Reservoir Quality Controlling Factor of the Asmari Reservoir in an Oil Field in Dezful Embayment, SW Iran

The Asmari Formation Oligo-Miocene in age is one of the most important reservoir rocks in SW Iran and Zagros basin and composed of carbonate rocks and locally sandstones and evaporates. In this research, reservoir quality controlling factors have been investigated in a well in one of the oil fields in Dezful Embayment, SW Iran. Based on this research, depositional environment, diagenesis and fracturing have been affected on reservoir quality. 3 distinct depositional settings can be recognized in the studied interval including tidal flat, lagoon, and shoal. Among these depositional setting, shoal environment with ooid grainstone microfacies along with interparticle porosity shows good reservoir characteristics. Diagenetic processes also play an important role on reservoir quality;dolomitization and dissolution have positive effects on porosity and enhances reservoir quality, while cementation, anhydritization and compaction have negative effect on it. Fracturing is another important factor affected on the carbonate reservoirs especially in the Asmari Formation.

Petrophysical Evaluation of Cape Three Points Reservoirs

The findings of a study to ascertain and assess the petrophysical characteristics of Cape Three Points reservoirs in the Western basin with a view to describe the reservoir quantitatively using Well Logs, Petrel and Techlog. The investigated characteristics, which were all deduced from geophysical wire-line logs, include lithology, porosity, permeability, fluid saturation, and net to gross thickness. To characterise the reservoir on the field, a suite of wire-line logs including gamma ray, resistivity, spontaneous potential, and density logs for three wells (WELL_1X, WELL_2X, and WELL_3X) from the Tano Cape Three Point basin were studied. The analyses that were done included lithology delineation, reservoir identification, and petrophysical parameter determination for the identified reservoirs. The tops and bases of the three wells analysed were marked at a depth of 1203.06 - 2015.64 m, 3863.03 - 4253.85 m and 2497.38 - 2560.32 m respectively. There were no hydrocarbons in the reservoirs from the studies. The petrophysical parameters computed for each reservoir provided porosities of 13%, 3% and 11% respectively. The water saturation also determined for these three wells (WELL_1X, WELL_2X and WELL_3X) were 94%, 95% and 89% respectively. These results together with the behaviour of the density and neutron logs suggested that these wells are wildcat wells.

Growth, Population Parameters and Stock Status of Sarotherodon galilaeus in Samandeni Reservoir, Burkina Faso

Mango tilapia, Sarotherodon galilaeus is one of the most caught fish species in the Samandeni multi-species fishing sites of which, few data on its biology and exploitation are available. The study aimed to Assess the stock status of S. galilaeus. Sampling was conducted from March, 2021 to February 2022 based on commercial fish catches to analyze growth parameters, first sexual maturity size and harvest status of the stock. A total of 572 specimens including 297 females and 275 males were examined. The stock assessment was performed by using the Length based Bayesian method of Biomass (LBB) and that of growth by the ELEFAN method. The growth parameters showed a seasonality of growth and females appeared to grow faster than males. On the other hand, males had a greater asymptotic length than females. Results on the estimated length of fish at first maturity showed that females firstly reached the maturity compared to males. The relative biomass (B/B0) estimated for the stock was higher than the relative biomass that produces maximum sustainable yield (BMSY/B0) indicating healthy biomass. In addition, the length at first sexual maturity was less than the length at the first catch, indicating the absence of overfishing of growth. In addition, extending the study to the various stocks of the reservoir would be important for the sustainable management of the Samandeni high economic fishing area.

Turbidite Dynamics and Hydrocarbon Reservoir Formation in the Tano Basin: A Coastal West African Perspective

This study examines the turbidite dynamics and hydrocarbon reservoir formation in Ghana’s Tano Basin, which is located in coastal West Africa. Through an exploration of geological processes spanning millions of years, we uncover key factors shaping hydrocarbon accumulation, including source rock richness, temperature, pressure, and geological structures. The research offers valuable insights applicable to exploration, management, and sustainable resource exploitation in coastal West Africa. It facilitates the identification of exploration targets with higher hydrocarbon potential, enables the anticipation of reservoir potential within the Tano Basin, and assists in tailoring exploration and management strategies to specific geological conditions of the Tano Basin. Analysis of fluvial channels sheds light on their impact on landscape formation and hydrocarbon exploration. The investigation into turbidite systems unveils intricate interactions involving tectonics, sea-level fluctuations, and sedimentation patterns, influencing the development of reservoirs. An understanding of sediment transport and depositional settings is essential for efficient reservoir management. Geomorphological features, such as channels, submarine canyons, and distinct channel types, are essential in this situation. A detailed examination of turbidite channel structures, encompassing canyons, channel complexes, convex channels, and U-shaped channels, provides valuable insights and aids in identifying exploration targets like basal lag, channel levees, and lobes. These findings underscore the enduring significance of turbidite systems as conduits for sediment transport, contributing to enhanced reservoir management and efficient hydrocarbon production. The study also highlights how important it is to examine the configuration of sedimentary layers, stacking patterns, and angular laminated facies to identify turbidites, understand reservoir distribution, and improve well design. The dynamic nature of turbidite systems, influenced by basin characteristics such as shape and slope, is highlighted. The research provides valuable insights essential for successful hydrocarbon exploration, reservoir management, and sustainable resource exploitation in coastal West Africa.

Baoziwan-Majiashan Area of Jiyuan Oilfield Analysis of Reservoir Characteristics and Main Control Factors in Long 4 5 Section

Based on the sheet, scanning electron microscope and high pressure mercury analysis method, this paper takes Jiyuan oilfield-Ma Jia mountain district 4 5 sandstone reservoir as the research object, from the reservoir petrology, pore type and porosity, permeability, the system analyzed the reservoir characteristics and its control factors. The results show that the sandstone in the 4 5 section of Baoziwan-Majiashan area of Jiyuan oilfield is fine in size and high in filling content. The pore types were dominated by intergranular pores and dissolved pores, with a low face rate. The reservoir property is relatively poor, with mean porosity of 11.11% and mean permeability of 1.16 × 10−3 µm2. In the low porous, low otonic background, the development of relatively high pore hypertonic areas. Compaction and cementation should play a destructive role in reservoir properties, and dissolution should play a positive role in reservoir properties. Compaction adjusts the migration of clay minerals and miscellaneous bases in the original sediment in the study area, greatly reducing the porosity and permeability of the reservoir;the development of the cement cement, carbonate cementation and some quartz secondary compounds reduces the storage space;the dissolution effect, especially the secondary dissolution pores of the reservoir, which obviously improves the properties of the reservoir.

Evaluation of Chang 2 Reservoir in Zichang Area, Ordos Basin

In this paper, the Chang 2 reservoir in Zichang Area of Ordos Basin, the second largest sedimentary basin in China, is classified and evaluated by using logging and core data, thin section identification and electron microscopy. The main sedimentary microfacies of Chang 213 is braided river delta sedimentary system in geological history, and there are three main sedimentary microfacies types: swamp microfacies, distributary channel microfacies and natural embankment microfacies on land. The heterogeneity in the study area is as follows: Chang 212 formation has the strongest heterogeneity, followed by Chang 211 formation with strong heterogeneity, and finally Chang 213 formation with medium heterogeneity. The reservoirs of Chang 2 member in the study area are dominated by IIIa, IIb and IIIb, and the reservoirs are mainly composed of ultra-low porosity and low permeability reservoirs and low porosity and low permeability reservoirs.

Reservoir Characteristics and Main Controlling Factors of the Flow III Section of the K Oilfield in the Weixinan Depression

In order to clarify the reservoir characteristics and main controlling factors of the flow three section of the K oil field in the Weixinan Depression, a study on the reservoir characteristics and main controlling factors of the flow three section of the K oil field in the Weixinan Depression has been carried out by utilizing the data of cores, casting thin sections, physical property tests and logging wells. The results show that the lithology of the reservoir in the flow three section of the study area is dominated by coarse sandstone and medium sandstone, followed by conglomerate-bearing sandstone and sand conglomerate. The porosity is mainly distributed in the range of medium-high porosity, and the permeability is mainly medium seepage, and the overall physical properties are good. The three sections of the stream in the study area mainly include four sedimentary microphases, namely, underwater diversion channel, estuarine dam, mat sand and inter-diversion bay. The underwater diversion channel has the best physical properties, characterized by coarse grains and low mud content. The medium and coarse sand content of various lithologic reservoirs is the main factor in the formation of high-quality reservoirs. Rock-forming action is an important factor affecting the physical properties of local reservoirs, comparing the compaction, cementation and dissolution between different sedimentary microphases, the underwater diverging river has the lowest rate of compaction and pore reduction, the highest rate of pore increase by dissolution, and the best physical properties. Therefore, the weakly cemented-strongly dissolved coarse sandstone phase developed in the microphase of the underwater diversion channel in section 3 of the flow in the study area is the most favorable reservoir.

Application of Secondary Logging Interpretation—Taking Yan 9 Reservoir in X Area as an Example

Logging data and its interpretation results are one of the most important basic data for understanding reservoirs and oilfield development. Standardized and unified logging interpretation results play a decisive role in fine reservoir description and reservoir development. Aiming at the problem of the conflict between the development effect and the initial interpretation result of Yan 9 reservoir in Hujianshan area of Ordos Basin, by combining the current well production performance, logging, oil test, production test and other data, on the basis of making full use of core, coring, logging, thin section analysis and high pressure mercury injection data, the four characteristics of reservoir are analyzed, a more scientific and reasonable calculation model of reservoir logging parameters is established, and the reserves are recalculated after the second interpretation standard of logging is determined. The research improves the accuracy of logging interpretation and provides an effective basis for subsequent production development and potential horizons.

Study on the Fine Configuration of Reservoir in River Facies Oilfield in Bohai Sea Area

The geological conditions of offshore shallow water delta oil reservoirs were complex, with limited well data and large well spacing. Taking A Oilfield in the Bohai Sea Area, China as an example, the target sand body was formed in a shallow water delta sedimentary environment, with well-developed underwater distributary channels and frequent branching and diversion. The reservoir was strong non-uniformity and uneven plane water cut pressure. To this end, based on the existing work of predecessors, combined with seismic, logging, and production dynamics data, and based on the genesis mechanism of shallow water delta reservoirs, the boundary of composite river channels was identified through seismic facies, and logging facies were used to subdivide them into single river levels within the composite river channels. Then, seismic waveform characteristics were applied to track and characterize the plane distribution of single river channels, guiding the efficient development of offshore shallow water delta oil fields and achieving increased storage and production in Bohai Oilfield, China.

Graded and Quantitative Technology and Application of Coal-Bearing Reservoir Based on Seismic Reflection Characteristics

Taiyuan formation is the main exploration strata in Ordos Basin, and coals are widely developed. Due to the interference of strong reflection of coals, we cannot completely identify the effective reservoir information of coal-bearing reservoir on seismic data. Previous researchers have studied the reservoir by stripping or weakening the strong reflection, but it is difficult to determine the effectiveness of the remaining reflection seismic data. In this paper, through the establishment of 2D forward model of coal-bearing strata, the corresponding geophysical characteristics of different reflection types of coal-bearing strata are analyzed, and then the favorable sedimentary facies zones for reservoir development are predicted. On this basis, combined with seismic properties, the coal-bearing reservoir is quantitatively characterized by seismic inversion. The above research shows that the Taiyuan formation in LS block of Ordos Basin is affected by coals and forms three or two peaks in different locations. The reservoir plane sedimentary facies zone is effectively characterized by seismic reflection structure. Based on the characteristics of sedimentary facies belt and petrophysical analysis, the reservoir is semi quantitatively characterized by attribute analysis and waveform indication, and quantitatively characterized by pre stack geostatistical inversion. Based on the forward analysis of coal measure strata, this technology characterizes the reservoir facies belt through seismic reflection characteristics, and describes coal measure reservoirs step by step. It effectively guides the exploration of LS block in Ordos Basin, and has achieved good practical application effect.

准噶尔盆地玛湖凹陷三叠系百口泉组储层特征及油气成藏规律

通过岩心分析测试、地震厚度预测、包裹体成藏期次分析以及源储配置关系研究,对准噶尔盆地玛湖凹陷三叠系百口泉组储层特征及油气成藏规律进行了刻画。研究结果表明:①玛湖凹陷斜坡区三叠系百口泉组主要发育扇三角洲沉积,岩性普遍较粗,相对优质的储集层主要分布于扇三角洲前缘水下分流河道微相及少量河口砂坝微相中,其成分以长石岩屑砂砾岩为主,其次为岩屑砂砾岩。岩石普遍较致密。岩心孔隙度为3.17%~23.40%,平均为9.04%,渗透率为0.01~934.00mD,平均为0.73mD,属低孔特低渗型储集层。储集空间类型以次生溶孔为主,可见粒间缝和其他微裂缝。②研究区油气主要来源于下二叠统风城组碱湖沉积的泥页岩,最厚处超过400m,为残留海—潟湖相沉积,水体盐度较高,岩性以云质泥岩和泥质岩为主。有机质类型以Ⅰ和Ⅱ1型为主,总有机碳含量(TOC)多大于1.0%,生烃潜量(S1+S2)多大于6.0mg/g,氯仿沥青“A”平均为0.2%,HI平均为322mg/g,有机质演化处于成熟阶段,为中等—好烃源岩。③研究区具有3期成藏特征,晚三叠世之前为第1期油气充注,未能聚集成藏,早侏罗世为第2期油气充注期,对应黄色荧光烃类包裹体;早—中白垩世为第3期油气充注期,对应蓝白色荧光烃类包裹体,后2期油气充注对百口泉组油气成藏起主要贡献作用。④研究区源储配置紧密性是导致玛湖西斜坡和玛湖东斜坡油气差异性聚集的核心要素。

四川盆地南部向斜区二叠系岩溶孔隙型石灰岩储层成因与天然气勘探新领域

随着油气勘探程度不断提高,勘探方向逐渐从构造高部位往向斜区拓展。但是,传统认识认为向斜区岩性一般较致密,寻找向斜区优质储层成为其油气获得勘探突破的关键因素之一。为此,以四川盆地南部向斜区中二叠统茅口组石灰岩为例,基于钻井岩心、薄片、测井以及地球化学等资料综合分析,开展了向斜区孔隙型石灰岩储层特征及成因研究,并建立了储层发育模式,指出了天然气勘探新方向。研究结果表明:(1)四川盆地南部向斜区茅口组发育岩溶孔隙型碳酸盐岩储层,储层岩性主要为泥晶—亮晶生屑石灰岩和亮晶生屑石灰岩,储集空间主要为生物体腔孔、生物铸模孔及粒内溶孔等组构选择性溶蚀形成的孔隙;(2)研究区茅口组储层平均孔隙度为4.07%,平均渗透率为0.273 mD,孔隙度与渗透率有明显的正相关关系,为典型的孔隙型储层;(3)茅口组储层段的铝、钪、锆及总稀土元素含量较低,锰和铁含量也较低,碳同位素值位于中二叠世海水沉淀方解石碳同位素值分布范围内,氧同位素呈现出一定的负偏;(4)茅口组岩溶孔隙型储层的形成与沉积期微地貌及高频层序控制的准同生期岩溶有关,溶蚀流体主要为大气淡水。结论认为,岩溶孔隙型储层在盆地内普遍发育,且该类储层远离不整合面,受沉积古地貌、沉积相带控制的准同生期岩溶改造,因此,天然气勘探思路需要向“有利沉积相带规模控储”方向转变,向斜区将是盆地内未来天然气勘探的重要新领域。

基岩油气成藏特征与中国陆上深层基岩油气勘探方向

基于全球基岩油气藏数据库和中国基岩油气藏解剖,深入分析基岩油气成藏特征,探讨深层基岩油气成藏的有利条件和勘探方向。研究表明:全球已发现的基岩油气田主要分布在埋深小于4500 m的中浅层,层位以太古宇和前寒武系为主,储集层岩性以花岗岩和变质岩为主;规模较大的基岩油气田主要分布在中新生代构造运动活跃的裂谷盆地、弧后盆地和前陆盆地。基岩油气成藏特征主要表现为:(1)以孔隙-裂缝型低孔特低渗储集层为主,非均质性强,强抗压实作用导致储集层物性不受埋深控制,规模成储期为盆地基底风化剥蚀期及后期构造改造期;(2)他源供烃,成藏组合可划分为烃源岩-基岩接触型和烃源岩-基岩分离型两大类;(3)烃源岩异常高压和基岩储集层常压-低压,导致烃源岩与储集层之间存在较大的压力差,有利于深层基岩抽吸成藏。基底构造活动性、成藏组合关系、深大断裂(尤其走滑断裂)发育程度及区域性盖层等是深层基岩选区评价的主要参数;古老克拉通盆地陆内裂谷边缘的前寒武系结晶基底、紧邻生烃凹陷的古生代褶皱基底和中新生代块断基底,均具有较好的成藏条件,是未来深层基岩油气勘探的主要方向。

深层碳酸盐岩储层酸压进展与展望

酸压改造是深层碳酸盐岩储层高效勘探开发的技术利器。随着勘探开发逐渐迈向特深层,厘清目前酸压技术发展现状与趋势至关重要。从酸压裂缝起裂与扩展、酸刻蚀水力裂缝与导流能力构建、酸压数值模拟技术3个方面阐释了酸压改造机理;分析了黏度控制型、生酸时间控制型、H+屏蔽吸附型、非盐酸基型等4类耐高温缓速酸液体系特点;系统梳理了我国深层碳酸盐岩酸压工艺技术发展的4个历程,剖析了目前9000 m以深特深层碳酸岩酸压面临的4个挑战:能否压开储层、地层温度突破酸液体系耐温极限、高温高压测试手段缺乏、储集体靶向沟通难度大。基于此,提出了5个酸压研究展望:特深井破裂压力精准预测、耐220℃多功能酸液体系研发、超高温高压实验平台构建、全在线酸压技术、超临界CO_(2)酸压技术探索,力求实现特深层碳酸盐岩高效立体开发。

深层古老碳酸盐岩-膏盐岩组合油气成藏特征

通过分析塔里木、四川和鄂尔多斯三大海相盆地埃迪卡拉系—奥陶系,并对比参考东西伯利亚、阿曼和澳大利亚Officer三大国外盆地新元古界—寒武系的地层特征,将碳酸盐岩-膏盐岩组合划分成碳酸盐岩类和膏盐岩类互为夹层型、碳酸盐岩类和膏盐岩类互层型以及碳酸盐岩类、膏盐岩类和碎屑岩类共生型3种类型,明确了碳酸盐岩-膏盐岩组合的概念及内涵。结果表明:(1)碳酸盐岩-膏盐岩组合的油气通常来源于泥页岩和泥质碳酸盐岩两类烃源岩,咸化环境膏盐岩可促进烃源岩生烃。(2)主要发育膏云坪型、颗粒滩和微生物丘型两大类白云岩储集层,准同生期或表生期的大气淡水淋滤是储集层规模发育的主要控制因素,后期埋藏溶蚀作用对储集层有调整和改造作用。(3)碳酸盐岩-膏盐岩组合油气成藏模式可划分为盐下成藏模式、盐上成藏模式和盐间成藏模式3大类8小类模式。塔里木盆地塔中隆起北坡、麦盖提斜坡和玛扎塔格前缘隆起带寒武系、四川盆地东部—南部地区寒武系和鄂尔多斯盆地奥陶系盐间马家沟组四段等为未来的有利勘探领域。

中上扬子地区震旦纪灯影组沉积期碳酸盐岩台地古地理格局及有利储集相带分布规律

【目的】中上扬子地区灯影组沉积期碳酸盐岩台地古地理格局及有利储集相带发育分布规律尚存争议,阻碍了灯影组油气勘探领域由绵阳—长宁拉张槽两侧向其他广大地区拓展。【方法】通过中上扬子地区灯影组30余条剖面(钻井)开展岩石类型划分及沉积相分析,【结果】进一步明确丘滩相以块状砂屑/鲕粒白云岩及柱状、穹窿状叠层石白云岩为特征,呈环带状分布在中上扬子台地(或内缓坡)边缘,向外过渡为中—外缓坡风暴岩或斜坡—盆地相区的滑塌角砾白云岩、泥质白云岩、硅质岩等。由于丘滩的阻挡作用,其内侧以低能的潮坪及潟湖沉积环境为主:其中潮坪相主要发育微生物纹层白云岩、穹窿—缓波状叠层石白云岩、凝块石白云岩夹砂屑白云岩、泥晶白云岩,纵向上常常形成米级—厘米级旋回;潟湖相主要由泥晶白云岩、含球粒/砂屑泥晶白云岩组成。相带时空分布表明灯影组在中上扬子地区总体呈现出进积的沉积趋势,内部包含2.5个层序,即三次进积(变浅)和两次退积(变深)旋回。【结论】由于灯影组在台地边缘—斜坡区域普遍遭到剥蚀,以及灯影组沉积期上扬子台地范围远超目前的板块边界,灯影组上部灯四段很少发现高能丘滩相带。在此背景下,局部地区(如松林—岩孔地区、中扬子台地周缘)灯影组中下部灯一段—灯二段(或蛤蟆井段、石板滩段)发育的丘滩相,是重要的有利储集相带。此外,处于海退体系域的灯二段中下部和灯四段上部(或相当层位)在中上扬子台地(或内缓坡)内部广泛发育微生物白云岩,也为储层发育有利相带。在中上扬子台地微生物白云岩广泛分布的背景下,进一步分析优质储层发育机理与分布规律才是找到油气接替区的关键。

塔里木盆地三大构造旋回油气成藏特征

塔里木盆地形成经历了南华纪—中泥盆世、晚泥盆世—三叠纪和侏罗纪—第四纪3大伸展-挤压构造旋回,其多旋回构造演化导致油气成藏和分布十分复杂。随着近年来盆地超深层已经成为油田的重点勘探领域,有必要对盆地的油气成藏规律进行深入探讨。本文基于最新的地震资料、钻井资料及油气地质资料,发现塔里木盆地油气规模成藏主力烃源岩为库车地区三叠系—侏罗系及塔西南地区石炭系—二叠系陆相烃源岩、台盆区寒武系海相烃源岩。盆内烃源岩及储盖组合的发育均受控于盆地3大伸展-挤压构造旋回,烃源岩的发育位置决定了塔里木盆地发育库车山前、北部坳陷、麦盖提斜坡及塔西南山前四大含油气系统。盆地在历经3大伸展-挤压旋回,其台盆区、库车前陆及塔西南前陆地区油气成藏组合差异大。台盆区发育石炭系膏泥岩与志留系—石炭系海相砂岩、奥陶系泥岩与灰岩、中寒武统膏盐岩与震旦系—寒武系白云岩储盖组合;库车地区发育新近系—第四系泥岩与砂岩、古近系膏盐层与白垩系砂岩、侏罗系泥岩与三叠系—侏罗系砂岩储盖组合;塔西南地区发育中新统泥岩-砂岩、古近系膏盐层与白垩系砂岩、石炭系—二叠系泥岩与碳酸盐岩储盖组合,分别组成了台盆区、库车及塔西南地区的上部、中部及下部组合。盆内烃源岩在加里东晚期、海西晚期—印支期、喜山期发生排烃,形成三期油气充注,结合塔里木盆地关键变革期的岩性、断裂、不整合及隆起的发育特征,构建了盆地三期成藏模式。

鄂尔多斯盆地石盒子组-山西组致密储层形成主控因素与发育模式:以彬长地区为例

明确致密储层“甜点”的分布是致密储层油气勘探的重点。通过岩心观察、薄片鉴定、X射线衍射、包裹体均一温度测定、常规物性分析等手段,对鄂尔多斯盆地南部彬长地区上古生界致密砂岩沉积特征、储层特征、成岩作用进行了详细研究,明确了储层形成的主要控制因素并建立了优质储层的发育模式。结果表明:沉积相是储层形成的基础,辫状河三角洲平原分流河道心滩微相岩石粒度粗,孔隙结构为小孔-中细喉型,储层物性相对较好;曲流河三角洲前缘水下分流河道及河口坝微相岩石粒度细,孔喉结构为微孔-微喉型,储层物性相对较差。成岩作用对优质储层的发育与分布具有重要控制作用。间歇性火山凝灰质在酸性地层蚀变为高岭石,而在碱性地层蚀变为绿泥石套膜,抑制了石英次生加大和方解石胶结,保护了储集空间。石英次生加大主要为泥岩转化形成的SiO_(2)渗滤到砂岩中形成的,中晚期方解石充填长石、岩屑溶孔为方解石顶底板胶结的主要原因。晚期构造改造形成的微裂缝无方解石胶结,改善了储层物性,对气藏起调整作用。彬长地区在3 750 m和3 900 m埋深段附近为2个溶蚀孔发育带。最优储层为溶蚀孔发育带内火山凝灰质转化形成的富含绿泥石套膜的中-粗砂岩;次优储层主要分布在溶蚀孔发育带内单砂体厚度较大、有旋回且无泥岩隔档的砂体的中下部,主要为缺少绿泥石套膜的中-粗砂岩,方解石胶结与石英次生加大作用最低。研究成果进一步深化了鄂尔多斯盆地南部地区上古生界致密砂岩优质储层发育的成因,对该地区天然气勘探开发具有重要指导意义。

川中侏罗系自流井组大安寨段页岩油储层特征及其勘探启示

为进一步指导四川盆地侏罗系自流井组大安寨段页岩油的勘探与开发,亟需理清页岩油的有利赋存岩相。通过岩心观察、薄片鉴定、高压压汞、核磁共振、岩石热解等实验,分析大安寨段页岩层系不同岩相的储集空间类型、孔隙结构特征及含油性。结果表明,大安寨段主要发育块状(泥质)介壳灰岩、层状泥质介壳灰岩、层状介壳页岩、纹层状含介壳页岩、块状含介壳黏土质页岩和页理状含粉砂黏土质页岩6类岩相;页岩物性远优于介壳灰岩,且随着灰质含量的增加孔径逐渐增大,但总孔体积和总连通体积逐渐减小;大安寨段页岩层系平均游离油(S1)值为1.31 mg/g,含油性中等,页理状含粉砂黏土质页岩与纹层状含介壳页岩S1值较高,分别为2.37 mg/g与1.82 mg/g。页理状含粉砂黏土质页岩和纹层状含介壳页岩的储集性较好、含油性较高,两者构成的岩相组合可作为大安寨段页岩油的重点勘探对象。

深层-超深层致密储层天然裂缝分布特征及发育规律

天然裂缝是深层-超深层致密储层的有效储集空间和主要渗流通道,影响着致密储层油气的运移、富集、单井产能、开发方式及开发效果。通过对近年来致密储层裂缝研究成果总结和文献综述,分析了深层-超深层致密储层天然裂缝分布特征及发育规律。将致密储层天然裂缝分为大尺度裂缝、中尺度裂缝、小尺度裂缝和微尺度裂缝4个级别。不同尺度裂缝分布具有幂律分布的特点,裂缝尺度越大,数量越少;裂缝尺度越小,数量越多。大、中尺度裂缝主要起渗流作用,小尺度裂缝主要起渗流和储集作用,而微尺度裂缝主要起储集作用。在地层埋藏过程中的应力体制演化决定了不同时期天然裂缝的类型、产状及其力学性质;构造应力大小、岩石力学层的力学性质和厚度差异控制了多尺度裂缝的形成分布及其发育程度。构造变形导致不同构造部位的局部应力和应变分布产生差异,增强了裂缝发育的非均质性。逆冲断层通过控制其上盘地层变形控制了“裂缝域”的分布规律;走滑断层的组合样式、活动方式和岩石力学层共同控制了相关裂缝的三维空间展布。裂缝形成演化过程中的开启-闭合规律决定了裂缝的储集空间,记录了裂缝有效性的演化历史。