bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on the Influence of Hydraulic Fracturing Operation on Local Fault Slip Under Non-Communication Condition Based on Numerical Simulation
Authors: Wang Kongyang , Han Yaotu , Xu Gang , Zhang Hui , Chen Bin , Jia Lixin , Xiao Yao , Yu Qinxin 
Published: September 2023

ABSTRACT
For unconventional reservoirs, hydraulic fracturing is a common development method. Casing deformation occurs frequently during fracturing operations. Severe casing deformation will block the fracturing tool from reaching the designed position, due to the subsequent fracturing operation between the casing deformation position and the fracturing stage cannot be carried out. According to the statistical results of various oilfields, at least half of casing deformation cases are related to the faults across the well trajectory. Classic theory presumed that the normal stress and friction coefficient of the fault surface will decrease after the high-pressure fluid of the fracturing operation flows into the fault. When the friction stress is less than the shear stress of the fault surface, the fault is activated to slip and cause deformation of the casing passing through the fault. However, the research results based on numerical simulation in this paper show that even if the fracturing fluid does not communicate the fault, the change of the shear stress field at the tip of the artificial fracture also can cause the local fault to slip, especially those faults which the shear stress and friction stress are relatively close. This result can better explain some casing deformation cases far from the fracturing operation stage. In this paper other results indicate that: (1) Unlike the classical theory that the fluid flow into the fault causes the slip of all the fault area, the change of local shear stress field by fracturing operation will only cause the local fault slip; (2) Because only local fault slips, the influence of fault length on fault slip is not obvious, but the fault length and fault slip are still in a positive correlation; (3) The short fault located in the extension line area of the artificial fracture can make the artificial fracture more inclined to propagation to the fault area, and the length difference between the half artificial fracture length of the same fracturing stage is about 20%. Based on the research results, the fault area intersected by the artificial fracture extension line is the most dangerous fault. For the well trajectory that must cross fault, adjusting the design scheme to cross the area with a small fault slip is one of the feasible means to reduce the fracturing casing deformation probability.
Assessing the Feasibility of Geological CO2 Storage in a Depleted Gas Field with Multi-Scale Coupled Reservoir Geomechanics Simulation
Authors: Pan Yuanwei , Lee Daegil , Lee Haeseon , Kim Jongsoo , Wang Xiao , Cho Jaekyoung , Qiu Kaibin , Lee Hoseob 
Published: September 2023

ABSTRACT
Korea National Oil Corporation (KNOC) is now leading the nation's 1st large-scale carbon capture and storage(CCS) demonstration project using a depleted gas reservoir in the East Sea of offshore Korea. The Donghae-1 gas field, first discovered in 1998, came online producing gas and condensate in 2004 putting the country in the list of hydrocarbon producers worldwide. The field shut down in 2021, and is now considered as one of the most immediate candidates for geological CO2 sequestration. As a candidate CO2 storage site, the geomechanical risks are vital to the injectivity, containment, and long-term sustainability which must be assessed and dealt with before field operations. To this end, cap rock integrity and well completion integrity evaluation of CO2 injection and storage are required for the feasibility study.
In an effort to evaluate the integrity of CO2 storage in Donghae-1 gas field, a thorough geomechanics study workflow was established. Core laboratory tests were firstly carried out to delineate geomechanical characteristics for both reservoir and cap rocks. The degradation of rock stiffness and strength was taken into consideration by treating core samples with CO2. 1D mechanical earth model (MEM) for a few selected wells was constructed honoring core testing results and logging data, and then the 3D MEM modelling was performed in full-field scale and in near wellbore scale. For the full field scale, the gas production was numerically simulated and history-matched before coupled reservoir geomechanics simulation for CO2 injection and plume migration was performed. To elevate the study to a comprehensive level, different CO2 operation scenarios were considered, covering different potential injection wells and maximum allowable injection conditions. Cap rock integrity was assessed by the failure criteria derived from core laboratory tests. As significant physical processes occur near wellbore, a well-centric and fine-grid sector model was built to delve more into hydraulic-mechanical coupled behavior in terms of rock integrity and well completion integrity.
This study indicates that it is less likely to damage the storage and cap rocks given the formation properties and the safe injection rate, and the potential risks of CO2 leakage are under control. Besides, multiple layers of shale above the target storage zones provide additional containment assurance. The workflow proposed in this study can be utilized to understand long-term behavior of CO2 storage, which is helpful to many similar CCS projects worldwide.
Study on High-Pressure Treatment of Unconventional Reservoirs with Water-Based Fluids
Authors: Zayas I. C. , Meegoda J. , Kolawole O. , Pinkert S. , Zhang D. 
Published: September 2023

ABSTRACT
Shales are tight rocks with ultra-low porosity and often contain hydrocarbons (oil and gas). Both the United States and Israel have abundant shale formations containing oil and gas. The majority of shale hydrocarbon production in the United States takes place in Permian basin, Texas, whereas the largest kerogen shale deposits in Israel occur in the Negev area. For the recovery of oil and gas, shale formations are hydraulically fractured by injecting water-based fluids under high pressure. To transition away from fossil fuel use and address atmospheric greenhouse gas levels, sequestration of carbon dioxide (CO2) and hydrogen (H2) storage is now proposed in depleted tight hydrocarbon formations, such as shales. Shales are composed largely of clays and silts, bound by carbonates to form ultra-tight matrices, and containing interconnected nano- to micro- to macro-voids with total porosities of 1-6%. The introduction of fracturing fluids and, potentially, other fluids for storage purposes (e.g., CO2 and H2) may cause changes to the ultra-tight shale matrix, as formations had previously been isolated for millions of years. These changes have been linked to reduced production of oil and gas and may affect possible storage of CO2 and H2. The interaction between artificially introduced fluids and shale formations, leading to softened shale, is attributed to the interlayer expansion of clays and the dissolution of cementing carbonates. This study seeks to investigate of the effects of interaction between various fluids and unconventional reservoir rock at high temperature and pressure for geo-storage implications. Shale-fluid interactions will be quantified through the lens of mineralogical, pore network, and mechanical property changes. of CO2 and H2.

INTRODUCTION
Shale formations have ultra-low porosity and permeability, and when shales contain hydrocarbons, are considered unconventional reservoirs. Large shale gas reserves are popularly located in China, United States, and Argentina; with 31.6, 17.6, and 22.7 trillion cubic meters of reserve, respectively (U.S. Energy Information Administration, 2015). Horizontal drilling and hydraulic fracturing are major methods of extracting the hydrocarbons trapped in these tight formations (Speight, 2020). Once both a vertical and horizontal well is drilled into the reservoir formation, high-pressure fluid is injected at a designed rate. The fluid, often a water-based brine, also contain proppants chosen to withstand the rock closure pressure as fractures propagate out perpendicular to the horizontal well. These new fractures increase the connectivity of formation pores and allow for the hydrocarbons stored within them to be recovered. Depleted unconventional oil and gas reservoirs therefore offer potential uses for nuclear and wastewater disposal, hydrogen storage, and carbon sequestration, due to their existing wells and fracture networks, and otherwise low porosity.
Experimental Fracture Creation in Cores: Permeability and Porosity Measurements of the Fractured Cores and the Use of Such Measurements in Analysis of Pressure Falloff Tests Following Well Stimulation
Authors: Mindygaliyeva B. , Uzun O. , Amini K. , Fleckenstein W. W. , Kazemi H. 
Published: September 2023

ABSTRACT
This paper presents an assessment of the stimulation of an existing, research, geothermal well in a potential enhanced geothermal system (EGS) in Utah, adjacent to the Roosevelt hydrothermal field. The geothermal well has undergone stimulation with the objective to extract heat efficiently from the field's low-permeability granitoid hot rock. This research focuses on deciphering the information content of the stimulated well's pressure transient test using laboratory-measured core data as guides. Specifically, fractures were created in the laboratory in several cores from a non-related granite outcrop and from the Utah FORGE granitoid geothermal reservoir. Matrix and fracture permeabilities and porosities, and pore compressibility were measured and, where appropriate, were used both as guides and input data in the interpretation of the analytical and numerical solutions of flow equations in history matching of the geothermal well measurements. The information obtained from the core experiments was of great value in conventional interpretation of pressure falloff tests. From a pragmatic point of view, our laboratory data suggest that the contribution of the matrix flow to the fracture flow is extremely small, and probably some of the pre-existing natural fractures reopen during well stimulation to provide the main path for fluid flow and, possibly, heat exchange in the stimulated geothermal wells.

INTRODUCTION
The process of drilling and completion of a pair of parallel injection-production wells in hot, dry rock (HDR) system at 7000-10000 ft depths in the Utah FORGE area is an extensive effort (Moore et al., 2020). Because the permeability and porosity of this HDR system are very small, there is no mobile hot brine in the formation to circulate to sufficiently extract the heat from the formation. The aforementioned injection-production pair shown in Fig. 1 (injector 16A(78)-32 and producer 16B(78)-32) are vertically placed parallel to each other and are intended to be connected by a set of hydraulic fractures (Kumar, D., & Ghassemi, 2019). At this point field attempts have been made to connect the two wells which are 300 ft apart (Allis & Moore, 2019) with three large hydraulic fracture (HF) stages. Each fracture has a relatively large surface area to provide a means of extracting heat from the formation via the injected water flowing through the fracture. However, there is a need for additional surface areas that are perceived as the surface areas of the micro- and macro-fractures in the stimulated volumes between three sets of parallel hydraulic fractures placed in the injection well. One does not know how permeable these smaller fractures are; nonetheless, it is anticipated that some of the innate fractures and the newly created ones provide additional permeability connection to the HDR matrix (Bruce Hill, 2021).
Evaluation of Shotcrete Performance from Full-Scale Load-Deflection Tests Using Numerical Analysis
Authors: Moon T. , Wang E. , Oh J. , Li K. , Ramandi H. L. , Zhang C. , Saydam S. 
Published: September 2023

ABSTRACT
Shotcrete is a support system that is sprayed onto the surface of excavated tunnels and mines to create a self-supporting layer. It is an economic and integral solution to ground support in civil and mining construction projects. To ensure the long-term stability and safety of underground structures, it is essential to understand shotcrete's performance and failure mechanisms and to develop effective design methods. While previous studies have elucidated the performance and failure mechanisms of shotcrete, many unknowns and misinterpretations remain. This study conducted a numerical analysis replicating full-scale load-deflection tests in comparison with field test results. Parametric studies were also performed on the interaction between support elements and shotcrete adhesion under different loading configurations. The simulation revealed that the ultimate capacity of the shotcrete liner is primarily governed by flexural tensile failure mode, and the residual bonded area along the shotcrete panel periphery after the major bonding failure plays an important role in increasing the apparent flexural failure resistance of the shotcrete liner. A new alternative shotcrete design method based on the bending moment coefficient has been proposed and compared with empirical support design methods.

INTRODUCTION
Shotcrete refers to a ground-support system that is pneumatically sprayed, typically onto the exposed surface or an excavation face to produce a compacted self-supporting and load-bearing layer for underground structures. Today shotcrete has become an essential component of an initial ground support system or permanent structural lining that can be an economic and integral solution to a host of applications in civil and mining construction. Therefore, it is crucial to comprehend the performance and failure mechanisms of shotcrete as a ground-support system and to develop practical and effective design methods that can ensure the long-term stability and safety of underground structures.
Many researchers, Barrett and McCreath (1995), Kaiser, and Tennent (2001), and Bernard (2004), have elucidated the performance and failure mechanism of the shotcrete liner. However, many unknowns and misinterpretations remain on the failure process of shotcrete panel, such as: the interactions between shotcrete and rock bolt configuration, and the effect of the shotcrete adhesion, etc. These factors play an important role in the understanding and development of a more practical and suitable shotcrete lining design. Thus, the main objective of the paper is to: 1) investigate the influence of those key factors which could affect the performance and the failure mechanism of the shotcrete, by means of replicating the full-scale load-deflection test using Finite Element Method (FEM) analysis, 2) propose a new method of shotcrete design based on the findings above.
Intelligent Switch Control Algorithm of the Push-The-Bit Rotary Steerable Drilling System
Authors: Shen Xinyu , Liu Sen , Su Qiang , Mi Guangyong , Deng Haibo 
Published: September 2023

ABSTRACT
Push-the-bit rotary steerable system (RSS) is a guide technology that realizes directional drilling by controlling the eccentric mechanism to push against the borehole wall. However, the control effect of push-the-bit RSS is often not satisfactory in many interference factors, such as rock anisotropy and trajectory deviation. An intelligent switch control algorithm based on push RSS is proposed to achieve a smooth trajectory, stable control, and efficient decision-making. Firstly, the control rules of thrust force and thrust orientation are given according to the actual drilling situation. Next, the decision results are substituted into the borehole trajectory prediction model to achieve an accurate prediction of the trajectory to be drilled. Finally, the intelligent switch and mechanical control effect are simulated using field data, and the control precision, trajectory complexity, calculation time, and other aspects are analyzed comprehensively. The results show that the on-off control algorithm can effectively overcome the influence of the system and other interference and get a smooth well trajectory. It also has high robustness and system response, helping to reduce the distance deviation between the wellbore trajectory and the designed trajectory.

INTRODUCTION
The critical task of wellbore trajectory control in oil and gas wells is to control the bit attitude to drill according to the pre-designed wellbore trajectory in the actual drilling process. Under actual working conditions, formation and drilling parameter changes make it challenging to obtain the real attributes of the formation, making it difficult to achieve accurate control of the wellbore trajectory. Given the above problems, relevant scholars have studied the control methods of wellbore trajectory, which can be divided into two categories: mechanical control and automatic control.
Currently, the commonly used mechanical control methods predict the segment to be drilled by force and deformation analysis of the steering tool and rock-bit interaction and constantly adjust variable parameters (pushing force, tool face, weight on bit, etc.) to implement the dynamic adjustment. Birades and Fenou (1998) proposed the "balanced curvature method" to predict the wellbore trajectory in the section to be drilled by changing the wellbore curvature until the lateral force decreases to zero or approaches zero. Guan et al. (2005) proposed the concept of "drilling trend Angle" considering the influence of design parameters of drill assembly on drilling trend and took it as an evaluation index of deviation building ability of guide tool. Wang et al. (2022) proposed a guidance tool trajectory prediction method based on zero lateral drilling rate criterion considering the influence of the drilling process.
Numerical Investigation of Mining-Induced, Hydromechanically-Coupled Responses for a Nevada Mine Site
Authors: Noonan G. E. , Lorig L. J. , Beale G. , Ferré P. A. 
Published: September 2023

ABSTRACT
Understanding the coupled interaction of rock and water under stress is often a key factor in assessing slope stability in open pit mining. In this paper, a numerical modeling research project is presented which demonstrates the concept of hydromechanical coupling (HMC) and assesses the sensitivity of contributing parameters to pressure responses observed in a piezometer sensor due to excavation of a mine slope. Site monitoring data showing HMC effects within a mine in Nevada are analyzed and reproduced using FLAC. This research aims to promote the understanding of HMC in pit slopes and provide improved guidance on how to plan mining activity, monitoring and slope design to incorporate the benefit of HMC effects.

INTRODUCTION
Open-pit mining is a dynamic process that involves the excavation of earth materials to retrieve ore. During the mining process, changes to the physical properties of the in-situ rock mass are induced. As excavations progress, pore pressure changes occur beyond the slope face, and, while some factors such as infiltration or recharge may increase the pore pressure, others may help reduce it. Consequently, understanding the relation between pore pressure changes and rock deformation is a key factor in ensuring the stability of slopes and maintaining safe mining conditions. Pore pressure can be measured, predicted, and managed through active dewatering and depressurization programs to control stability.
In this research paper, 2D modeling using FLAC v8.1 is presented to help explain observed behaviors in piezometer monitoring data from a mine site in Nevada, and to provide a hydromechanical explanation for these behaviors using simple model illustrations. Different case scenarios using a variation of mechanical and hydrological input parameters are performed. Varied parameters are those which govern pore pressure responses caused by induced changes in total effective stress (unloading) of the rock mass, such as elastic modulus, porosity, and permeability. Results are presented and discussed for each modeling case scenario using pore pressure history at a point representing the piezometer sensor location.
The Secondary Brine Discharge Efficiency of Salt Cavern Gas Storage Was Improved by the Chemical Cementation Method
Authors: Yao Er-dong , Zhang Kun 
Published: September 2023

ABSTRACT
Salt cavern gas storage has become one of the world's important natural gas strategic reserves and emergency peaking facilities. However, most salt cavern gas reservoirs in China are built in layered salt layers. After leaching, a large number of insoluble mudstones is loosely accumulated in bottom of the cavity, and occupies a large amount of storage capacity (1/3-2/3). After the first gas injection and brine discharge in the salt cavern, there is still 2-5m of water left to the bottom. Furthermore, there is still a large amount of water in the pores of insoluble mudstones, resulting in a large storage capacity loss. Therefore, it is urgent to explore the technique of secondary brine discharge to drain more brine away.
In this study, a lab simulated brine discharge device was set up. If conventional sand control screen is used, the brine discharge efficiency was quite low and a mass of mudstones plugged the pipeline. The permeability of the pipeline can be reduced to 0.1mD. The reason for the blockage of the pipeline is that the mudstone particles are loosely accumulated and can migrate into the pipeline with the fluid. To solve this problem, we propose to use the chemical cementation method to improve the efficiency of secondary brine discharge. In order to improve the mudstone porosity after cementation, a foam resin system with bisphenol A epoxy resin and corresponding curing agent was prepared. It can cure sand at room temperature and 80 °C in 4 days to form a porous solid with high conductivity. This solid formed by foam resin and sands has good sand control performance. Under a constant gas injection pressure (0.1MPa), the pipeline flow and sand production were tested, and the temperature resistance and salt resistance were also tested. The experimental results show that the measured permeability of the foam sand system can reach more than 15mD, the sand production can be controlled within 0.5% in the secondary brine discharge process and is greatly reduced. The foam resin system has good temperature resistance and salt resistance, and can still have good sand control and conductivity under the temperature of 20°C-80°C and brine concentration of 0-26%. This study provides a new idea for the secondary brine drainage and sand fixation of salt cavern gas storage.