Organic matter enrichment model of fine-grained rocks in volcanic rift lacustrine basin:A case study of lower submember of second member of Lower Cretaceous Shahezi Formation in Lishu rift depression of Songliao Basin,NE China

Based on sedimentary characteristics of the fine-grained rocks of the lower submember of second member of the Lower Cretaceous Shahezi Formation(K_(1)sh_(2)^(L))in the Lishu rift depression,combined with methods of organic petrology,analysis of major and trace elements as well as biological marker compound,the enrichment conditions and enrichment model of organic matter in the fine-grained sedimentary rocks in volcanic rift lacustrine basin are investigated.The change of sedimentary paleoenvironment controls the vertical distribution of different lithofacies types in the K_(1)sh_(2)^(L)and divides it into the upper and lower parts.The lower part contains massive siliceous mudstone with bioclast-bearing siliceous mudstone,whereas the upper part is mostly composed of laminated siliceous shale and laminated fine-grained mixed shale.The kerogen types of organic matter in the lower and upper parts are typesⅡ_(2)–Ⅲand typesⅠ–Ⅱ_(1),respectively.The organic carbon content in the upper part is higher than that in the lower part generally.The enrichment of organic matter in volcanic rift lacustrine basin is subjected to three favorable conditions.First,continuous enhancement of rifting is the direct factor increasing the paleo-water depth,and the rise of base level leads to the expansion of deep-water mudstone/shale deposition range.Second,relatively strong underwater volcanic eruption and rifting are simultaneous,and such event can provide a lot of nutrients for the lake basin,which is conducive to the bloom of algae,resulting in higher productivity of typesⅠ–Ⅱ_(1)kerogen.Third,the relatively dry paleoclimate leads to a decrease in input of fresh water and terrestrial materials,including TypeⅢkerogen from terrestrial higher plants,resulting in a water body with higher salinity and anoxic stratification,which is more favorable for preservation of organic matter.The organic matter enrichment model of fine-grained sedimentary rocks of volcanic rift lacustrine basin is established,which is of reference significance to the understanding of the organic matter enrichment mechanism of fine-grained sedimentary rocks of Shahezi Formation in Songliao Basin and even in the northeast China.

Accumulation and exploration of continental shale gas resources of Cretaceous Shahezi Formation in Lishu fault depression,Songliao Basin,NE China

Distribution characteristics,organic matter development characteristics,gas-bearing characteristics,reservoir characteristics,and preservation conditions of the Shahezi Formation shale of Lower Cretaceous in the Lishu fault depression,Songliao Basin,NE China,are analyzed using organic geochemical,whole rock,and SEM analysis data,and CO_(2)and N_(2) adsorption and high-pressure mercury injection experiment data in combination with the tectonic and sedimentation evolution of the region to reveal the geological conditions for enrichment and resource potential of continental shale gas.The organic-rich shale in the Lower Cretaceous of the Lishu fault depression is mainly developed in the lower submember of the second member of the Shahezi Formation(K_(1)sh_(2)^(1) Fm.)and is thick and stable in distribution.The shale has high TOC,mainly types II_(1) and II_(2) organic matter,and is in the mature to the over-mature stage.The volcanic activity,salinization,and reduction of the water environment are conducive to the formation of the organic-rich shale.The shale reservoirs have mainly clay mineral intergranular pores,organic matter pores,carbonate mineral dissolution pores,and foliated microfractures as storage space.The pores are in the mesopore range of 10–50 nm,and the microfractures are mostly 5–10μm wide.Massive argillaceous rocks of lowland and highstand domains are deposited above and below the gas-bearing shale separately in the lower submember of the K_(1)sh_(2)^(1) Fm.,act as the natural roof and floor in the process of shale gas accumulation and preservation,and control the shale gas enrichment.Based on the above understandings,the first shale gas exploration well in Shahezi Formation was drilled in the Lishu fault depression of Songliao Basin.After fracturing,the well tested a daily gas production of 7.6×10^(4) m^(3),marking a breakthrough in continental shale gas exploration in the Shahezi Formation(K1 sh Fm.)of the Lishu fault depression in Songliao Basin.The exploration practice has reference significance for the exploration of continental shale gas in the Lower Cretaceous of Songliao Basin and its periphery.

Factors controlling the formation and evolution of source rocks in the Shahezi Formation,Xujiaweizi fault depression,Songliao Basin

The types and quality of source rocks in the Shahezi Formation are the key factors affecting the distributions of various deep gas reservoirs in the Xujiaweizi fault depression in Songliao Basin.To clarify the quality differences and origins of different types of source rocks in the Shahezi Formation,this study reconstructed the sedimentary and water environment,determined the controlling effects of fault activity,sedimentary facies,and paleo-sedimentary environment on the quality of various source rocks,by making full use of seismic,logging,core,organic geochemical and element geochemical analysis.The results show that two types of source rocks developed in the Shahezi Formation,namely,mudstones and coals.The mudstones have a relatively high abundance of organic matter,which consists of type-Ⅱ kerogen and partial type-Ⅲ kerogen,and are concentrated in Sha-I Member.The coals have a high abundance of organic matter,which consist of type-Ⅲ kerogen,and are mainly distributed in Sha-Ⅱ Member.During the deposition of Sha-I Member,intense fault activity formed arrow,deep-water lacustrine basins with high salinity and strong reducibility on the downthrow sides of faults.During the deposition of Sha-II Member,fault activity progressively weakened,and the areas of lacustrine basins enlarged to their maximum values and became wide,shallow-water basins with low salinity and low reducibility.The development of source rocks was controlled by fault activity,sedimentary facies,and paleo-sedimentary environment.Fault activity formed accommodation space on the downthrown sides of faults for mudstone accumulation,thus determining mudstone thickness.The sedimentary environment controlled the organic matter input and determined the distribution of mudstones and coals.The paleo-sedimentary environment,which consisted of paleo-salinity,as well as paleo-water depth and redox conditions,affected the accumulation and preservation of organic matter and is the main controlling factor for the quality difference of various source rocks in the Shahezi Formation.

Origin and Evolution Process of Overpressure in the Shahezi Formation of Xujiaweizi Fault Depression in the Northern Songliao Basin,NE China

It is of great significance for deep oil and gas exploration to understand the origin and evolution behind overpressure.Overpressure occurs in the deep Shahezi Formation of Xujiaweizi fault depression.However,due to limited degree of exploration,there are some problems in the study area,such as unclear understanding of the origin of overpressure and the vague investigation of overpressure evolution.To clarify the impact of overpressure on oil and gas migration and accumulation in the study area,this study focuses on the research of the origin and evolution of overpressure in the Shahezi Formation of the study area,utilizing single well logging parameters and combining methods such as microthermometry of fluid inclusions,laser Raman spectrum,and basin simulation.The results show that the overpressure of the Shahezi Formation in Xujiaweizi fault depression is primarily generated by hydrocarbon generation pressurization,and the evolution of overpressure is closely related to hydrocarbon generation.The development of overpressure can be divided into two evolutionary stages:early hydrocarbon generation pressurization and late uplift release,with slight variations in different regions.Tight glutenite gas reservoirs in the Shahezi Formation are characterized by continuous charging.The overall charging period ranges from the late Denglouku to the early Mingshui(110-67 Ma ago).There is an obvious paleo-overpressure during the gas reservoir formation period.The gas generation period of source rocks occurred approximately 125-60 Ma ago,and the main gas generation period(112-67 Ma ago)highly coincides with the period of natural gas charging.The anomalously high pressure during the accumulation period is considered the significant driving force for natural gas charging.In addition,the sustained effect of overpressure provides better conditions for the preservation of tight gas reservoirs within the source.The results of the study are of guiding significance for the in-depth exploration and development of deep tight sandstone gas in the Shahezi Formation of Xujiaweizi fault depression.

松辽盆地徐家围子断陷白垩系沙河子组超压形成机制及其演化特征

综合利用钻井、测井、压力测试以及分析化验等资料,对松辽盆地徐家围子断陷白垩系沙河子组现今超压特征及形成机制进行了分析,采用数值模拟方法对不同构造单元、不同岩性烃源岩超压的演化进行了定量恢复,并对超压贡献率进行了计算。研究结果表明:①徐家围子断陷白垩系沙河子组现今为常压-弱超压系统,凸起区超压最大;烃源岩超压以生烃增压作用为主,其次为欠压实作用,而储层超压为烃源岩超压对其的超压传递造成,与断裂及背斜的形成和发育密切相关。②研究区沙河子组烃源岩超压主要为煤层和富有机质泥岩的生烃增压作用,通常煤层生烃增压贡献率最大,富有机质泥岩次之,贫有机质泥岩超压较低,而生烃凹陷及周缘富有机质泥岩生烃增压贡献率高于煤层;凹陷区烃源岩生烃增压贡献率高于斜坡带和凸起区。③研究区沙河子组超压的演化可分为3个阶段,白垩纪早—中期为缓慢增压阶段,烃源岩因欠压实作用和缓慢生烃作用产生超压,经沙河子组—营城组沉积期活动性断裂和背斜传递至储层,储层超压缓慢增长;白垩纪晚期为快速增压阶段,烃源岩大量生气,生烃增压作用和欠压实作用产生的超压持续传递,储层超压快速升高,该阶段造成的储层超压占现今总超压的90%;古近纪早期至今为保持稳定阶段,构造稳定,烃源岩的生烃增压作用和欠压实作用稳定,超压基本保持不变,储层超压稳定增长。④研究区沙河子组不同岩性地层超压的差异性演化控制着天然气的分布,源、储过剩压力差为油气运移提供了动力条件,贫有机质泥岩盖层为下覆储层提供了封闭条件。

Methane adsorption effected by pore structure of overmature continental shale:Lower Cretaceous Shahezi Formation,Xujiaweizi Fault,Songliao Basin

Overmature continental shale is commonly developed,but few studies have given insight into its pore structure and sorption capacity.Various techniques,including SEM,helium porosity and permeability,N_(2)/CO_(2)adsorption,MICP,and NMR,were used to detect the pore structure of shale from the Shahezi Formation,Xujiaweizi Fault,Songliao Basin.The excess methane adsorption volumes were measured by the volumetric method and modeled by the Langmuir model.Based on the findings,the most developed pores are intraparticle pores in clay minerals,followed by the dissolution pores in feldspar,but organic pores are uncommon.The selected shales have low helium porosity(mean 1.66%)and ultralow permeability(mean 0.0498×10^(−3)μm^(2)).The pore throats are at the nanoscale,and the pore-throat size distributions are unimodal,with most less than 50 nm.The studied shales are characterized by the lower specific surface area(SSA)and pore volume(PV)but the larger average pore diameter.The total SSA is contributed by the micro-and mesopores,while the PV is dominated by meso-and macropores.The pore structures are more complex and controlled by multiple factors,such as mineral compositions and diagenesis,but organic matter is not critical.The maximum absolute adsorption methane volume(VL)is 0.97−3.58 cm^(3)/g(mean 1.90 cm^(3)/g),correlating well with the total SSA,SSA,and pore volume of micropores,which indicates that methane is mainly adsorbed and stored in micropores,followed by mesopores.

徐家围子断陷沙河子组烃源岩形成古环境及主控因素

【目的】明确沙河子组优质烃源岩形成的主控因素,为松辽盆地深层天然气勘探方向优选提供地质依据。【方法】综合利用岩心、有机地球化学和元素地球化学等多种资料,系统研究沙河子组沉积环境和水体环境,明确了断裂活动、沉积相和古沉积环境对烃源岩有机质丰度、类型的控制作用。【结果】沙河子组发育暗色泥岩和煤岩两种类型烃源岩,沙Ⅰ段沉积期断裂活动强,水体相对局限、深度大,形成的“深水窄盆”盐度高、还原性好,以半深湖相泥岩为主,沙Ⅱ段时断裂活动弱,湖盆面积达到最大,形成的“浅水宽盆”盐度低、还原性变差,烃源岩以滨浅湖相煤岩为主。【结论】断裂活动在下降盘为泥岩堆积提供可容纳空间,控制了泥岩厚度;沉积环境影响有机质输入,决定了泥岩有机质类型和煤岩分布;由古盐度、古水深和氧化还原组成的古沉积环境影响有机质的富集和保存,是导致现今烃源岩质量差异的主要原因。

徐家围子断陷沙河子组煤岩气成藏条件及突破方向

为明确徐家围子断陷煤岩气勘探有利区,综合地震、岩心和地球化学等多种资料,系统分析了煤岩气成因、烃源岩类型、储层特征和储盖组合等有利成藏条件。结果表明:(1)沙河子组1号、2号煤层是形成于三角洲前缘和滨浅湖沼泽环境的稳定煤岩,煤岩厚度为3~10m,TOC平均约为29.65%,正处于高—过成熟阶段;(2)沙河子组煤层气以甲烷为主,为自生自储的高—过成熟煤型气;(3)煤岩储集空间类型多样,以张性微裂隙、原生植物组织孔、气孔和矿物质孔为主,孔隙度和渗透率分别平均为4.74%和4.42mD,是深层有利储层;(4)沙河子组顶部发育泥岩、泥质粉砂岩2种盖层和3种储盖组合,顶底泥岩型和顶泥底砂型储盖组合封闭性高,与煤层内广泛分布的超压封存箱一起,为煤岩气的保存创造了有利条件;(5)在煤层气藏地质特征研究基础上,通过生烃模拟估算研究区各生烃洼槽的资源量,并结合煤岩厚度、埋藏深度、成熟度等多种参数,优选宋站洼槽1号煤层和徐西洼槽2号煤层2个有利区,泥质盖层厚度大于5m的区域为近期煤层气勘探突破方向。

松辽盆地北部全油气系统成藏模式与勘探潜力

松辽盆地作为一个多套优质烃源岩大面积发育的大型陆相叠合盆地,由于受多期构造与沉积的复合控制和改造,油气藏富集规律复杂多样。为进一步落实松辽盆地北部油气成藏条件与勘探潜力,基于全油气系统新概念,将松辽盆地北部划分为2个全油气系统:以青山口组为生油岩,嫩江组为区域盖层的储盖组合,形成了常规油、致密油、页岩油多类型有序成藏的上部石油系统;以沙河子组为烃源岩,登娄库组为区域盖层的储盖组合,形成了营城组火山岩、沙河子组砂砾岩等多种气藏差异富集的下部天然气系统。以此为基础,研究了松辽盆地北部油气藏的基本油气地质条件、常规-非常规油气的共生特征与油气分布情况。上部石油系统青山口组源岩经过生烃增压、幕式排烃后,地层压力释放,页岩储层形成自封闭体系,内部干酪根持续生烃、油气原位成藏,形成大规模连续分布的“立体式”页岩油藏;扶余油层致密油受生烃增压作用的控制、油气向下“倒灌”,形成断裂下排-横向运移、源-储侧向对接充注成藏。下部天然气系统沙河子组源岩持续生烃,受源储关系、储层特征和输导通道等成藏要素的耦合控制,形成中央古隆起“源储叠置、不整合输导、淋滤层聚气、高部位富集”,营城组火山岩气藏“下生上储、深断裂通源、高部位聚气”和沙河子组致密气“自生自储、断裂控砂、超压控富”等3种成藏模式。研究成果对松辽盆地不同类型油气资源分布预测和勘探具有重要指导意义。

松辽盆地徐家围子断陷沙河子组沉积相类型及演化模式

【目的】徐家围子断陷沙河子组致密砂砾岩储层具有非常大的天然气勘探潜力,有望成为大庆油田深层火山岩气藏勘探的重点接替领域。【方法】综合运用岩心、录井、测井及地震等资料,对徐家围子断陷沙河子组沉积相展布及沉积演化模式开展了研究。【结果与结论】徐家围子断陷沙河子组发育辫状河三角洲、扇三角洲、具供给水道的远岸浊积扇、近岸水下扇、扇三角洲前端滑塌浊积扇以及浅湖—半深湖、深湖相等沉积相。安达凹陷、徐东凹陷以及肇州凹陷东侧的缓坡带接受来自肇东—朝阳沟基底古隆起的碎屑物质而发育辫状河三角洲沉积,局部发育由远源供给水道形成的湖底浊积扇沉积体;安达凹陷、徐东凹陷、徐西凹陷以及肇州凹陷西侧等徐西陡坡带接受来自中央隆起带粗碎屑物而发育扇三角洲沉积体系,以近源短流为基本特征,局部发育近岸水下扇沉积,且由于湖盆边缘发育的扇三角洲沉积体不稳定,在扇三角洲沉积体前方形成滑塌浊积扇沉积。

徐家围子断陷沙河子组主干断裂形成演化与地层剥蚀特征

主干断裂的活动控制着徐家围子断陷沙河子组的建造与改造。为了明确断裂活动,运用位移距离曲线方法系统分析了徐家围子断陷主干断裂的生长活动特征,通过不整合面下的同向轴特征分析了徐家围子断陷沙河子组沉积末期的剥蚀改造作用。结果表明:徐家围子断陷主干断裂分段特征明显,徐西断裂与宋西断裂在火石岭组沉积时期分别是数条分段的小断裂,在沙河子组沉积时期连通为整条断裂并持续控陷活动;徐中断裂在沙河子组沉积时期弱伸展弱控陷,在沙河子组沉积末期作为薄弱带发生压扭反转;徐东断裂带中的徐东正断层在沙河子组沉积时期弱控陷,徐东逆断层在营城组一段沉积末期的反转作用下形成;沙河子组沉积末期的反转作用对沙河子组厚度与构造格局产生明显改变,沿徐西断裂与宋西断裂存在较强的剥蚀,徐西断裂北端升平凸起尤为强烈,徐中断裂压扭反转产生一定的走滑分量并遭受剥蚀,徐东逆断层在营城组一段沉积末期的反转中形成,对沙河子组厚度无明显改变,但对徐东构造带构造格局产生明显影响。研究成果可为徐家围子断陷古构造恢复与进一步勘探提供理论参考。

中国东北松辽盆地沙河子组分段特征及地质意义:对陆相含油气沉积盆地的启示

徐家围子断陷是松辽盆地北部深层天然气资源最富集的地区,也是松辽盆地北部勘探程度最高的含气断陷。下白垩统沙河子组地层是松辽盆地徐家围子断陷的主要烃源岩,研究其地质和地球物理特征对深层资源勘探开发至关重要。位于中国东北部的松科二井钻探深度达7018 m,获得了最完整连续的断陷层岩芯,为分析沙河子组地层提供了重要数据。本文研究根据松科二井的最新岩芯测试和测录井成果,重新统计并厘定了沙河子组地层分层层序及深部资源特征。松科二井揭示的沙河子组地层的顶、底年龄分别约为112 Ma和118 Ma,属于Aptian中期-Albian早期,是松辽盆地断陷层油气生产的重要时期。基于测井资料,厘定沙河子组地层厚度为2624.01 m(岩芯深度3335.99~5960.00 m),并将沙河子组从底部到顶部划分为SQ1~SQ5五个三级层序。其中,SQ5层序烃源岩发育,成熟度高,处于高成熟-过成熟阶段,发育Ⅲ型干酪根。在SQ5层序内检测出35层气测异常,累计厚度79 m,暗色泥岩累计厚度占该层序地层厚度的59%,最具深层天然气勘探潜力,SQ2层序次之。基于上述研究,本文提出了沙河子组地层的沉积演化模式,为全球海陆相沉积对比研究提供了新视野,同时,加强对松辽盆地深部沙河子组非常规油气资源评价研究,对松辽盆地油气勘探向深部拓展具有重要的引领和示范意义。

致密砂砾岩成储界限及分级评价标准——以松辽盆地徐家围子断陷白垩系沙河子组为例

徐家围子断陷下白垩统沙河子组砂砾岩储层是松辽盆地深部重要的致密气藏储层,其孔渗关系复杂,给成储界限的厘定和储层分级评价带来挑战。针对沙河子组砂砾岩储层,采用水膜厚度法、充注动力法、试气产能法和力学平衡法厘定了理论下限、成藏下限、有效渗流下限和成储上限,根据不同成岩作用主控因素下的孔渗关系确定成储界限物性值。在此基础上,结合储层微观孔隙结构差异划分储层类型,建立致密储层分级评价标准,并利用测井资料将分级评价标准进行应用,为研究区致密气甜点区优选提供依据。将沙河子组砂砾岩分为常规储层、Ⅰ—Ⅳ级致密砂砾岩储层和非储层,成储界限与分级评价结果具有很好的匹配关系。其中,常规储层孔隙度大于9%,渗透率大于0.05×10^(-3)μm^(2);Ⅰ级致密储层孔隙度为8%~9%,渗透率为(0.01~0.05)×10^(-3)μm^(2);Ⅱ级致密储层孔隙度为5%~8%,渗透率为(0.001~0.01)×10^(-3)μm^(2);Ⅲ级致密储层孔隙度为3.5%~5%,渗透率为(0.2~1)×10^(-6)μm^(2);Ⅳ级致密储层孔隙度为2%~3.5%,渗透率为(0.05~0.2)×10^(-6)μm^(2);非储层的孔隙度小于2%,渗透率小于0.05×10^(-6)μm^(2)。致密砂砾岩气产量受控于致密储层类型;Ⅰ级、Ⅱ级致密储层是致密气高产的有利层段;徐家围子断陷北部安达—宋站地区有利储层厚度较大,为致密气勘探开发甜点区。

火山断陷型湖盆细粒沉积岩有机质富集模式——以松辽盆地梨树断陷下白垩统沙河子组二段下亚段为例

以松辽盆地梨树断陷下白垩统沙河子组二段下亚段(简称沙二下亚段)沉积特征为例,采用有机岩石学、主微量元素及生物标志化合物分析等方法,探讨火山断陷型湖盆细粒沉积岩有机质富集条件及富集模式。研究结果表明,沉积古环境的变化控制沙二下亚段不同岩相类型的垂向分布,并将其划分为上、下两部分,下部主要发育块状长英质泥岩夹含生屑长英质泥岩,上部主要发育纹层状长英质页岩和纹层状细粒混积页岩;下部有机质干酪根类型以Ⅱ2—Ⅲ型为主、上部以Ⅰ—Ⅱ1型为主,且总体呈现出上部有机碳含量较下部增高的特征。分析认为,火山断陷型湖盆有机质富集的主要条件为:①持续增强的裂陷作用是导致古水深加大的直接因素,基准面上升使深水沉积范围随之扩大,泥页岩发育规模相应增大;②相对强烈的水下火山喷发与裂陷作用具有同时性,火山活动可为湖盆提供大量营养物质,有利于藻类的勃发,并导致Ⅰ—Ⅱ1型干酪根生产力较高;③相对干旱的古气候导致河流淡水及陆源物质(包括陆源高等植物Ⅲ型干酪根)输入减少,形成高盐度、缺氧分层的水体,咸水湖盆有利于有机质保存。在此基础上,建立的火山断陷型湖盆细粒沉积岩有机质富集模式,对深化松辽盆地沙河子组乃至中国东北地区同期火山断陷型湖盆细粒沉积岩有机质富集机制的地质认识,具有一定的参考借鉴意义。

松辽盆地北部中央古隆起基岩气藏形成条件与有利勘探区

为寻找松辽盆地中央古隆起基岩天然气富集区,分析了其天然气成因和有利成藏条件,优选了基岩气藏有利勘探区块。研究结果表明:①松辽盆地北部中央古隆起天然气组分和成因与徐家围子断陷类似,均是以甲烷为主的高—过成熟的煤型气,显示基岩气藏气源主要来自古隆起东侧徐家围子断陷。②优质烃源岩、有利储层、立体输导通道和优良盖层等有利条件耦合是形成基岩气藏的关键,沙河子组烃源岩泥岩和煤岩TOC平均分别为4.33%和32.56%,处于高过成熟阶段,宋站和徐西等生烃洼槽生烃强度普遍大于180×10^(8)m^(3)/km^(2),是基岩重要的气源;受风化和破裂作用影响,基岩顶、底形成的风化壳孔缝层、内幕裂缝层等有利储层孔隙度分别为4.3%和1.3%,渗透率分别为0.45 mD和6.3 mD;风化壳、断层和裂缝耦合形成“S”型、“T”型和“断缝体”型输导通道,促进了天然气的侧向运移;登娄库组泥岩厚度大、突破压力高,且其形成时间早于天然气大规模运移和充注成藏期,使得基岩气藏得以保存。③中央古隆起带可分为3个有利勘探区,北部汪家屯凸起和昌德凸起主要为风化壳气藏,发育“S”型、“T”型输导通道,气藏受输导通道和保存条件联合控制,南部肇州凸起则以基岩内幕气藏为主,发育“断缝体”型输导通道,气藏受储层厚度、物性和圈闭影响明显。

松辽盆地梨树断陷沙河子组页岩与泥岩差异与成因

松辽盆地下白垩统沙河子组泥页岩是松辽盆地深部断陷层主力烃源岩,也是松辽盆地陆相页岩气最具潜力的层系。中国地质调查局在松辽盆地钻探了松科2井和吉梨页1井均证实了沙河子组页岩气具有可观的资源潜力,尤其是吉梨页油1井首次在松辽盆地梨树断陷沙河子组陆相页岩中获得直井日产7.6×10^(4)m^(3)的高产页岩气流.

松辽盆地徐家围子断陷白垩系沙河子组深层致密气成藏机理及勘探突破

松辽盆地徐家围子断陷沙河子组砂砾岩埋深大、岩性致密,目前对其成藏控制因素认识不足,且受投资成本和勘探开发技术的制约,沙河子组一直未能实现储量和产量的突破。使用地震、岩心、测井、录井及地质分析化验资料,从煤系烃源岩生烃潜力、致密砂砾岩展布、储集物性、地层超压等方面分析了沙河子组致密气成藏控制因素,力图寻找富气甜点、指导井位部署。结果表明,沙河子组储层与烃源岩叠置,致密非浮力成藏动力过程致使异常高压的出现,并造就了满盆含气的格局。沙河子组致密砂砾岩储层在纵横向上叠置发育,储层内部发育的多层高孔渗带成为致密砂砾岩气藏的“甜点”。在致密气成藏理论的指导下,精准刻画了优质富气“甜点”的分布并设计了最优气井轨迹,充分发挥地质工程一体化优势,以优快钻井和最优改造体积为目标,部署了宋深9-平5井,测试产量达106×10^(4)m^(3)/d,取得了沙河子组致密气藏的重大突破,为后期松辽盆地沙河子组致密气藏勘探开发带来了广阔的前景。

不同热模拟实验煤热解产物特征及动力学分析

利用Rock-Eval-Ⅱ型热解仪、TG-MS(热失重—质谱联用仪)及金管装置对松辽盆地沙河子组煤样进行了热模拟实验。TG-MS实验中甲烷生成温度对应的Ro与地质条件下气态烃产物生成时的成熟度接近,而Rock-Eval-II实验中烃气生成时对应的Ro要远小于地质条件下气态烃产物生成时对应的成熟度。TG-MS实验中煤生甲烷终止温度约为850℃,对应的Ro约为5.3%(10℃/min升温速率)。金管实验650℃时(Ro约为4.9%,升温速率2℃/h)煤生气能力尚未结束,气态烃质量产率一直呈增长趋势,同时高温阶段密闭体系中甲烷的来源主要是有机质的初次裂解。煤生气动力学参数在徐家围子地区的应用结果表明,不同生烃装置热裂解实验下获得的动力学参数外推结果差别很大,建议采用TG-MS实验装置模拟地质条件下烃源岩边生气边排出的情况,采用金管装置热裂解实验模拟存在二次裂解的封闭体系下的生气情况。

松辽盆地深层地质结构及致密砂砾岩气勘探

基于全盆地野外露头、钻井、地震资料及地球化学分析数据,研究了松辽盆地深层地质结构特征、断陷基本地质规律、沙河子组致密气成藏地质条件及下步勘探方向。通过系统对比分析,明确盆地深层地质结构表现为下断上坳的双层结构,断陷期以断裂或地层超覆与隆(凸)起为界、由隆(凸)起相互间隔的断陷独立发育。与断陷形成演化相关的断裂可分为区域深大断裂、基底控陷断裂和洼内次级断裂3类,阐明了3类断裂在断陷群形成演化中的作用。结合区域构造和盆地演化特征分析,明确致密砂砾岩气、火山岩和基岩潜山等3大勘探领域,沙河子组致密砂砾岩气是目前最具勘探前景的战略新领域。在沙河子组基本石油地质特征分析基础上,提出砂砾岩是沙河子组碎屑岩储集层优势岩类,母岩成分、沉积结构、沉积相带及成岩作用是砂砾岩有利储集层主控因素。沙河子组气藏属典型自生自储型,发育岩性和构造两种气藏类型,陡缓两带有利沉积相带控制储集层展布、岩性圈闭形成及气藏规模,断陷内部次级断裂控制构造圈闭的形成及天然气的富集。通过综合评价优选出7个沙河子组致密砂砾岩气勘探最为现实的断陷。

松辽盆地梨树断陷十屋油田区营城组、沙河子组储层成岩作用分析

通过大量钻井岩心铸体薄片、扫描电镜、压汞、阴极发光、X-衍射、包裹体等分析,对松辽盆地梨树断陷十屋油田区沙河子组、营城组储层的成岩作用、成岩序列及孔隙演化进行了深入研究。该区主要成岩作用有压实作用、胶结作用、溶蚀作用及构造破裂作用,其中对储层物性具建设性的作用主要有溶蚀作用和构造破裂作用,而具破坏性作用的主要有压实作用和胶结作用。砂岩储层孔隙类型主要为原生粒间孔、粒间溶蚀扩大孔及少量裂缝的组合,以溶蚀孔隙为主。建立了砂岩储层的成岩序列,即机械压实→石英、长石次生加大→构造破裂→长石等铝硅酸盐溶蚀→粒状方解石胶结→早期进油→破裂→第二期溶蚀→连晶方解石胶结→晚期油气充注。研究认为,影响本区储层储集性能的主控因素为储层的沉积环境、成岩作用、构造作用及油气充注等因素。