塔里木盆地寒武系膏盐岩对盐下白云岩储层的影响

塔里木盆地寒武系盐下白云岩作为重要的战略接替区已成为近年来的研究热点.前人主要集中对寒武系白云岩的形成机制和膏盐岩的封盖作用进行了研究,而关于膏盐岩对白云岩储层的影响则少有涉及.本文总结了塔里木盆地寒武系白云岩储层特征,同时探讨了膏盐岩对白云岩储层的影响机制,以期为寒武系盐下白云岩勘探提供指导.塔里木盆地寒武系白云岩主...     

湖相白云岩成因模式及其储集性

湖相白云岩的成岩作用是非常规油气储层中非常活跃的话题,其成因模式以及储集性的研究对以碳酸盐岩为储层的油气勘探具有重要意义。通过综述前人关于湖相碳酸盐岩领域的研究成果,总结出以下几点:湖相白云岩成因模式主要有原生生物成因、准同生成因以及热液成因;湖相白云岩的储集空间类型包括以生物体腔孔为代表的原生孔、酸性流体作用下形成的溶蚀孔洞、白云石化作用或重结晶作用形成的晶间孔以及构造应力作用下形成的裂缝等4大类;其物性和孔隙结构分别受控于沉积环境及生物种类、酸性流体的溶蚀能力、白云岩化模式以及构造活动强度和岩石脆性等。以上研究成果可为湖相碳酸盐岩,乃至其他成因的碳酸盐岩物性影响因素以及油气地质意义研究提供借鉴参考。     

鄂尔多斯盆地奥陶系马家沟组白云岩储层特征及成因机制

鄂尔多斯盆地奥陶系白云岩是重要的天然气储集层,对其白云岩成因和储层发育规律的研究对于碳酸盐岩深层勘探理论的发展具有重要意义。文章基于大量岩心、薄片的观察,并结合稳定碳氧同位素、稀土元素、白云岩有序度、地层水、包裹体特征等地球化学分析,对盆地奥陶系存在的两种典型白云岩储层的发育特征和形成机理进行了详细研究。分析表明,含硬石膏结核或柱状晶的泥粉晶白云岩主要为潮坪蒸发环境的萨布哈成因,其规模储层的发育主要受到长时不整合的控制,不整合面以下发育大量硬石膏结核和柱状晶溶模孔;颗粒滩白云岩主要为回流渗透成因,其储层孔隙的发育主要受到海平面高频升降的影响,发育多旋回的粒（晶）间孔隙型储层。虽然两种白云岩的白云石化流体都为浓缩海水,但由于白云石化的机制和速率不同,二者的原始孔隙类型和特征迥异。两种白云岩孔隙在后期的成岩改造和演变过程中,既有相同之处,又有明显的区别。这一认识也将对深层的白云岩储层勘探提供指导作用。     

白云石化作用及白云岩储层研究进展

白云石化作用和白云岩储层一直都是碳酸盐岩研究中的重要领域。近年来,随着实验分析技术的进步以及油气勘探的深入,对白云岩的研究也取得了诸多进展:1数值模拟技术逐步应用到白云岩研究中,实现了白云石化模式研究由定性到定量的转变;2对微生物白云石化的研究不断加强,识别出了微生物相关白云石的特殊显微形貌特征并对其生物矿化机制进行了分析;3对已有白云石化模式的重新审视:包括对混合水白云石化的修正、对回流白云石化的扩展以及对构造—热液白云石化模式的丰富;4在白云石化与孔隙相关关系的研究中,突破了白云石化增孔的传统认识,逐步强调白云石化在孔隙保存方面的作用;5注重研究白云岩结构、成岩环境、原始相带以及白云岩形成之后的溶蚀改造等因素对白云岩储层发育的控制作用。在未来的研究中,应加强3个方面内容,一是对白云岩结构演化规律的定量研究,二是在成岩流体示踪方面要加强对新技术手段(如二元同位素、Mg同位素)的使用,同时注意借鉴成矿流体研究中的成熟技术和方法,三是要加强对深部白云岩储层形成和保存机制的探索。     

鄂尔多斯盆地奥陶系盐下白云岩储层特征、成因及分布

奥陶系盐下白云岩储层是鄂尔多斯盆地中东部天然气勘探的重要接替领域.基于钻井岩心、微观薄片、物性分析及地球化学特征等资料,应用微区多参数实验分析方法,对奥陶系盐下白云岩储层特征、成因与分布开展了系统研究.结果表明:①奥陶系盐下主要发育颗粒滩白云岩和微生物白云岩储层,其中颗粒滩白云岩储层岩性为砂屑白云岩、鲕粒白云岩和粉—细...     

Multiple Dolomitization and Fluid Flow Events in the Precambrian Dengying Formation of Sichuan Basin,Southwestern China

The Precambrian Dengying Formation is a set of large-scale, extensively dolomitized, carbonate reservoirs occurring within the Sichuan Basin. Petrographic and geochemical studies reveal dolomitization was a direct result of precipitation by chemically distinct fluids occurring at different times and at different intensities. Based on this evidence, dolomitization and multiple fluid flow events are analyzed, and three types of fluid evolution models are proposed. Results of analysis show that Precambrian Dengying Formation carbonates were deposited in a restricted peritidal environment(630–542 Ma). A high temperature and high Mg~(2+) concentration seawater was a direct result of dolomitization for the micrite matrix, and for fibrous aragonite in primary pores. Geochemical evidence shows low δ~(18)O values of micritic dolomite varying from-1.29‰ to-4.52‰ PDB, abundant light rare earth elements(REEs), and low dolomite order degrees. Microbes and meteoric water significantly altered dolomite original chemical signatures, resulting in algal micritic dolomite and the fine-grained, granular, dolosparite dolomite having very negative δ~(18)O values. Finely crystalline cement dolomite(536.3–280 Ma) and coarsely crystalline cement dolomite have a higher crystallization degree and higher order degree. The diagenetic sequence and fluid inclusion evidence imply a linear correlation between their burial depth and homogenization temperatures, which closely resemble the temperature of generated hydrocarbon. Compared with finely crystalline dolomite, precipitation of coarsely crystalline dolomite was more affected by restricted basinal fluids. In addition, there is a trend toward a more negative δ~(18)O value, higher salinity, higher Fe and Mn concentrations, REE-rich. Two periods of hydrothermal fluids are identified, as the exceptionally high temperatures as opposed to the temperatures of burial history, in addition to the presence of high salinity fluid inclusions. The early hydrothermal fluid flow event was characterized by hot magnesium-and silicon-rich fluids, as demonstrated by the recrystallized matrix dolomite that is intimately associated with flint, opal, and microcrystalline quartz in intergranular or intercrystalline pores. This event was likely the result of a seafloor hydrothermal chimney eruption during Episode I of the Tongwan Movement(536.3±5.5 Ma). In contrast, later hydrothermal fluids, which caused precipitation of saddle dolomite, were characterized by high salinity(15–16.05 wt% NaCl equivalent) and homogenization temperatures(250 to 265°C), δ~(18)O values that were more enriched, and REE signatures. Geochemical data and the paragenetic sequence indicate that this hydrothermal fluid was related to extensive Permian large igneous province activity(360–280 Ma). This study demonstrates the presence of complicated dolomitization processes occurring during various paleoclimates, tectonic cycles, and basinal fluids flow; results are a useful reference for these dolomitized Precambrian carbonates reservoirs.     

Genesis of Dolomite from Ma55–Ma510 Sub-members of the Ordovician Majiagou Formation in the Jingxi Area in the Ordos Basin

We clarified three stages of dolomitization and secondary changes by studying the petrology and geochemistry characteristics of dolomite from the Ma55–Ma510 sub-members of the Ordovician Majiagou Formation in the Jingxi area in the Ordos Basin: (1) Syngenetic microbial dolomitization is characterized by formation of dolomite with a mainly micrite structure and horse tooth-shape dolomite cements. (2) Seepage reflux dolomitization during the penecontemporaneous period superposed adjustment functions such as recrystallization and stabilization in the middle-deep burial stage, forming dolomites mainly consisting of micro crystal and powder crystal structure. (3) Powder dolomite, fine dolomite, and medium-coarse crystalline dolomite formed in pores and fractures in the middle-deep burial stage. The secondary concussive transgression-regression under a regressive background is an important condition for the occurrence of many stages of dolomitization in the study area. The basin was an occlusive epicontinental sea environment in the Ma5 member of the Ordovician Majiagou Formation sedimentary period. In the sediments, sulfate content was high, which is conducive to the preservation of microbial activity and microbial dolomitization. Micritic dolomite formed by microbial dolomitization provides good migration pathways for seepage reflux dolomitization. Affected by evaporation seawater with increased Mg/Ca ratio, seepage reflux dolomitization was widely developed and formed large-scale dolomite, and underwater uplifts and slopes are favorable areas for dolomite. In the middle-deep burial stage, dolomitizing fluid in the stratum recrystallized or stabilized the previous dolomite and formed a small amount of euhedral dolomite in the pores and fractures.     

鄂尔多斯盆地大牛地气田马家沟组储层类型成因及其主控因素

鄂尔多斯盆地大牛地地区奥陶系马家沟组油气勘探持续获得突破,实践表明马五段整体含气,但储层类型多,成因复杂。为系统归纳该段储层成因类型,通过岩心观察、薄片鉴定、阴极发光薄片观察、全岩X射线衍射分析、碳氧同位素分析等方法,对储集空间类型和储层发育主控因素进行了研究。结果表明,研究区马家沟组储层发育晶间孔、晶间溶孔、微裂缝、残余粒间孔和粒内溶孔等。储层发育的有利沉积相为局限台地藻云坪和蒸发台地膏云坪,并受回流渗透白云石化机制控制。表生岩溶作用对马五₅亚段储层无明显控制作用。研究区储层根据成因可分为四种类型:膏溶型储层、弱改造破裂型云岩储层、粉晶白云岩储层和同生溶蚀颗粒型储层。膏溶型储层和粉晶白云岩储层是主要的储层类型,膏溶型储层与沉积环境盐度和表生期岩溶作用有关,主要发育膏模孔;粉晶白云岩储层主要受海平面下降期的回流渗透白云石化控制,以晶间孔为主。以上四类储层成因类型的认识,对下一步鄂尔多斯盆地马五段的优质储层预测具有指导意义。     

环开江—梁平海槽长兴组台缘礁滩相储层特征及成岩作用

通过岩心观察、薄片鉴定、电镜扫描、阴极发光、物性分析,对四川盆地东部环开江—梁平海槽上二叠统长兴组礁滩相储层特征、储层成岩作用进行研究,并初步建立成岩演化序列。储层特征研究发现,长兴组储层发育良好,储集岩以"花斑状"生屑云岩和生物礁云岩为主,粒间孔、粒间溶孔和粒内溶孔较为发育,孔隙度总体介于2%~6%,渗透率集中在0.1~1 m D,结合孔渗相关关系将其划分为4种储层类型:"低孔高渗"型、"中孔中渗"型、过渡型、"高孔低渗"型。储层成岩作用研究发现,储层在成岩阶段经历了多期胶结、压实、白云岩化、溶蚀、构造破裂等成岩作用。由于成岩作用对孔隙结构的改造,孔隙演化整体上呈减小趋势。胶结作用及压实作用使得原生孔隙大幅度减少,对储层的形成具有破坏性作用,溶蚀及白云岩化作用对储层的形成具有建设性作用,构造破裂对储层进一步优化改造。研究表明原生粒间孔和早成岩期岩溶及热液白云岩化作用形成的早期次生孔隙不仅是现今储层储集空间的雏形,也基本决定了储层的最终面貌。     

南羌塘坳陷古油藏带布曲组白云岩储层特征及控制因素分析

羌塘盆地布曲组白云岩储层是整体致密背景下的"甜点"储层,深入研究其发育的控制因素,是进行有利区预测的基础。通过野外地质剖面观察、岩心观察、铸体薄片鉴定,结合实测分析,对白云岩储集空间进行分类,并分析其发育的控制因素。结果表明,南羌塘坳陷古油藏带布曲组白云岩储层发育在碳酸盐岩台地的台内滩中,高位体系域晚期的滩间洼地局限水体提供白云化流体。储层中发育晶内溶孔、晶间孔、晶间溶孔、溶蚀孔洞,物性较好。储层质量受沉积作用、成岩作用及构造作用共同控制。台内滩发育的颗粒灰岩能够保存更多的连通孔隙,为后期流体改造提供运移通道,滩后局限水体提供白云石化流体。浅埋藏阶段白云石化是储集空间发育的最有利因素。燕山运动Ⅱ幕的构造挤压形成热点,提供形成孔隙充填鞍形白云石的热流体,同时该流体能够溶蚀围岩。古油藏破坏过程中的酸性流体和大气淡水对储层进行溶蚀改造,对储层具有关键性改造意义的是浅埋藏阶段的白云石化和第一次生烃前的有机酸溶蚀。     

塔北地区寒武系下丘里塔格群白云石化模式

针对塔北上寒武统下丘里塔格群复杂的白云石化作用,通过岩石学和地球化学分析认为下丘里塔格群埋藏后主要经历3期白云石化流体作用：早期浅埋藏环境下高浓度卤水在台缘带的迁移促进了渗透回流白云石化作用发生,形成残余颗粒幻影结构的粉晶白云岩,具有碳氧同位素负偏和微量元素Fe、Mn、Sr、Ba元素质量分数较低的特征;第二期流体主要为地层孔隙残余高盐度海水,在埋藏压实作用下白云岩发生重结晶作用,晶粒结构广泛发育,具有同位素碳正氧负和微量元素呈现富Mn贫Fe及低Sr高Ba的特征,该时期是晶间孔和晶间溶孔发育的主要时期;第三期流体主要为沿基底断裂上涌的高温富镁热液流体,发育构造-热液白云石化作用形成大量鞍状白云石,具有富Mn贫Fe和氧同位素负偏明显等特征。     

湖北秭归地区震旦系灯影组白云岩地球化学特征及其成因意义

白云岩化流体性质与成岩作用是近年来碳酸盐岩成岩作用研究的热点,研究白云岩的成因有利于进一步认识白云岩储层的形成机制并为优质储层的预测提供依据。通过岩石学、矿物学(X射线衍射)、地球化学(微量元素、稀土元素、碳氧同位素)方法,系统研究湖北秭归地区灯影组不同类型白云岩的成因,并分析了可能的白云岩化模式。样品的微量元素特征显示,秭归地区白云岩未受到陆源碎屑物质的影响,形成于气候干旱、海水咸度较大且氧化的沉积环境中;Sr含量特征显示白云岩发生了较为彻底的白云岩化,其成岩环境为温度较高的埋藏环境,成岩过程中未受到淋滤作用的影响;秭归地区白云岩化流体主要来源于海水。结合蒸发白云岩(萨布哈)及埋藏白云岩化模式解释了秭归地区泥微晶白云岩及晶粒白云岩的形成过程。     

川东地区震旦系灯影组储层特征及其控制因素

采用宏观和微观相结合的 方法,通过扫描电镜、阴极发光等手段,分析川东地区震旦系灯影组钻井、岩心和露头剖面样品的镜下岩石学特征,研究川东地区震旦系灯影组白云岩储层的特征及控制因素。研究结果表明灯影组白云 岩储层主要发育在灯二段和灯四段,主要储集岩类型为微生物白云岩、颗粒白云岩和距两期风化壳0~200 m范围内的角砾白云岩和溶孔白云岩;储集空间以次生的孔、缝、洞为主,主要为粒间溶孔、粒内 溶孔、次生晶间孔、构造裂缝、溶洞等。沉积环境是影响灯二段储层发育的主要因素,其有利储集相带主要是位于水动力能量较强的或有利于造礁生物繁殖的高能颗粒滩和微生物云坪沉积环境;溶蚀作 用,特别是古岩溶作用是灯四段储层发育的主要因素。早期的桐湾运动形成了灯影组的大规模孔洞,而其后的构造运动则建立了研究区内特别复杂的孔隙－洞穴－裂缝系统。     

Characteristics of hydrothermal-structure-controlled fracture-vug dolomite reservoir and its influence on oil-water distribution: Lower Cretaceous,Baiyinchagan sag,Erlian Basin,North China

Fractures and vugs were used as the primary dolomite reservoir space in the study area, which improved the reservoir’s physical properties and influenced the distribution pattern of oil and water that were developed in the Upper Tenger Formation, Lower Cretaceous, Baiyinchagan sag, Erlian Basin. Based on the core observation data, thin slice analysis, and image logging, the cave-fractured reservoir was primarily developed in the actic region near the side of a depositional fault. Tectonic and diagenetic fractures were the primary types of fractures. High-angle tectonic fractures in the closure and open status were developed well in dolomitic mudstone, while a low-angle fracture and reticulate fractures were developed in the tectonic-hydrothermal hybrid process and were filled with hydrothermal minerals. The reservoir was located in low-lying land; therefore, detrital grain pressolution fractures were formed by burial diagenesis. Intergranular and intrangranular dissolved pores, which were formed by hydrothermal activity, were developed primarily in the highly dolomite lithology. According to the diagenesis temperature of dolomite from a carbon-oxygen isotope analysis, multiple hydrothermal fluid injection events occurred, and dolomitization ensued before massive hydrocarbon migration. The dissolution of organic acids formed by hydrocarbon charges after dolomitization and inorganic acid produced by burial di agenesis for soluble minerals effectively promoted the reservoir properties. Strong heterogeneity due to lithology and fracture-vug systems led to intricate oil-water relationships. Four statuses occurred, including cave-fracture oil, isolated oil, stored oil, isolated water, and stored water. The oil-water distribution patterns were established based on the core observation.     

渤海湾盆地南堡凹陷火山岩特征及其有利成藏条件分析

研究表明,渤海湾盆地南堡凹陷火山岩发育区的岩浆活动热事件促进了烃源岩的早熟,有利于生烃和成藏.其火山岩与烃源岩的三种组合方式,具有良好的油源条件,且多分布在有利的圈闭上,具有油气富集的最基本条件.火山岩储集空间主要为裂缝、微裂缝和粒间溶蚀孔隙等,其发育主要受岩性、粒度、构造应力和充填期四大因素控制,其裂隙主要发育期和油气聚集期相近从而有利于聚油成藏.火山岩型油气藏的勘探将成为南堡凹陷油气储量和产量新的增长点.     

鄂尔多斯盆地南缘中寒武统张夏组鲕粒滩相储层特征及主控因素

鄂尔多斯盆地寒武系深层具有良好的勘探潜力,中寒武统张夏组为寒武系勘探的重要目的层系。通过野外剖面详测和岩心、薄片观察及实验分析,对张夏组储层的特征、成因及主控因素进行了分析和研究,并预测了有利储层发育区。研究表明:①张夏组主要发育台缘鲕粒白云岩和台内鲕粒白云岩2类储层。②台缘带鲕粒滩累计厚度集中在50~300 m之间,鲕粒粒径平均为1.25 mm,鲕粒白云岩储集空间以溶蚀孔洞、粒间溶孔和晶间(溶)孔为主,平均测井孔隙度和渗透率分别为2.0%和0.038×10^-3μm²。③台内鲕粒滩厚度在50~120 m之间,鲕粒粒径平均为0.85 mm,鲕粒白云岩储集空间以溶蚀孔洞、粒间溶孔为主,平均测井孔隙度和渗透率分别为3.3%和2.787×10^-3μm²。④张夏组储层受鲕粒滩相、白云石化以及三级/四级层序界面控制,台缘规模有利储层发育在四级海退层序中上部的鲕粒白云岩地层中,台内规模有利储层发育在寒武系顶部不整合面之下的鲕粒白云岩地层中。预测台缘岐山—旬邑一带和台内陇东地区为两大规模有利储层发育区。     

开江—梁平台内海槽东段长兴组白云岩储层沉积-成岩系统研究

为了指导部署四川盆地白云岩储层中钻井,在油气钻井岩心观察与描述、野外剖面实测和样品采集的基础上,结合镜下薄片鉴定、X衍射、物性和地球化学特征分析,对开江—梁平台内海槽东段长兴组白云岩储层的沉积-成岩系统进行了深入研究。认为台地边缘生物礁和台地边缘浅滩为最重要的储集相带,颗粒白云岩、生物礁白云岩和晶粒白云岩为最主要的储集层岩性,晶间孔、晶间溶孔和超大溶孔为目的层最有效的储集空间,孔洞缝复合型储层为目的层最优质的储集类型。综合分析认为,长兴组沉积-成岩系统与白云岩储层在时空上具有良好的耦合关系,台地边缘生物礁和台地边缘浅滩相控制了白云岩储层的区域分布范围,而不同成岩系统对储层的贡献程度不同。其中:地层封存卤水与混合热卤水成岩系统是储层形成的基础与关键,地层封存卤水形成低孔低渗的孔隙型Ⅲ类储层,混合热卤水形成中孔中渗的孔洞型Ⅱ类储层;构造热液成岩系统对储层贡献最大,并形成高孔高渗的孔洞缝复合型Ⅰ类优质储层。     

基于激光U-Pb定年的埋藏白云岩形成过程——以塔里木盆地永安坝剖面下奥陶统蓬莱坝组为例

埋藏白云石化作用是形成厚层块状白云岩的主要机制之一,但其形成过程一直存在争议。本文以塔里木盆地永安坝剖面蓬莱坝组为例进行解剖,在露头和薄片岩石学研究的基础上,利用激光U-Pb定年和同位素分析,剖析了蓬莱坝组白云岩形成时期及演化过程,取得三个方面的认识：（1）蓬莱坝组发育四种类型白云岩：藻纹层白云岩、自形-半自形细中晶白云岩、雾心亮边自形中晶白云岩和他形粗晶白云岩,不同类型白云岩垂向互层发育;（2）U-Pb定年结果显示蓬莱坝组受三期云化作用改造,分别为准同生期云化作用、晚奥陶世到志留纪浅埋藏云化作用（464±12Ma到433±22Ma）及泥盆纪埋藏云化作用（382±29Ma）,浅埋藏云化作用会对准同生白云石造成重结晶,而埋藏云化作用表现为白云石次生加大,存在寒武系云化流体卷入,影响U-Pb定年;（3）规模白云岩的发育为沉积环境和构造埋藏演化史共同作用的结果,提出塔中北斜坡和塔北南缘为规模白云岩发育区,这对本区油气勘探具有重要的指导意义。     

Multistage dolomitization and distribution of dolomitized bodies in Early Jurassic carbonate platforms (Southern Alps,Italy)

The Early Jurassic dolomitized carbonates are a hydrocarbon exploration target in Northern Italy. Of these carbonates, the Liassic Albenza Formation platform and the overlying Sedrina Formation shelf were studied to define a pervasive dolomitization model and to shed light on dolomite distribution in the sub‐surface. Field work, as well as analyses of well cores, stable isotopes, trace elements and fluid inclusions, was carried out on the outcropping thrust belt and sub‐surface deformed foreland of the Southern Alps. Petrographic analyses showed a first, pervasive, replacement dolomitization phase (D1) followed by volumetrically less important dolomite cement precipitation phases (D2, D3 and D4). The δ¹⁸O values fall between ?8·2‰ and 0·1‰ Vienna‐Pee Dee Belemnite with the more depleted samples belonging to dolomite cement‐rich dolostones; the δ¹³C ranges from 2·6‰ to 3·7‰ Vienna‐Pee Dee Belemnite. Analysis of trace elements showed different Fe and Mn contents in the sub‐surface and outcropping dolostones, and a higher Fe in the younger dolomite cements. An increase in the precipitation temperature (up to 130 °C from fluid inclusion data) and a decrease in diagenetic fluid salinity (from sea water to brackish) are observed from the first pervasive replacement dolomite to the dolomite cement phases. Field observations indicate that, in the Albenza Formation, dolomitization was limited to palaeohighs or faulted platform margins in the Early Jurassic carbonates. The pervasive replacement phase is interpreted based on a ‘compaction model’; the formation fluids expelled from compacting basinal carbonates could have funnelled along faults into permeable palaeohighs. The high homogenization temperature of the dolomite cements and decreased salinities indicate precipitation at great depth with an influx of meteoric water. These data, along with the thermal history, suggest that the dolomite cements precipitated according to the ‘tectonic squeegee’ dolomitization model. The dolomite precipitation temperature was set against the thermal history of the carbonate platform to interpret the timing of dolomite precipitation. The dolomite precipitation temperatures (90 to 100 °C) were reached in the studied formations first in the thrust fold belt (Early Tertiary, 60 Ma), and then in the foreland succession during the Late Tertiary (10 Ma). This observation suggests that the dolomite precipitation fronts moved southwards over time, recording a ‘diagenetic wave’ linked to the migration of the orogenic system. Observations suggest that the porosity increased during the first phase of replacement dolomitization while the dolomite cementation phases partially occluded the pores. The distribution of porous dolomitized bodies is therefore linked to the ‘compaction dolomitization’ model.     

苏盖特布拉克剖面肖尔布拉克组储层建模研究及其勘探意义

明确塔里木盆地肖尔布拉克组储层的品质、规模及分布规律对指导寒武系盐下领域的勘探具有重要意义。通过对柯坪地区苏盖特布拉克剖面的解剖,阐明了肖尔布拉克组主要发育与藻(蓝细菌)有关的微生物白云岩(层纹石白云岩、凝块石白云岩、叠层石白云岩和藻格架白云岩)、黏结藻屑白云岩、藻砂屑白云岩、泥—粉晶白云岩和含砂屑泥—粉晶白云岩,自下而上的岩相组合指示缓坡型台地沉积特征;孔隙类型主要为溶蚀孔洞,粒(晶)间溶孔和藻格架溶孔,总体具有中高孔—中低渗的特征,孔隙的发育与岩相具有明显的相关性,其中藻砂屑白云岩和具有格架结构的微生物白云岩储层物性最好;通过二维地质建模及基于数字露头的三维地质建模,揭示了肖尔布拉克组储层具有较好的层位性、相控性和规模性,古隆起围斜部位的中缓坡丘滩体是储层发育的有利相带。