The Muglad basin is a continental rift basin during the Mesozoic-Cenozoic on the southern Central Africa Shear Zone (CASZ). The Fula sag is a hydrocarbon-rich depression in the north of Muglad basin. With the improvement of exploration degree, Fula sag has been in the stage of fine exploration for complex fault blocks. Therefore, strengthening the study of fault characteristics and evolution will help in deepening the understanding of the hydrocarbon accumulation rules in this area and guiding the next step of oil and gas exploration. Taking Fula sag as an example, the characteristics, evolution of faults, and their controlling effects on hydrocarbon in the study area were analyzed. Conclusions are listed as followed. We have obtained innovative knowledge as followed: faults in the study area can be divided into three levels and five combination features; continuously active faults control the formation of “inherited” sag; faults in Fula sag have a controlling role in the development of hydrocarbon source rocks and central reservoir assemblages in the AG Formation. The research results have been applied in exploration deployment.

The Upper Paleogene lacustrine fine-grained sandstones in the hinterlands of the northern Qaidam Basin mainly contain two sweet spot intervals. Fracture/fault, microfacies, petrology, pore features, diagenesis, etc., were innovatively combined to confirm the controlling factors on the reservoir quality of shallow delta-lacustrine fine-grained sandstones. The diagenesis of the original lake/surface/meteoric freshwater and acidic fluids related to the faults and unconformity occurred in an open geochemical system. Comprehensive analysis shows that the Upper Paleogene fine-grained sandstones were primarily formed in the early diagenetic B substage to the middle diagenetic A substage. Reservoir quality was controlled by fault systems, microfacies, burial-thermal history, diagenesis, hydrocarbon charging events (HCE), and abnormally high pressure. Shallow and deep double fault systems are the pathways for fluid flow and hydrocarbon migration. Sandstones developed in the high energy settings such as overwater (ODC) and underwater distributary channels (UDC) provide the material foundation for reservoirs. Moderate burial depth (3 000–4 000 m), moderate geothermal field (2.7–3.2 °C/100 m), and late HCE (later than E3) represent the important factors to protect and improve pore volume. Meteoric freshwater with high concentrations of CO2 and organic acids from thermal decarboxylation are the main fluids leading to the dissolution and reformation of feldspar, rock fragments, calcite and anhydrite cements. Abnormally high pressure caused by the undercompaction in a large set of argillaceous rocks is the key to form high-quality reservoirs. Abnormal pressure zones reduced and inhibited the damage of compaction and quartz overgrowth to reservoir pores, allowing them to be better preserved. A reservoir quality evaluation model with bidirectional migration pathways, rich in clay minerals, poor in cements, superimposed dissolution and abnormally high pressure was proposed for the ODC/UDC finegrained sandstones. This model will facilitate the future development of fine-grained sandstone reservoirs both in the Upper Paleogene of the Qaidam Basin and elsewhere.

AbstractAt the end of the Palaeozoic Era, most species on Earth disappeared completely and the global sedimentary environment and biology changed dramatically. The Permian–Triassic boundary (PTB) was studied in three sections of the middle Upper Yangtze Platform, SW China: Xingwen well and Zhijin and Shangsi sections. These sections are characterized by carbonate-platform, toe-of-slope and basin facies, respectively. Detailed analysis of 100 closely spaced thin-sections revealed a total of 24 microfacies and 11 microfacies associations based on the dominant carbonate grain size and the skeletal material (type and proportion). Six bioassemblages are documented for the first time, spanning c. 1 Ma across the boundary succession, including normal, resurrected and miniaturized Permian biota, and cyanobacteria-dominated, survival post-crisis and neonatal Triassic biota. The Xingwen well indicated sedimentary evolution from a rimmed carbonate platform to a homoclinal carbonate ramp, as well as a sharp fall in sea level just prior to the PTB in the study area. The Zhijin section revealed a slope setting, in which toe-of-slope and middle-ramp microfacies are identified. The Shangsi section showed a complete evolution of basin and outer-ramp microfacies and bioassemblages. Fossil evidence showed that the Permian biota (trilobites, gastropods and phylloid algae) occurred in the uppermost Changhsingian stage and was overlain by biomicrites with miniaturized ostracods (< 0.2 mm in size). This indicated that the major extinction horizon is located up to 14 cm below the PTB, which lies in the middle–lower segments of the miniaturized ostracod layer.

The Tarim-Qaidam collision occurred along the southeastern margin of the Tarim Craton in the Early Paleozoic. This collision resulted in the formation of the Altun Suture, a Proto-Tethyan suture. It is one of the northernmost suture zones in the Tethysides. This Proto-Tethyan suture was not re-opened during the period of Paleo-and NeoTethyan history, and, of course, no Paleo-or NeoTethyan suture was superimposed on it. The collision-related structures in response to this collision are well-preserved in the Tarim Basin. They were discovered during our careful seismic interpretation. The syn-collision structures mainly include a foreland fold-thrust belt (the Tangguzibas foreland fold-thrust belt) and three large basement-involved anticlines (the Lunnan, Tadong and Tazhong anticlines). While the post-collision structures are a series of normal faults and their combinations of en echelon fault zones. From the deformation characteristics of these syn-collision structures, it was inferred that their related collision occurred in the southeastern margin of the Tarim Craton. It is the Tarim-Qaidam collision which resulted in the formation of the Early Paleozoic Altun Suture. Analyzing the growth strata, un-conformities, fault growth index and the strata involved in the collision-related deformation, the syn-collision structures were formed in the Late Ordovician to Early Silurian, and the post-collision structures in the Middle Silurian to Middle Devonian. It can be fairly deduced that the Tarim-Qaidam collision initiated in the Late Ordovician, lasted to the Early Silurian, and then evolved into the post-collision extensional stage of the Middle Silurian-Middle Devonian.

The Central Africa Shear Zone (CASZ) harbors abundant hydrocarbon resources within its Central Fault Zones (CFZs). The studies of CASZ have dominantly focused on the evolution and superimposition processes of prototype basins in CASZ. Meanwhile, research on the geometry and segmental growth of main faults in CFZs remains poorly understudied, which limits hydrocarbon exploration. In this paper, we focus on the CFZ of the Fula sag as an example of CASZ and utilize the 3-D throw mapping technique along with the maximum throw subtraction method to investigate its geometric and growth processes. Results show faults in the northern and central parts of the CFZ form multiple Y-shaped combinations, and a system of sub-parallel faults in the south forms the bookshelf faults. Meanwhile, the divergent overlapping transfer zone is identified in the CFZ. Our investigation found abrupt changes in throw-distance diagrams of main faults in the CFZ, which indicate that the main faults, F-1, F-3 and F-2, are laterally segmented into 4, 4, and 3 segments, respectively. As an intracontinental passive rift basin, the Fula sag has undergone three major rifting cycles since the Early Cretaceous, triggered by the segmental expansion of the Atlantic Ocean, the rapid opening of the Indian Ocean, and the separation of the Red Sea. Our analysis also reveals that the main faults in the CFZ were primarily active during the second rifting, with the fault segments undergoing isolated growth, soft linkage, and eventually forming fully grown faults during the third rifting. We observe a significant decrease in activity intensity during the transition between the second and third rifting cycles. Our findings provide insights into the growth and activity of the CFZ faults, which are applicable to other CFZs of similar origin in rift basins, and provide suggestions for hydrocarbon exploration and production.

Introduction: The Muglad basin, located on the southern Central Africa Shear Zone, is an intracontinental passive rift basin. The Fula sag, situated in northeastern of the basin, is a hydrocarbon-rich depression. As exploration advanced, the Fula sag has entered the stage of fine exploration for complex fault blocks. Therefore, studying the characteristics and evolution of faults can aid in deepening the understanding of hydrocarbon accumulation rules in the area, and guide the next steps of oil and gas exploration. Previous studies have primarily focused on the division of fault level and their role in hydrocarbon accumulation, but have not delved into the geometric features and evolution of the fault system across the entire Fula sag.Methods: In this paper, we systematically studied the fault system and its hydrocarbon control within the sag using petroleum seismic reflection profiles, as well as logging data.Results and Discussion: And the conclusions are as followed: 1) tectonic features in diverse areas of the Fula sag vary significantly from a shovel-like half-graben to the asymmetric graben, and faults in the study area can be classified into five combination features. 2) Three complete rift-sag cycles have developed since the early Cretaceous, with continuously active faults controlling the formation of “inherited” sag. 3) The strong activity of faults in the first and second riftting period led to the development of mainly AG-Formation source rocks and middle reservoir-forming assemblages in the Fula sag. Additionally, the formation and distribution of oil and gas reservoirs in the sag were controlled by the faults in the central fault zone and the western steep slope zone. Furthermore, hydrocarbons migrated and formed reservoirs through the main faults in the central fault zone and the western main fault. Our research will provide a valuable insight for understanding the petroleum geological characteristics of basins with a similar genesis mechanism.

West and Central African superimposed rift basins are Meso-Cenozoic multicycle intra-continental rift basins developed on the Precambrian crystalline basement. Previous studies mainly focused on the formation and superimposition process of several prototype basins developed in a single superimposed basin, but it is rarely documented that research on the different contemporaneous complex superimposed rift basins in the same tectonic region as well as those superimposed rift basins with different prototypes basins in vertical through time has been carried out. Based on the geological, geophysical, and geochemical data obtained during the oil and gas exploration activities in the West and Central African superimposed rift basins recently, combined with the previous research results, this paper focuses on the basin evolution, formation and superimposition process of prototype basins through time of the West and Central African superimposed rift basins. Results show that since the breakup of Gondwana, affected by the relative movements among the Northwest African block, the Northeast African block, and the Central and South African block of the African continent and the tectonic events of the surrounding plates, the West and Central African superimposed rift basins have roughly experienced three phases of tectonic evolution, namely, Early Cretaceous, Late Cretaceous and Paleogene-Neogene. Early Cretaceous evolution phase is the key period of the formation and evolution of the rift basins, during which the boundary faults of these rift basins develop and act intensively. Three types of prototype basins are developed, including rift basin, strike-slip pull-apart basin and aulagu basin. Basement subsidence of these rift basins is the largest with the fastest subsidence rate among the total subsidence. Lower Cretaceous sedimentary filling has the largest percent in the total filling, and sedimentary systems in whole rifts system are non-marine elastic deposition. During Late Cretaceous evolution phase, these early prototype basins were inherited. However, the difference in rifting and the sedimentary filling among those rift prototype basins become larger. The Early Cretaceous sedimentary system also evolved into a marine-continental sedimentary system. During Paleogene-Neogene, the evolution of West and Central African superimposed rift basins became more complex, and the difference was further intensified. The rifting, strike-slip and compression-reversion occurred simultaneously in different basins, during which the rift prototype basins or inversion deformation developed. According to the differences in prototype basin type, sedimentary filling and vertical superimposition of the prototype basins in these three phases, these superimposed rifts in Central and Western Africa are divided into two types, inherited superimposed basins and reversed superimposed basins. They are further divided into eight subtypes, namely, early-developed superimposed basins, successive superimposed basins, dynamic superimposed basins, late-developed type I superimposed basins, late-developed type II superimposed basins, and rift-inverted superimposed basins, aurora-inverted superimposed basins, and strike-slip-inverted superimposed basins. The characteristics of different types of superimposed basins are discussed. These results are of great significance for deepening the understanding of the geological evolution of superimposed rift basins and guiding the search for favorable oil and gas enrichment areas and exploration activities in such basins worldwide.

Palogue油田的发现打开了Melut盆地古近系勘探新方向,证实了北部凹陷为富油气凹陷.Palogue油田具有以下白垩统为主力烃源岩,古近系为主力成藏组合的跨时代运聚风格,幔源CO2气体对油气的聚集和改造具有不可忽略的作用.通过对CO2气体、原油特征、生标特征、包裹体特征进行研究,结合地层埋藏史,分析油气特征及成藏期次.结果表明:Palogue油田具有两期成藏的特征,古近纪中期发生第1期油气成藏事件,随后原油被降解;古近纪晚期-新近纪以来,伴随幔源CO2气体油气发生第2次运移充注事件,且CO2气体对油藏进行了强烈的气洗作用.

Research on strike-slip faults and their control on the accumulation and distribution of oil and gas in petroliferous basins plays an important role in guiding oil and gas exploration activities. Based on the interpretation and analysis of seismic and drilling logging data, the geometry, evolution process, genetic mechanism and control on the accumulation of oil and gas of strike-slip faults in the Termit Basin are studied by applying coherent techniques. The results show that the strike-slip faults in the Termit Basin are mainly developed in the Trakes Slope in the eastern margin of the basin. The principal displacement zone of these strike-slip faults extending mainly in NNW-SSE and NW-SE, their en-echelon extension fractures (T fracture) are in south-north trending with dextral movement and right-lateral stepping. Most of these strike-slip faults are transtensional faults with few transpressional faults. Negative flower structures and Y-style fault combinations are widely developed, while straightly steep faults andpositive flower structures are locally developed. These strike-slip faults are the result of Cretaceous normal faults subjected to later shear stress in Paleogene Eocene Oligocene. The strike-slip mechanism is that differentially transverse compressive stress between blocks induces shear deformation of early normal faults. Since the Paleogene, the collision accumulation effect of the Eurasian plate and the African plate has formed a near-EW compressive stress inside the African plate. The nonhomogeneous distribution of stress at the northern boundary of the African plate caused differential movement between the Northwest African block and the Northeast African block, which induced the transformation of the Early Cretaceous normal faults on the Trakes Slope into a transtensional strike-slip faults. This series of strike-slip faults formed a group of antithetic fault block traps in Paleogene Sokor1 Formation,Sokor2 Formation and the Upper Cretaceous Yogou Formation, and these strike -slip faults are also vertical migration channels for oil and gas, which are beneficial for the hydrocarbon generated by Upper Cretaceous source rocks to migrating upward and accumulating in the Paleogene reservoirs.

The dolomite in 3rd member of Yingshan Formation in Gucheng area is a significant exploration field in the east of Tarim Basin. High-quality dolomite reservoir reworked by hydrothermal activities is the key to expand exploration. Based on petrographic characteristics, this paper analyzed hydrothermal properties, clarified the precise dating and stages of hydrothermal process, and discussed hydrothermal effects on dolomite reservoir using U-Pb dating technique, combined with analysis of carbon and oxygen, strontium, magnesium isotopes and rare earth elements. The study shows that micrite-medium grained dolomites taken place in paracontemporaneous-shallow buried phase and hydrothermal products in research area. There are two stages of hydrothermal processes. The first stage hydrothermal process is very low in magnesium content in the Middle-Late Ordovician, at the result of saddle dolomite filling in fractures/vugs and coarse dolomite formed by recrystallization aged 464 +/- 12Ma similar to 473. 9 +/- 9. 1Ma by U-Pb dating with oxygen isotope negative compared with normal marine dolomite, strontium isotope values higher than Early Ordovican sea values and positive Eu anomalies. The contents of strontium, ferrum and magnesium are relatively low. The second stage hydrothermal process is high in calcium content in the Late Ordovician-Early Silurian, at the result of calcite filling in fractures/vugs and dissolution of existing dolomites, aged 448 +/- 15Ma similar to 457. 4 +/- 6. 6Ma by U-Pb dating with significantly negative oxygen isotope and enriched LREE and positive Eu anomalies. The strontium content is high while manganese content is low. Migration pathway of the second stage hydrothermal process as a key of dolomite reservoir dissolution is NNE fracture zones developing high-quality reservoir, which provides a basis for the prediction of favorable zones.

中西非叠合裂谷盆地是发育在前寒武系结晶基底之上的中-新生代多旋回陆内裂谷盆地,以往的研究主要针对跨不同世代、不同性质原型盆地叠合构成的盆地,但对于由多期裂谷活动形成的叠合裂谷盆地,其叠合改造模式及其动力学机制研究尚不深入.本文基于近年来在中西非裂谷系油气勘探开发中获得的有关地质、地球物理和地球化学资料,结合前人研究成果,重点研究了中西非裂谷系盆地演化阶段、不同阶段原型盆地发育特征、多期叠合、改造类型、模式及其动力学背景.研究表明,自冈瓦纳大陆裂解以来,受非洲大陆周缘板块构造事件及西北非陆块、东北非陆块和中南非陆块间相对运动的影响,中西非裂谷系盆地大致经历了早白垩世、晚白垩世、古近纪-新近纪三个构造演化阶段.早白垩世阶段断裂活动最为强烈,是裂谷盆地主干断裂形成时期,在不同构造部位发育了裂谷盆地、走滑-拉分盆地和坳拉谷盆地三类原型盆地,盆地基底沉降速率最大,地层沉积充填厚度大,沉积体系均为陆相碎屑沉积,奠定了裂谷盆地形成演化的基础;晚白垩世阶段,早白垩世原型盆地继承发展,但盆地间裂谷发育程度差异性凸显,沉积充填特征差异变大,由早白垩世统一陆相沉积体系演变为海、陆相并存的沉积体系;古近纪-新近纪阶段,该裂谷系盆地发育变得更为复杂,差异性进一步加剧,裂谷作用、走滑作用和挤压反转作用在不同盆地同步发生,期间可持续发育裂谷盆地或发生挤压反转和构造变形.根据三个阶段原型盆地在盆地性质、沉积充填、垂向叠加、构造变形等方面的差异,将中西非叠合裂谷盆地划分为"继承叠合型"和"反转改造型"两类,进一步划分为"早断型"、"继承型"、"叠加型"、"晚断Ⅰ型"、"晚断Ⅱ型"以及"裂谷盆地反转型"、"走滑-拉分盆地反转型"、"坳拉谷盆地反转型"八种,并讨论了不同类型叠合盆地特征及其动力学背景.这些成果对于深化裂谷盆地形成演化地质认识,指导在全球该类盆地中优选油气有利富集区和油气勘探均具有重要意义.

含油气盆地走滑构造及其控藏作用研究可以揭示研究区构造特征、形成演化过程,深化油气成藏条件和油气富集规律认识,对于指导油气勘探部署具有重要意义.基于地震与钻井资料的解释与分析,运用断层相干体切片等三维地震精细解释、复杂构造分析等技术,对在Termit盆地东缘Trakes斜坡首次发现的走滑构造几何学、演化过程、成因机制及其控藏作用进行了研究.研究结果表明,Termit盆地东缘Trakes斜坡发育系列走滑断层,其主走滑带走向为北北西-南南东和北西-南东向,其雁列断层(T破裂)走向近南北,呈右旋右阶排列;走滑构造性质以张扭性为主,少量为压扭性,其剖面样式以负花状构造与Y型断裂为主,少量直立断层,局部发育正花状构造;上述走滑构造是早期先存正断层受后期剪切作用的结果,主走滑变形阶段为古近纪始新世-渐新世;新生代以来欧亚板块与非洲板块碰撞,其累积效应在非洲板块内部形成了近南北向挤压应力,由于挤压应力在非洲板块北部边界的不均衡性,造成西北非陆块与东北非陆块发生差异运动,这种差异运动导致Trakes斜坡早期发育的早白垩世正断层发生张扭性走滑变形.在该系列走滑断层带内,形成一系列古近系Sokor1组和Sokor2组以及上白垩统Yogou组反向断块圈闭,其主走滑位移带构成油气垂向运移通道,有利于上白垩统烃源岩生成油气向上运移、在浅层聚集与成藏.

F Sub-Basin located in NE of M Basin which is a typical rifted basin in Sudan. With the progress of exploration and development for more than 20 years, remained traps are limited with small area, deep targets, and complex structure and the difficulty increased for exploration and development. More challenges come out for: 1) poor data quality and mis-tie of 2D and 3D seismic data of deep targets resulted from different acquisition and processing parameters in different time; 2) uncertainty and difficulty of identifying faulted traps on deep targets from complex geological conditions. More researches and methods have been tested to solve the problems. Finally, some new integrated trap identification technologies have been formed, such as integrated interpretation with processing technology, integrated seismic interpretation technology with geology and integrated seismic interpretation technology with time and spatial data etc., and new faulted traps which hadn’t been found with normal interpretation methods before have been identified and new break-through have been made for deep targets of AG in old oil fields. It is sure that systematic progressive exploration and development and the application of integrated trap identification technology are efficient ways for less input, more output and early benefit for complex faulted basin.

被动大陆边缘深水油气勘探是近年来全球油气勘探热点领域,新发现的大油气田中海域特别是深水区已占主导地位.将同一大陆边缘盆地群进行统一的构造演化与地层充填分析,统计已发现油气田的地质特征,明确其成藏条件和成藏模式,对于区域级别油气区带优选和新项目的获取具有重要指导意义.文章通过IHS、Wood Mackenzie等油气田数据库资料,结合油气勘探新发现和部分内部新项目评价资料等,系统分析东非海域9个盆地深水区油气形成的地质背景及油气成藏条件,指出深水油气有利区带分布.研究表明,东非海域盆地群经历了早石炭世—三叠纪卡鲁裂谷、侏罗纪马达加斯加裂谷和白垩纪至今的被动大陆边缘3个演化阶段,基底断裂受印度洋转换断层、大陆边缘伸展断裂系统和东非裂谷系断裂系统联合控制,由北往南可划分为4个构造段,不同构造段盆地剖面结构和地层充填差异明显.东非海域共发育下侏罗统、中上侏罗统—白垩系和古近系3套烃源岩;形成了海相浊积砂岩和三角洲砂岩两种类型优质储层和海相厚层页岩区域性盖层,储盖组合良好;可划分为证实的新生界和白垩系及推测的上二叠统—侏罗系3套深水成藏组合;形成了漂移早—中期供源、漂移期成藏,裂谷期与漂移早期供源、裂谷期—漂移期成藏,以及裂谷期供源、漂移期成藏3种深水油气成藏模式.东非海域被动大陆边缘时期,形成了大型三角洲及深水重力流沉积物混合的扇复合体和无大型古河流供给、以滑塌形成为主的近岸叠置小型扇朵叶体两种类型的深水扇体;白垩系和古近系深水油气有利区带具有一定的继承性,主要位于坦桑尼亚盆地南部、鲁伍马盆地北部等地区,勘探目标以天然气勘探和碎屑岩勘探为主.

喀土穆盆地是一个中新生代裂谷盆地,位于中非裂谷系最东端,盆内发育十多个凹陷.本次研究基于岩屑和原油样品的地球化学分析,重点对盆地内K凹陷和D凹陷下白垩统烃源岩进行研究.结果表明,K凹陷下白垩统AJ组发育一套较为优质的湖相泥岩,厚度为40～180 m,以Ⅱ型有机质为主,整体热演化为低熟-成熟阶段;AJ组泥岩的姥植比多为0.5～2之间,属于半还原-半氧化环境,有机质以半咸水湖泊中水体生物和陆源高等植物混源为主.而D凹陷的下白垩统D3组发育一套中等到好的气源岩,以Ⅱ2～Ⅲ型有机质为主,整体热演化为成熟-高成熟阶段,总有机碳比AJ组稍低,但厚度很大在200～500 m之间.从K凹陷向南到D凹陷,有机质中高等植物来源占比增高,藻类和细菌来源有机质占比降低,盆地中原油的萜烷和甾烷含量均较低,藿烷含量高,具有典型的中非裂谷系原油特征.结合有机质类型和成熟度,喀土穆盆地K凹陷未来勘探应以油为主,D凹陷以气为主,其余凹陷潜力有限.

Melut盆地北部凹陷为富油气凹陷,具有岩性地层油气藏形成的基本条件.针对深层白垩系和岩性地层油气藏勘探尚未取得突破的现状,通过开展层序地层学和沉积相研究,建立了统一的层序地层格架,明确了Melut盆地北部凹陷源上、源内各主要层序岩性地层油气藏的勘探潜力与方向.研究表明:源上主要发育Yabus上段—Adar—Lau高位域,有利相带为河流、三角洲、扇三角洲,主要形成构造-岩性圈闭;源内主要发育Galhak—Algayger湖侵域,有利相带为三角洲前缘、滑塌浊积扇和洪水浊积扇,主要形成岩性和构造-岩性圈闭.综合分析认为,源内层序是寻找构造-岩性油气藏的主要勘探目标.在有利构造背景下发育良好的储盖组合是Melut盆地白垩系成藏的关键因素,辫状河三角洲前缘相带是白垩系油气成藏的优势相带,上白垩统Galhak组是白垩系油气成藏的主要目的层段.研究结果对Melut盆地北部凹陷下步勘探具有指导意义.

通过分析特提斯构造域东段区域地质和含油气盆地勘探开发基础数据,从板块构造演化入手,系统编制特提斯构造域东段沉积构造演化剖面图和生储盖组合剖面图,研究盆地演化阶段、叠合特征、油气成藏条件及油气藏类型,揭示中亚和中国西部前陆盆地演化和油气富集规律异同.研究表明:古亚洲洋、古特提斯洋和新特提斯洋控制了特提斯构造域东段的区域构造分带、盆地演化、盆地类型及油气成藏模式.根据古洋壳缝合线可分为北、中、南3个构造带,古生代以来多期微板块的拼贴,导致特提斯构造域东段含油气盆地演化分为3个演化阶段,早古生代伸展、晚古生代挤压、早中生代伸展和新生代挤压构造作用控制了研究区盆地的叠合演化,发育下古生界、上古生界和中生界3套区域分布的优质烃源岩和下古生界、上古生界、中生界和新生界4套储盖组合,形成多种类型的油气藏.

基于C30重排藿烷(C30DH)和C30藿烷(C30H)热稳定性差异,研究了C30DH/C30H作为油气运移方向和充注途径的可行性.结果发现:C30DH结构稳定性高于C30H,C30DH/C30H参数具有成熟度属性;同时对比分析C30DH/C30H参数与咔唑类参数的相关性,认为两者之间正相关性明显,表明C30DH/C30H参数不仅是良好的热成熟度参数还是良好的石油充注运移参数.M油田位于Fula凹陷东部,M油田原油为弱氧化-还原、淡水-微咸水环境下低等藻类与高等植物混源生成,属于同一族群原油.利用C30DH/C30H参数示踪Fula凹陷M油田石油充注方向,油气运移途径主要为自北向南,同时还发育自西向东的运移途径;咔唑类参数也验证了C30DH/C30H参数示踪油气运移的准确性.结果表明C30DH/C30H参数是示踪石油充注途径的有效参数.

Sharaf-AG Low Uplift is located in the central area of Nugara Depression in Muglad Basin, Sudan. It has similar faulted system as the other oil and gas rich sub-basin but it doesn’t have much discovery in oil and gas. So the study of tectonic characteristics has been carried. After detailed seismic interpretation and analysis, the traps controlled by the northwest normal fault have a ‘beaded’ distribution characteristic from southwest to northeast under an extensional- torsional stress. And maybe it destroyed the storage of oil and gas in this area.

Fula Sub-Basin, located in NE of Muglad Basin, is the most important production base for block 6, which is one of the important overseas project of CNPC. With the progress of exploration and development for more than 20 years’, remained traps are limited with small area, deep targets, and complex structure and the difficulty increased for exploration and development. More challenges come out for: when the traps were formed? how did the faults and structures control the reservoirs? what’s the relationship between complex reservoir and fault blocks? All these questions need answers for fault system and paleostructure restoration. Horizon flatten technology is a new technology for structure restoration, but it has not been generally used for overseas projects because of the complexity of the technology. Some new applications of horizon flattening technology with seismic data have been tried for deep study of structure and reservoirs in Fula sub-basin. Horizon flattening technology can be used for not only paleo-structure restoration but also seismic interpretation, fault analysis and reservoir analysis of lower targets. Some cases have been provided and new understandings have been given. These applications are effective and can be popularized to exploration and development in similar sub-basin with complex fault system.