The Late Triassic Mungaroo Formation of the Exmouth Plateau was investigated through an integrated,stratigraphically and geographically extensive study to characterize its source rock potential and depositional contro...The Late Triassic Mungaroo Formation of the Exmouth Plateau was investigated through an integrated,stratigraphically and geographically extensive study to characterize its source rock potential and depositional controls.Geochemical,petrographic,and palynological analyses reveal highly variable organic richness across the formation,with total organic carbon(TOC) content values ranging from very low in sand-dominated intervals to notably high in coal-bearing mudstones.The Mungaroo Formation exhibits diverse organic composition,with TOC content ranging from 0.63 % to 54.18 %,demonstrating that while certain intervals contain significant organic richness,others are notably lean in organic content.Petrographic analyses reveal the presence of dinoflagellates,liptodetrinite,sporinite,and cutinite,suggesting transitional settings with varying marine influence.Thermal maturity assessments indicate a range of maturity levels,with vitrinite reflectance(Ro) values ranging from 0.45 % to 1.39 %,reflecting thermal maturity of immature to post-mature stage.Rock-Eval pyrolysis parameters support these observations,highlighting varying stages of hydrocarbon generation.Biomarker characteristics further confirm the mixed organic origin and complex paleo-depositional environments within the Mungaroo Formation.The presence of both marine and terrigenous biomarkers underscores the depositional history of the region,with Pristane/Phytane ratios(Pr/Ph) indicating oxidizing environments typically associated with terrigenous plants' input.Palynological data indicates strong terrigenous influence within both the wells Mercury-1 and Jupiter-1,characterized by proximal delta-plain environments.展开更多
North Carnarvon Basin is a gas province with minor oily sweet spots in deepwater area with water depth more than 500 m,which is one of the hot spots of global petroleum exploration for its series of giant hydrocarbon ...North Carnarvon Basin is a gas province with minor oily sweet spots in deepwater area with water depth more than 500 m,which is one of the hot spots of global petroleum exploration for its series of giant hydrocarbon discoveries in recent years.However,the degree of oil and gas exploration in deepwater area is still low,and the conditions for oil and gas accumulation are not clear.Based on the current exploration situation and latest database of fields,applying multidisciplinary analysis of hydrocarbon geology,hydrocarbon accumulation elements and its exploration direction of North Carnarvon Basin in deepwater area are analyzed.The results show that there are three sets of main source rocks in deepwater area of North Carnarvon Basin,which are Triassic marine shale in Locker Formation and delta coal-bearing mudstone with thin carbonaceous mudstone in Mungaroo Formation,Lower–Middle Jurassic paralic carbargilite and coal measure strata in Athol Formation and Murat Formation,Cretaceous delta mudstone in Barrow Group and marine shale in Muderong Formation.Most source rock samples show gas-prone capability.The coarse sandstone of delta facies in Middle–Upper Triassic Mungaroo Formation is the most important reservoir in deepwater area,Lower Cretaceous Barrow Group deep-water gravity flow or underwater fan turbidite sandstone is the secondly main reservoir.Lower Cretaceous marine shale in Muderong Formation is most important regional caprock.Triassic mudstone in Mungaroo Formation is an important interlayer caprock in deepwater area.There are two main reservoir accumulation assemblages in deepwater area,one is Triassic structural-unconformity plane reservoir accumulation assemblage of Locker Formation to Mungaroo Formation,and the other is Lower–Middle Jurassic Athol Formation and Murat Formation–Lower Cretaceous stratigraphic lithology-structural reservoir accumulation assemblage of Barrow Group to Muderong Formation.There are three main control factors of hydrocarbon Accumulation:One is coupling of source and seal control hydrocarbon distribution area,the second is multi-stage large wave dominated deltas dominate accumulation zone,the third is direction of hydrocarbon migration and accumulation in hydrocarbon-rich generation depression was controlled by overpressure.The south of Exmouth platform in deepwater area is adjacent to hydrocarbon rich depression zone,reservoir assemblage is characterized by“near source rocks,excellent reservoir facies,high position and excellent caprocks”,which is the main battlefield of deepwater oil and gas exploration in North Carnarvon Basin at present.There are a lot of fault block traps in the northern structural belt of Exmouth platform,and the favorable sedimentary facies belt at the far end of delta plain in Mungaroo Formation is widely distributed,which is the next favorable exploration zone.The Lower Cretaceous,which is located at the concave edge uplift adjacent to the investigator depression and the Exmouth platform,also has a certain exploration prospect in northwest of deepwater area.展开更多
文摘The Late Triassic Mungaroo Formation of the Exmouth Plateau was investigated through an integrated,stratigraphically and geographically extensive study to characterize its source rock potential and depositional controls.Geochemical,petrographic,and palynological analyses reveal highly variable organic richness across the formation,with total organic carbon(TOC) content values ranging from very low in sand-dominated intervals to notably high in coal-bearing mudstones.The Mungaroo Formation exhibits diverse organic composition,with TOC content ranging from 0.63 % to 54.18 %,demonstrating that while certain intervals contain significant organic richness,others are notably lean in organic content.Petrographic analyses reveal the presence of dinoflagellates,liptodetrinite,sporinite,and cutinite,suggesting transitional settings with varying marine influence.Thermal maturity assessments indicate a range of maturity levels,with vitrinite reflectance(Ro) values ranging from 0.45 % to 1.39 %,reflecting thermal maturity of immature to post-mature stage.Rock-Eval pyrolysis parameters support these observations,highlighting varying stages of hydrocarbon generation.Biomarker characteristics further confirm the mixed organic origin and complex paleo-depositional environments within the Mungaroo Formation.The presence of both marine and terrigenous biomarkers underscores the depositional history of the region,with Pristane/Phytane ratios(Pr/Ph) indicating oxidizing environments typically associated with terrigenous plants' input.Palynological data indicates strong terrigenous influence within both the wells Mercury-1 and Jupiter-1,characterized by proximal delta-plain environments.
基金This study was funded by Jiangxi Provincial Natural Science Foundation(20202BABL211019)the National Science and Technology Major Project(2016ZX05026007)+2 种基金the National Major Fundamental Research and Development Project(2009CB219400)Open Fund Project of Key Laboratory of Sedimentary Mineralization and Sedimentary Mineral Resources in Shandong Province(DMSM 2019008)National Natural Science Foundation of China(41502081).
文摘North Carnarvon Basin is a gas province with minor oily sweet spots in deepwater area with water depth more than 500 m,which is one of the hot spots of global petroleum exploration for its series of giant hydrocarbon discoveries in recent years.However,the degree of oil and gas exploration in deepwater area is still low,and the conditions for oil and gas accumulation are not clear.Based on the current exploration situation and latest database of fields,applying multidisciplinary analysis of hydrocarbon geology,hydrocarbon accumulation elements and its exploration direction of North Carnarvon Basin in deepwater area are analyzed.The results show that there are three sets of main source rocks in deepwater area of North Carnarvon Basin,which are Triassic marine shale in Locker Formation and delta coal-bearing mudstone with thin carbonaceous mudstone in Mungaroo Formation,Lower–Middle Jurassic paralic carbargilite and coal measure strata in Athol Formation and Murat Formation,Cretaceous delta mudstone in Barrow Group and marine shale in Muderong Formation.Most source rock samples show gas-prone capability.The coarse sandstone of delta facies in Middle–Upper Triassic Mungaroo Formation is the most important reservoir in deepwater area,Lower Cretaceous Barrow Group deep-water gravity flow or underwater fan turbidite sandstone is the secondly main reservoir.Lower Cretaceous marine shale in Muderong Formation is most important regional caprock.Triassic mudstone in Mungaroo Formation is an important interlayer caprock in deepwater area.There are two main reservoir accumulation assemblages in deepwater area,one is Triassic structural-unconformity plane reservoir accumulation assemblage of Locker Formation to Mungaroo Formation,and the other is Lower–Middle Jurassic Athol Formation and Murat Formation–Lower Cretaceous stratigraphic lithology-structural reservoir accumulation assemblage of Barrow Group to Muderong Formation.There are three main control factors of hydrocarbon Accumulation:One is coupling of source and seal control hydrocarbon distribution area,the second is multi-stage large wave dominated deltas dominate accumulation zone,the third is direction of hydrocarbon migration and accumulation in hydrocarbon-rich generation depression was controlled by overpressure.The south of Exmouth platform in deepwater area is adjacent to hydrocarbon rich depression zone,reservoir assemblage is characterized by“near source rocks,excellent reservoir facies,high position and excellent caprocks”,which is the main battlefield of deepwater oil and gas exploration in North Carnarvon Basin at present.There are a lot of fault block traps in the northern structural belt of Exmouth platform,and the favorable sedimentary facies belt at the far end of delta plain in Mungaroo Formation is widely distributed,which is the next favorable exploration zone.The Lower Cretaceous,which is located at the concave edge uplift adjacent to the investigator depression and the Exmouth platform,also has a certain exploration prospect in northwest of deepwater area.
