The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global attention.Despite this,several exploration wells in this area fail,which can be primarily contributed to a lack ...The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global attention.Despite this,several exploration wells in this area fail,which can be primarily contributed to a lack of understanding of the basin's structures and hydrocarbon accumulation conditions.This study examines these characteristics utilizing gravity,seismic and drilling data,and finally makes a comparison with the Cote d’Ivoire Basin,a typical transform margin basin in the South Atlantic.The results suggest that the Senegal Basin,influenced by multiple transform faults and a weak Paleozoic basement,experienced three evolutionary stages:rifting,transitional,and drifting.Each stage contributed to the development of distinct depositional sequences-syn-rift sequences,sag sequences,and continental margin sequences,respectively.The Triassic-Early Jurassic rifting stage predominantly formed continental deposits,like fluvial,lacustrine,and deltaic deposits,in the syn-rift sequences.The Middle-Late Jurassic transitional stage,influenced by transform faults,witnessed the formation of marginal ridges or submarine uplift zones.These zones,in conjunction with landward high terrains,formed a restricted environment promoting the development of source rocks in the sag sequences.During the drifting stage,three types of reservoirs,namely platform carbonate rocks,deltas,and slope-floor fans were formed.Notably,large-scale hydrocarbon reservoirs have been found in the deltas and the slope-floor fans both in the Senegal Basin and the Cote d’Ivoire Basin.The Upper Jurassic-Aptian platforms exhibit thick carbonate rocks and organic reefs on their edges,suggesting substantial potential for hydrocarbon exploration in the Senegal Basin.展开更多
The development of pores in a clastic reservoir is one of the most important research subjects in oil-gas exploration and development, whereas the many reasons for the formation of secondary porosity have increased th...The development of pores in a clastic reservoir is one of the most important research subjects in oil-gas exploration and development, whereas the many reasons for the formation of secondary porosity have increased the degree of difficulty in such research. Thus the research aims are to discover the controlling factors of solutional voids in feldspars and to predict favorable regions for these voids. Macroscopic and systematic researches into the relationship between the kaolinite content in the feldspar solutional void developed area of the Chang 2 reservoir group of the Triassic Yanchang Formation in the Midwest Ordos Basin and the solutional void in feldspar have been made, and from this it can be determined that the kaolinite content has an indicative function to the distribution of the solutional void in feldspar. Solutional void in feldspar is relatively well developed at the area where kaolinite content is high. Although the factors affecting kaolinite content are complicated, yet that of the research area is mainly affected by the impact of the leaching atmospheric water acting on the palaeogeomorphology. Three favorable zone belts for the development of solutional voids in feldspars are forecasted on the basis of restoration of palaeogeomorphology.展开更多
To predict joint development characteristics of coal seams, joint characteristics of rock seams from 88field stations were observed and comparisons were made between joint characteristics of coal and rock seams at 10 ...To predict joint development characteristics of coal seams, joint characteristics of rock seams from 88field stations were observed and comparisons were made between joint characteristics of coal and rock seams at 10 coal outcrops. Additionally, detailed joint measurements of underground coal seams were taken at two coal mines. This study investigated the effects of seam thickness, lithology, and structure on joint development and established the relationship between joint development of coal and rock seams, which allowed predictions of predominant joint densities for the No.5 coal seam in the southeastern margin of the Ordos basin. The results show that outcrop and underground coal seams exhibit the same joint systems as rock seams. The joints are mainly upright. Predominant joints strike 55° on average, followed by joints striking 320°. The joint density of the coal seam is 18.7–22.5 times that of the sandstone seam at the same thickness. The predominant joint density of the No.5 coal seam, controlled by the structure, is 4–20 joints per meter. Joint densities exhibit high values at intersecting areas of faults and folds and decrease values in structurally stable areas. The permeability increases exponentially with increasing density of the predominant joints.展开更多
Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weat...Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weath- ering, leaching, and onlap. At the same time, the structural body may be divided into three layers, including upper layer, mid layer, and lower layer. The upper layer with good primary porosity serves as the hydrocarbon migration system, and also accumulates the hydrocarbon. The mid layer with compactness and ductility can play a role as cap rock, the strength of which increases with depth. The lower layer with good secondary porosity due to weathering and leaching can form the stratigraphic truncation traps. A typical stratigraphie reservoir lying in the unconformity between the Jurassic and Triassic in the north-west margin of the Junggar basin was meticulously analyzed in order to reveal the key controlling factors. The results showed that the hydrocarbon distribution in the stratigraphic onlap reservoirs was controlled by the onlap line, the hydro- carbon distribution in the stratigraphic truncation reser- voirs was confined by the truncation line, and the mid layer acted as the key sealing rock. So a conclusion was drawn that ＂two lines （onlap line and truncation line） and a body （unconformity structural body）＂ control the formation and distribution of stratigraphic reservoirs.展开更多
基金funded by the projects of the SINOPEC Science&Technology Department(P21043-3,P23181)the Basic Prospective Research Projects of SINOPEC,China(P22214-2,P22214-1).
文摘The recent discovery of large oil and gas fields in the deep-water of the Senegal Basin has drawn global attention.Despite this,several exploration wells in this area fail,which can be primarily contributed to a lack of understanding of the basin's structures and hydrocarbon accumulation conditions.This study examines these characteristics utilizing gravity,seismic and drilling data,and finally makes a comparison with the Cote d’Ivoire Basin,a typical transform margin basin in the South Atlantic.The results suggest that the Senegal Basin,influenced by multiple transform faults and a weak Paleozoic basement,experienced three evolutionary stages:rifting,transitional,and drifting.Each stage contributed to the development of distinct depositional sequences-syn-rift sequences,sag sequences,and continental margin sequences,respectively.The Triassic-Early Jurassic rifting stage predominantly formed continental deposits,like fluvial,lacustrine,and deltaic deposits,in the syn-rift sequences.The Middle-Late Jurassic transitional stage,influenced by transform faults,witnessed the formation of marginal ridges or submarine uplift zones.These zones,in conjunction with landward high terrains,formed a restricted environment promoting the development of source rocks in the sag sequences.During the drifting stage,three types of reservoirs,namely platform carbonate rocks,deltas,and slope-floor fans were formed.Notably,large-scale hydrocarbon reservoirs have been found in the deltas and the slope-floor fans both in the Senegal Basin and the Cote d’Ivoire Basin.The Upper Jurassic-Aptian platforms exhibit thick carbonate rocks and organic reefs on their edges,suggesting substantial potential for hydrocarbon exploration in the Senegal Basin.
文摘The development of pores in a clastic reservoir is one of the most important research subjects in oil-gas exploration and development, whereas the many reasons for the formation of secondary porosity have increased the degree of difficulty in such research. Thus the research aims are to discover the controlling factors of solutional voids in feldspars and to predict favorable regions for these voids. Macroscopic and systematic researches into the relationship between the kaolinite content in the feldspar solutional void developed area of the Chang 2 reservoir group of the Triassic Yanchang Formation in the Midwest Ordos Basin and the solutional void in feldspar have been made, and from this it can be determined that the kaolinite content has an indicative function to the distribution of the solutional void in feldspar. Solutional void in feldspar is relatively well developed at the area where kaolinite content is high. Although the factors affecting kaolinite content are complicated, yet that of the research area is mainly affected by the impact of the leaching atmospheric water acting on the palaeogeomorphology. Three favorable zone belts for the development of solutional voids in feldspars are forecasted on the basis of restoration of palaeogeomorphology.
基金Financial support for this work, provided by the National Science and Technology Major Project (No. 2011ZX05034-001)
文摘To predict joint development characteristics of coal seams, joint characteristics of rock seams from 88field stations were observed and comparisons were made between joint characteristics of coal and rock seams at 10 coal outcrops. Additionally, detailed joint measurements of underground coal seams were taken at two coal mines. This study investigated the effects of seam thickness, lithology, and structure on joint development and established the relationship between joint development of coal and rock seams, which allowed predictions of predominant joint densities for the No.5 coal seam in the southeastern margin of the Ordos basin. The results show that outcrop and underground coal seams exhibit the same joint systems as rock seams. The joints are mainly upright. Predominant joints strike 55° on average, followed by joints striking 320°. The joint density of the coal seam is 18.7–22.5 times that of the sandstone seam at the same thickness. The predominant joint density of the No.5 coal seam, controlled by the structure, is 4–20 joints per meter. Joint densities exhibit high values at intersecting areas of faults and folds and decrease values in structurally stable areas. The permeability increases exponentially with increasing density of the predominant joints.
文摘Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weath- ering, leaching, and onlap. At the same time, the structural body may be divided into three layers, including upper layer, mid layer, and lower layer. The upper layer with good primary porosity serves as the hydrocarbon migration system, and also accumulates the hydrocarbon. The mid layer with compactness and ductility can play a role as cap rock, the strength of which increases with depth. The lower layer with good secondary porosity due to weathering and leaching can form the stratigraphic truncation traps. A typical stratigraphie reservoir lying in the unconformity between the Jurassic and Triassic in the north-west margin of the Junggar basin was meticulously analyzed in order to reveal the key controlling factors. The results showed that the hydrocarbon distribution in the stratigraphic onlap reservoirs was controlled by the onlap line, the hydro- carbon distribution in the stratigraphic truncation reser- voirs was confined by the truncation line, and the mid layer acted as the key sealing rock. So a conclusion was drawn that ＂two lines （onlap line and truncation line） and a body （unconformity structural body）＂ control the formation and distribution of stratigraphic reservoirs.
