Unconventional Resources from Exploration to Production

Zee, Y.

doi:10.1016/b978-0-12-802238-2.00001-8

Cited by 9 publications

(2 citation statements)

References 30 publications

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“…The term “unconventional reservoirs” refers to low reservoir quality formations where artificial stimulations are required to achieve production in commercial quantities. , Following this definition, the recognized types of unconventional gas recourses are tight gas, coal-bed methane, gas hydrates, and shale gas reservoirs . At present, development of shale gas reservoirs is the fastest-growing not only in North America, but it is also growing on a large scale globally due to their potential reserve .…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO₂ Injection in Shale Gas Reservoirs

et al. 2023

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Development of shale gas reservoirs is the fastest growing area on a large scale globally due to their potential reserves. CO2 has a great affinity to be adsorbed on shale organic surface over CH4. Therefore, CO2 injection into shale reservoirs initiates a potential for enhanced gas recovery and CO2 geological sequestration. The efficiency of CO2 enhanced gas recovery (CO2-EGR) is mainly dominated by several shale properties and engineering design parameters. However, due to the heterogeneity of shale reservoirs and the complexity of modeling the CO2–CH4 displacement process, there are still uncertainties in determining the main factors that control CO2 sequestration and enhanced CH4 recovery in shale reservoirs. Therefore, in view of the previous sensitivity analysis studies, no quantitative framework, accurate CO2-EGR modeling, or design process has been identified. Thus, this work aimed to provide a practical screening tool to manage and predict the efficiency of enhanced gas recovery and CO2 sequestration in shale reservoirs. To meet our objectives, we performed correlation analysis to identify the strength of the relationship between the examined shale properties and engineering design parameters and the efficiency of CO2-EGR. Data for this study was gathered across publications on a wide subset of numerical modeling studies and experimental investigations. The sensitivity of data was further improved by a hybrid approach adopted for handling the missing values to avoid bias in our data set. Our results indicate that CO2 flooding might be the best applicable option for CO2 injection in shale reservoirs, whereas the huff-and-puff scenario does not seem to be a viable option. The efficiency of CO2-EGR increases as the pressure difference between injection pressure and reservoir pressure increases. The results show that shallow shale reservoirs with high fracture permeability, total organic content, and CO2–CH4 preferential adsorption capacity are favorable targets for CO2-EGR. Moreover, our results indicate that a successful hydraulic-fracture network with effective values of fracture permeability and conductivity is essential for a higher CO2-EGR efficiency. Well spacing and fracture half-length are crucial engineering features in CO2-EGR process design that must be carefully optimized due to their negative effect on CH4 production and positive effect on CO2 storage. Our statistical analysis lays a foundation for efficient CO2-EGR design and implementation and presents an important contribution to the field of reaching the target of net-zero CO2 emissions for energy transitions.

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Section: Introductionmentioning

confidence: 99%

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO₂ Injection in Shale Gas Reservoirs

et al. 2023

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“…The Ordos Basin is rich in oil and gas resources and is the second-largest sedimentary basin in China in terms of area. − In the basin, the upper Paleozoic tight sandstones (designated via He permeabilities <1 mD or in situ permeabilities <0.1 mD, which require artificial stimulation to produce economic gas flow) in the Ordos Basin have provided the majority of gas production over the past 20 years. ,− Except for the tight sandstone gas reservoirs in the upper Paleozoic strata, few gas reservoirs of commercial value have been found in the remaining formations of the Ordos Basin . The recent discovery of commercially valuable natural gas reservoirs in the Middle–Lower Triassic strata in the northeastern margin of the Ordos Basin opens new possibilities for gas exploration in the Ordos Basin.…”

Section: Introductionmentioning

confidence: 99%

Characterizations of Middle–Lower Triassic Reservoir Quality and Gas Accumulations in the Northeastern Margin of the Ordos Basin, China

Wang

Liu

et al. 2023

Energy Fuels

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New Middle−Lower Triassic gas reservoirs were found in the eastern margin of the Ordos Basin, which provides new possibilities for gas exploration in the Ordos Basin. However, there are few relevant studies on these gas reservoirs. In this study, we use porosity−permeability measurements, optical light microscopy, scanning electron microscopy, mercury intrusion capillary pressure experiments, core-scale low-field nuclear magnetic resonance experiments, fluid inclusion analysis, burial history reconstruction, organic geochemistry data, and wireline log data to systematically investigate the reservoir quality and accumulation pattern of Middle−Lower Triassic gas reservoirs. The Middle−Lower Triassic sandstones are mostly lithic arkose, with a small amount of feldspathic litharenite. In comparison to the upper Paleozoic tight sandstone, the Middle−Lower Triassic sandstones exhibit a superior pore structure and increased porosity and permeability. A significant portion of the Middle−Lower Triassic sandstones can be referred to as "conventional sandstones" (porosities >12% and permeabilities >1 mD). The source rocks of the Middle−Lower Triassic gas reservoirs are most likely the upper Paleozoic coal and organic-rich mudstone, and the accumulation of natural gas occurred in the Early Jurassic to Late Cretaceous. The gas accumulation in the sandstones of the Middle−Lower Triassic reservoirs was mainly driven by buoyancy. The initiation and extension of vertical faults with small displacement in the northeast margin of the Ordos Basin enabled gas to move through the faults from the deep upper Paleozoic source rocks to the Middle−Lower Triassic reservoirs. Since gas accumulation relies on buoyancy, conventional sandstone layers with good reservoir properties are more likely to reach high gas saturation and are the primary targets for exploration and development.

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Level of thermal maturity estimation in unconventional reservoirs using interval inversion and simulating annealing method

Valadez Vergara,

Szabó

2024

Acta Geophys.

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This study presents a novel geophysical approach for estimating the level of thermal maturity (LOM) in unconventional hydrocarbon reservoirs using well log data. LOM is a crucial parameter for assessing the hydrocarbon generation potential of source rocks, but it traditionally relies on laboratory measurements of core samples, which can be time-consuming and costly. The proposed method combines two techniques: interval inversion for estimating total organic carbon (TOC) content from well logs and simulated annealing (SA) optimization for deriving LOM from the estimated TOC. The interval inversion method enables accurate TOC estimation by jointly interpreting multiple well logs over depth intervals, overcoming limitations of conventional point-by-point inversion. Using the estimated TOC, the SA algorithm optimizes an energy function related to Passey's empirical TOC-LOM relationship, iteratively finding the optimal LOM value that best fits the well log data. This approach provides a continuous in situ LOM profile along the borehole without requiring core measurements. The effectiveness of the method is demonstrated through case studies on datasets from the North Sea (Norway), the Pannonian Basin (Hungary), and the Kingak Formation (Alaska). The LOM estimates show good agreement with reported maturity levels and allow reliable reservoir characterization. Statistical analysis confirms the robustness and accuracy of the results. By reducing dependence on core data, this integrated inversion-optimization workflow streamlines the reservoir prospecting phase, enhancing operational efficiency. The method holds promising applications across diverse geological settings for cost-effective evaluation of unconventional hydrocarbon plays.

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Unconventional Resources from Exploration to Production

Cited by 9 publications

References 30 publications

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO₂ Injection in Shale Gas Reservoirs

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO₂ Injection in Shale Gas Reservoirs

Characterizations of Middle–Lower Triassic Reservoir Quality and Gas Accumulations in the Northeastern Margin of the Ordos Basin, China

Level of thermal maturity estimation in unconventional reservoirs using interval inversion and simulating annealing method

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Unconventional Resources from Exploration to Production

Cited by 9 publications

References 30 publications

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO2 Injection in Shale Gas Reservoirs

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO2 Injection in Shale Gas Reservoirs

Characterizations of Middle–Lower Triassic Reservoir Quality and Gas Accumulations in the Northeastern Margin of the Ordos Basin, China

Level of thermal maturity estimation in unconventional reservoirs using interval inversion and simulating annealing method

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Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO₂ Injection in Shale Gas Reservoirs

Statistical Analysis of Controlling Factors on Enhanced Gas Recovery by CO₂ Injection in Shale Gas Reservoirs