Article
Geology
Babatunde Olanipekun, Karem Azmy
Summary: The study indicates that the sandstone reservoir of the Tithonian Jeanne d'Arc Formation in the Terra Nova oilfield underwent early dolomite cementation and subsequent diagenetic events, playing a significant role in controlling reservoir quality. The diagenetic processes were influenced by depositional settings, with cycles of early dolomite cementation and subsequent events controlling the sandstone porosity structure and quality.
Article
Geosciences, Multidisciplinary
Leo G. Giannetta, Nathan D. Webb, Shane K. Butler, Nathan P. Grigsby
Summary: Clay microporosity in sandstones can lead to inaccuracies in water saturation calculations and reduce effective pore space in evaluating formations. A petrographic study was conducted on the fluvial facies of the Mississippian Cypress Sandstone to characterize and quantify clay mineral microporosity, leading to more accurate saturation calculations. The research highlights the importance of studying microscale mineralogical properties in reservoir characterization.
Article
Environmental Sciences
Zhiqi Guo, Xiaoying Qin, Cai Liu
Summary: This study proposes a rock-physics-based approach to compute the pore-microfracture indicator (PMI) from elastic properties for pore structure evaluation in tight sandstones. Seismic characterization of pores and microfractures provides valuable information in predicting high-quality tight gas sandstone reservoirs. The computed PMI using seismic data can predict permeable zones and provide valuable information for sweet spot characterization in tight gas sandstone reservoirs.
Article
Engineering, Environmental
Caoyuan Niu, Zheming Zhu, Lei Zhou, Xiaohan Li, Peng Ying, Yuqing Dong, Shuai Deng
Summary: This study reveals that cyclic freeze-thaw has a significant impact on the dynamic fracture behavior of rocks, leading to increased porosity and crack velocity, as well as decreased crack initiation time and dynamic fracture toughness. Sandstone is susceptible to freeze-thaw weathering, with the roughness of the fracture surface indicating intergranular fracture playing a dominant role in sandstone failure.
COLD REGIONS SCIENCE AND TECHNOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Emily M. Hoyt, John N. Hooker
Summary: Fractures in limestone layers in the Appalachian Basin in Central Pennsylvania exhibit layer-parallel characteristics, unlike shales, and are accompanied by layer-perpendicular fractures forming a boxwork-like pattern. The driving mechanism of fractures is likely related to the diagenetic transition of biogenic silica to quartz, as evidenced by the presence of silica grains in various forms and calcite cement in the fractures. Additionally, silica migration away from the fracturing layers may have caused volume loss and prevented vertical contraction of the host rock, while silica precipitation may have decreased permeability and induced fracturing via fluid overpressure.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Engineering, Geological
Lei Zhou, Weiting Gao, Liyuan Yu, Zheming Zhu, Jianxing Chen, Xingkai Wang
Summary: This study investigated the evolution laws of physical and fracture properties of different rock materials under high-temperature geological conditions. The results showed that the fracture characteristics of the rock materials changed from brittle fracture to plasticity fracture with increasing temperature, and the fracture toughness decreased. The study also observed changes in fracture morphologies with increasing temperature.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2022)
Article
Engineering, Geological
Penghai Zhang, Honglei Liu, Kai Guan, Tao Xu, Qinglei Yu, Tianhong Yang
Summary: This study introduces a novel shear model and AE measurement method to estimate the size distribution characteristics of microfractures in sandstone specimens, with results indicating that the microfracture sizes obtained through this method are closer to reality.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Geosciences, Multidisciplinary
Prabal Shankar Das, Rima Chatterjee, Sumangal Dasgupta
Summary: This study used a rock physics template (RPT) approach to model the impacts of mechanical compaction and chemical diagenesis on porosity reduction in the Barail Sandstone. This study also analyzed the effects of diagenesis, rock frame constituents, and pore fluids on seismic amplitude response using a probabilistic amplitude variation with angle (AVA) approach.
NATURAL RESOURCES RESEARCH
(2022)
Article
Geology
Shoukat Husain Khan, Ying-Ming Sheng, Muhammad Saleem Mughal, Birendra Pratap Singh, Muhammad Rustam Khan, Chengjun Zhang
Summary: This study describes the sedimentological aspects of the Lower Cambrian Khewra Sandstone and its lithostratigraphic correlation with globally distributed coeval red sandstones, providing insights into the Pan-African Orogeny. The study suggests that the Khewra Sandstone was deposited in a fluvio-deltaic environment as tempestites, and its provenance can be traced back to the craton interior and recycled orogen. The diagenesis of the sandstone varies in different parts, with the upper part being a potential hydrocarbon reservoir rock.
SEDIMENTARY GEOLOGY
(2022)
Article
Geology
Shoukat Husain Khan, Ying-Ming Sheng, Muhammad Saleem Mughal, Birendra Pratap Singh, Muhammad Rustam Khan, Chengjun Zhang
Summary: This study focuses on the sedimentological aspects of the Lower Cambrian Khewra Sandstone and its lithostratigraphic correlation to understand the imprints of Pan-African Orogeny. The Khewra Sandstone is interpreted to be tempestites deposited under a fluvio-deltaic depositional environment, mainly derived from the craton interior and recycled orogen provenance. Diagenetic action significantly affects the lower and middle parts of the sandstone, while the upper part acts as a potential hydrocarbon reservoir rock.
SEDIMENTARY GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Richard H. Worden, James E. P. Utley
Summary: Porosity and permeability are crucial factors in determining the reservoir quality of sandstone. This quality is influenced by primary sedimentary characteristics and subsequent diagenetic modifications. SEM-EDS is a useful tool for studying various aspects of sandstone diagenesis, including mineralogy, particle characteristics, and cement distribution.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Energy & Fuels
Fuyong Wang, Fanchao Zeng, Lu Wang, Xianmu Hou, Hui Cheng, Jian Gao
Summary: This study analyzed the fractal characteristics of pore spaces in tight sandstones from the Ordos Basin in China, using NMR and RCP techniques. It showed that the fractal dimensions of pore spaces with movable fluids were negatively correlated with permeability and reservoir quality index, with fractal dimensions approaching 3 indicating less favorable petrophysical properties. Different fractal models were compared for calculating fractal dimensions, with the 3D capillary model found to be the most accurate for evaluating tight sandstone properties.
Article
Geosciences, Multidisciplinary
Wenchao Dou, Mian Lin, Luofu Liu, Langbo Jia
Summary: This study investigated the relationship between chlorite rims and porosity evolution in the Chang 7 sandstones of the Upper Triassic Yanchang Formation in the Ordos Basin in northcentral China. The results showed that chlorite rims inhibited the formation of quartz cementation, but other factors such as compaction and other cements also controlled the porosity evolution of sandstones. Chlorite rims only played an important role in porosity preservation when quartz cementation was the main process of porosity destruction.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Hui Rong, Yangquan Jiao, Liqun Wu, Xinfu Zhao, Minqiang Cao, Weihong Liu
Summary: An exceptional example in the Qianjiadian area, Songliao Basin, illustrates the effects of igneous intrusions on diagenesis and reservoir quality of sandstone. The intrusion of diabase dikes has been found to impact sandstone diagenesis through two stages, resulting in changes in reservoir quality. Hydrothermal fluids generated by the diabase dikes have influenced the development of secondary pores in the sandstone.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Geosciences, Multidisciplinary
Andreas Pauli de Castro, Carlos Conforti Ferreira Guedes, Fernando Farias Vesely, Deise Marli da Silveira, Lara Ferreira Neves
Summary: This study investigates the sedimentary provenance and its control on reservoir quality in the Maracangalha Formation. Petrography analysis and X-Ray Fluorescence data reveal a granite-gneissic terrain as the primary source area for quartz-feldspathic sandstones. The sources contribute recycled sedimentary and metasedimentary rocks, leading to the occurrence of specific litho and quartzose petrofacies. The mineral composition and primary texture of sandstones significantly influence diagenetic processes and the formation of secondary porosity. Understanding sedimentary provenance, composition, and diagenesis is crucial for predicting reservoir quality.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Emily M. Hoyt, John N. Hooker
Summary: Fractures in limestone layers in the Appalachian Basin in Central Pennsylvania exhibit layer-parallel characteristics, unlike shales, and are accompanied by layer-perpendicular fractures forming a boxwork-like pattern. The driving mechanism of fractures is likely related to the diagenetic transition of biogenic silica to quartz, as evidenced by the presence of silica grains in various forms and calcite cement in the fractures. Additionally, silica migration away from the fracturing layers may have caused volume loss and prevented vertical contraction of the host rock, while silica precipitation may have decreased permeability and induced fracturing via fluid overpressure.
MARINE AND PETROLEUM GEOLOGY
(2021)
Article
Geochemistry & Geophysics
Junpeng Wang, Lianbo Zeng, Xianzhang Yang, Chun Liu, Ke Wang, Ronghu Zhang, Xiguang Chen, Yuanji Qu, Stephen E. Laubach, Qiqi Wang
Summary: The ultra-deep low-porosity sandstone oil and gas reservoirs in the Kuqa thrust belt of Tarim Basin are important sources of natural gas supply in China. Fracture types and patterns, including shear-mode and opening-mode fractures, were described using outcrops from four exposed folds in the study area. Fracture distribution, density, aperture size, and kinematics varied between different locations on the folds, with shear-mode fractures dominating the flanks and opening-mode fractures localized in fold hinges.
Article
Geosciences, Multidisciplinary
J. N. Hooker, J. Cartwright, B. Stephenson, C. C. Day
Summary: A study on calcite veins in the Marcellus Formation reveals that the veins were formed through a combination of continuous fibrous growth and punctuated fracture-opening increments. The continuous growth is due to pressure-solution creep, while the incremental opening is caused by overpressured, mineral-saturated fluid. The study provides insights into the formation mechanism and deformation conditions of calcite veins.
GEOLOGICAL MAGAZINE
(2022)
Article
Geosciences, Multidisciplinary
Bethany Rysak, Julia F. W. Gale, Stephen E. Laubach, David A. Ferrill
Summary: We investigated the evolution of hydraulic fracture networks through observations of hydraulic fractures in core, attributes of natural hydraulic fractures, and analogue models. Our results show that complex fracture networks are formed in self-sourced reservoir strata during hydraulic fracturing. Mechanical stratigraphic boundaries and other heterogeneities play a key role in enhancing fracture network complexity, resulting in an increased number of hydraulic fractures and total fracture surface area. This study provides valuable insights for the evaluation, completion, production, and fracture modeling of unconventional reservoirs.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Geosciences, Multidisciplinary
Rodrigo S. M. Correa, Randall Marrett, Stephen E. Laubach
Summary: This study presents a methodology that quantifies the arrangement of fractures in space by considering position, size, and orientation. Point process statistics are used to analyze distances between fractures and estimate the randomness in comparison with input data. The method can differentiate at least four types of spatial arrangements and identify preferential associations between distance, fracture length, and orientation.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Stephanie R. Forstner, Stephen E. Laubach
Summary: Using examples of regional opening-mode fractures in sandstones from the Cambrian Flathead Formation in Wyoming, this study demonstrates that quartz deposits preferentially fill fractures up to ca. 0.05 mm wide. Fractures transition from being mostly sealed to mostly open over a narrow size range of opening displacements from 0.05 to 0.1 mm. The study also reveals that trace connectivity at microscopic and outcrop scale is similar, but most porosity is found in outcrop-scale fractures. Near faults, trace connectivity increases as wide porous fractures preferentially shear, but pore space is lost due to the development of microbreccia, resulting in a lower potential for fluid flow.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Rodrigo S. M. Correa, Estibalitz Ukar, Stephen E. Laubach, Irene Aubert, Juliette Lamarche, Qiqi Wang, Daniel F. Stockli, Lisa D. Stockli, Toti E. Larson
Summary: The Castellas fault in Provence, southern France, underwent two deformation phases during the Upper Cretaceous and the Eocene. Studies on the fault zone provide insights into its formation, evolution, and the properties that influenced fluid flow behavior.
MARINE AND PETROLEUM GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
John N. Hooker, Randall Marrett, Qiqi Wang
Summary: The coefficient of variation (CV) can distinguish regular spacing or clustering from random sequences in 1D spatial or time-series data. This study uses Monte Carlo simulations to derive robust confidence intervals for distinguishing 1D patterns from random signals using CV. The simulations show that CV is negatively skewed for small fracture populations. Additionally, a new alternative statistic, CV', is proposed which is unbiased and retains the capability of CV to distinguish nonrandomness in 1D sequences.
JOURNAL OF STRUCTURAL GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Qiqi Wang, Wayne Narr, Stephen E. Laubach
Summary: Using various geological observations and statistical methods, this study investigates the spatial arrangement and intensity of fractures in the East Painter Reservoir anticline in Wyoming. The results show that the degree of clustering and intensity of fractures vary with structural position, with the backlimb exhibiting more clustered fractures but lower intensity compared to the forelimb. Petrographic analysis reveals that quartz plays a role in sealing narrow fractures, while wider fractures can be sealed by quartz, calcite, or quartzose cataclasite. The findings suggest that shear on preexisting fractures in the forelimb may lead to numerous but less spatially correlated open fractures.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Mahmood Shakiba, Larry W. Lake, Julia F. W. Gale, Stephen E. Laubach, Michael J. Pyrcz
Summary: This study proposes using Ripley's K-function as a method of point pattern analysis to quantify the spatial arrangement of fracture nodes. The method can be applied to fracture networks with different orientations and supports edge correction in circular and rectangular study domains. The feasibility of the method is demonstrated through applications on two natural fracture datasets.
MARINE AND PETROLEUM GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Stephen E. Laubach, Lianbo Zeng, John N. Hooker, Qiqi Wang, Ronghu Zhang, Junpeng Wang, Bo Ren
Summary: This volume discusses the progress made in studying brittle structures in deep and ultra-deep sedimentary basins. The research focuses on the effects of faults and fractures on fluid charge and resource recovery in sandstone, carbonate rocks, shale, and other types of rock. The study includes drilling wells that are expected to exceed 10 km in depth in deep, deformed, and tectonically active basins in China. The results indicate that open fractures, fractures with sealing calcite, and enhanced host-rock porosity are present in these deep settings, and their abundances are related to the diagenetic history rather than their origins. Additionally, the study compares the diagenesis differences between deep and shallower depths, which may influence fracture size, spatial arrangement, and connectivity.
JOURNAL OF STRUCTURAL GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
J. N. Hooker, R. F. Katz, S. E. Laubach, J. Cartwright, P. Eichhubl, E. Ukar, D. Bloomfield, T. Engelder
Summary: Arrays of natural opening-mode fractures exhibit systematic patterns in size and spatial arrangement. The depth of formation appears to play a critical role in controlling these patterns. While physical factors such as stress and strain are considered, temperature-dependent chemical processes have not been fully incorporated into fracture formation models.
JOURNAL OF STRUCTURAL GEOLOGY
(2023)
Article
Geosciences, Multidisciplinary
Julia F. W. Gale, Andras Fall, Inessa A. Yurchenko, Walaa A. Ali, Stephen E. Laubach, Peter Eichhubl, Robert J. Bodnar
Summary: In this study, the timing of three generations of fractures in Barnett Shale was determined using crosscutting relations, fluid inclusion assemblage temperatures, and a burial history model. The results provide important insights into the formation and evolution of fractures.