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.

远源致密砂岩气成藏主控因素及成藏概率定量评价——以四川盆地西南部中侏罗统沙溪庙组气藏为例

四川盆地西南部(以下简称川西南部地区)中侏罗统沙溪庙组致密砂岩气藏属于远源次生气藏,不同构造天然气富集差异性大,成藏主控因素不清。为此,基于远源致密砂岩气成藏条件分析,对比了川西南部地区沙溪庙组7个含气构造的成藏差异性,明确了成藏主控因素,在综合考虑控制致密砂岩气成藏差异性的各类地质因素的基础上,建立了远源致密砂岩气成藏概率的定量评价方法,并预测了天府气田简阳区块沙溪庙组天然气储量丰度。研究结果表明:(1)川西南部地区沙溪庙组主要发育构造—岩性气藏,天然气均源自下伏上三叠统须家河组煤系烃源岩,不同含气构造在天然气组分、储层特征、输导保存条件等方面存在明显差异;(2)烃源岩排烃能力奠定了物质基础,断—盖配置决定了天然气富集层系,断—储耦合控制着天然气聚集效率,储层品质决定了天然气富集规模;(3)烃源岩排烃能力指数、源—储距离指数、储层物性指数、储层厚度指数、断—盖耦合类型指数及断—储配置类型指数可作为评价致密砂岩气成藏概率指标,提出的远源致密砂岩气成藏概率指数(HAI)可用于该地区远源致密砂岩气地质储量预测。结论认为,HAI与储量丰度具有很好的正相关关系,并预测了天府气田简阳区块的HAI值为0.53,沙溪庙组气藏的储量丰度为1.32×10^(8)m^(3)/km^(2),提出的天然气成藏定量评价方法准确度较高,为川西南部地区沙溪庙组天然气勘探开发指明了方向。

特提斯洋与古亚洲洋协同演化控制下的塔里木台盆区油气富集效应

显生宙特提斯洋和古亚洲洋2大构造域演化历史对塔里木盆地产生了巨大的影响,其效应包括原型盆地的形成与沉积充填过程及油气成藏与调整改造等。原特提斯洋和古亚洲洋分别经历了扩张、俯冲-消减和关闭-碰撞造山过程。特提斯域经历了原特提斯、古特提斯和新特提斯3个阶段,具有此消彼长的关系。古亚洲洋在新元古代—古生代多陆-岛-洋的格架下经历了复杂的伸展—聚敛过程。受特提斯洋(昆仑-阿尔金分支洋)和古亚洲洋(南天山洋分支)协同演化控制,塔里木盆地经历了新元古代—早古生代和晚古生代—新生代2个从伸展—聚敛的巨型盆地旋回,与海平面升降和气候旋回匹配,形成了优质烃源岩、多类型规模性储层和盖层,构成了油气形成的优越物质基础。特提斯洋和古亚洲洋多圈层协同演化控制的油气富集效应体现在:①多类型盆地原型与后期构造改造决定了塔里木台盆区不同部位油气成藏与富集的差异性;②北部坳陷广泛分布的优质烃源岩,是塔北—顺托—塔中地区大型油气富集区形成的基础;③多期构造运动伴随的构造破裂与古岩溶作用造就了断控缝洞型和岩溶缝洞型2类各具特点且规模发育的储集体;④区内构造与地温场差异演化决定了油气聚集区内油气相态与次生改造的规律性变化。台盆区大型古隆起和不整合面、走滑断裂带、高能相带及其叠加区是油气有利目标区。

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)。

破碎颗粒堆积方式对渗透率应力敏感性的影响机制

颗粒堆积下的渗透性量化对采空区冒落带、断层破碎带阻水性能、低渗煤层应力敏感性评估具有重要意义。基于Hertz变形假设,构建了不同颗粒堆积方式的渗透率演化模型,分析了不同颗粒排列结构下应力敏感性及主控因素,探讨了本体变形与结构变形的应力敏感性作用机制。研究表明:若仅考虑本体变形,渗透率应力敏感性和组合颗粒数呈反比,颗粒弹性模量是加卸载试验中应力敏感性主导因素;颗粒发生结构变形的应力敏感性远高于本体变形,和结构变形程度呈正比(颗粒组合结构调整);颗粒结构应力敏感性是结构变形、等效弹模、结构调整综合作用的结果;数值验证了不同颗粒结构应力敏感性的合理性,不同位置渗透率的调整是导致孔压非均匀分布、渗透性变化的主要因素;研究结果表明低渗储层(煤层)存在强应力敏感性,与岩石、流体性质密切相关。

松辽盆地他拉海地区萨、葡油层断砂输导油气能力主控因素与油气富集规律

为了研究松辽盆地北部他拉海地区萨、葡油层油气富集规律,在萨、葡油层油气成藏模式及输导油气通道构成研究的基础上,通过分析断裂和砂体输导油气能力主控因素及其分布特征,结合油气富集特征,对断砂输导油气能力影响因素与油气富集关系进行研究。结果表明:他拉海地区油源断裂输导油气能力的主控因素是成藏期古断距和下伏青一段源岩排烃强度,下伏青一段源岩排烃强度与葡萄花油层油气富集之间关系密切,是造成其油气主要分布在东部的主要原因;油源断裂古断距与萨尔图油层油气富集关系密切,是造成其油气主要分布在西部的主要原因;砂体输导油气能力主控影响因素是古构造脊和优势相砂体发育及分布,古构造脊发育及分布与萨、葡油层油气富集关系密切,其发育及分布是造成油气主要富集在其东部和中北部的主要原因。研究成果为以断砂输导体系为主的勘探地区油气成藏分析提供理论参考。

XH凹陷中南部背斜带油气分布特征与成藏主控因素

为了厘清XH凹陷中南部背斜带的油气成藏主控因素,解剖了中南部T气田、H气田、R气田等3个典型油气田。研究表明:中南部背斜带油气成因、来源和成藏期次一致,但油气分布却存在显著差异性,主要表现在富集程度、纵向分布层位和平面赋存位置3个方面。分析认为,造成油气分布差异性的主控因素为断裂系统、烃源岩分布、源-储构造叠合关系和断-砂耦合关系。断裂系统的差异性决定纵向上油气分布层位以及构造内部的差异化富集程度;平湖组煤系烃源岩成熟度和厚度分布的差异性决定区域油气富集程度;花港组源外成藏背景下,成藏期平湖组烃源层顶面构造与花港组储集层构造叠合关系决定局部构造汇烃强度;中南部花港组强水道化背景下,断层与砂体耦合关系决定单层油气成藏规模。

珠江口盆地西江凹陷XJ-A构造古近系成藏主控因素及模式

以珠江口盆地西江凹陷XJ-A构造为研究对象,在构造、地层、地震等资料以及对岩心、薄片和流体包裹体分析的基础上,对其开展油气成藏条件和动态成藏过程研究,厘清成藏主控因素,建立油气成藏模式。结果表明,XJ-A构造古近系烃源岩有机质丰度较高,主要为Ⅱ_(1)~Ⅱ_(2)型干酪根,生油潜力较大;发育辫状河三角洲沉积砂体,多为Ⅱ类及以上级别储层,适合大规模成藏;成藏期通源断裂活动速率降低,油气在超压驱动下主要通过断层、砂体和裂缝输导运移成藏。结合包裹体均一温度测试和埋藏史分析,油气充注可划分为三个期次:第一期(距今15.9~10.8Ma)为低熟原油充注期,第二期(距今10.8~5.4Ma)为成熟原油主力充注期,第三期(距今5.4~0Ma)为成熟原油混合部分天然气的充注期。在烃源岩良好、储集物性优越及超压充注的背景下,XJ-A构造古近系油气成藏主控因素为烃源条件、储集条件和输导条件。油气成藏模式具有“旁生侧储、下生上储、近源成藏、超压强供”的特征。

准噶尔盆地永进地区油气藏成藏条件及其主控因素研究

【目的】通过对永进地区油气藏成藏条件及主控因素展开分析,旨在为该区进一步勘探提供理论依据。【方法】以侏罗系齐古组为目的层,通过分析成藏条件,明确主控因素,研究沉积微相及断裂对油气藏成藏的控制作用。【结果】研究区烃源岩主要来自二叠系,在浅水三角洲沉积背景下,发育大套连续的厚度大、物性好的储层,在此之上发育较为稳定的盖层,保存条件良好。研究区经多期构造运动形成多组通源断裂,喜山期形成封堵断层,构造圈闭条件较好;断裂构造和倾斜的储层砂体为油气提供了良好的垂向和横向运移通道。【结论】沉积演化和走滑断层控制齐古组成藏模式,应重点寻找永进地区构造-岩性油气藏。研究成果为该地区进一步勘探指明了方向。

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。

海上中深层油气藏开发早期优势储层预测方法及应用——以渤海D油田沙河街组一段为例

海上中深层油气藏开发早期实钻资料少,地震资料品质差,储层横向变化快,纵向不同油组储层厚度、储层结构差异大,造成优势储层精确预测难度大。选取渤海D油田沙河街组一段开展储层展布主控因素分析,通过古地貌恢复、地震属性分析以及储层聚类分析对优势储层进行预测。研究结果表明:D油田沉积早期储层受古地貌控制,优势储层发育于沟谷、斜坡带;沉积中期储层受古地貌及物源供给双重控制,优势储层发育于1井区西侧高部位;沉积晚期储层受物源供给影响,优势储层主要发育于1井区南东块。研究成果成功指导了D油田开发方案井位优化及随钻实施,取得较好效果,可为相似油田提供借鉴。