bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complex Well-Interferences During Multi-Wells Hydraulic Fracturing in Sichuan Deep Shale Gas Reservoir
Authors: Tang Xuanhe , Zhu Haiyan , He Yongsheng , Yang Haixin , Hu Yongzhang , Ci Jianfa , Zhong Jingmin , Wu Jianzhong , Lin Shili 
Published: November 2023

Abstract
As the first deep shale gas block in China, Weirong gas shale is characterized with complicated geological structures, heterogeneous natural fractures distribution, high geo-stress and high horizontal stress difference. Multi types of frac-hits were monitored in under the well spacing of 400 m, including frac-hit to the adjacent well, frac-hit to the multi-wells in same pad, frac-hit to the wells in different pads with the distance of over 1000 m. To investigate the mechanism of these frac-hits, an integrated DFN-FEM numerical model is built for multi-wells hydraulic fracturing. Involved with the field data, some conclusions can be drawn based on the simulation hydraulic fractures and induced stresses: (1) Due to the strong inducing effect of discontinuities, the high density of natural fractures or large size fault plays the main role on multi-wells frac-hit; (2) the frac-hit is enhanced with a larger induced stress range under a smaller natural fracture stiff-ness; (3) a stronger frac-hit can be detected with the shale of a lower cohesion and internal friction angle; (4) different fracturing sequences among multi wells present different induced stress among wells, the staggered fracturing sequence can highly weaken the frac-hit (5) the different injection parameters (injection intensity, injection rate, fluid viscosity, etc) mainly affect the frac-hit magnitude, merely change the frac-hit type.
Geomechanical Evaluation of an Offshore Salt Cavern for Hydrogen Storage
Authors: Brouard B. , Delahaye S. , Su K. , Pichat A. 
Published: November 2023

Abstract
In the frame of the energy transition, producing hydrogen offshore is more and more considered as an efficient and competitive way to transport energy from remote wind farms to the continent and scenarios were hydrogen production, transport and storage facilities are set in the offshore are being investigated. Salt cavities could be developed in the Zechstein and offer large storage capacities to accommodate the high intermittency of wind-farms activity and hydrogen production. In such context, TotalEnergies-OneTech conducted a feasibility study for an offshore storage in Netherland, assessing the technical challenges but also the efficiency and durability of salt cavity facing high frequency injection and withdrawal rates. This paper presents a geomechanical study that was carried out with the aim of answering several questions relating to the design and thermomechanical behaviour of a cavern during its operation. One objective of this study was also to simulate the most severe accident that could occur, namely a blowout.
Drilling Challenges and New Opportunities to Discover and Develop Geothermal Sector in the Middle East – Saudi Arabia: Jizan and Al Lith Area Case Studies
Authors: Kauffman Demond , Bageri Mohammed , Cullum Daryl 
Published: November 2023

Abstract
This paper reviews the potential for geothermal energy development in Saudi Arabia, with a focus on the Jizan and Al Lith regions. Saudi Arabia has favorable geology for geothermal, including young volcanic rocks and fractured basement rocks. However, drilling geothermal wells presents challenges like high temperatures, lost circulation due to fractured formations, and environmental regulations. The paper analyzes data on fracture dimensions from Al Lith, Jizan, Tuscany (Italy), and the Geysers (USA). The average fracture width in Al Lith is 20 mm and in Jizan is 0.1-1.5 mm. Lost circulation causes significant non-productive time (NPT) in geothermal drilling worldwide. The paper provides recommendations for lost circulation materials based on fracture widths. Case studies from successful geothermal drilling in Tuscany and the Geysers are presented. The Geothermal Specific Fluid (GSF) system used in these regions is proposed for Saudi Arabia, as lab tests show it can withstand temperatures in excess of 480°C. The paper concludes that with careful planning and technology transfer, the geothermal potential of Saudi Arabia can be unlocked, helping diversify its energy mix.
Optimizing Refracturing Models in Tight Oil Reservoirs: An Integrated Workflow of Geology and Engineering Based on Four-Dimensional Dynamic Stress Field
Authors: Ren Jiawei , Mu Lijun , Li Xiangping , Bai Jianwen , Mao Zhenyu , Gong Yiwen , Liu Chuxi , Yu Wei , Miao Jijun , Chen Junbin , Zhao Edward 
Published: November 2023

Abstract
Integrated modelling of refracturing is a comprehensive and complex task for engineers involved in field development, especially in previously developed mature fields. The modelling process requires consideration of numerous factors to accurately predict fracture propagation patterns during refracturing and production. During the initial fracturing process, hydraulic fractures generate an altered induced stress field. Later, during the post-fracturing production process, hydrocarbon extraction causes formation pore pressure depletion, leading to further alterations in the stress field. However, due to the complexity of these phenomena, most existing workflows simplify the coupled simulation problems of stresses at different stages in the modeling process. Consequently, this often results in questionable hydraulic fracture geometries during refracturing and suboptimal refracturing designs.
The goal of this study is to develop a novel integrated workflow for refracturing, specifically tailored for complex fracture networks. This model incorporates the hydraulic fracture propagation process during the initial fracturing and dynamic stress changes during the initial production process. It employs artificial intelligence algorithms to calibrate the wellhead treating pressure using physics-based model, enabling a better understanding of the initial fracturing fracture geometries. The production history match is then conducted based on the initially calibrated hydraulic fracture geometries, preserving the precision of the original fracture geometry. Additionally, geomechanics modeling is conducted to obtain dynamic stress changes during the initial production process. For the refracturing design, the fracture propagation model for the refracturing process is later conducted on the depleted stress field. Following a 240-day period after refracturing, the production history is matched using an artificial intelligence-assisted reservoir simulator. Our results indicate that due to prolonged production, significant changes occur in the stress field during the initial development period, with an average horizontal stress deviation angle of approximately 35 degrees in the near-well zone. With the combined influence of the changing stress field and natural fractures, refracturing results in longer and more complex hydraulic fractures geometries, ultimately increasing individual well production.
UPVC Test Design, Interpretation, and Simulation for Compaction and Subsidence
Authors: Kusolsong S. , Adisornsupawat K. , Mohamad-Hussein A. 
Published: November 2023

Abstract
In the field which exhibit relatively high rate of compaction and subsidence, rock mechanics laboratory testing is crucial to explain the rock deformation during production period. In the studied field, the conventional core is planned for different rock mechanics testing, and uniaxial pore volume compressibility (UPVC) tests were allocated for understanding behavior of rock compressibility. With limited core availability, 8 samples were planned for the test. There are several failure criteria that can be used to describe reservoir compaction in the carbonate reservoir, critical state is one of them. Critical state failure criterion was used to represent the behavior of rock at field scale geomechanical modelling as most of input parameters can be derived from the laboratory tests. With limited knowledge of how UPVC test should be designed to provide the interpretation for collapse pressure, hardening parameter, the first version of UPVC stress path cannot reveal the on-set of pore collapse during the core depletion. The UPVC test was then re-designed, and the results show the clear evidence of pore collapse behavior which varies with porosity. Due to limited sample, the collapse pressure can be interpreted only in a limited range of porosity. With uncertainty of the laboratory measurement, the relationship between hardening parameters and the reservoir property e.g., porosity cannot be derived. With all UPVC test results, the collapse pressure as a function of porosity can be derived. To ensure that the interpreted parameters for critical state criterion can mimic the stress-strain relationship during UPVC test, finite element modelling using “single element simulation” was used for the model validation. This simulation will simulate the rock deformation during laboratory test at core scale, both in elastic regime and yielding. With proper failure criterion and provided input parameters, the single element simulation can mimic the actual stress strain relationship during laboratory test and provide the confidence of using those input parameters and criterion later in the field scale geomechanical modelling and simulation.
Characterization of Maximum Horizontal Stress from Wellbore Failures – A Case Study from the Tight Paleozoic Hamra Quartzite Oil Reservoir of Oued Mya Basin, Algeria
Authors: Baouche Rafik , Sen Souvik , Benmamar Salim , Perumalla Satya 
Published: November 2023

Abstract
The Cambro-Ordovician Hamra Quartzite Formation is one of the important reservoirs from Algerian Sahara. The objectives of this study were to characterize the wellbore breakouts and constrain the maximum horizontal stress (Shmax) based on the inferred compressive failures within the Paleozoic reservoir. A-Quality breakouts were deciphered within the reservoir interval from a cumulative of 138m of acoustic image log indicating a mean SHmax orientation of N118˚E±8˚. Interpreted breakout widths exhibit a range between 32.6˚ and 90.81˚, which indicated a SHmax range of 24.4-34.7 MPa/km. The average breakout width of 62.58˚ translates to a SHmax gradient range of 27.2 and 31.2 MPa/km. The relative magnitudes of the principal stresses indicate a strong strike-slip tectonic stress state with a SHmax/Shmin ratio of 1.41-1.81 within the Ordovician interval. Following the frictional faulting-based stress polygon approach, measurement of minimum horizontal stress (Shmin) from minifrac tests and observations of compressive failures from acoustic image log provided strong constraints on the SHmax magnitude in the studied Ordovician tight reservoir interval in the absence of core-measured rock strength.
A Machine Learning Framework for Quality Assurance and Prediction of Well Trajectory Deviations
Authors: Khalifa H. , Tomomewo O. S. , Benarbia A. , Dehdouh A. , Berrehal B. E. 
Published: November 2023

Abstract
Hole deviation in drilling, influenced by geological formations and drilling mechanics, brings about increased operational costs, boundary disputes, collision risks, and safety concerns. Traditional measurement tools, susceptible to magnetic interference, often produce skewed readings. In addressing this challenge, our research introduces an ML model leveraging data from gyro runs, which are immune to magnetic interferences. After processing a comprehensive dataset of geophysical well log parameters, various ML models were trained. The Random Forest Classifier emerged as the most efficient, boasting a 97% accuracy rate. To validate its robustness, the model underwent a blind test on two distinct new wells, achieving an overall accuracy of 89%, further underscoring its reliability. This model, aptly named "Path Guard", was subsequently deployed as a user-friendly web application, offering the industry an accessible tool for predicting drilling path deviations. Through the integration of artificial intelligence and data science into drilling and geomechanics, our approach not only enhances current operations but also paves the way for potential real-time, automated systems in drilling deviation management.
Using ELFEN-Horizon To Assess the Geomechanical Response of ExxonMobil’s GoM ST54 Field Due to CO2 Injection
Authors: Davies D. L. , Bere A. , Mahadevan S. , Parfitt D. , Garai A. 
Published: November 2023

Abstract
ExxonMobil’s GoM ST54 (South Timbalier Block 54) is used as a benchmark problem to assess the geomechanical response due to CO2 injection. The problem looks to evaluate various modelling capabilities such as geometry preparation, geostatic equilibration, surface heave and fault slip due to injection. Modelling efficiency and post processing capabilities are other key features that are assessed by the problem. This paper aims to share the knowledge gained from modelling an industry scale CO2 injection operation using an efficient finite element (FE) modelling workflow using ELFEN-Horizon. All modelling inputs such as material properties, initial stress state with horizontal stress anisotropy and azimuth considerations were supplied in the form of ECLIPSE grids. A key feature of the model is that is uses the ECLIPSE grid (including the degenerated hex elements) as the FE mesh, since this is water-tight geometry including discrete faults. The model efficiently establishes a pre-injection geostatic equilibrium including development of contact stresses across the fault network. Thereafter the model simulates the CO2 injection and shut-in phases. The injection induces a low level fault slip (&lt;10mm) and a surface uplift (~12mm).
Novel Fresh Water-Based Mud System in Highly Reactive Shale Formation: Experimental and Case Studies
Authors: Ba Geri Mohammed , Kauffman Demond , Cullum Daryl 
Published: November 2023

Abstract
This paper investigates a novel water-based mud (NWBM) system for drilling in reactive shale formations. Laboratory experiments were conducted to evaluate the performance of NWBM with the Novel Polymeric Additive (NPA). Tests measured rheology, shale swelling, and high temperature/high pressure (HTHP) filtration loss. The results showed that NWBM with NPA significantly reduced mud filtration loss by over 78% compared to traditional water-based mud (TWBM). It also inhibited shale swelling by 40% and increased the rate of penetration by 28%. A case study in Bahrain demonstrated the successful field application of NWBM in reactive anhydrite formations. Despite wellbore stability challenges, the NWBM system enabled faster drilling with zero non-productive time (NPT). This research indicates that NWBM with NPA is a promising drilling fluid for reactive shale drilling. It can enhance drilling performance, reduce risks, and achieve operational efficiency. Further work is needed to optimize NWBM formulations for specific shale plays and evaluate environmental impacts. Field trials in different shale formations will help demonstrate the technology. This study provides a comprehensive overview of NWBM for drilling in reactive shales. The fluid system has great potential to overcome issues like wellbore instability, fluid loss, and NPT in challenging shale wells.
Three-Dimensional Visualization of a Complex Fracture Network Formed by True-Triaxial Testing
Authors: Wu P. S. , Abdelaziz A. , Grasselli G. 
Published: November 2023

Abstract
Serial-sectioned images were three-dimensionally reconstructed to visualize the fracture network within an outcropped cube, sourced from the Montney Formation, the largest unconventional natural gas resource in Canada, that was hydraulically fractured in the lab under conditions similar to real field operations. Following the experiment, the fractured cube was saturated with fluorescent materials to distinguish the fracture network from the rock matrix and provide common spatial references for a modified serial-sectioning and photographing method using ultraviolet light. The obtained serial-sectioned images underwent image processing, distortion removal calibration, and image registration for three-dimensional visualization, including reconstruction and segmentation. The results highlighted the significant influence of bedding planes and rock anisotropy on the generated fracture network geometry. These observations have important implications on the evaluation of the stimulated rock volume, as well as on completion strategies, as preferential opening of bedding planes might result in horizontal intra-well connectivity and increase parent-child interactions.
Monitoring Ultrasonic Velocity of Late Jurassic Carbonate Rocks Saturated by Brine and Supercritical CO2 Using Coda Wave Analysis
Authors: Perbawa A. , Chandra V. , Vahrenkamp V. 
Published: November 2023

Abstract
This study focuses on monitoring the velocity of carbonate rocks saturated with brine and supercritical CO2 using a triaxial apparatus. The main objective is to investigate the effects of these fluids on the geophysical properties of carbonate rocks. The specimens were obtained from the Late Jurassic Arab-D formation outcropping in Wadi Daqlah, north of Riyadh, central KSA. This outcrop serves as an analog for the prolific Arab-D subsurface hydrocarbon reservoirs. Ultrasonic transducers were utilized to monitor P and S wave velocities across various stages, including isotropic loading, brine injection, CO2 heating, and the transition from brine to supercritical CO2 fluids. We used coda wave analysis to obtain more accurate first arrival times of ultrasonic data. P and S wave velocities increase with effective stress following a power function. Temperature decreases elastic moduli more than the reduction of bulk mass density. This results in slower P and S wave velocities. P wave velocity drops rapidly for brine-saturated rock that is invaded by supercritical CO2, due to a sudden reduction of elastic properties. Our study demonstrates the complexity of velocity changes resulting from variable fluid saturations, mass densities and elastic moduli.
Geomechanics Analysis for High Breakdown Pressure of Deep Tight Sandstone Formation: A Case Study
Authors: Kong Hui , Wang Rong , Cheng Ning , Hu Shimeng , Jiang Fumin , Wei Chaoyang , Hu Zhongyu , Sheng Mao 
Published: November 2023

Abstract
Deep tight sandstone gas resources over 4000 m have become an important unconventional natural gas in Junggar Permian Basin, China. Multistage hydraulic fracturing on exploratory wells were used to create the complicate fracture network in the reservoir. However, the high formation breakdown pressure has become a major problem to reach a successful hydraulic fracturing. The wellhead pressure easily exceeds the allowable maximum pressure. This paper proposes a workflow to identify the major reasons for the high breakdown pressure of deep tight sandstone formation and confirms the downhole mechanical-specific energy model can be used to identify the engineering sweet spots. First, we re-visited the available data from one of the pioneer horizontal well H01 in the target play and collected 12 cores from the formation for a comprehensive geomechanics analysis of high fracture pressures and strong heterogeneity, focusing on rock strength, natural fracture density, and reservoir permeability. Results indicate that the fracturing fluid filtration coefficients of the rock matrix in target layer are very small in the range of 10-5m/s1/2, which makes a low permeable formation. G function analysis shows that natural fractures are not developed in the hard-fracturing stage of well H01, the fracture shape is simple. Besides, the downhole mechanical specific energy in this stage was calculated and higher than that in other stages. The present results confirm the major reasons of high breakdown pressure of deep tight sandstone formation, including the impermeable rock matrix, less natural fractures, and high rock mechanical strength.
Predicting Rate of Penetration Using the Dual Seq2Seq Model
Authors: Pan Tao , Li Zhen , Zhang Chengkai , Song Xianzhi , Zhu Lin , Yan Zhi , Zhu Zhaopeng , Sun Yuan , Ni Pengbo 
Published: November 2023

Abstract
Machine learning models have made significant strides in efficiently and accurately predicting rate of penetration (ROP) recently. Traditional machine learning models primarily rely on time-series parameters like the weight on bit, et al. while often overlooking non time-series features such as tool combinations. This study proposes an intelligent ROP prediction method based on a dual-input sequence-to-sequence model (Dual-S2S), which simultaneously considers both temporal and non-temporal factors to achieve accurate ROP predictions. First, time-series features, as well as non-time-series features are elaborately selected to serve as model inputs. Then, the natural language processing technique is employed to represent non time-series features and reduce the dimensionality. Next, to solve the lag of time-series model in long-series prediction, the differences in ROP are treated as the prediction target to calibrate the model. Finally, five field drilling datasets are used to comprehensively evaluate the performance of the Di-S2S model. The results indicate that the Di-S2S model surpasses traditional time-series models such as GRU and LSTM in terms of prediction accuracy, with average relative errors reduced by approximately 8% and 9%, respectively. Moreover, the incorporation of ROP differences for calibration further reduces the average relative error by approximately 4%. The proposed Di-S2S model exhibits a high level of predictive accuracy and offers valuable insights for optimizing the drilling process and enhancing drilling efficiency.
Fractures Propagation Feature of Multi-Cluster Fracturing on Deep Laminated Shale Oil Reservoir
Authors: Lv Jiaxin , Hou Bing 
Published: November 2023

Abstract
In order to improve the production efficiency of oil and gas in the Sichuan Basin, it is necessary to study the propagation behavior of hydraulic fractures in the deep laminated continental shale oil reservoir. This study used the cohesive zone method to establish a numerical model for multi-fracture propagation in deep laminated shale oil reservoirs. Parameters such as cluster spacing and pump rate injection mode were taken into account. Through analysis of pore pressure and fracture width data, the feature of multi-fracture propagation in multi-cluster fracturing is revealed. The simulation results demonstrated that smaller cluster spacing exacerbates the uneven distribution of fracturing fluid flow between clusters, leading to increased competition and propagation of inter-cluster fractures, most transverse fractures were unable to fully propagate. Moreover, when the pump rate is low, lamina are easily activated. With pump rate increasing, hydraulic fractures tend to branch along microfractures surrounding the lamina, activating multiple layers. In the deep laminated continental shale reservoir, 8m cluster spacing and faster liquid injection rate are recommended as it effectively increase the probability of the main fracture penetrating the interlayer and effectively stimulate reservoir.
Mapping out COVID-19, Social Distancing, Pandemic in Juxtaposition with Sexual Desires Practices in a Gay Latino Immigrants Men [GLIM] Study
Authors: Betancourt Gerardo 
Published: November 2023

COVID-19 reminded us of the fragility of human beings once humankind had felt they had mastered health, weather, and natural conditions in the world. For many generations, there was no memory of any pandemic close to our lived experience. During the pandemic, I was waiting to start the interviews for my research on Gay Latino immigrant men in Ontario, Canada. Because of COVID, my advisory committee accepted adding three questions about COVID to be analyzed along with the semi-structured questionnaire focused on sexual health practices among Latino immigrants in interracial sexual/romantic relationships. The findings result in the understanding of the role of sex on Gay Latino men and the strategies they developed to somehow deal with the lockdowns, social distancing, the risk of getting infected with COVID-19, and simultaneously satisfy their sexual and romantic needs.