil testing productivity method and mechanical balance method,respectively.Cluster analysis method was used to compare the differences in pore-throat structure of different tight reservoirs,determine the grading criterion of tight reservoirs,and analyze its correlation with the limit of reservoir formation.The results show that the boundary between tight reservoir and conventional reservoir corresponds to the upper limit of physical properties,the boundary of classⅡand classⅢtight reservoirs corresponds to the lower limit of effective flow,the boundary of classⅢand classⅣtight reservoirs corresponds to the lower limit of reservoir forming,and the theoretical lower limit of tight reservoir corresponds to the boundary between tight reservoir and non-reservoir.Finally,the application results of the grading evaluation criterion show that the tight oil productivity is highly controlled by the type of tight reservoir,and classⅠand classⅡtight reservoirs are the favorable sections for high production of tight oil.

Classification and control factors of pore-throat systems in hybrid sedimentary rocks of Jimusar Sag, Junggar Basin, NW China

Aiming at the complicated problem of the genesis of high-quality hybrid sedimentary rocks,the pore-throat systems,controlling factors and fluid mobility of hybrid sedimentary rocks in the Permian Lucaogou Formation in Jimusar Sag were examined.The results show that the hybrid sedimentary rocks contain 5 types of pore-throat system,intergranular(Type A),mixed intergranular-dissolved-intercrystalline(Type B),dissolved(Type C),mixed dissolved-intercrystalline(Type D)and intercrystalline(Type E)ones.The pore-throat systems are controlled by 3 major factors,the component content and arrangement(CCA)of hybrid sedimentary rocks,sedimentary environment and diagenesis.CCA controls the matrix support mode of hybrid sedimentary rocks,and therefore controls the types and changes of pore-throat system.The sedimentary environment mainly controls the macroscopic distribution of pore-throat system,i.e.,hybrid sedimentary rocks deposited in the near source and high-energy environment are characterized by high content of coarse-grained component,granular/interbedded-support mode,and development of Type A and Type B pore-throat systems.Hybrid sedimentary rocks deposited in the medium-energy environment far from source are characterized by dolomitic/mud support mode and Type C and Type D pore-throat systems.Hybrid sedimentary rocks deposited in low-energy environment far from source have mainly Type E and Type D pore-throat systems.Diagenetic processes such as compaction and calcite cementation make the proportions of Type A and Type C pore-throat systems decrease further.In the hybrid sedimentary process of sandy-mud,pore-throat system types show a change of"A→B→C→D",in that of dolomite-sand,pore-throat system types show a change of"A→C→D→E"or"B→D→E",and in that of dolomite-mud,pore-throat system types show a change of"D→E",which are affected in details by the contents of coarse-grain component,feldspar and dolomite.The reservoir with Type A pore-throats has the best physical properties and fluid mobility,and the reservoirs with Type D and Type E pore-throats have the poorest.The movable fluid distribution is related to the matrix support mode,and the larger pores in hybrid sedimentary rocks of dolomite/mud support mode have no obvious advantage in fluid mobility.The findings of this study provide a geological basis for evaluating and building reasonable interpretation model of hybrid sedimentary rocks sweet spot.

Application of NMR on Quantificational Characterization of Tight Glutenite Reservoirs Pore Size

Quantificational characterization of the microscopic pore structure is the key to evaluating tight reservoirs. Since tight reservoirs mainly develop nano-pores which are difficult to fully characterize pore throats＇ distribution by single conventional experimental method, there＇s an urgent need to establish a characterization method by jointing several conventional experimental methods.

Prediction of Total Organic Carbon Content Based on Geostatistical Inversion:A Case of Qingshankou Formation in Wangfu Depression,Songliao Basin

Currently, there are two main methods to obtain total organic carbon （TOC） content in mud shale geochemical analysis and AlgR model. Geochemical analysis can obtain accurate TOC content, but it has the problem of higher cost and less samples. The AlgR model can obtain TOC content variable values in well profile conveniently and quickly, but it can＇t predict TOC content in mud shale in cross-hole area. Both the methods can＇t meet the needs of resources evaluation of shale oil in the back ground of strong organic heterogeneous in mud shale.