Pub Date : 2022-07-01Epub Date: 2022-05-16DOI: 10.1016/j.liver.2022.100099
Kenji Okumura, Seigo Nishida, Hiroshi Sogawa, Gregory Veillette, Roxana Bodin, David C Wolf, Abhay Dhand
Background: : Since its declaration as a global pandemic on March11th 2020, COVID-19 has had a significant effect on solid-organ transplantation. The aim of this study was to analyze the impact of COVID-19 on Liver transplantation (LT) in United States.
Methods: : We retrospectively analyzed the United Network for Organ Sharing database regarding characteristics of donors, adult-LT recipients, and transplant outcomes during early-COVID period (March 11- September 11, 2020) and compared them to pre-COVID period (March 11 - September 11, 2019).
Results: : Overall, 4% fewer LTs were performed during early-COVID period (4107 vs 4277). Compared to pre-COVID period, transplants performed in early-COVID period were associated with: increase in alcoholic liver disease as most common primary diagnosis (1315 vs 1187, P< 0.01), higher MELD score in the recipients (25 vs 23, P<0.01), lower time on wait-list (52 vs 84 days, P<0.01), higher need for hemodialysis at transplant (9.4 vs 11.1%, P=0.012), longer distance from recipient hospital (131 vs 64 miles, P<0.01) and higher donor risk index (1.65 vs 1.55, P<0.01). Early-COVID period saw increase in rejection episodes before discharge (4.6 vs 3.4%, P=0.023) and lower 90-day graft/patient survival (90.2 vs 95.1 %, P<0.01; 92.2 vs 96.5 %, P<0.01). In multivariable cox-regression analysis, early-COVID period was the independent risk factor for graft failure at 90-days post-transplant (Hazard Ratio 1.77, P<0.01).
Conclusions: : During early-COVID period in United States, overall LT decreased, alcoholic liver disease was primary diagnosis for LT, rate of rejection episodes before discharge was higher and 90-days post-transplant graft survival was lower.
背景:自2020年3月11日宣布为全球大流行以来，COVID-19对实体器官移植产生了重大影响。本研究的目的是分析COVID-19对美国肝移植(LT)的影响。方法:我们回顾性分析了联合器官共享网络数据库中covid早期(2020年3月11日至9月11日)供体、成人肝移植受体和移植结果的特征，并将其与covid前(2019年3月11日至9月11日)进行了比较。结果:总体而言，在covid - 19早期进行的LTs减少了4%(4107例对4277例)。与covid - 19前相比，在covid - 19早期进行移植与以下因素相关:酒精性肝病(最常见的原发性诊断)增加(1315 vs 1187, P< 0.01)，受者MELD评分较高(25 vs 23, PPP=0.012)，离受者医院的距离较远(131 vs 64英里，PPP=0.023)，移植/患者90天生存率较低(90.2% vs 95.1%， PPP)。在美国的早期covid期间，总体LT下降，酒精性肝病是LT的主要诊断，出院前排斥事件发生率较高，移植后90天存活率较低。
{"title":"Inferior Liver Transplant Outcomes during early COVID-19 pandemic in United States.","authors":"Kenji Okumura, Seigo Nishida, Hiroshi Sogawa, Gregory Veillette, Roxana Bodin, David C Wolf, Abhay Dhand","doi":"10.1016/j.liver.2022.100099","DOIUrl":"10.1016/j.liver.2022.100099","url":null,"abstract":"<p><strong>Background: </strong>: Since its declaration as a global pandemic on March11<sup>th</sup> 2020, COVID-19 has had a significant effect on solid-organ transplantation. The aim of this study was to analyze the impact of COVID-19 on Liver transplantation (LT) in United States.</p><p><strong>Methods: </strong>: We retrospectively analyzed the United Network for Organ Sharing database regarding characteristics of donors, adult-LT recipients, and transplant outcomes during early-COVID period (March 11- September 11, 2020) and compared them to pre-COVID period (March 11 - September 11, 2019).</p><p><strong>Results: </strong>: Overall, 4% fewer LTs were performed during early-COVID period (4107 vs 4277). Compared to pre-COVID period, transplants performed in early-COVID period were associated with: increase in alcoholic liver disease as most common primary diagnosis (1315 vs 1187, <i>P</i>< 0.01), higher MELD score in the recipients (25 vs 23, <i>P</i><0.01), lower time on wait-list (52 vs 84 days, <i>P</i><0.01), higher need for hemodialysis at transplant (9.4 vs 11.1%, <i>P</i>=0.012), longer distance from recipient hospital (131 vs 64 miles, <i>P</i><0.01) and higher donor risk index (1.65 vs 1.55, <i>P</i><0.01). Early-COVID period saw increase in rejection episodes before discharge (4.6 vs 3.4%, <i>P</i>=0.023) and lower 90-day graft/patient survival (90.2 vs 95.1 %, <i>P</i><0.01; 92.2 vs 96.5 %, <i>P</i><0.01). In multivariable cox-regression analysis, early-COVID period was the independent risk factor for graft failure at 90-days post-transplant (Hazard Ratio 1.77, <i>P</i><0.01).</p><p><strong>Conclusions: </strong>: During early-COVID period in United States, overall LT decreased, alcoholic liver disease was primary diagnosis for LT, rate of rejection episodes before discharge was higher and 90-days post-transplant graft survival was lower.</p>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"19 1","pages":"100099"},"PeriodicalIF":1.8,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9110062/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85322470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Structural decoupling in the Zagros fold‐and‐thrust belt, SW Iran, is controlled by the presence of intermediate detachment horizons within the Phanerozoic stratigraphic column such as intervals rich in evaporites. The effectiveness of the detachment horizons varies across the Zagros, and controls the style of folding and therefore the formation of structural traps. In this paper, field mapping, seismic interpretation and well data is used to investigate the complex structural style at six large‐scale anticlines located on either side of the surface trace of the NW‐SE trending Zagros Frontal Fault system in the South Dezful Embayment (Central Zagros). At some of these anticlines, lower – middle Miocene evaporites in the Gachsaran Formation decouple the folded overlying succession from the competent, underlying interval which includes the Asmari Formation reservoir. Anticlines to the northeast of the surface exposure of the fault have undergone four times more shortening than anticlines to the southwest. This localized shortening compared to regional values has resulted in some cases in complex asymmetric folding, and in severe structural decoupling above and below the Gachsaran Formation. However, other anticlines to the NE of the fault which underwent a similar amount of shortening, but in which the thickness of the Gachsaran Formation is reduced and the salt content is lower, show a harmonic style of folding above and below the formation. Thus, the efficiency of the Gachsaran detachment varies throughout the study area and appears to be controlled mainly by the total thickness of the formation, the net thickness of salt‐rich intervals within it, and the amount of structural shortening across the Zagros Frontal Fault system. These observations could be relevant to similar structural domains both in the Zagros and in other fold‐and‐thrust belts where intermediate detachment horizons and regional‐scale faults have together controlled the configuration of folds and structural traps.
{"title":"STRUCTURAL STYLE IN THE SOUTH DEZFUL EMBAYMENT, SW IRAN: COMBINED INFLUENCE OF THE ZAGROS FRONTAL FAULT SYSTEM AND THE DETACHMENT IN THE MIOCENE GACHSARAN FORMATION","authors":"Islam Tavakolian, A. Yassaghi, M. Najafi","doi":"10.1111/jpg.12821","DOIUrl":"https://doi.org/10.1111/jpg.12821","url":null,"abstract":"Structural decoupling in the Zagros fold‐and‐thrust belt, SW Iran, is controlled by the presence of intermediate detachment horizons within the Phanerozoic stratigraphic column such as intervals rich in evaporites. The effectiveness of the detachment horizons varies across the Zagros, and controls the style of folding and therefore the formation of structural traps. In this paper, field mapping, seismic interpretation and well data is used to investigate the complex structural style at six large‐scale anticlines located on either side of the surface trace of the NW‐SE trending Zagros Frontal Fault system in the South Dezful Embayment (Central Zagros). At some of these anticlines, lower – middle Miocene evaporites in the Gachsaran Formation decouple the folded overlying succession from the competent, underlying interval which includes the Asmari Formation reservoir. Anticlines to the northeast of the surface exposure of the fault have undergone four times more shortening than anticlines to the southwest. This localized shortening compared to regional values has resulted in some cases in complex asymmetric folding, and in severe structural decoupling above and below the Gachsaran Formation. However, other anticlines to the NE of the fault which underwent a similar amount of shortening, but in which the thickness of the Gachsaran Formation is reduced and the salt content is lower, show a harmonic style of folding above and below the formation. Thus, the efficiency of the Gachsaran detachment varies throughout the study area and appears to be controlled mainly by the total thickness of the formation, the net thickness of salt‐rich intervals within it, and the amount of structural shortening across the Zagros Frontal Fault system. These observations could be relevant to similar structural domains both in the Zagros and in other fold‐and‐thrust belts where intermediate detachment horizons and regional‐scale faults have together controlled the configuration of folds and structural traps.","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48680340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Escobar, J. G. Díaz, G. Márquez, C. Boentec, R. Tocco
This paper investigates the timing of hydrocarbon generation in the northern part of the Urdaneta West field in the NW of the Lake Maracaibo Basin, NW Venezuela, based on 1D basin modelling at three wells referred to as wells X, Y and Z. Kitchen areas were identified and secondary migration directions were inferred based on analyses of the thermal and burial history of the Upper Cretaceous La Luna Formation source rock and the geochemistry of 20 oil samples from the Río Negro Formation reservoir. Aliphatic hydrocarbons in the oil samples were analysed by gas chromatography – mass spectrometry (GC‐MS) while the vanadium‐nickel and sulphur contents were determined by energy dispersive X‐ray spectrometry and inductively coupled plasma optical emission spectroscopy, respectively. Bulk and molecular characterizations indicated that the oils originated from a marine carbonate source rock containing oil‐prone Type II kerogen, consistent with generation by the La Luna Formation.
{"title":"THE LA LUNA/RÍO NEGRO(.) PETROLEUM SYSTEM AT THE URDANETA WEST FIELD, LAKE MARACAIBO BASIN, NW VENEZUELA: 1D BASIN MODELLING AND SECONDARY OIL MIGRATION","authors":"M. Escobar, J. G. Díaz, G. Márquez, C. Boentec, R. Tocco","doi":"10.1111/jpg.12820","DOIUrl":"https://doi.org/10.1111/jpg.12820","url":null,"abstract":"This paper investigates the timing of hydrocarbon generation in the northern part of the Urdaneta West field in the NW of the Lake Maracaibo Basin, NW Venezuela, based on 1D basin modelling at three wells referred to as wells X, Y and Z. Kitchen areas were identified and secondary migration directions were inferred based on analyses of the thermal and burial history of the Upper Cretaceous La Luna Formation source rock and the geochemistry of 20 oil samples from the Río Negro Formation reservoir. Aliphatic hydrocarbons in the oil samples were analysed by gas chromatography – mass spectrometry (GC‐MS) while the vanadium‐nickel and sulphur contents were determined by energy dispersive X‐ray spectrometry and inductively coupled plasma optical emission spectroscopy, respectively. Bulk and molecular characterizations indicated that the oils originated from a marine carbonate source rock containing oil‐prone Type II kerogen, consistent with generation by the La Luna Formation.","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43293216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Khalid Shoaib, Zaheer Zafar, Zeeshan Ali Raja, S. Burley
The Northern Potwar Deformed Zone (NPDZ) of the frontal Himalayas in northern Pakistan hosts many oil and gas fields located in thrust sheets and associated folds. The presence of fractures in Paleogene carbonates at >3 km target depths with very little or no primary porosity is an essential part of reservoir storage and connectivity. Predicting fracture presence, distribution and orientation is therefore key to successful exploration, appraisal and field development in the NPDZ.
{"title":"RATANA FIELD, POTWAR FOLD BELT, NORTHERN PAKISTAN: HIGH INTENSITY FRACTURE ZONES RELATED TO MAJOR THRUST FAULTS AS REVEALED BY SEISMIC FRACTURE PREDICTION","authors":"Khalid Shoaib, Zaheer Zafar, Zeeshan Ali Raja, S. Burley","doi":"10.1111/jpg.12819","DOIUrl":"https://doi.org/10.1111/jpg.12819","url":null,"abstract":"The Northern Potwar Deformed Zone (NPDZ) of the frontal Himalayas in northern Pakistan hosts many oil and gas fields located in thrust sheets and associated folds. The presence of fractures in Paleogene carbonates at >3 km target depths with very little or no primary porosity is an essential part of reservoir storage and connectivity. Predicting fracture presence, distribution and orientation is therefore key to successful exploration, appraisal and field development in the NPDZ.","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42563220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Oblasov, I. Goncharov, A. Derduga, I. Kunitsyna
The NW Greater Caucasus and surrounding areas have a long history of petroleum production dating back to the mid‐19th century. However the origin of the oil and gas is still a matter of debate. This paper focusses on a study area to the north of the western Greater Caucasus covering the West and East Kuban Basins and neighbouring structural highs where oil and natural gas occur in reservoir units of Neogene, Paleogene, Cretaceous and Jurassic ages. The study is based on the results of organic geochemical and stable carbon isotope analyses of 21 samples of associated gases from 16 oil fields. The gas samples' compositions were investigated together with the δ13C values of C1 to C5 alkanes. Twenty of the gas samples were of thermogenic origin and one was mixed (thermogenic and secondary microbial). δ13C values for CH4 for all the gas samples varied over a wide range from ‐62.3 to ‐30.0 ‰, indicating major variations in the thermal maturity of the respective source rocks.
{"title":"GEOCHEMISTRY AND CARBON ISOTOPE CHARACTERISTICS OF ASSOCIATED GASES FROM OILFIELDS IN THE NW GREATER CAUCASUS, RUSSIA","authors":"N. Oblasov, I. Goncharov, A. Derduga, I. Kunitsyna","doi":"10.1111/jpg.12822","DOIUrl":"https://doi.org/10.1111/jpg.12822","url":null,"abstract":"The NW Greater Caucasus and surrounding areas have a long history of petroleum production dating back to the mid‐19th century. However the origin of the oil and gas is still a matter of debate. This paper focusses on a study area to the north of the western Greater Caucasus covering the West and East Kuban Basins and neighbouring structural highs where oil and natural gas occur in reservoir units of Neogene, Paleogene, Cretaceous and Jurassic ages. The study is based on the results of organic geochemical and stable carbon isotope analyses of 21 samples of associated gases from 16 oil fields. The gas samples' compositions were investigated together with the δ13C values of C1 to C5 alkanes. Twenty of the gas samples were of thermogenic origin and one was mixed (thermogenic and secondary microbial). δ13C values for CH4 for all the gas samples varied over a wide range from ‐62.3 to ‐30.0 ‰, indicating major variations in the thermal maturity of the respective source rocks.","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2022-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47230929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crude oil reserves in tight Middle and Lower Jurassic reservoirs are of increasing exploration interest in the central Sichuan Basin, SW China. However, the origin of these “tight oils” is poorly understood. In this study, sixteen samples of light oils/condensates from tight Middle and Lower Jurassic reservoir rocks were analysed using gas chromatography (GC) and isotope ratio mass spectrometry to investigate the oils’ origin and to classify them into genetic families. The tight oils can be divided into two families. Family I oils occur in the Gongshanmiao oilfield where reservoir units comprise the Da'anzhai Member of the Lower Jurassic Ziliujing Formation, the Lower Jurassic Lianggaoshan Formation, and the First Member of the Middle Jurassic Shaximiao Formation. Family I oils are characterized by relatively low values of the methylcyclohexane (MCH) and cyclohexane (CH) indexes, low values of Mango's parameter K2 for light hydrocarbon composition, and relatively negative δ13C values ranging from -30.8‰ to -28.9‰. Family I oils are inferred to be self-sourced by lacustrine shales in the Da'anzhai Member and the Lianggaoshan Formation in the study area, both of which are rich in sapropelic organic matter. These source rocks also charged reservoirs in the First Member of the Shaximiao Formation. By contrast, the newly discovered Family II oils, which occur at the Jinhua oilfield and the as-yet undeveloped Qiulin and Bajiaochang structures, are reservoired in the Second Member of Shaximiao Formation. Family II oils have higher values of the MCH index, CH index and Mango's K2 parameter, and δ13C values varying from -27.5‰ to -25.4‰. These oils have similar light hydrocarbon compositions and δ13C values to oils derived from source rocks in the Upper Triassic Xujiahe Formation which contain dominantly humic organic matter. Family II oils are therefore inferred to be derived from the coaly mudstones in the Xujiahe Formation.
The different compositions of the tight oils in the First and Second Members of the Shaximiao Formation appear to be controlled by the distribution and thickness of source rocks in the study area. Thus, the Gongshanmiao oilfield where Family I oils occur in the First Member is close to the depocentre of source rocks in the Da'anzhai Member and Lianggaoshan Formation. These source rocks are inferred to have charged the First Member reservoirs which may also be present in nearby oil- and gas-bearing structures such as Nanchong and Yingshan. By contrast, Family II oils occur in tight reservoirs in the Second Member in areas with thick successions of Upper Triassic Xujiahe Formation mudstone source rocks, such as the Jinhua oilfield. In areas where both source rocks are present such as the Zhongtaishan and Lianchi oilfields, Shaximiao Formation reservoirs appear to contain both Family I and Family II oils.
{"title":"COMPOSITION OF LIGHT HYDROCARBONS IN JURASSIC TIGHT OILS IN THE CENTRAL SICHUAN BASIN, CHINA: ORIGIN AND SOURCE ROCK CORRELATION","authors":"Xiaolin Lu, Meijun Li, Tengqiang Wei, Changjiang Wu, Youjun Tang, Xiaojuan Wang, Haitao Hong, Yuan Liu, Zichao Ran","doi":"10.1111/jpg.12811","DOIUrl":"10.1111/jpg.12811","url":null,"abstract":"<p>Crude oil reserves in tight Middle and Lower Jurassic reservoirs are of increasing exploration interest in the central Sichuan Basin, SW China. However, the origin of these “tight oils” is poorly understood. In this study, sixteen samples of light oils/condensates from tight Middle and Lower Jurassic reservoir rocks were analysed using gas chromatography (GC) and isotope ratio mass spectrometry to investigate the oils’ origin and to classify them into genetic families. The tight oils can be divided into two families. Family I oils occur in the Gongshanmiao oilfield where reservoir units comprise the Da'anzhai Member of the Lower Jurassic Ziliujing Formation, the Lower Jurassic Lianggaoshan Formation, and the First Member of the Middle Jurassic Shaximiao Formation. Family I oils are characterized by relatively low values of the methylcyclohexane (MCH) and cyclohexane (CH) indexes, low values of Mango's parameter K<sub>2</sub> for light hydrocarbon composition, and relatively negative δ<sup>13</sup>C values ranging from -30.8‰ to -28.9‰. Family I oils are inferred to be self-sourced by lacustrine shales in the Da'anzhai Member and the Lianggaoshan Formation in the study area, both of which are rich in sapropelic organic matter. These source rocks also charged reservoirs in the First Member of the Shaximiao Formation. By contrast, the newly discovered Family II oils, which occur at the Jinhua oilfield and the as-yet undeveloped Qiulin and Bajiaochang structures, are reservoired in the Second Member of Shaximiao Formation. Family II oils have higher values of the MCH index, CH index and Mango's K<sub>2</sub> parameter, and δ<sup>13</sup>C values varying from -27.5‰ to -25.4‰. These oils have similar light hydrocarbon compositions and δ<sup>13</sup>C values to oils derived from source rocks in the Upper Triassic Xujiahe Formation which contain dominantly humic organic matter. Family II oils are therefore inferred to be derived from the coaly mudstones in the Xujiahe Formation.</p><p>The different compositions of the tight oils in the First and Second Members of the Shaximiao Formation appear to be controlled by the distribution and thickness of source rocks in the study area. Thus, the Gongshanmiao oilfield where Family I oils occur in the First Member is close to the depocentre of source rocks in the Da'anzhai Member and Lianggaoshan Formation. These source rocks are inferred to have charged the First Member reservoirs which may also be present in nearby oil- and gas-bearing structures such as Nanchong and Yingshan. By contrast, Family II oils occur in tight reservoirs in the Second Member in areas with thick successions of Upper Triassic Xujiahe Formation mudstone source rocks, such as the Jinhua oilfield. In areas where both source rocks are present such as the Zhongtaishan and Lianchi oilfields, Shaximiao Formation reservoirs appear to contain both Family I and Family II oils.</p>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"45 2","pages":"163-177"},"PeriodicalIF":1.8,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41350535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. D. Bromhead, F.S.P. van Buchem, M.D. Simmons, R.B. Davies
In order to facilitate the search for new play concepts and exploration opportunities, a sequence stratigraphic synthesis of the Cenomanian–Turonian interval of the Arabian Plate has been compiled. The synthesis is based on published datasets which have been analysed within a temporal framework constrained by biostratigraphy and isotope stratigraphy. The high stratigraphic resolution allows the palaeogeography of the study area to be mapped within 3rd order depositional sequences, and the relative influence of eustacy and tectonics on basin development to be evaluated. This significantly improves the prediction of stratigraphic architecture and depositional morphology at the scale of the entire tectonic plate.
{"title":"SEQUENCE STRATIGRAPHY, PALAEOGEOGRAPHY AND PETROLEUM PLAYS OF THE CENOMANIAN – TURONIAN SUCCESSION OF THE ARABIAN PLATE: AN UPDATED SYNTHESIS","authors":"A. D. Bromhead, F.S.P. van Buchem, M.D. Simmons, R.B. Davies","doi":"10.1111/jpg.12810","DOIUrl":"10.1111/jpg.12810","url":null,"abstract":"In order to facilitate the search for new play concepts and exploration opportunities, a sequence stratigraphic synthesis of the Cenomanian–Turonian interval of the Arabian Plate has been compiled. The synthesis is based on published datasets which have been analysed within a temporal framework constrained by biostratigraphy and isotope stratigraphy. The high stratigraphic resolution allows the palaeogeography of the study area to be mapped within 3rd order depositional sequences, and the relative influence of eustacy and tectonics on basin development to be evaluated. This significantly improves the prediction of stratigraphic architecture and depositional morphology at the scale of the entire tectonic plate.","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"45 2","pages":"119-161"},"PeriodicalIF":1.8,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpg.12810","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44178183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fibrous calcite bed-parallel veins (BPVs) are a typical feature of the Upper Jurassic – Lower Cretaceous Vaca Muerta Formation in the subsurface of the Neuquén Basin (Argentina). The formation is considered to be the main source rock in the basin as well as an important unconventional play. This study examines the growth of BPVs through an analysis of core from three wells located along a transect extending for some 150 km from the NE Platform near the basin margin in the east to the Agrio fold-and-thrust belt at the Andean deformation front in the west. The main objective is to integrate fluid inclusion data with the palaeothermal and palaeopresure evolution obtained from a regional-scale 2D basin and petroleum systems model to examine the timing of fracture development and its relationship with hydrocarbon generation in the Vaca Muerta Formation through time.
The apertures of BPVs were measured in more than 360 m of core from three wells (wells A, D and E). This data was combined with optical petrography to investigate the number of calcite cementation events, and the temperature of cement precipitation based on fluid inclusion data. The organic geochemical and mineralogical characteristics of the Vaca Muerta source rock were also analysed. The integrated results were incorporated into a poro-elastic basin model to investigate the impact of horizontal shortening due to Andean compression on pore pressure development and fracturing in the Vaca Muerta Formation. This framework allowed the timing of BPV formation to be determined together with possible mechanisms governing overpressure conditions through time.
Near the Andean deformation front in the west of the modelled section where the Vaca Muerta Formation is in the wet gas window (well D) and dry gas window (well A), BPVs are characterized by two or more generations of calcite fibres indicating multiple growth phases. Calcite which precipitated during cementation event 1 (E1) in the internal zones of BPVs consists of crystals oriented perpendicular to fracture walls, indicating perpendicular vein opening. Calcite precipitated during cementation event 2 (E2) in the outer zones of BPVs includes curved and oblique crystals. During this phase, shear occurred between the opening vein walls as a result of horizontal shortening. Cementation event 3 (E3) is characterized by an equant mosaic of calcite crystals which preserve intracrystalline porosity. E1cements formed between 110 and 90 Ma with trapping temperatures of ∼112 °C (upper Vaca Muerta, well A) and ∼125 °C (lower Vaca Muerta, well D). Fracturing resulted from disequilibrium compaction and from volumetric expansion due to primary cracking of kerogen within the oil window. E2 cements record a trapping temperature of ∼159 °C and formed between 70 and 55 Ma (lower Vaca Muerta, well D) during maximum burial of the Vaca Muerta Formation, synchronous with the secondary cracking of retained liquid hydrocarbons and the beginning of An
{"title":"DEVELOPMENT OF FIBROUS CALCITE VEINS RELATED TO HYDROCARBON GENERATION AND OVERPRESSURING IN ORGANIC-RICH SHALE SOURCE ROCKS: THE VACA MUERTA FORMATION, NEUQUÉN BASIN, ARGENTINA","authors":"J. B. Spacapan, M. Comerio, R. Ruiz, E. Rocha","doi":"10.1111/jpg.12814","DOIUrl":"10.1111/jpg.12814","url":null,"abstract":"<p>Fibrous calcite bed-parallel veins (BPVs) are a typical feature of the Upper Jurassic – Lower Cretaceous Vaca Muerta Formation in the subsurface of the Neuquén Basin (Argentina). The formation is considered to be the main source rock in the basin as well as an important unconventional play. This study examines the growth of BPVs through an analysis of core from three wells located along a transect extending for some 150 km from the NE Platform near the basin margin in the east to the Agrio fold-and-thrust belt at the Andean deformation front in the west. The main objective is to integrate fluid inclusion data with the palaeothermal and palaeopresure evolution obtained from a regional-scale 2D basin and petroleum systems model to examine the timing of fracture development and its relationship with hydrocarbon generation in the Vaca Muerta Formation through time.</p><p>The apertures of BPVs were measured in more than 360 m of core from three wells (wells A, D and E). This data was combined with optical petrography to investigate the number of calcite cementation events, and the temperature of cement precipitation based on fluid inclusion data. The organic geochemical and mineralogical characteristics of the Vaca Muerta source rock were also analysed. The integrated results were incorporated into a poro-elastic basin model to investigate the impact of horizontal shortening due to Andean compression on pore pressure development and fracturing in the Vaca Muerta Formation. This framework allowed the timing of BPV formation to be determined together with possible mechanisms governing overpressure conditions through time.</p><p>Near the Andean deformation front in the west of the modelled section where the Vaca Muerta Formation is in the wet gas window (well D) and dry gas window (well A), BPVs are characterized by two or more generations of calcite fibres indicating multiple growth phases. Calcite which precipitated during cementation event 1 (E1) in the internal zones of BPVs consists of crystals oriented perpendicular to fracture walls, indicating perpendicular vein opening. Calcite precipitated during cementation event 2 (E2) in the outer zones of BPVs includes curved and oblique crystals. During this phase, shear occurred between the opening vein walls as a result of horizontal shortening. Cementation event 3 (E3) is characterized by an equant mosaic of calcite crystals which preserve intracrystalline porosity. E1cements formed between 110 and 90 Ma with trapping temperatures of ∼112 °C (upper Vaca Muerta, well A) and ∼125 °C (lower Vaca Muerta, well D). Fracturing resulted from disequilibrium compaction and from volumetric expansion due to primary cracking of kerogen within the oil window. E2 cements record a trapping temperature of ∼159 °C and formed between 70 and 55 Ma (lower Vaca Muerta, well D) during maximum burial of the Vaca Muerta Formation, synchronous with the secondary cracking of retained liquid hydrocarbons and the beginning of An","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"45 2","pages":"219-248"},"PeriodicalIF":1.8,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45208360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Conall Cromie, Nicola Scarselli, Jonathan Craig, Moin R. Khan, Abid Hussain
The Makran accretionary wedge developed as a result of subduction of the Arabian Plate beneath the southern margin of Eurasia since the Eocene. Interpretation of 2D seismic profiles calibrated to offshore well data in a study area to the south of Gwadar Bay (SW Pakistan) indicates a major period of accretion from the mid-Miocene, as evidenced by the occurrence of thick growth strata associated with large-scale imbricate thrusts. The thrust faults originate from a deep detachment within the mud-rich Oligocene interval, and well-developed piggy-back basin successions occur in thrust hanging walls. In the study area, the thrust structures are sealed by a thick, progradational Pliocene to Recent interval in which the presence of submarine canyons, up to 2.5 km across, indicate that sedimentary transport was from the north.
Fluid escape pipes and associated amplitude anomalies are observed in the seismic profiles studied and may be related to upward migration of thermogenic hydrocarbons from depth, as heavy hydrocarbon fractions <C3 have been reported from nearby wells. The hydrocarbons are believed to have been sourced from the Oligocene Hoshab Shale and to have then migrated up through a sedimentary succession in which permeability barriers are largely absent. Hanging wall anticlines mapped in the study area could provide structural traps, and turbidites in the Lower Miocene Panjgur Formation may represent a potential reservoir. Amplitude anomalies are also observed adjacent to shallow fluid escape pipes within the topsets of clinoforms in the Pleistocene Chatti and Omara Formations, and probably indicate the presence of biogenic hydrocarbons sourced from distal mudstones in bottomset strata.
{"title":"TECTONOSTRATIGRAPHIC EVOLUTION AND HYDROCARBON PROSPECTIVITY SOUTH OF GWADAR BAY, MAKRAN ACCRETIONARY WEDGE, OFFSHORE SW PAKISTAN","authors":"Conall Cromie, Nicola Scarselli, Jonathan Craig, Moin R. Khan, Abid Hussain","doi":"10.1111/jpg.12812","DOIUrl":"10.1111/jpg.12812","url":null,"abstract":"<div>\u0000 <p>The Makran accretionary wedge developed as a result of subduction of the Arabian Plate beneath the southern margin of Eurasia since the Eocene. Interpretation of 2D seismic profiles calibrated to offshore well data in a study area to the south of Gwadar Bay (SW Pakistan) indicates a major period of accretion from the mid-Miocene, as evidenced by the occurrence of thick growth strata associated with large-scale imbricate thrusts. The thrust faults originate from a deep detachment within the mud-rich Oligocene interval, and well-developed piggy-back basin successions occur in thrust hanging walls. In the study area, the thrust structures are sealed by a thick, progradational Pliocene to Recent interval in which the presence of submarine canyons, up to 2.5 km across, indicate that sedimentary transport was from the north.</p>\u0000 <p>Fluid escape pipes and associated amplitude anomalies are observed in the seismic profiles studied and may be related to upward migration of thermogenic hydrocarbons from depth, as heavy hydrocarbon fractions <C<sub>3</sub> have been reported from nearby wells. The hydrocarbons are believed to have been sourced from the Oligocene Hoshab Shale and to have then migrated up through a sedimentary succession in which permeability barriers are largely absent. Hanging wall anticlines mapped in the study area could provide structural traps, and turbidites in the Lower Miocene Panjgur Formation may represent a potential reservoir. Amplitude anomalies are also observed adjacent to shallow fluid escape pipes within the topsets of clinoforms in the Pleistocene Chatti and Omara Formations, and probably indicate the presence of biogenic hydrocarbons sourced from distal mudstones in bottomset strata.</p>\u0000 </div>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":"45 2","pages":"179-199"},"PeriodicalIF":1.8,"publicationDate":"2022-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jpg.12812","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41989075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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