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The Lower Silurian Longmaxi rapid-transgressive black shale and organic matter distribution on the Upper Yangtze Platform, China
Shi, Zhensheng (PetroChina Research Institute of Petroleum Exploration and Development) | Zhou, Tianqi (PetroChina Research Institute of Petroleum Exploration and Development) | Qi, Ling (PetroChina Research Institute of Petroleum Exploration and Development)
Abstract The characteristics and formation of maximum flooding (MF) black shales are important aspects in defining the geology of fine-grained reservoirs. The MF black shales are located at the bottom of the Longmaxi Formation on the Upper Yangtze Platform, corresponding to graptolite zone LM1. Seismic interpretation, X-ray diffraction entire rock analysis, total organic carbon (TOC) tests, and field emission scanning electron microscopy analysis indicate that the MF black shales have an average content of 49.3% quartz (85% clay size), 10.5% calcite, 8.4% dolomite, and 23.4% clay minerals. The quartz content increases basinward, whereas the clay mineral content decreases. The shale has developed during rapid sea level rise, with a thickness of 0.5โ2.8ย m that gradually thickens basinward. The TOC content, averaging 5.4%, gradually decreases basinward, with four distinct stacking patterns. The mineral composition and thickness of the Longmaxi shale are related closely to rapid transgression, biology, and volcanism during the period of sedimentation. Rapid transgression has led to a decrease in terrestrial input and shale thickness. In addition, biological activity and volcanism have caused the prevalence of microcrystalline quartz. Shales with high TOC content are related to anoxic conditions, along with low sedimentation rates and high primary productivity. The combination of an anoxic water column, weak dilution, and enhanced organic matter (OM) supply have enhanced the preservation of the OM. The four TOC stacking patterns are related to the water depth. The supply of clay minerals decreases with increasing water depth, whereas the degradation and recycling of OM decrease the TOC content. The sediment accommodation increases with increasing water depth, resulting in four TOC stacking patterns.
- Europe (1.00)
- Asia > China > Sichuan Province (0.69)
- Phanerozoic > Paleozoic > Silurian > Llandovery (1.00)
- Phanerozoic > Mesozoic (1.00)
- Phanerozoic > Paleozoic > Ordovician (0.98)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral (1.00)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (3 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Health, Safety, Environment & Sustainability > Environment (1.00)
The Lower Silurian Longmaxi rapid-transgressive black shale and organic matter distribution on the Upper Yangtze Platform, China
Shi, Zhensheng (PetroChina Research Institute of Petroleum Exploration and Development) | Zhou, Tianqi (PetroChina Research Institute of Petroleum Exploration and Development) | Qi, Ling (PetroChina Research Institute of Petroleum Exploration and Development)
Abstract The characteristics and formation of maximum flooding (MF) black shales are important aspects in defining the geology of fine-grained reservoirs. The MF black shales are located at the bottom of the Longmaxi Formation on the Upper Yangtze Platform, corresponding to graptolite zone LM1. Seismic interpretation, X-ray diffraction entire rock analysis, total organic carbon (TOC) tests, and field emission scanning electron microscopy analysis indicate that the MF black shales have an average content of 49.3% quartz (85% clay size), 10.5% calcite, 8.4% dolomite, and 23.4% clay minerals. The quartz content increases basinward, whereas the clay mineral content decreases. The shale has developed during rapid sea level rise, with a thickness of 0.5โ2.8ย m that gradually thickens basinward. The TOC content, averaging 5.4%, gradually decreases basinward, with four distinct stacking patterns. The mineral composition and thickness of the Longmaxi shale are related closely to rapid transgression, biology, and volcanism during the period of sedimentation. Rapid transgression has led to a decrease in terrestrial input and shale thickness. In addition, biological activity and volcanism have caused the prevalence of microcrystalline quartz. Shales with high TOC content are related to anoxic conditions, along with low sedimentation rates and high primary productivity. The combination of an anoxic water column, weak dilution, and enhanced organic matter (OM) supply have enhanced the preservation of the OM. The four TOC stacking patterns are related to the water depth. The supply of clay minerals decreases with increasing water depth, whereas the degradation and recycling of OM decrease the TOC content. The sediment accommodation increases with increasing water depth, resulting in four TOC stacking patterns.
- Europe (1.00)
- Asia > China > Sichuan Province (0.69)
- Phanerozoic > Paleozoic > Silurian > Llandovery (1.00)
- Phanerozoic > Mesozoic (1.00)
- Phanerozoic > Paleozoic > Ordovician (0.98)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral (1.00)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Maverick Basin > Eagle Ford Shale Formation (0.99)
- (3 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Health, Safety, Environment & Sustainability > Environment (1.00)
To understand the petrophysical properties of an unconventional reservoir, well log data are used to investigate the rock properties of the shales in the areas of interest. The petrophysical evaluation comprises quality checking and editing of the available well logs. Additionally, the description of their properties, evaluation of the intervals of interest, and calculations to estimate the shale or clay volumes, TOC content, and brittleness index for the available wells are the main steps that should be followed in the initial log analysis. The estimation of the shale volume in the zone of interest can be performed in the available wells using the normalized version of the Gamma-Ray log (GRn), and using both neutron and density porosity logs. Following the concept that the increase in radioactivity of the organic-rich shales is related to their organic matter content, the GR and spectral GR responses need to be corrected for uranium before estimating clay content.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > North Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > Montana > Williston Basin > Bakken Shale Formation (0.99)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
The evaluation of a rocks past, present, and future potential to generate hydrocarbons by quantifying the elements and processes that control the evolution of an effective source rock in the context of petroleum exploration and exploitation. Methods of source rock evaluation have become increasingly valuable as the oil and gas industry continually raises standards on efficiency and effectiveness. By analyzing properties of potential source rocks, E&P companies are able to estimate the total volume and quality of exploitable hydrocarbons in a sedimentary basin, which are determining factors in risk analysis for both conventional and unconventional plays. The broadest element in source rock evaluation is the total organic carbon, or TOC, of a rock. TOC is the weigh percent of organic carbon present in a rock which is measured by the amount of CO2 released through combustion.
- Geology > Rock Type > Sedimentary Rock (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
- Geology > Rock Type > Sedimentary Rock (0.57)
- Geology > Geological Subdiscipline > Geochemistry (0.57)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (0.57)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
To understand the petrophysical properties of an unconventional reservoir, well log data are used to investigate the rock properties of the shales in the areas of interest. The petrophysical evaluation comprises quality checking and editing of the available well logs. Additionally, the description of their properties, evaluation of the intervals of interest, and calculations to estimate the shale or clay volumes, TOC content, and brittleness index for the available wells are the main steps that should be followed in the initial log analysis. The estimation of the shale volume in the zone of interest can be performed in the available wells using the normalized version of the Gamma-Ray log (GRn), and using both neutron and density porosity logs. Following the concept that the increase in radioactivity of the organic-rich shales is related to their organic matter content, the GR and spectral GR responses need to be corrected for uranium before estimating clay content. This element forms compounds that sorbs to clays and organic material in both cases where their depositional environment is anoxic marine or oxidizing lacustrine.
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)
- North America > United States > South Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > North Dakota > Williston Basin > Bakken Shale Formation (0.99)
- North America > United States > Montana > Williston Basin > Bakken Shale Formation (0.99)
- Information Technology > Knowledge Management (0.40)
- Information Technology > Communications > Collaboration (0.40)
The Devonian Shales of the Madre De Dios Basin as an Unconventional Resource System
Bejarano, Kim (YPFB Chaco S.A. Bolivia) | Cordova, Abigail (YPFB Chaco S.A. Bolivia) | Goncalves, Ana (YPFB Chaco S.A. Bolivia) | Contreras, Jaime (YPFB Chaco S.A. Bolivia) | Cruz, Carlos Enrique (CG7 Petroleum, Argentina) | Villalba, Damiรกn (GeoLab Sur S.A. Argentina) | Perez, Daniel (dp Consultora, Argentina)
Abstract The Madre de Dios Basin, covering approximately 70,000 km in Bolivia, has remained unexplored in terms of its hydrocarbon resources. The primary objective of this study was to assess its unconventional hydrocarbon potential, specifically shale oil. To facilitate the analysis and evaluation of the unconventional potential of the Madre de Dios Basin, information from well data and 2D seismic surveys has been employed and integrated to construct a geological model aimed at comprehending the Devonian basin's configuration, serving as the principal objective as an unconventional reservoir. Furthermore, the new geochemical analyses revealed values for the entire section (180 m approx.), with Total Organic Carbon (TOC) values over 2%, Hydrogen Index (HI) between 400 and 600 mg HC/g TOC, and low Oxygen Index (rarely exceeding 50 mg CO2/g TOC). This is consistent with a high-quality, oil-prone, "rich" Type II kerogen. Furthermore, an exceptional basal section in the Lower Tomachi, informally referred to as "Tomachi Rich Net," exhibits TOC peak values up to 14%. The assessment results that have followed a probabilistic analysis based on the Total Oil methodology of Jarvie (2012), have disclosed significant potential. This has successfully warranted a world-class consideration as an unconventional hydrocarbon source rock. Introduction The Madre de Dios Basin is in the northwest of Bolivia and is shared with neighboring countries Brazil and Peru (Figure 1). It covers an area of approximately 315,000 km, with roughly 35% situated within Bolivia (Beicip-Franlab, 2016). Morphologically, the region is densely covered with rainforest vegetation and traversed by various robust Amazonian-type rivers and swamps, which pose substantial challenges for any petroleum operations. Geologically, the basin was once part of an intracratonic marine basin during the Paleozoic era before experiencing regional uplift during the Mesozoic. It possesses a stratigraphic record ranging from Precambrian to Cenozoic rocks. Historically, the Upper Devonian, specifically the Tomachi Formation (Frasnian; Figure 2), has been cited as a potential source rock. Previously, Peters et al. (1997) and Bande et al. (2022) described Tomachi as a high-quality organic-rich rock with hydrocarbon-generating potential, deposited in a marine siliciclastic platform environment under suboxic to anoxic conditions. OBI (1991) also presented a valuable petroleum-source rock correlation between the oil produced from the Tomachi sandstone at 1266 m MD and three rock samples from well W-X1. The correlation is highly accurate with the sample at 1525 m MD, situated in the richest and closest section to the base of the Tomachi Rich. It was inferred that the produced oil was generated from this basal section.
- South America > Peru (1.00)
- South America > Argentina > Neuquรฉn Province > Neuquรฉn (0.29)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.62)
- South America > Peru > Madre De Dios Basin (0.99)
- South America > Argentina > Patagonia > Neuquรฉn > Neuquen Basin > Vaca Muerta Shale Formation (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.89)
- (3 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Geochemical characterization (1.00)
Comparative Studies by Rock Eval Pyrolysis and its Impact on the Evaluation of Producible Fluids: Pozo Anticlinal Aguada Bandera Formation, Argentina
Iturrerรญa, Santiago Genta (YPF Tecnologia) | Brea, Fabiรกn (YPF Tecnologia) | Otegui, Gastรณn (YPF Tecnologia) | Guanco, Raรบl (YPF Tecnologia) | Palafox, Gastรณn Iovine (YPF) | Brisson, Ignacio (YPF)
Abstract Rock-Eval pyrolysis is widely used as a screening technique, allowing for the characterization of source rocks in terms of potential, maturity, quality, and hydrocarbon content. In most cases, the method used with this equipment is the Basic/Bulk-Rock method. Originally developed to characterize source rocks in conventional reservoirs, its application in unconventional reservoirs (hybrids or shale plays) to evaluate the content of free hydrocarbons (HC) presents certain limitations and disadvantages. That is why IFP Energies Nouvelles developed a new method (Rock Eval Shale Play Method) for better estimation of free and/or absorbed hydrocarbons in unconventional reservoirs. In this work, we present a comparative study applied to lacustrine shale in the Golfo San Jorge Basin, Argentina, to assess how is the recovery of free and adsorbed hydrocarbons. The Rock Eval Shale Play method proved to be the most appropriate and the results obtained could be confirmed with high quality oil recovered in the well test. The characteristics of the recovered petroleum, combined with the results obtained in this study, lead to a favorable prospective outlook for the Pozo Anticlinal Aguada Bandera Formation as a potential Neocomian shale to continue evaluating. Introduction Rock-Eval pyrolysis is one of the analytical techniques used in petroleum geochemistry as a screening tool used to perform a quick evaluation of the source rock. This method is widely used by geochemists to obtain information regarding organic richness, source rock quality and thermal maturity. Basically Rock-Eval pyrolysis (developed and patented by IFP) is an open-system programmed pyrolysis method that subjects rock samples to a controlled heating and pyrolytic decomposition process, simulating the geological conditions that buried sediments experience over geologic time. The primary goal of this technique is to determine the organic richness, quality, and maturation state of sedimentary rocks, allowing geologists to assess their potential as source rocks for hydrocarbon (HC) generation. The method's fundamental principle lies in the pyrolysis of organic matter within rock samples, releasing various hydrocarbon compounds as well as CO2 and CO. By measuring the products of this thermal decomposition and cracking, geochemists can evaluate the potential of the source rock as an initial screening step.
- South America > Argentina > Patagonia (0.88)
- South America > Argentina > Neuquรฉn Province > Neuquรฉn (0.28)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geology > Structural Geology > Tectonics > Compressional Tectonics > Fold and Thrust Belt (0.61)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.47)
- South America > Argentina > Patagonia > Neuquรฉn > Neuquen Basin > Vaca Muerta Shale Formation (0.99)
- South America > Argentina > Patagonia > Golfo San Jorge Basin (0.99)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Geochemical characterization (1.00)
Characterizing the First Shale Oil Play Offshore South China by Advanced Logging Suite
Fan, Caiwei (CNOOC Zhanjiang Ltd.) | Gao, Yongde (CNOOC Zhanjiang Ltd.) | Liu, Bo (Baker Hughes) | Wu, Jinbo (CNOOC Zhanjiang Ltd.) | Cao, Yehong (Baker Hughes) | Li, Jun (Baker Hughes) | Alarcon, Nora P (Baker Hughes)
Abstract China ranks third in the world in terms of shale oil resources (Nie et al, 2016, Zhao et al, 2020, Zou et al, 2020); however, this is limited to onshore basins with widely discovered shale oil in the Permian, Triassic, Jurassic, Cretaceous and Paleogene settings (Wang et al, 2020). The shale oil resource potential in offshore basins is still an uncharted territory. The first offshore shale oil appraisal well was drilled in the Beibu Gulf Basin in the western South China Sea in June 2022. Compared with the onshore shale oil reservoir, the offshore shale oil play is younger, showing less diagenetic compaction, and has higher pressure coefficient. It is featured by strong heterogeneity, complex mineralogical composition, and unclear pore structure. Accurate and continuous evaluation on total organic carbon, mineralogical composition, lithofacies, total porosity and brittleness index are crucial for the shale oil test zone selection and stimulation design. To evaluate the oil-bearing potential, storage capacity, fluid movability and fracturing feasibility of shale oil formations, conventional formation evaluation alone, even with supporting core analysis and 3D borehole core pyrolysis are still insufficient. The advanced logging suites including spectroscopy, nuclear magnetic resonance (NMR), borehole imaging and crossed-dipole acoustic waveform analyses were integrated to enhance these evaluations. Elemental weight fractions from spectroscopy logs are utilized to calculate total organic carbon, mineralogical composition, and matrix density. NMR logs are acquired to provide porosity (total and effective) as WY-1 oil saturation (total and movable). Borehole imaging logs provide the in-situ stress direction which is used for the stimulation design. In this case study, 3D borehole core pyrolysis tests analyzed source rock maturity using 7 sidewall samples, and showed the source rock with high Ro, which means high maturity, indicating the high movability of the shale oil. The dry weight fraction of a total of 9 minerals were determined from the spectroscopy logs, namely quartz, potassium feldspar and plagioclase, pyrite, siderite and illite, kaolinite, dolomite and calcite. Among these minerals, quartz and illite are the two most abundant, with an average 38.2% and 30.3% respectively. The mineralogical composition was validated with X-ray diffraction (XRD), showing very good agreement. Then, brittleness index and TOC of the target formation is calculated based on the mineralogical composition. The result shows TOC is inversely correlated with brittleness index. Total oil saturation and movable oil saturation were obtained from NMR logs. Finally, shale oil test zone was selected primarily based on the brittleness index and the percentage of movable oil saturation rather than TOC and total porosity. The test result confirmed the effective selection with production of oil 20m/day and gas 1589m/day in total. Spectroscopy and NMR logging connect oil-bearing potential, reservoir petrophysical properties and fracturing feasibility throughout the entire shale oil evaluation. The shale oil test zone selection strategy for offshore basins is quite different from onshore basins, which can be a new reference and could be utilized for future appraisal wells.
- Asia > China (1.00)
- North America > United States > Texas (0.68)
- Phanerozoic > Paleozoic > Permian (0.54)
- Phanerozoic > Mesozoic > Triassic (0.54)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (1.00)
- Geology > Mineral (1.00)
- Geology > Geological Subdiscipline (1.00)
- South America > Colombia > Llanos Basin (0.99)
- South America > Argentina > Mendoza > Neuquen Basin (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- (5 more...)
Surveillance, Analysis, and Optimization (SA&O) During Active Drilling Campaign
Zhang, Yanfen (Chevron U.S.A. Inc., Covington, LA, U.S.A.) | Bovet, Paul (Chevron U.S.A. Inc., Covington, LA, U.S.A.) | Samano, Lorelea (Chevron U.S.A. Inc., Houston, TX, U.S.A.) | Isabu, Ozzy (Chevron U.S.A. Inc., Covington, LA, U.S.A.) | Chima, Andres (Chevron U.S.A. Inc., Covington, LA, U.S.A.) | Everson, Erik (Chevron U.S.A. Inc., Covington, LA, U.S.A.) | Sun, Kai (Chevron U.S.A. Inc., Houston, TX, U.S.A.)
Abstract Deepwater drilling is an expensive complex operation. Real-time surveillance data and analysis for drilling operations are very important for ensuring safety and cost control. Due to the high production rate and high expense of deepwater wells, there are usually not many wells planned for developing a deepwater field. Therefore, the results of each well hold particular significance as additional reservoir surveillance data and are crucial for optimizing field development and production forecasts. The subject field of this paper is WRB (pseudonym) which is a deepwater field located in the Gulf of Mexico. In the past few years, about one to two new wells per year came online at WRB field. Thus, there has been a constant stream of surveillance data from both drilling new wells and production/injection at existing wells. All the surveillance data were processed and utilized for updating the reservoir simulation model that ultimately serves as the engine for optimizing the future well locations. This paper is intended to review and share the key learnings and best practices of Surveillance, Analysis and Optimization (SA&O) during the active drilling campaign of WRB field. A comprehensive effort was undertaken to review the historic surveillance activities carried out during drilling and post-drill, and to review the consequent value-adding decisions from effective use of surveillance information.
- North America > United States > Texas (0.46)
- North America > Canada > Alberta (0.46)
- Asia > Middle East > Kuwait (0.28)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Geological Subdiscipline > Geochemistry (1.00)
- Asia > Middle East > Kuwait > Ahmadi Governorate > Arabian Basin > Widyan Basin > Greater Burgan Field > Wara Formation (0.99)
- Asia > Middle East > Kuwait > Ahmadi Governorate > Arabian Basin > Widyan Basin > Greater Burgan Field > Ratawi Formation (0.99)
- Asia > Middle East > Kuwait > Ahmadi Governorate > Arabian Basin > Widyan Basin > Greater Burgan Field > Mauddud Formation (0.99)
- (4 more...)