bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat Extraction and Interlayer Interference in Heterogeneous Multi-Layer Commingled Production Oil Reservoir
Authors: Xu Fuqiang , Song Xianzhi , Song Zihao , Wang Gaosheng , Shi Yu 
Published: September 2022

ABSTRACT:
Geothermal development of oil reservoirs using abandoned or high water-cut wells has received a lot of attention. The heterogeneity is a common feature of oil reservoir, and it cases the production characteristics are distinct. We have established a coupling model of oil-water two-phase heat flow in the heterogeneous multi-layer commingled production reservoir. The model considers local thermal non-equilibrium (LTNE) and is a dual porosity model, which can be used to describe the fluid flow in the fractured reservoir. Using the model, the effects of different reservoir characteristics and injection parameters on production characteristics are analyzed. Reservoir characteristics include dip angle, cubic matrix block side length, and injection parameters include injection temperature and mass flow. Under the conditions studied in this paper, after 5 years, the maximum differences of production temperature and deviation values can reach 27.5 °C and 65.34% at different injection mass flow, respectively. The maximum deviation value difference can reach 45.90% at different cubic matrix block side length, while the impact on production temperature is small. The injection temperature and dip angle have a relatively small impact on the above production characteristics. This study has certain significance for the application of geothermal energy in oilfields.

1. INTRODUCTION
Geothermal energy is one of the important renewable energy sources, with advantages such as features weather independence, stable, operationally reliable, and environmentally friendly nature (Wang et al. 2018). Compared with the utilization of shallow geothermal energy, the high drilling cost has led to the slow development of mid-deep geothermal resources. Many oil reservoirs have produced liquids with water content of more than 95% and have become "hydrothermal geothermal fields". Some oil wells in high water-cut oil fields have reached their economic limits and have even been abandoned. The oilfield area usually has a high geothermal gradient, and many abandoned wells have abundant geothermal resources, such as Texas, Oklahoma, Louisiana and North Dakota in the United States, and Songliao Basin, Bohai Bay Basin, and Ordos Basin in China (Augustine and Falkenstern 2014; Jiang et al. 2019). Using abandoned oil wells to develop geothermal energy can alleviate the pressure of energy supply and demand, save drilling and sealing well costs, and control the pollution of abandoned wells (Cheng et al. 2016; Lin et al. 2021).
Experimental Study on Water Absorption Characteristics of Interbedded Lithology in Low Permeability Reservoir
Authors: Fang Zheng , Chen Mian , Yin Daiyin , Yu Yanbo , Si Xiang , Yang Kang 
Published: September 2022

ABSTRACT:
In the development of low permeability reservoirs, long-term high pressure water injection leads to the formation of high conductivity water-injection induced fractures and the injection water into the non-reservoir lithologic section has also been found in the field inspection well sampling. However, the previous core evaluation is mainly based on reservoir lithology, and the water absorption characteristics of barrier and interlayer lithology and its influence on development effect were not clear. In view of the above problems, this paper takes Daqing Chaoyanggou oilfield as an example, studies the longitudinal lithologic distribution characteristics according to the field logging data and coring data, and statistics the main lithology in the non-reservoir lithologic section of Chaoyanggou oilfield. The water absorption characteristic experiment was carried out and the relevant reservoir parameters were clarified. Numerical simulation of reservoir considering interlayer water absorption is carried out by using Eclipse. The research results show that mudstone basically has no permeability, saturated water absorption coefficient increases with the increase of injection end pressure, and decreases with the increase of injection end to sample center distance. Silty mudstone has a certain permeability and water absorption characteristics between mudstone and argillaceous siltstone, and there is a phenomenon of fluid pressure transmission in the pores. The water absorption characteristic of argillaceous siltstone is consistent with the compression characteristics of fluid. The numerical simulation results of reservoirs with compartments are also more accurate, which explains the high injection-production ratio but low production in low permeability reservoirs. The results of this study have certain guiding significance for the efficient development of low permeability reservoirs.

1. INTRODUCTION
Low permeability reservoir is characterized by small pore and throat radius, complex pore structure, low reservoir permeability and strong longitudinal and plane heterogeneity. In the process of development, there are common phenomena such as high injection-production ratio and difficult to establish effective drive system [1-4]. Recent field sampling has also revealed that injected water has penetrated into the interbed(Fig.1), which, combined with the physical and development characteristics of low permeability reservoirs, may be due to long-term high-pressure water injection, which has caused waterflooding induced fractures in the reservoir and caused the injected water to penetrate into the interbed [5]. However, the factor of lithologic water absorption of interbed is not taken into account when formulating development strategy and calculating development index.
Estimation of Fluid Flow Boundary Conditions: The Role of Pressure Transient Analysis in Safe CO2 Sequestration and Underground Storage
Authors: Amirlatifi Amin , Eckert Andreas , Nygaard Runar 
Published: September 2022

ABSTRACT:
Conducting safe and effective waste disposal and sequestration processes relies on an accurate determination of the reservoir extent and the prevailing boundary conditions. Due to the limitations surrounding the acquisition and analysis of the reservoir geometry, waste disposal, cuttings re-injection, and CO2 sequestration studies are based on simplifying assumptions regarding the lateral and vertical fluid flow boundary conditions. These assumptions can jeopardize the study’s outcomes, especially for green fields. Common boundary conditions considered are limited to either open (steady-state) or closed (semi-steady state) lateral boundaries, alongside a complete or partially sealing caprock. This study uses pressure transient analysis to provide a quantitative tool to assess a wider variety of fluid flow boundary conditions. We show that a short drawdown followed by a pro-longed buildup test can identify the fluid flow boundary condition, including closed, open, semi-open, and infinite systems. The significant difference in CO2 storage capacity and the different geomechanical risks associated with various fluid flow boundary conditions suggest that the presented methodology should be considered prior to fluid injection scenarios.

1 INTRODUCTION
Geologic sequestration is an increasingly important strategy to dispose of drilling fluids, saltwater, and hazardous waste and to reduce the CO2 concentration in the atmosphere (Mortezaei et al., 2021). The most viable CO2 sequestration targets include deep saline aquifers and mature hydrocarbon fields (Garcia et al., 2010; Sarhosis et al., 2018; Bachu, 2003; Holloway, 2001; Holloway and Savage, 1993; Klara et al., 2003). The fluid flow boundary conditions of the target storage medium need to be known to predict the target formation’s storage capacity, the spreading of the injected plume, and the geomechanical risks associated with the pore pressure increase. The current practices commonly consider an assortment of simplified boundary conditions that include open and closed boundaries when it comes to sequestration.
Feasibility Study and Design of an Underground Entry/ Access Structure at an Underground Gold Mine
Authors: Carlisles B. B. , Koroznikova L. , Javidan F. , Khandelwal Manoj 
Published: September 2022

ABSTRACT:
This paper investigates the viability of an increase in waste rock storage by backfilling the Falcon pit and extending the portal of the Fosterville gold mine, located in Bendigo, Australia. The structure will maintain the current access to the tunnel whilst developing a fillable void. Once completed the project will allow for a total increase of 900,000 cubic metres of storage. Furthermore, a finite element study has been conducted to investigate the structural performance of a proposed design using corrugated steel sheets. Stresses and displacements are studied taking into account various design factors such as steel properties and geometry. Results demonstrate the location of critical stress values according to the proposed design. The selection of optimum steel geometry is also investigated with regards to the factor of safety.

1. INTRODUCTION
Gold mining has been a part of Bendigo’s history since the discovery of the first deposits of alluvial gold by Kennedy and Farrell in 1851. Fosterville, one of the gold mines in the area, is located 20 kilometers out of Bendigo, Australia.
Gold was first found in Fosterville in 1894 and during 9 years of operation 0.87 t of gold was produced. Mining of shallow oxide opens pits re-commence in 1991 using a heap leach operation process, which ceased in 2001. A feasibility study into sulphide gold-bearing ore processing was completed in 2003 and the first stage of commercial production began in 2005. The operation started by extracting low-grade, near-surface mineralization (Table 1) (T Fuller & Hann, 2019).
Fosterville’s deposit is hosted within an interbedded turbidite sequence of sandstones, siltstones and shales. The primary gold mineralization follows disseminated arsenopyrite and pyrite forming as a selvage to veins in a quartz-carbonate vein stockwork. The deposits have average grades of 5-10 g/t Au (Fig. 1). The sulphide mineralization is overprinted by visible gold within-host quartz veins. Visible gold is becoming more frequent at depth and with the discovery of the Eagle zone and soon after the Harrier zone (Fig. 1), these deposits are high-grade (2.29 Mt @ 23.1 g/t Au) (Table 2), reaching the highest assays seen in recent history, 191 g/t Au over 2.55 m in the Swan zone. Visible gold is observed within quartz-carbonate veins, with a noticeable increase in recent years as underground mining has advanced deeper. Visible gold particles are predominantly specks (up to 3mm), however more rarely they can be &gt; 5mm (T Fuller & Hann, 2019).
Effect of Multiple Loading Rates on Uniaxial Compressive Strength of Rock
Authors: Meerza J. B. , Khandelwal Manoj 
Published: September 2022

ABSTRACT:
It is of crucial significance to study the effect of loading rate on the behaviour of rock because engineering structures are subjected to multiple loading conditions in their entire life. Although rock behaviour under single loading rate has been widely studied but very limited research has been conducted to study the performance of rock strength subjected to multiple loading conditions. This paper presents an experimental study of the effects of single and multiple strain rates on Sandstone samples. The first set of samples was tested at constant strain rates until failure to determine the peak uniaxial compressive strength (UCS). For the second set of samples, the first strain rate was applied to the sample up to a predetermined load, and then the second strain was initiated to find out the influence of multiple loading rates on the UCS of rock samples.

1. INTRODUCTION
Geo-mining engineering deals with the extraction of minerals from the earth’s crust with the application of science and technology. Mining activities can cause severe disturbance in the natural environment, which results in the loss of hundreds of lives. For example, the misunderstanding of rock’s physical and mechanical properties in mining may lead to severe geological disasters which are to occur during the mining extraction process. Therefore, mining engineers must be concerned not only with the production and processing of minerals but also should anticipate the damage to be caused to the environment both during and after the extraction process in mining. Rock physical and mechanical properties are very important parameters for the safety and stability of any geo-mining engineering design and construction (Cheshomi et al, 2015; Khandelwal and Ranjith, 2017).
There is an increasing trend towards infrastructural development all over the world. The extraction process of minerals from the earth’s crust may cause disturbance in the natural environment and may lead to geological disasters due to the misunderstanding of geo-mechanical properties (Du et al, 2020). Therefore, it is of great importance to investigate the effect of multiple loading rates on the uniaxial compressive strength of rock (Lajtai, 1991; Zhang et al, 1999, 2000; Khandelwal et al, 2013; Wang et al, 2020). These engineering structures are made either on the rock mass or in the rock mass. There is no denying the fact that engineering materials are subjected to multiple loading rates during their whole life (Li et al, 1998). The effects of single and multiple loading rates on strength with stress characteristics of rocks are important in defining input loading which is used in the mining designs. The effects of different strain rates have significant effects on the process of rock breakage as well as peak strength value (Olsson, 1991). Although material behaviour under a single loading mode has been extensively studied, very limited research has been conducted to investigate the performance of brittle materials subjected to varying loading conditions.
Design of Larger Span Overhanging Cliffs Constructed in Himalayas
Authors: Emad M. Z. , Waqas M. 
Published: September 2022

ABSTRACT:
Road construction and maintenance is challenging in Himalayan region of Pakistan. The operators must deal with slope stability issues and falling rocks. In addition, the slope heights are huge that have a greater impact on economics and feasibility of operations. To deal with this situation the contractors create a slot (or overhanging cliff) in the base of the slope, especially in competent rock. These address some of the issues like reduced excavation costs and avoiding tumbling rock falls from top of the slope. Thus, it reduces overall excavation cost and construction time. While the occasional fall of rocks and debris on the highways is diverted by hanging cliff or rock cover, the construction design of these structures is purely based on experience. The problem add-on when an expansion in span or height is desired in existing roads. This paper summarizes the stability study of overhanging cliffs and evaluates its design in challenging ground. An extension of a national highway case study for existing span of 7 m tunnel is studied. Numerical modeling is used to study the stability of road overhanging cliff. Different scenarios are modeled in consultation with the field practitioners and a stable design is proposed for extension.

1. INTRODUCTION
Overhanging rock slopes are excavated in hard rocks along steep hill side roads. It looks like a half tunnel whose one side is open on the valley side as presented in Figure 1. The crown remains hanging or cantilevered with tunnel having one abutment. These structures are constructed in very strong rocks of Himalayan regions of South Asia (Anbalagan et al., 2003). Similar structures can be found in United States, Europe, Saudi Arabia, and Philippines. Construction of highways and roads along steep hillside is challenging. It is easier to excavate a smaller portion of rock. In Himalayas natural slope heights ranges up to more than 5000 m with slope angles up to 70 degrees (Ali et al., 2019). Generally, the excavation of such a slope will require excavation and creation of benches for stability. This will automatically increase project costs and will not help much with maintenance later. Many other issues like sliding, low safety, rock falling, and frequency of accidents during construction may arise (Terzaghi, 1962). The overhanging structure is not anyway near to the conventional tunneling. It is based on hit and trial and no scientific input is there. Also, the literature is silent on scientific design of such structures. A few references (Paronuzzi and Serafini, 2009; Schlotfeldt et al., 2018; Tokashiki and Aydan, 2010; Tsesarsky and Hatzor, 2009) studied some features and stability assessment of overhanging cliffs.
Effect of Chamfer Geometry of PDC Cutters on the Impact Resistance, Wear Resistance and Rock Cutting Efficiency
Authors: Wei Jiusen , Hu Guiyu , Shi Xiaolei , Shao Fangyuan , Liu Wei , Gao Deli 
Published: September 2022

ABSTRACT:
Polycrystalline diamond compact (PDC) drill bit is widely applied in drilling engineering. Under harsh downhole conditions, the quasi-brittle characteristics of PDC cutters may be a severe drawback of drill bits, which readily causes premature impact failure. In order to improve the durability of PDC cutters without compromising the cutter aggressiveness, the planar diamond table with modified cutter edge geometry was experimentally investigated. The experiment included progressive drop test (PDT) and vertical turret lathe (VTL) wear test. The cutting forces were measured using a dynamometer load cell. Overall test results were compared together. The results showed that a single-chamfer cutter performs best under the dry VTL test without coolant and generates a lower cutting force. The dual chamfer geometries showed a significant impact resistance without compromising other properties. Because the commonly used mechanical specific energy (MSE) has a negative relationship with cutting efficiency, therefore, the ratio between the volume of rock cuttings and energy consumed on rock cutting process was calculated to represent the cutting efficiency or namely aggressiveness, so as overall analysis performances with same correlation trend between cutting edge geometry and cutter properties. From the overall comparison, it is found that cutters with a sharper edge can enhance the aggressiveness but has a worse impact resistance; Cutters with complex and large edge size bring a good impact resistance but lead to lower aggressiveness.

1. INTRODUCTION
It is well known that PDC drill bits are becoming more widely used to drill oil & gas wellbores. As the key component of PDC drill bits, PDC cutter is composed of a polycrystalline diamond layer and a cobalt-cemented tungsten carbide substrate. The PDC cutter is sintered under high-pressure (typically 5-8 GPa) and high-temperature (typically 1400-1650 °C) conditions. During sintering, the cobalt that existed in the substrate turns molten and wets through the diamond powder bed at a short duration. All diamond particles are then bonded together to form a solid polycrystalline structure (Shin et al. 2004; Hong et al. 1991; Akaishi et al. 1991). Enhancing the physical properties of PDC cutters will undoubtedly make the bits drill faster and deeper. The physical properties of PDC cutters play an important or even predominant role in the drilling performance of PDC bits.
Energy Partitioning During Fracturing in Granite Under Stress Relaxation
Authors: Zafar Sana , Hedayat Ahmadreza , Moradian Omid 
Published: September 2022

ABSTRACT:
Time-dependent deformation affects the fracturing in rocks and can reduce their failure strength. Such time-dependent deformations are important for surface and underground structures, which are typically designed for long operational time. The weakening of rock with time is directly related to the evolution of microcracks and in this study, we focused on the micromechanics of the fractures produced in crystalline rocks under time-dependent loading conditions. Stress relaxation experiments were conducted on double-flawed prismatic Barre granite specimen in the laboratory to investigate the fracturing processes in terms of the source mechanics and the source physics. Absolute calibration of the AE sensors was performed in the laboratory to identify individual sensor responses for a known source (ball drop). Source parameter analysis was undertaken using spectral fitting method obtained for the displacement spectra at each source location. Corner frequency and seismic moment were determined, ranging from 350 kHz to 650 kHz and 10−4 to 10−1, respectively. Finally partitioning of input and output energies during the fracture propagation under monotonic and multistage relaxation loading conditions was determined. Results suggest that the amount of radiated seismic energy during multistage relaxation experiments is almost the same as in the monotonic loading experiments, however, the number of cracks produced in case of multistage relaxation is higher than that of the monotonic loading experiments.The finding of this study can help us to better understand the fracturing processes in the various field applications dealing with time-dependent failure in rocks.

1. INTRODUCTION
Time-dependent behavior can be described as a phenomenon caused by the weakening of a rock mass with time, such as creep, consolidation/dilation, swelling, and stress relaxation. A detailed knowledge of the time-dependent behavior of rocks is important to predict the long-term stability of underground structures (Diederichs and Kaiser, 1999), surface structures and rock slopes (Yu et al., 2012; Zhang et al., 2020), and nuclear waste repositories (Nara et al., 2010).
Microscale Investigation of Strength and Failure Behavior of Rock-Concrete Interfaces Under Tensile Loading
Authors: Shams G. , Rivard P. , Moradian O. 
Published: September 2022

ABSTRACT:
Tensile failure and detachment of rock-concrete interfaces in civil engineering structures such as gravity dams is considered as one of the critical factors in controlling the stability of these structures. Despite the large number of studies, the fracturing process along the rock-concrete interfaces under tensile loading is not yet well understood. In this study, digital image correlation and acoustic emission techniques were employed to investigate the effect of the interface on the strength and the fracture properties of granite-mortar specimens under tensile loading. Our results indicated that the tensile strength of the granite-mortar interfaces was smaller than that of either the granite or the mortar. It was found that the tensile strength of the interface was controlled by both interface (adhesive strength) and the mortar (cohesive strength). The DIC results showed that FPZ is mainly limited to a narrow band along the interface, while the AE analysis revealed that the FPZ covers the interface area and a considerable portion of the mortar. AE better illustrated that the fracture may initiate at the interface and then kink into the mortar. In addition, it was seen that the surface roughness of the generated fractures is material dependent, i.e., fractures generated in granite were roughest, while fractures formed along the interface had the lowest roughness values. The finding of this study can improve our understanding of the tensile strength and behavior of rock-concrete interfaces, leading to the safer design of engineering structures.

1. INTRODUCTION
In geomechanics, rock-concrete interfaces are frequently seen in civil and mining engineering applications such as tunnel linings, concrete gravity dams, concrete retaining walls, socketed piers, and shotcrete as a support for rock mass (Fishman, 2009; Chang et al., 2018). In such structures, the interface between rock and concrete is usually considered as the weakest structural zone, causing the initiation and growth of cracks and final failure along the interface (Zhong et al., 2014; Dong et al., 2019).