Differential Hydrocarbon Enrichment and its Main Controlling Factors in Depressions of the Bohai Bay Basin Differential Hydrocarbon Enrichment and its Main Controlling Factors in Depressions of the Bohai Bay Basin

Significant differential hydrocarbon enrichment occurs in depressions in a petroliferous basin.There are multiple depressions in the Bohai Bay Basin, and each depression as a relatively independent unit of hydrocarbon generation, migration and accumulation, contains significantly different hydrocarbon generation conditions and enrichment degree. On the basis of previous documents and a large number of statistical data, this work comparatively analyzed the differential hydrocarbon enrichment and its major controlling factors in depressions of the Bohai Bay Basin. The results show that depressions in the Bohai Bay Basin have various hydrocarbon enrichment degrees, and can be categorized into four types, namely enormously oil-rich, oil-rich, oily and oil-poor depressions. In general, the enormously oil-rich and oil-rich depressions are distributed in the eastern part of the basin along the Tan-Lu and Lan-Liao faults, whereas depressions in the western part of the basin are poor in hydrocarbons. Moreover, the vertical distribution of hydrocarbons is also highly heterogeneous, with Pre-Paleogene strata rich in hydrocarbons in the northern and western depressions, Paleogene strata rich in hydrocarbons in the entire basin, and Neogene strata rich in hydrocarbons in the off-shore areas of the Bohai Bay Basin. From early depressions in onshore areas to the late depressions in offshore areas of the Bohai Bay Basin, the source rocks and source-reservoir-cap rock assemblages gradually become younger and shallower, and the hydrocarbon resource abundance gradually increases. Hydrocarbon supplying condition is the key factor constraining the hydrocarbon enrichment for different depressions,while the main source-reservoir-cap rock assemblage, sufficient hydrocarbons and the transportation capacity of faults control the vertical distribution of hydrocarbons. The main factors controlling hydrocarbon enrichment are different for different layers. The hydrocarbon supplying condition of source rocks is the key controlling factor, whereas the source-reservoir configuration, the main sourcereservoir-cap rock assemblages, and the fault transportation are the main factors of hydrocarbon enrichment in the Paleogene, Paleogene and Neogene, respectively.

Major controlling factors and hydrocarbon accumulation models of large-scale lithologic reservoirs in shallow strata around the Bozhong sag,Bohai Bay Basin,China

Based on the practice of oil and gas exploration and the analysis of shallow lithologic reservoirs,combined with the allocation relationship and enrichment law of oil and gas accumulation factors,main controlling factors and models of hydrocarbon accumulation of large lithologic reservoirs in shallow strata around the Bozhong sag are summarized,and favorable exploration areas are proposed.The coupling of the four factors of“ridge-fault-sand-zone”is crucial for the hydrocarbon enrichment in the shallow lithologic reservoirs.The convergence intensity of deep convergence ridges is the basis for shallow oil and gas enrichment,the activity intensity of large fault cutting ridges and the thickness of cap rocks control the vertical migration ability of oil and gas,the coupling degree of large sand bodies and fault cutting ridges control large-scale oil and gas filling,the fault sealing ability of structural stress concentration zones affects the enrichment degree of lithologic oil and gas reservoirs.Three enrichment models including uplift convergence type,steep slope sand convergence type and depression uplift convergence type are established through the case study of lithologic reservoirs in shallow strata around the Bozhong sag.

Differences and controlling factors of composite hydrocarbon accumulations in the Tazhong uplift, Tarim Basin, NW China

Based on three-dimensional seismic interpretation, structural and sedimentary feature analysis, and examination of fluid properties and production dynamics, the regularity and main controlling factors of hydrocarbon accumulation in the Tazhong uplift, Tarim Basin are investigated. The results show that the oil and gas in the Tazhong uplift has the characteristics of complex accumulation mainly controlled by faults, and more than 80% of the oil and gas reserves are enriched along fault zones. There are large thrust and strike-slip faults in the Tazhong uplift, and the coupling relationship between the formation and evolution of the faults and accumulation determine the difference in complex oil and gas accumulations. The active scale and stage of faults determine the fullness of the traps and the balance of the phase, that is, the blocking of the transport system, the insufficient filling of oil and gas, and the unsteady state of fluid accumulation are dependent on the faults. The multi-period tectonic sedimentary evolution controls the differences of trap conditions in the fault zones, and the multi-phase hydrocarbon migration and accumulation causes the differences of fluid distribution in the fault zones. The theory of differential oil and gas accumulation controlled by fault is the key to the overall evaluation, three-dimensional development and discovery of new reserves in the Tazhong uplift.

Main Controlling Factors and Accumulation Model of Chang 9 Reservoir in Northwest Ordos Basin, China

In northwestern Ordos Basin, the Triassic reservoir Chang 9 has favorable reservoir forming conditions, extensive reservoir development, and huge potential for oil exploration and exploitation. Studying the main controlling factors and accumulation model of Chang 9 reservoir in this area can provide a basis for the production targets, and assist in formulating reasonable development technology policy. In this paper, to explore and summarize the hydrocarbon accumulation model, the Chang 9 reservoir were analyzed from the aspects of oil source, fracture, oil migration, structure, lithology and reservoir physical properties for the main controlling factors in this area. Organic geochemical and geological comprehensive analysis that the oil-source of the Chang 9 reservoir in the northwest of Ordos Basin is derived from Chang 7 hydrocarbon source rocks. The fractures provide a sound channel for the "vertical multi-point filling" of the oil source from Chang 7 to Chang 9. The crude oil migrates vertically from Chang 7 to Chang 9, then expands horizontally to form a reservoir. Structures play an important role in controlling the distribution of reservoirs, the control by sand in small layer and physical property is also obvious. This paper creatively establishes the reservoir accumulation model of Chang 9 in northwest of Ordos Basin, which is characterized by Vertical multi-point filling, horizontal expansion becomes oil pool. It reveals the genetic mechanism of the development of Chang 9 multi-reservoir in the study area, which provides guidance for exploration and evaluation deployment.

Controlling factors of marine shale gas differential enrichment in southern China

Based on the exploration and development practice of marine shale gas in Fuling, Weiyuan, Changning, Luzhou and Southeast Chongqing in southern China, combined with experiments and analysis, six factors controlling differential enrichment of marine shale gas are summarized as follows:(1) The more appropriate thermal evolution and the higher the abundance of organic matter, the higher the adsorption and total gas content of shale will be.(2) Kerogen pyrolysis and liquid hydrocarbon cracking provide most of the marine shale gas.(3) The specific surface area and pore volume of organic matter rich shale increased first and then decreased with the increase of thermal evolution degree of organic shale. At Ro between 2.23% and 3.33%, the shale reservoirs are mainly oil-wet, which is conducive to the enrichment of shale gas.(4) The thicker the roof and floor, the higher the shale gas content. The longer the last tectonic uplift time and the greater the uplift amplitude, the greater the loss of shale gas will be.(5) The buried depth and dip angle of the stratum have different controlling and coupling effects on shale gas in different tectonic positions, resulting in two differential enrichment models of shale gas.(6) The effective and comprehensive matching of source, reservoir and preservation conditions determines the quality of shale gas accumulation. Good match of effective gas generating amount and time, moderate pore evolution and good preservation conditions in space and time is essential for the enrichment of shale gas.

Hydrocarbon accumulation principles in troughs within faulted depressions and their significance in exploration

Previously,troughs in continental faulted depressions were usually considered as a zone of hydrocarbon generation and expulsion rather than a zone for hydrocarbon accumulation.If they were confirmed to be the source kitchen,the possibility that they could constitute potential plays would be overlooked in the subsequent exploration program.Based on the hydrocarbon exploration practice of the Jizhong Depression and the Erlian Basin in the past several years,this paper discusses a new understanding that reservoir distribution is controlled by multiple factors and lithological accumulations are more likely to form in trough areas.It further documents the three main factors controlling the formation of large lithological hydrocarbon accumulations in trough areas.The paper also discusses the new concept that structural and lithological accumulations not only co-exist but also complement each other.We propose that fan-delta fronts on inverted steep slopes in troughs,delta fronts and sublacustrine fans on gentle slopes,channel sands along toes of fault scarps are favorable locations for discovery of new oil accumulations.The application of this concept has led to the discovery of several hundreds of million tonnes of oil in place in trough areas in the Jizhong Depression and the Erlian Basin.

玛湖凹陷及周缘白碱滩组勘探突破与新认识

为明确玛湖凹陷白碱滩组砂体分布规律和油气成藏模式,评价其油气勘探前景,综合钻井、测井、地震、分析化验等资料,系统梳理白碱滩组二段沉积规律和成藏特征。白碱滩组二段为辫状河三角洲—滩坝—浊积扇沉积序列,发育水下分流河道砂、滩坝砂和浊积砂3种不同类型的砂体,辫状河三角洲前缘亚相以河道砂为主,滨—浅湖发育滩坝砂,半深湖—深湖受坡折带控制发育多个浊积扇体,浊积砂呈朵叶状分布,建立了水下分流河道—滩坝—浊积扇的沉积控砂模式。研究区发育9大走滑断裂体系,其中,走滑断裂直通型、走滑断裂伴生型和走滑断裂接力型3种断裂组合能够有效沟通二叠系风城组烃源岩,作为油气垂向高效运移通道,白碱滩组二段整体具有走滑断裂通源、断裂砂体配置控藏和优质储集层富集的成藏模式。

西非Termit盆地石油地质特征及成藏主控因素

西非Termit盆地是中国石油在非洲极为重要的勘探开发区块。在充分利用钻井、分析化验和地震资料基础上,开展了Termit盆地石油地质特征和成藏主控因素研究,研究表明:①Ter-mit盆地历经前裂谷期、同裂谷期、后裂谷期三大构造演化阶段,同裂谷期发育早晚两期裂谷作用形成中生代—新生代叠置裂谷盆地,宏观具有“东西分带、南北分块”的构造结构特征,控制圈闭的形成与分布。②发育上白垩统Yogou组分布广(18000 km^(2))、厚度大(600~1400 m)、成熟度适中(Ro值为0.7%~1.3%)的海相烃源岩,配置上白垩统Yogou组顶部发育的海相三角洲、古近系Sokor1组辫状河三角洲砂体,及古近系Sokor2组区域性分布的泥岩盖层,形成了上、下两套成藏组合;③明确古近系、白垩系成藏主控因素,古近系为“下生上储”的次生油气藏,油气平面和垂向分布受生烃灶、区域盖层、油源断层和优势沉积相控制,白垩系为“自生自储”原生油藏,油气富集受区域构造活动强度和白垩系内幕构造控制。④构建了基于海相广覆式烃源岩的跨世代油气成藏模式,明确Dinga断阶带、Fana凸起和Araga地堑是古近系油气勘探的有利区带,造活动相对较弱的Moul凹陷及Dinga断阶带南部是白垩系油气勘探的有利区带。地质认识指导勘探部署,在尼日尔Termit盆地获得了重大勘探突破,累计探明石油地质储量超7亿t,为中国石油海外油气增储上产奠定了坚实的基础。

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。

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.

下刚果—刚果扇浊积水道沉积演化与成藏主控因素——以A油田下中新统X砂组为例

下刚果—刚果扇盆地为深水浊积岩油气勘探成功的典型含油气盆地。盆内广泛发育的浊积水道为重要储层类型,蕴含丰富的油气资源。前人从构造和沉积等角度对深水水道沉积模式及控制因素进行了大量研究,取得了长足进展(Henry et al.,2019;陈华等,2021)。然而也有大量实钻资料表明水道体系内部砂体期次的沉积发育和叠置关系非常复杂,储层非均质性很强(张文彪等,2017)。

西湖凹陷中央背斜带中南部区带油气成藏主控因素与勘探方向

西湖凹陷深层—超深层油气资源勘探潜力大,具有良好的勘探前景。为明确西湖凹陷中央背斜带中南部区带的油气成藏主控因素,对西湖凹陷中央背斜带的构造背景、沉积特征、烃源岩条件和储层性质进行分析研究。通过分析西湖凹陷中央背斜带中南部不同区带油气分布特征,总结了油气富集的分布规律以及差异成藏的主控因素,建立了成藏模式。结果表明,西湖凹陷中央背斜带中南部的油气成藏主控因素为早期通源断裂与砂体耦合及晚期保存条件,并根据储盖组合及油气分布规律划分为平湖组、花港组、龙井组3个成藏组合,其中花港组是主要的成藏层系,花港组具备发育岩性体的沉积环境,具有岩性、地层圈闭形成条件;烃源岩持续生烃提供了充足的油气源,深层—超深层砂岩储集性能依然保持较好,在3900~3700 m低渗储层广泛发育,有利沉积相带叠合次生溶蚀控制优质储层分布,油气充注与圈闭的形成时间配置关系好。研究结果对于西湖凹陷的持续勘探开发具有一定的指导意义。

Advances and problems in hydrocarbon exploration in the Tazhong area, Tarim Basin

Located in the middle of the Tarim Basin, Tazhong is a typical area of compound reservoirs rich in oil and gas found in the Carboniferous, Silurian and Ordovician strata. The proved, probable and possible reserves （3P reserves） in the area amount to 5×108 tons, so it is of great significance to study the advances and problems in hydrocarbon exploration in the Tazhong area. On the basis of exploration history and analysis of scientific problems, we outline eight achievements： distribution characteristics of reservoirs, stages of reservoir formation, different sources of oil and gas and their respective contributions, the effective regional caprock and reservoir-caprock combinations dominating the vertical distribution of hydrocarbon reservoirs, the control of the Tazhong Palaeo-uplift on reservoir formation and establishing geologic models, structure balance belts influencing the reconstruction and residual potential of reservoirs after accumulation, the rules and mechanisms of fractures controlling oil and gas, and the types of favorable reservoirs and their characteristics of controlling oil and gas distribution. We further point out the main problems about the oil and gas exploration in the Tazhong area and put forward some relevant proposals.

The controlling factors of oil and gas charging and accumulation of Puguang gas field in the Sichuan Basin

Combined with oil and gas transport and accumulation, structure-lithology evolution history, and with geochemistry and synthesizing geology methods, this paper studies the oil and gas discharge history of Puguang large scale gas field and the main controlling factors of oil accumulation. The natural gas in Puguang gas field is mainly coal-derived gas and oil-racked gas. The main hydrocarbon is Upper Permian coal mudstone and Lower Silurian mud shale with organic material. Puguang gas field has gone through discharge and adjustment 3 times, and it has favorable palaeostructure location, high quality dredge and effectively conserving conditions.

松辽盆地南部断陷层火山岩储层特征及油气成藏主控因素

松辽盆地南部断陷层火石岭组中-基性火山岩广泛发育,是松辽盆地深层油气勘探的热点。本文通过宏观到微观多尺度综合分析,开展火山岩形成与分布、岩性岩相与火山机构类型、储集空间特征和油气成藏特征等方面研究,总结深层火山岩有效储层形成机制及成藏主控因素。研究表明:(1)火石岭组中-基性火山岩分布广泛,多呈低幅丘状、多期叠置连片分布;火山岩主要发育3种岩相、7种亚相;发育“孔隙+缝网”复合型有效储集空间类型;(2)火山机构控制岩性、岩相分布,决定原生孔隙的形成与分布;构造作用、溶蚀作用利于构造裂缝及次生溶蚀孔缝的形成,是控制形成优质储层的关键因素;(3)优质储层和保存条件是油气富集的主控因素。

冀中坳陷束鹿潜山带油气成藏主控因素与成藏模式

近年来,束鹿潜山带油气勘探取得重大突破,展现出冀中坳陷南部潜山较大的油气勘探潜力。但是,潜山带油气成藏主控因素与成藏模式还未开展系统研究和总结,严重制约了研究区下一步的油气勘探。本论文基于大量的钻井、测录井、地球化学资料、样品测试分析以及盆地模拟的方法,系统剖析了束鹿潜山带不同类型潜山的油气成藏条件,揭示了油气成藏主控因素,并建立了油气成藏模式。结果表明,束鹿潜山带油气成藏主控因素为供烃条件、输导体系以及保存条件,其中供烃条件一定程度上控制了油气成熟度与分布,输导体系控制了油气的运聚和规模,而保存条件控制了原油性质与富集。束鹿潜山带的洼中隆潜山经历了古近系沙河街组二段(Es2)沉积末期—东营期(Ed)和明化镇期(Nm)—现今两期油气充注过程,为近源断层输导断背斜聚集的油气成藏模式;而斜坡带潜山只经历了明化镇期(Nm)—现今一期低熟—正常原油充注过程,为远源不整合输导反向断块-高潜山聚集的油气成藏模式。研究成果可为研究区潜山带油气成藏机理的认识和油气勘探提供科学依据。

“双源”控制的窄河道致密砂岩气富集高产模式——以四川盆地金秋气田中侏罗统沙溪庙组为例

四川盆地中部金秋气田中侏罗统沙溪庙组致密砂岩气资源潜力大,但该区致密砂岩气高效勘探开发面临着诸多技术难题,亟须开展致密砂岩气富集高产主控因素及模式研究,进而明确该区天然气富集高产规律,为有利区优选和高产井部署提供理论依据。为此,以金秋气田沙溪庙组二段一亚段(以下简称沙二1亚段)窄河道砂岩为研究对象,利用钻井岩心、测井、地震及生产动态资料等,厘清了天然气分布特征,明确了天然气富集高产主控因素,构建了“双源”控制的窄河道致密砂岩气藏富集高产模式。研究结果表明:①不同砂组不同河道段含气性差异大,高产井主要分布于6号砂组JQ5H井区东北部、ZQ1井区东南部,8号砂组QL16井区中南部及东部、JQ8井区中西部、JQ5H井区西北部,9号砂组ZQ1井区东南部。②沙二1亚段天然气富集高产受控于优越的烃源岩条件、优质储层的发育程度和高效输导体系。③在优越的烃源岩条件下,砂体连通性好且发育有利的断—砂“V”字形组合砂体的天然气充注动力强、充注阻力小,天然气充注程度较高,易形成天然气富集高产区。④东部的JQ5H井区和ZQ1井区,与角1号断裂“V”字形对接的连通砂体内Ⅰ、Ⅱ类储层占比高的河道段为天然气富集区;以须家河组为主要气源的西部QL16井区和JQ8井区,高产井分布在西南部河道砂体连通性最好的8号砂组,自西南向东北压力损失小且持续保持好,为天然气富集区。结论认为,“双源”控制的窄河道致密砂岩气藏富集高产模式揭示了四川盆地金秋气田沙溪庙组致密砂岩气富集高产规律,支撑了该区致密砂岩气高效勘探开发,并为相似地质条件下的气田的勘探开发提供参考。

西非北部塞内加尔盆地油气富集规律与勘探方向

西非北部塞内加尔盆地是位于前寒武系—古生界结晶基底之上的巨型裂谷−被动陆缘叠合盆地。笔者基于地震、典型钻井、测井资料及国际油气商业数据库和勘探的最新成果,结合区域地质背景和盆地构造沉积演化特征,分析盆地油气成藏条件、成藏特征和富集规律,并预测未来勘探方向。研究表明,盆地经历前裂谷、同裂谷和被动陆缘3期构造演化阶段,盆地结构呈“北缓南陡”形态,具体表现为“北部窄陆架缓陆坡、南部宽陆架陡陆坡”特征。盆地发育裂陷期湖相和被动陆缘期海相两套烃源岩,裂陷期烃源岩对盆地深水区白垩系成藏具有重大贡献,被动陆缘期烃源岩在上覆地层较厚时才成熟。盆地可划分为3种油气成藏模式。①陆架区下生上储,断层沟通不整合,陆架三角洲前缘浊积砂岩成藏模式。②斜坡坡脚区下生上储、断砂配置输导、近源供烃成藏模式。③深水−超深水区下生上储,垂向运移,构造−地层型浊积砂岩成藏模式。陆架边缘三角洲前缘砂体、斜坡坡脚处的浊积水道和海底扇、深水区浊积水道和浊积扇是塞内加尔盆地重点勘探领域,深水区大型构造−地层圈闭为盆地最重要的勘探目标。

东营凹陷滩坝油气成藏主控因素与成藏模式

东营凹陷南坡东段沙四上亚段滩坝油藏具有良好的勘探潜力,由于滩坝储层分布复杂、油气成藏规律不清,制约了勘探工作的深入开展,因此需要对其油藏主控因素和成藏模式展开研究。通过对研究区有效储层、源藏关系与压力环境、断裂系统与优势运移路径等的综合分析,明确了控制油气成藏的主要因素,并建立了成藏模式。

古龙凹陷姚一段致密油藏成藏主控因素及成藏模式

综合地震、地质、地球化学、生产测试等资料,在古龙凹陷姚一段致密油藏类型和分布规律研究的基础上,明确其成藏主控因素及成藏模式。结果表明:古龙凹陷姚一段发育5种致密油藏,由古龙向斜向周缘斜坡由砂岩透镜体油藏变为上倾尖灭岩性油藏、断层-岩性油藏和断块油藏,鼻状凸起顶部为断背斜油藏;致密油藏的形成受烃源岩及超压分布、圈闭类型、油源断裂和优质储集层联合控制,青一段湖相泥岩不仅是致密油藏的物质基础,其形成的异常高压是古龙向斜致密油充注的主要动力;大规模成藏前各类圈闭已形成,两侧高部位构造圈闭和构造-岩性圈闭是致密油运移指向区以及有利的聚集部位,主成藏期开启的反转期断层是致密油垂向运移的主要通道,分流河道优质储集层是致密油聚集的有利储集层;各构造单元成藏主控因素和模式存在差异,古龙向斜为“超压驱动、断层垂向输导、局部甜点富集”成藏模式,新站鼻凸为“超压+浮力接力驱动、断层垂向输导、有利圈闭聚集”成藏模式,新肇斜坡为“超压+浮力联合驱替、断-砂接力运移、有利储集层聚集”成藏模式。