North Africa, which is one of the main oil and gas producing regions in the world, is best known for its subsalt Paleozoic-Triassic reservoirs and Paleozoic source rocks. Hydrocarbon abundance varies greatly from one ...North Africa, which is one of the main oil and gas producing regions in the world, is best known for its subsalt Paleozoic-Triassic reservoirs and Paleozoic source rocks. Hydrocarbon abundance varies greatly from one structural domain to another areally and from one stratigraphic interval to another vertically. Analyses of the essential elements and geological processes of the Paleozoic petroleum system indicate that the distribution of the Lower Silurian shale source rocks, the development of a thick Mesozoic overburden, the presence of the Upper Triassic-Lower Jurassic evaporite seal are the most important factors goveming the distribution of the Paleozoic-sourced hydrocarbons in North Africa. The Mesozoic sequence plays a critical role for hydrocarbons to accumulate by enabling the maturation of the Paleozoic source rocks during the Mesozoic-Paleogene times and preserving the accumulated hydrocarbons. Basins and surrounding uplifts, particularly the latter, with a thick Mesozoic sequence and a regional evaporite seal generally have abundant hydrocarbons. Basins where only a thin Mesozoic overburden was developed tend to have a very poor to moderate hydrocarbon prospectivity.展开更多
Sandi Arabia is renown for its rich oil and gas Mesozoic.However,the discovery of Paleozoic fields in resources with the bulk of the reserves reservo/red in the the late 1980s has encouraged further exploration in the...Sandi Arabia is renown for its rich oil and gas Mesozoic.However,the discovery of Paleozoic fields in resources with the bulk of the reserves reservo/red in the the late 1980s has encouraged further exploration in the Paleozoic.This paper reviews the salient features of the Paleozoic petroleum geology in central Saudi Arabia and discusses the main factors controlling hydrocarbon accumulation in the Paleozoic.The Lower Silurian Qusaiba hot shale is the principal source rock for the hydrocarbons discovered in the Ordovician to Permian reservoirs.Of them,the Permo-Carboniferous Unayzah and Upper Ordovician Sarah Formations have the best exploration potential.The key factors controlling hydrocarbon accumulation in the Unayzah Formation are migration pathways and reservoir petrophysics.The key factors controlling hydrocarbon accumulation in the Sarah Formation are reservoir petrophysics and the development of structural traps.展开更多
The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations...The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations and stable isotope analyses. The early precipitation of mixed-layer illite/smectite, siderite, calcite, ankerite and kaolin proceeded at the presence of Late Permian connate meteoric waters at temperatures of up to 60℃. These evolved connate pore waters were also parental to quartz, which formed at temperatures of up to 87℃. The phase of maximum burial was characterized by development of filamentous illite and late calcite at temperatures of up to -90℃. Subsequent uplifting and cooling led to deep meteoric influx from surface, which in turn resulted in dissolution of labile grains and carbonate cements, and formation of second generation of kaolin. Dawsonite was the last diagenetic mineral precipitated and its formation is genetically related to deep-seated mamagtic sourced CO2.展开更多
In order to reveal the development mechanism of high-quality clastic rock reservoir, the basic characteristics of Sha-3 Member of the Shahejie Formation in the Raoyang sag, Bohai Bay Basin, are analyzed based on cores...In order to reveal the development mechanism of high-quality clastic rock reservoir, the basic characteristics of Sha-3 Member of the Shahejie Formation in the Raoyang sag, Bohai Bay Basin, are analyzed based on cores observation, thin-sections and SEM images, and petrophysical properties measurements as well. It is found that high-mature composition and texture, early oil charging, and dissolution are the main factors controlling the formation and preservation of pores in deep reservoirs. Compaction is the major factor destructing pores, whereas formation overpressure is conducive to the preservation of original pores, high compositional and medium textural maturity can enhance the resistance capacity to compaction and protect primary pores. Early oil charging could lead to temporary cessation of diagenesis and thus inhibit the cementation. When organic acids entered reservoir formations, considerable amounts of secondary pores were formed, leading to the local improvement of petrophysical properties. When predicting good quality belt in exploration of deep basin, it is recommended that the superimposing effects of the multiple factors(overpressure, early oil charging, compositional and textural maturity, diagenesis) be taken into consideration.展开更多
Using the latest global datasets of hydrocarbon fields and reservoirs,this study systematically investigates the characteristics of differential hydrocarbon enrichment and its primary controlling factors in the southe...Using the latest global datasets of hydrocarbon fields and reservoirs,this study systematically investigates the characteristics of differential hydrocarbon enrichment and its primary controlling factors in the southern Tethys Domain within the context of Tethys tectonic evolution.The results indicate that although the southern Tethys Domain comprises only one-third of the Tethys Domain in areal extent,it hosts nearly 80%of its total hydrocarbon reserves,exhibiting a markedly uneven distribution pattern.Specifically,the Middle East sub-segment is identified as the core enrichment area,with the Arabian Basin serving as a typical example.Through tectonic subdivision,classification of sedimentary basins,analysis of source rock distribution and reservoir-seal assemblages,as well as an integrated investigation of the relationship between succeeding paleo-uplifts and hydrocarbon enrichment,the study demonstrates that the superimposition patterns of prototype basins,the scale and distribution of source rocks,the effectiveness of reservoir-seal assemblages,and the basement paleo-uplifts are the key factors governing hydrocarbon enrichment in the southern Tethys Domain.The findings of this study provide valuable references for deeper understanding of hydrocarbon accumulation patterns in the central and northern Tethys Domain and even other global regions with similar geological settings,and offer a scientific basis for selection of favorable play fairways in the southern Tethys Domain.展开更多
The North Carnarvon Basin, which lies in the North West Shelf of Australia, is highly rich in gas resources. As a typical passive marginal basin, it experienced the pre-rifting, early rifting, main rifting, late rifti...The North Carnarvon Basin, which lies in the North West Shelf of Australia, is highly rich in gas resources. As a typical passive marginal basin, it experienced the pre-rifting, early rifting, main rifting, late rifting, post-rifting sagging and passive margin stages. The basin was mainly filled with thick Mesozoic-Cenozoic sediments, of which the Mesozoic hosts the principal source, reservoir and seal intervals. Mesozoic palaeogeography has an important control on the oil and gas distribution. Triassic gas-prone source rocks of deltaic origin deter-mine the high endowment of natural gases in the North Carnarvon Basin. The more restricted distribution of oil accumulations is controlled by oil source rocks in the Upper Jurassic Dingo Claystone. The Muderong Shale deposited in the Early Cretaceous marine transgression provides the effective regional seal for the underlying oil and gas reservoirs.展开更多
文摘North Africa, which is one of the main oil and gas producing regions in the world, is best known for its subsalt Paleozoic-Triassic reservoirs and Paleozoic source rocks. Hydrocarbon abundance varies greatly from one structural domain to another areally and from one stratigraphic interval to another vertically. Analyses of the essential elements and geological processes of the Paleozoic petroleum system indicate that the distribution of the Lower Silurian shale source rocks, the development of a thick Mesozoic overburden, the presence of the Upper Triassic-Lower Jurassic evaporite seal are the most important factors goveming the distribution of the Paleozoic-sourced hydrocarbons in North Africa. The Mesozoic sequence plays a critical role for hydrocarbons to accumulate by enabling the maturation of the Paleozoic source rocks during the Mesozoic-Paleogene times and preserving the accumulated hydrocarbons. Basins and surrounding uplifts, particularly the latter, with a thick Mesozoic sequence and a regional evaporite seal generally have abundant hydrocarbons. Basins where only a thin Mesozoic overburden was developed tend to have a very poor to moderate hydrocarbon prospectivity.
文摘Sandi Arabia is renown for its rich oil and gas Mesozoic.However,the discovery of Paleozoic fields in resources with the bulk of the reserves reservo/red in the the late 1980s has encouraged further exploration in the Paleozoic.This paper reviews the salient features of the Paleozoic petroleum geology in central Saudi Arabia and discusses the main factors controlling hydrocarbon accumulation in the Paleozoic.The Lower Silurian Qusaiba hot shale is the principal source rock for the hydrocarbons discovered in the Ordovician to Permian reservoirs.Of them,the Permo-Carboniferous Unayzah and Upper Ordovician Sarah Formations have the best exploration potential.The key factors controlling hydrocarbon accumulation in the Unayzah Formation are migration pathways and reservoir petrophysics.The key factors controlling hydrocarbon accumulation in the Sarah Formation are reservoir petrophysics and the development of structural traps.
文摘The fluid flow history during diagenesis of sandstones in the Upper Permian Black Jack Formation of the Gunnedah Basin has been investigated through integrated petrographic observations, fluid inclusion investigations and stable isotope analyses. The early precipitation of mixed-layer illite/smectite, siderite, calcite, ankerite and kaolin proceeded at the presence of Late Permian connate meteoric waters at temperatures of up to 60℃. These evolved connate pore waters were also parental to quartz, which formed at temperatures of up to 87℃. The phase of maximum burial was characterized by development of filamentous illite and late calcite at temperatures of up to -90℃. Subsequent uplifting and cooling led to deep meteoric influx from surface, which in turn resulted in dissolution of labile grains and carbonate cements, and formation of second generation of kaolin. Dawsonite was the last diagenetic mineral precipitated and its formation is genetically related to deep-seated mamagtic sourced CO2.
基金Supported by the China National Science and Technology Major Project(2011ZX05006-005)
文摘In order to reveal the development mechanism of high-quality clastic rock reservoir, the basic characteristics of Sha-3 Member of the Shahejie Formation in the Raoyang sag, Bohai Bay Basin, are analyzed based on cores observation, thin-sections and SEM images, and petrophysical properties measurements as well. It is found that high-mature composition and texture, early oil charging, and dissolution are the main factors controlling the formation and preservation of pores in deep reservoirs. Compaction is the major factor destructing pores, whereas formation overpressure is conducive to the preservation of original pores, high compositional and medium textural maturity can enhance the resistance capacity to compaction and protect primary pores. Early oil charging could lead to temporary cessation of diagenesis and thus inhibit the cementation. When organic acids entered reservoir formations, considerable amounts of secondary pores were formed, leading to the local improvement of petrophysical properties. When predicting good quality belt in exploration of deep basin, it is recommended that the superimposing effects of the multiple factors(overpressure, early oil charging, compositional and textural maturity, diagenesis) be taken into consideration.
基金Supported by National Natural Science Foundation of China(92255302,91755104)Fundamental Research Cooperation Project under the Strategic Cooperation Plan between PetroChina and Peaking University(23-2-1).
文摘Using the latest global datasets of hydrocarbon fields and reservoirs,this study systematically investigates the characteristics of differential hydrocarbon enrichment and its primary controlling factors in the southern Tethys Domain within the context of Tethys tectonic evolution.The results indicate that although the southern Tethys Domain comprises only one-third of the Tethys Domain in areal extent,it hosts nearly 80%of its total hydrocarbon reserves,exhibiting a markedly uneven distribution pattern.Specifically,the Middle East sub-segment is identified as the core enrichment area,with the Arabian Basin serving as a typical example.Through tectonic subdivision,classification of sedimentary basins,analysis of source rock distribution and reservoir-seal assemblages,as well as an integrated investigation of the relationship between succeeding paleo-uplifts and hydrocarbon enrichment,the study demonstrates that the superimposition patterns of prototype basins,the scale and distribution of source rocks,the effectiveness of reservoir-seal assemblages,and the basement paleo-uplifts are the key factors governing hydrocarbon enrichment in the southern Tethys Domain.The findings of this study provide valuable references for deeper understanding of hydrocarbon accumulation patterns in the central and northern Tethys Domain and even other global regions with similar geological settings,and offer a scientific basis for selection of favorable play fairways in the southern Tethys Domain.
基金financially supported by National Science and Technology Major Project of the Chinese Ministry of Science and Technology (No.2011ZX05031-001-007HZ)
文摘The North Carnarvon Basin, which lies in the North West Shelf of Australia, is highly rich in gas resources. As a typical passive marginal basin, it experienced the pre-rifting, early rifting, main rifting, late rifting, post-rifting sagging and passive margin stages. The basin was mainly filled with thick Mesozoic-Cenozoic sediments, of which the Mesozoic hosts the principal source, reservoir and seal intervals. Mesozoic palaeogeography has an important control on the oil and gas distribution. Triassic gas-prone source rocks of deltaic origin deter-mine the high endowment of natural gases in the North Carnarvon Basin. The more restricted distribution of oil accumulations is controlled by oil source rocks in the Upper Jurassic Dingo Claystone. The Muderong Shale deposited in the Early Cretaceous marine transgression provides the effective regional seal for the underlying oil and gas reservoirs.
