bluuebunny/crossref_metadata_2025_split huggingface dataset:
Granite Rock Mass Identification and Geothermal Well Location Deployment Based on the Wide Field Electromagnetic Method: A Case Study of Sanshui Basin
Authors: Zhang Q. X. , Zhang Y. , Feng J. Y. , Luo J. 
Published: August 2024

ABSTRACT:
Due to the special geological environment, two sets of geothermal reservoirs of Buxin Formation with lithology of sandstone and deep volcanic rocks have been formed in Sanshui Basin. Although a lot of research progress has been made in the geological conditions such as heat source, channel, reservoir and cover layer in this area, the depth and range of deep dry hot rock mass are not clear. Therefore, effective exploration methods are needed to provide technical support for geothermal well deployment and resource assessment. In this paper, based on the principle of wide field electromagnetic method (WFEM), four survey lines are laid to explore the geothermal resources in the study area. Secondly, the underground resistivity data are obtained by the location information of the field source and measurement points on the surface and the observed electric field signals. Finally, the electrical cross-section is interpreted with geological data. The results show that the longitudinal section can be roughly divided into four electrical layers of "low-high-low-high", which are Paleogene, Cretaceous, Permian-Carboniferous, and granite basement. According to the distribution of granite, the range of deep granite body with high resistance has been delineated, which provides a prerequisite for the geothermal well deployment.

1. INTRODUCTION
The special geological environment of Sanshui Basin leads to the formation and enrichment of CO2 gas, which indicates that there may be deep geothermal resource potential in this area. At present, oil and gas drilling is mainly concentrated in the depth range of 700∼1300 m (Chen, et al., 2008). The drilling temperature is not high, but the geothermal gradient is about 3.1 °C/100m. Based on the geothermal gradient, it is inferred that there may be carbonate or igneous bedrock reservoirs in the bedrock uplift structure of the deep concave area to form the accumulation of medium-high temperature geothermal resources.
From the perspective of sedimentary evolution, there are two sets of geothermal reservoirs in the Sanshui Basin. The first set of reservoirs are limestone and dolomite deposited in Carboniferous-Permian-Triassic period, and the second set of reservoirs are sandstone deposited in Buxin Formation and rhyolite and trachyte formed by volcanic eruption. (Chen, 2018). At the same time, the mudstone of Buxin Formation provides good capping conditions for the sandstone reservoir, volcanic rock reservoir and limestone reservoir Triassic-Carboniferous. The development of faults in this area provides a good migration channel for deep geothermal fluid and heat flow, so the sedimentary evolution and fault development characteristics determine the vertical development of two sets of deep geothermal reservoir-cap assemblage systems.
Geological Analysis of Typical Geothermal Systems in East of China
Authors: Feng Jianyun , Zhang Ying , Luo Jun , Zeng Yan , Yun Xiaorui , Liao Dawei , He Zhiliang , Zhang Ying , Luo Jun , Zeng Yan , Yun Xiaorui , Liao Dawei 
Published: August 2024

ABSTRACT:
Eastern China, which lies to the east of the Hu Huanyong Line that connects the Heihe and Tengchong areas, has a high population density, a developed economy, and a huge demand for energy. To determine the geothermal resources in eastern China, this study analyzed the typical geothermal systems in this region based on disciplines of structural geology, and petrology. As a result, this study determined the distribution patterns of medium and deep geothermal resources in this region. Eastern China is a superimposed region of three major global tectonic domains, namely Paleo-Asia, Circum-Pacific, and Tethyan. Its crust-mantle structure presents a special flyover pattern, while its shallow surface has alternating basins and mountains and well-spaced uplifts and depressions. Studies have shown that medium-high-temperature geothermal resources in China are mainly distributed in the Mesozoic-Cenozoic basins in eastern China. However, they are dominated by medium-temperature geothermal resources with low abundance. The geothermal reservoir types mainly include porous sandstone reservoirs, karstified fractured-vuggy carbonate reservoirs, and fissured granite reservoirs.

1. INTRODUCTION
Eastern China, which lies to the east of the Hu Huanyong Line that connects the Heihe and Tengchong areas, consists of Northeast China, North China, the middle and lower reaches of the Yangtze River, Southwest China, and South China from north to south, has a high population density, hosting 96% of the total population of China, as well as a developed economy and a huge demand for energy (Fig. 1).
As an earth-derived energy source, geothermal resources are clean, renewable, and highly competitive and can be used for indoor heating, industrial and agricultural utilization, and power generation. The successive launch of national projects in China, such as the Deep Resource Exploration and Exploitation Program, began the exploration of the deep earth in China, and important achievements have been increasingly achieved in basic geology and geothermal geology. Moreover, research on deep-crust temperature and crust-mantle dynamic mechanisms has been gradually intensified (Shi 1990; Xu et al., 1995; He et al., 2001; An et al., 2007; Wang et al., 2012; Qiu et al., 2015). Remarkable progress has been made in research on terrestrial heat flow (Jiang et al., 2016, 2019), geothermal system types (Chen et al., 1996; Zhang et al., 2017), the division of geotectonic units and geothermal units (Pan et al., 2009; He et al., 2017), the selection and evaluation of optimal exploration areas (He et al., 2020; Zhang et al., 2020; Ke et al., 2022), hot dry rock development experiments (Wang et al., 2022), and geothermal applications (Wang et al., 2014), laying a solid foundation for the study of deep geothermal resources.
Modeling Erosion in Hollow Cylinder Tests: The Case of Low Pressure Under Variable Confining Stress
Authors: Kakonitis Panos , Papaloizou Loizos , Gravanis Elias , Sarris Ernestos 
Published: August 2024

ABSTRACT:
Modelling the erosional behavior of rock cores in hollow cylinder tests is a formidable task because it involves coupled hydro-mechanical processes. In a recent work of the authors, we proposed semi-analytical hydro-mechanical framework for modelling erosion at laboratory scale through the hollow cylinder test. The model was based on the kinematic formulation of classic hydro-mechanical models also known as volumetric sand production models. The original formulation was constructed to include variable confining stress and flow rate conditions. In this new formulation, a power law dependency of the erosion coefficient λ with stress is incorporated to investigate its dependency on the variable external radial stress boundary condition reflected on the sand production curve. This is a significant update with respect to the previous formulation that assumed a constant sand production coefficient. Results show an improved performance with respect to experimental results. This model can be used to systematically calibrate sand production coefficients for different types of rocks.

1. INTRODUCTION
Sand production is a phenomenon where solid (predominantly sand) particles are produced together with hydrocarbons during production operations. This sand influx to the wellbore is responsible for causing various operational and mechanical issues within the wellbore and surface facilities. To avoid such issues, an appropriate design of bottom hole completion technique remains a formidable task especially when the reservoir rock is an unconsolidated sandstone. Completion engineers are requested to choose between open hole or cased, cemented and perforated completions but when opting for communication between the well and the formation may cause further formation stability issues albeit manageable if gravel packed. The main reason for this dilemma is the mechanically weak behavior of sandstones especially if they are unconsolidated. Actually, significant percentage of the world' s hydrocarbon reservoirs are hosted in unconsolidated sandstone rocks which might present high risk of sand production. Once sand production onsets, cleaning operations cause time delays and costly investments due to time consuming and expensive workovers. To avoid these delays, operators are forced to restrict production rates, hence reducing the drawdown to cut-down formation stresses which are now believed to be one of the root-causes of sand production after reaching rock failure. Kakonitis et al. (2023a), Fattahpour et al. (2012), Deng et al. (2019), Nouri et al. (2007).
Insights into Fracture Dynamics Through Advanced Coupled Flow and Geomechanics Modeling
Authors: Pei Yanli , Sepehrnoori Kamy 
Published: August 2024

ABSTRACT:
This work develops an advanced coupled flow and geomechanics model, integrating the Embedded Discrete Fracture Model (EDFM) and the Extended Finite Element Method (XFEM), to enhance unconventional reservoir exploration. The model, now refined for multiple fracture scenarios, uniquely simulates multiphase compositional flow and matrix-fracture deformations, overcoming the limitations of simplified empirical models in capturing dynamic fracture behaviors during the reservoir injection-production process. Benchmarked against established standards like Sneddon and Elliot's problem, the model through an iterative coupling accurately predicts fracture property changes under various reservoir and operational conditions. Key findings underscore the influence of matrix permeability and rock stiffness on fracture apertures and reservoir pressure as well as stress fields throughout development cycles. The study demonstrates that reduced fracture angles relative to the flow path lead to elevated reservoir pressures and more uniform fracture property changes, while higher pressure differentials intensify stress around fractures, correlating positively with fracture aperture variations. This model contributes to a better understanding of well productivity optimization and effective reservoir management, particularly in addressing the challenges posed by the dynamic properties of multiple fractures during the reservoir injection-production process.

1. INTRODUCTION
The application of hydraulic fracturing has transformed tight formations into viable resources for the oil and gas industry, presenting both opportunities and challenges in reservoir management and production optimization (Gaurav et al., 2012; Wang et al., 2020; Mehrabi et al., 2021; Pei and Xiong, 2023; Wang and Olson, 2023). Despite the initial high production rates, the rapid decline in output due to fracture closure and conductivity loss remains a critical concern (Yu and Sepehrnoori, 2014; Fan et al., 2017; Xu et al., 2019). Additionally, the slip and opening of fractures induced by fluid injection are common in reservoirs rich in fractures and faults (Zoback and Gorelick, 2012; Kumar and Ghassemi, 2018; Ren et al., 2018; Kamali and Ghassemi, 2020). Such changes, driven by variations in pore pressure and the consequent response in local in-situ stresses (Marongiu-Porcu et al., 2016; Safari et al., 2017; Pei and Sepehrnoori, 2022; Pei et al., 2022), necessitate a precise understanding of fracture dynamics to sustain reservoir productivity.
Insights from Thermohydromechanical Simulations for Real-Time Monitoring of UHS in Saline Aquifers
Authors: Okoroafor E. R. 
Published: August 2024

ABSTRACT:
Real-time continuous monitoring provides high-resolution spatial and temporal data for tracking fluid migration. In this study, we numerically investigate the temperature, pressure, strain and displacement responses in potential monitoring wells locations during cyclic hydrogen injection into saline aquifers. A coupled thermohydromechanical flow model was used to mimic the injection and withdrawal of hydrogen. Potential locations for injection and monitoring wells are mapped. The primary focus of the analysis was to determine the temperature, pressure, strain and displacement responses and what they could inform about hydrogen distribution.
The study shows that pressure, temperature, displacement and seismicity are key parameters to track the cyclic behavior of hydrogen in the subsurface. The recommended locations for such measurements include for Pressure, Temperature, and Displacement, monitoring tools are best placed at the above-storage reservoir. For Strain, and induced seismicity – in or near the storage reservoir. These insights have practical implications for the design of monitoring wells equipped with monitoring sensors and for enhancing data interpretation practices.

1. INTRODUCTION
Underground hydrogen storage in porous media has the potential to complement renewable energy resources by storing excess energy from these resources during low demand and releasing the energy during peak demand. Hydrogen can be produced via electrolysis. Excess energy can be stored as hydrogen in geological media like salt caverns or porous media. However, there are few experiences with hydrogen storage in porous media (summarized in Zivar et al., 2021), and the few cases are not hydrogen stored with 100% purity.
There have been instances of the application of numerical modeling to understand the behavior of hydrogen in porous media (summarized in Okoroafor et al., 2023), but few of these works discuss or capture the geomechanical implications of hydrogen storage in porous media. The storage integrity of underground hydrogen storage in porous media remains a critical concern, especially regarding potential losses during the cyclical processes of hydrogen injection and withdrawal. Current understanding lacks insights into the geomechanical implications of hydrogen storage in porous media, making it imperative to address this gap. Thus, the primary objective of this study is to investigate and enhance storage integrity during hydrogen storage within porous media. Specifically, the study aims to anticipate and mitigate potential integrity issues by analyzing various parameters, including pressure, temperature, displacement, strain, stress, and fluid composition, throughout different hydrogen storage and withdrawal phases.
Damage Mechanism and Parameter Optimization of Rock Mass Blasting Under High In-Situ Stress
Authors: Zhang Xin , Xia Xiang , Li Haibo , Fu Shuaiyang 
Published: August 2024

ABSTRACT:
The response of blasting effects during deep rock excavation processes is significantly influenced by high in-situ stress conditions. It plays a pivotal role in guiding both the preliminary design and subsequent implementation of support systems. This paper utilizes numerical simulation methods to simulate blasting under high in-situ stress, wherein the detonation process of high-energy explosives was simplified as instantaneous loading applied to the borehole walls. Through a combination of numerical simulations and on-site experiments, the study explores the evolution of blasting-induced damage. Adjustments and optimizations are applied to the blasting sequence, blasthole layout and explosive charge weight. The findings indicate that the scope of rock damage is reduced with the increasing of in-situ stress, there exists a transition of rock failure mode from tensile-shear to compressive-shear, and the detrimental effect of blast on tunnel safety matters less and less. In addition, excessively large spacing hinders effective penetration, while too small spacing will reduce the blasting efficiency. Under the circumstance with a constant borehole layout, the explosive charge governs the evolution of the blasting damage zone and the pre-blast area exhibits cyclic cumulative damage.

1. INTRODUCTION
Blasting in rock masses holds significant importance for engineering construction. In the past time, researchers have concentrated on the entire process of rock damage (initiation, propagation, and temporal evolution), as well as the mechanism of crack propagation with respect to the distance from the blast hole experimentally and simulation-based. The effectiveness of rock breaking primarily manifests through the action of detonation gases generated by explosive initiation and the propagation of stress waves that cause damage to the rock mass. Under the influence of blasting gases, rock damage near the blasthole is predominantly in the form of tensile failure (Pramanik & Deb, 2015), while at a distance, shear failure prevails (C. Ding et al., 2023). The extent of crack propagation depends on the surrounding rock conditions near the blasthole (Kutter & Fairhurst, 1971; Hagan, 1980; Trivino & Mohanty, 2015).
Deformation and Failure Mechanism of Ultra-Deep Dolomite and FDEM Numerical Simulation
Authors: Li Hongda , Lu Yunhu , Li Ji , Zeng Ping 
Published: August 2024

ABSTRACT:
The mechanism of rock deformation and failure in ultra-deep reservoirs is unclear, so this article takes ultra-deep dolomite as the research object and conducts rock mechanics experiments. Based on the damage variable theory model of Weibull distribution, the combined finite-discrete element method (FDEM) is used to numerically simulate the deformation and failure of dolomite. The results show that: (1) The compressive strength of ultra-deep dolomite is relatively high, and the failure is mainly brittle shear failure. Under high temperature and low confining pressure, the failure of dolomite exhibits a high angle shear fracture, accompanied by the development of secondary fractures. Under high temperature and high confining pressure, the failure mode of dolomite is often accompanied by other shear fractures in addition to one main shear fracture. (2) In the initial deformation stage, the linear characteristics of ultra-deep dolomite are more obvious. As the compression deformation deepens, the internal damage of the rock intensifies, gradually transitioning from elastic deformation to plastic deformation. The maximum damage rate occurs near the peak failure point and the fractures are formed at the macro level. In the post peak stage, the internal damage rate of the rock rapidly slows down and gradually reaches the residual strength.

1. INTRODUCTION
The first ten thousand meters geological exploration well in China, "Deep Taco 1 Well," was drilled on May 30, 2023 in the Tarim Oilfield in the hinterland of the "Sea of Death" Taklamakan Desert. However, the current drilling technology for ultra-deep and complex wells remains one of the global drilling challenges (Li et al., 2018; Li et al., 2020). The ultra-deep formation has characteristics such as high temperature and high pressure, brittle transition of rock mechanical properties, poor wellbore stability, poor drillability of the formation, and low drilling production efficiency. Among them, obtaining the mechanical characteristics of ultra-deep rock and studying the deformation and failure mechanism of deep rock are important theoretical and technical foundations to solve these problems, and basic research needs to be carried out in advance.
Productivity Prediction of Multilateral Horizontal Wells in Low-Permeability Gas Reservoirs Under Two-Phase Flow Conditions
Authors: Guo Xinyang , Cheng Shiqing , Bai Wenpeng , Cai Dingning , Xu Zexuan , Wang Yang 
Published: August 2024

ABSTRACT:
The productivity of multilateral horizontal wells will decrease rapidly after water breakthrough, which brings challenges to accurately predict production. In this paper, a semi-analytical model for predicting the productivity of multilateral horizontal wells considering two-phase flow is established based on the principle of conformal transformation and superposition of potential functions. The model considers the effects of various factors such as gas slippage effect and reservoir stress sensitivity. Compared to the conventional productivity prediction model, the model can not only consider variable mass flow in horizontal wellbore, but also different combinations of multiple branches. The results of field case and sensitivity analysis show that the productivity of multilateral wells decreases with the increase of gas-water volume ratio and reservoir stress sensitivity coefficient, and increases with the increase of gas slippage coefficient and the angle between branch wellbore and main wellbore. The presented model can help to better understand the flow characteristics of water-producing multilateral horizontal wells and accurately calculate the productivity, which is of great significance for the development of low-permeability gas reservoirs.

1. INTRODUCTION
Multilateral wells are widely used in complex reservoirs with the improvement of drilling and completion technology (Ouyang and Aziz, 2001; Tabatabaei and Ghalambor, 2011; Hassan et al., 2017). Compared to conventional vertical wells, multilateral horizontal wells can create more contact area with reservoir and effectively increase gas well productivity, making it an attractive option for efficient exploitation of low permeability reservoirs (Wang et al., 2015; Zhou et al., 2016).
The research on horizontal well productivity began in the 1950s. Many attempts have been made to characterize the productivity of horizontal wells, and several models have been presented. Analytic models are widely accepted because they are very convenient to use. Borisov (1984) proposed a production capacity model for horizontal wells in steady state. The assumptions of the model are: the formation is homogeneous and isotropic, the drain boundary is elliptical, the fluid is incompressible, and the formation damage caused by drilling and completing the well is ignored. The analytical model has more assumptions and is not realistic, so its use is limited.