bluuebunny/crossref_metadata_2025_split huggingface dataset:
Review of Remedial Cementing: Factors, Design Considerations, and Case Studies
Authors: Youssef Amir Shokry , Mahmoud Ahmed Abdulhamid , Elkatatny Salaheldin 
Published: August 2024

ABSTRACT:
Remedial cementing operations in the oil and gas industry are indispensable for ensuring well integrity and mitigating environmental risks. This paper delves into the multifaceted factors that influence the effectiveness of remedial cementing processes, with a dual focus on achieving longevity and minimizing negative environmental impacts while safeguarding groundwater. Through an in-depth examination of various case studies, it offers comprehensive insights into the operational intricacies involved in different remedial applications. The analysis underscores the pivotal role of meticulous planning, precise execution, and the utilization of advanced technologies in achieving successful cementing remediation projects. Moreover, it explores in detail the diverse factors that influence remedial cementing design, including problem identification, cement preparation methodologies, injectivity testing, and cost-benefit analysis. By presenting successful case histories, the paper vividly illustrates how remedial cementing contributes to enhancing well integrity and optimizing production, thereby highlighting the ongoing innovation and refinement in response to the evolving challenges of wellbore construction.

1. INTRODUCTION
Cement serves as a crucial barrier in well construction, primarily aimed at establishing a secure bond around the casing string. Its fundamental role is to furnish the casing with essential mechanical support and to thwart any fluid migration by effectively sealing off potential pathways, including microannuli and fractures, which could undermine well integrity (Chen et al., 2022; Gu et al., 2023). Beyond ensuring mechanical stability, proficient cementing also plays a pivotal role in sealing operations. The capability of cement to seal is paramount in safeguarding groundwater and mitigating environmental risks (Abdelaal & Elkatatny, 2023).
The durability of cement stands as a critical measure, ensuring its resilience against both environmental factors and downhole conditions throughout an extended duration (Bybee, 2015). Additionally, it is imperative to verify the reliability and effectiveness of cement in safeguarding wells, thus contributing to the sustained success of oil and gas operations in the long run (Elhassan et al., 2023).
Drilling Data Based Approach for Real-Time Gamma Ray Prediction in Surface Holes Using Artificial Intelligence
Authors: Youssef Amir Shokry , Elkatatny Salaheldin , Abdulraheem Abdulazeez 
Published: August 2024

ABSTRACT:
Gamma-ray (GR) logging involves the measurement of natural formations' radioactivity, serving as a valuable tool for distinguishing various lithologies and correlating zones. A prevalent approach is to record GR data up to the surface through the casing while pulling out of the hole (POOH) using reservoir section logging tools. Although GR measurements are very helpful, they are seldom recorded in the top section. This study utilizes artificial intelligence (AI) techniques—specifically artificial neural network (ANN) and adaptive neurofuzzy inference system (ANFIS)—to predict real-time surface hole GR by leveraging drilling parameters and mud weight data. Training on datasets from six wells with a total of 2,100 data set yielded accurate predictions, with the ANN model slightly surpassing ANFIS in performance. The models were and assessed for accuracy using metrics such as root mean square error (RMSE), average absolute percentage error (AAPE), and correlation coefficient (R). These models offer substantial benefits by providing real-time GR data for analysis, thereby eliminating the necessity for post-drilling recordings. This advancement not only saves time and costs associated with logging but also enhances the efficiency of data-driven decision-making during drilling operations.

1. INTRODUCTION
Gamma-ray (GR) logs stand as pivotal tools in formation evaluation within the petroleum industry, offering direct insights into geological formations. Equipped with detectors that measure the total gamma ray intensity, GR logging tools serve various purposes, notably in distinguishing between shale and non-shale formations. This distinction arises from the distinctive response exhibited by shale formations, correlating closely with the shale content within the formation. Consequently, formations rich in radioactive materials like carbonates and sandstone tend to yield lower GR values, whereas increased shale content results in higher GR values (A. A. A. Mahmoud et al., 2017; K. A. Mahmoud et al., 2019; Wang et al., 2018). Beyond lithology identification and zone correlation, GR logs find utility in shale volume calculations within reservoir rocks, facilitating the precise classification of productive and non-productive zones based on predetermined shale volume thresholds (Ibrahim & Elkatatny, 2022). While GR logs serve as valuable inputs for modeling lithological effects, it's notable that they are not typically recorded during surface hole drilling. Instead, the conventional approach involves recording GR data up to the surface through casing during the pull-out-of-hole (POOH) process using reservoir section logging tools. This underscores the necessity for a real-time model capable of lithology identification by predicting GR logs from surface drilling parameters in addition to the mud parameters.
Numerical Approach to Evaluate Cements Sheath Barrier During Reservoir Compactation in Vertical Oil Wells
Authors: Velilla J. D. U. , Fontoura S. A. B. , Melo D. D. E. F. , Braga J. J. V. , Dias R. , Okama C. S. 
Published: August 2024

ABSTRACT:
Reservoir depletion during hydrocarbon production can lead to rock compaction. This compaction is caused by the progressive decrease in pore pressure within the porous matrix. This paper presents an axisymmetric numerical approach to evaluate the integrity of the cement and casings inside the well due to the effect of compaction. A displacement field is used as a model boundary condition and gradually applied during the production stage after the well construction. The construction of the well is considered from the geostatic equilibrium of the materials, followed by the drilling and cementing. Finally, the subsidence stage is created where the applied displacement field displaces the rock column and consequently the cement and casing. The von Mises stress curve for the casing, and the plastification index of the cement and casing were examined. It was observed that areas with the greatest von Mises stresses were proportional to areas with the greatest displacements of the rock column. A significant impact of the top of cementation (TOC) on integrity was observed. The cement acts as a transmitter of displacements to the casing, which can impact the integrity of both the cement and casing in the preceding phases before the production phase.

1. INTRODUCTION
Reservoir depletion during hydrocarbon production can lead to reservoir compaction. The compactation is a densification associated with the rearrangement of the rock matrix when fluids are lost in the porous medium. Such densification affects upper layers, causing deformations that can be observed even on the seabed. These deformations can cause structural problems in oil wells, such as fractures in upper layers, loss of cement integrity, and excessive traction or compression over the casing (Figure 1).
The main goal of this work is to develop a numerical axisymmetric methodology for analyzing the mechanical integrity of casing subjected to subsidence loads. For that purpose, the finite element method will be used. This method allows consideration of several simultaneous effects such, rock-cement-casing contact interactions, different materials within the model, advanced constitutive models, among others.
Real-Time Rate of Penetration Prediction for Motorized Bottom Hole Assembly Using Artificial Intelligence
Authors: Youssef Amir Shokry , Elkatatny Salaheldin , Abdulraheem Abdulazeez , Rahmatullah Idham 
Published: August 2024

ABSTRACT:
Efficient drilling operations hinge on accurately obtaining the rate of penetration (ROP), a crucial parameter influencing well delivery costs and overall project timelines. While existing predictive models predominantly cater to rotary and rotary steerable system bottom hole assemblies (BHAs), motorized BHAs have received comparatively less attention. Addressing this gap, our study introduces a pioneering artificial intelligence (AI) model powered by artificial neural networks (ANN) to forecast ROP for motorized BHAs. By integrating surface drilling parameters, mud characteristics, and motor output features, the model undergoes rigorous training, validation, and testing on a comprehensive dataset sourced from six wells in the Middle East, encompassing over 5,800 data points. Robust evaluation metrics, including Root mean square error (RMSE) and correlation coefficient (R), affirm the model's exceptional accuracy (R of 0.97) in predicting ROP. Beyond its predictive capabilities, the ANN-based model provides valuable insights into the impact of diverse drilling parameters on motorized BHA performance, enabling operators to optimize ROP, minimize drilling costs, and enhance overall operational efficiency in the field.

1. INTRODUCTION
Drilling optimization remains a key focus in the quest to boost overall drilling efficiency while minimizing operational time and costs. Among the pivotal tools in this endeavor are downhole mud motors, integral components of the BHA (Koulidis et al., 2023). These motors play crucial roles in both directional and vertical drilling, operating by converting the mud circulation energy from drilling fluid to generate the required revolution and associated torque (El-sayed et al., 2020). Positive displacement motors (PDM) are particularly favored for their operational simplicity, with drilling torque indicated by the differential pressure they create, and motor revolution primarily determined by flow rate (Tschirky, 1978). Extensive case studies worldwide have underscored the efficacy of downhole motor BHAs in enhancing drilling performance, leading to improved ROP, reduced nonproductive time (NPT), shortened drilling cycles, and substantial cost savings (Chen et al., 2018; Feng et al., 2014; Wu et al., 2013; Yin et al., 2014).
Role of Landing Point Selection and Completion Optimization in Stacking and Staggering Decisions – A Multi Domain Integration from Geology to Engineering
Authors: Narasimhan Santhosh , Van Delinder Steve W. , Hewett Tom A. , Arcano Nelson Suarez , Olaoye Olubiyi , Mainali Pukar 
Published: August 2024

ABSTRACT:
Unlocking the true potential of unconventional reservoirs requires the integration of multi domain data sets ranging from geology to engineering. Since Niobrara is one of the most heterogenous reservoirs, both vertically and laterally, it requires integrating petrophysics and geomechanics with completion frac modeling to define a proper landing candidate and completion design. This paper discusses the factor(s) that are most important in justifying the good production performances such as landing point interval, thickness, rock type (geology), geomechanics (stress and strength) and completion design. Though many times the answer is the combination of all these factors contributes to the production performance, it becomes essential to prioritize these factors to successfully extract not only the short-term but also the long-term production without compromising the wellbore integrity. This paper discusses the selection of multiple landing points between Niobrara B Marl, Niobrara C Marl and Turner formations initially using the slick water design. Subsequently, Niobrara C Marl zones are tested using the gel design to evaluate changes and improvements in the conductive fracs compared to slick water design without stress shadow in consideration. Since the cost of gel design is significantly higher than the slick water design, improved production needs to be justified. High poro-perm zones such as the Turner are always completed using the gel design. Taking stress-shadow into consideration, NIO C Marl was fracced immediately after fraccing the Turner with minimal bleed off in the pressure. NIO C Marl in-situ (before depletion) conductivity was compared between slick water and gel designs using with and without stress shadow approaches. Overall, this paper will discuss and capture the factors causing NIO C Marl performance using different completion designs and the changes in the conductivity during stress shadowing. This approach brings in depth knowledge for stacking and staggering operational needs.

1. PETROPHYSICS
For a successful source-rock resource assessment, we need to have proper and accurate well logging measurements but also it is necessary to integrate the petrophysical logs with geochemical, petrological and geomechanical parameters. Other geological, reservoir, and fluid analyses are equally important when assessing unconventional resource potential as has been demonstrated in previous studies. This paper applied a phased approach, which is the known most effective method for evaluating a potential hydrocarbon resource, with clearly defined criteria that must be fulfilled prior to further capital expenditures.
Induced Seismicity in Geothermal Settings: Historical Perspective, Enhanced Geothermal Systems, Setbacks, and Future Directions
Authors: Kaven J. Ole 
Published: August 2024

ABSTRACT:
Geothermal energy exploration and production has a long history of inducing seismicity, both beneficial and disastrous. Seismicity is common in naturally occurring geothermal systems as they often are co-located in areas with high strain rates, low permeability but fractured rocks, and a shallow brittle-ductile transition. These conditions generally limit the maximum magnitudes of earthquakes, whether tectonic or induced. Furthermore, seismicity often aids in the identification of prominent fluid and heat pathways within the geothermal resource. Engineered or Enhanced Geothermal systems (EGS) need not be located in geologic settings akin to conventional geothermal resources and, thus, may have unknown fault and fracture locations and extents owing to lower tectonic seismicity prior to exploration and thicker crust increasing the likelihood of larger magnitude seismicity. Several EGS projects have experienced earthquakes during the exploration portion of the projects that caused significant damage, e.g. Basel, Switzerland (2006) and Pohang, South Korea (2017). Other more recent EGS projects have experienced little seismicity of concern for the safe operation of reservoir development, e.g. Milford, Utah (2022) and Blue Mountain, Nevada (2022). Both sites benefited from experience gained in previous EGS projects, extensive site characterization, and adherence to Best Practices developed in response to earlier unsuccessful projects. In all cases, probabilistic seismic hazard analyses (PSHA) are crucial steps during planning and stimulation. These generally include a variety of models that can range from simple relationships between expected seismicity and injected volume to detailed geomechanical models of resulting seismicity. Aseismic deformation is seldomly accounted for, although recent research suggests it plays a significant role in the deformation in geothermal resources. Here I will discuss the inclusion of deterministic reservoir models in standard PSHA models and focus on the effects of aseismic deformation in geothermal and EGS settings. Continual improvement in PSHA and reservoir exploration and stimulation that are part of EGS development can ensure that the vast potential of EGS can be unlocked safely.
Calibration of 2D Finite Element Method Rockbolt Models to Fiber-Optic Axial Load Testing Data for Grouted Rebar Rockbolts
Authors: Fischer C. P. , Diederichs M. S. , Forbes B. 
Published: August 2024

ABSTRACT:
In modern numerical modelling software, several rockbolt models are available to practitioners for the design of tendon rock support in underground excavations. In this research, two applicable rockbolt models for the modelling of grouted rebar rockbolts are implemented in the 2D Finite Element Method (FEM) modelling program RS2, and compared to the behaviour of fiber-optic instrumented grouted rebar rockbolts in axial pull testing by Forbes (2020). Rockbolt models are assigned strength and stiffness properties based on manufacturer specifications and parameters found in the literature, and model results are compared to Forbes (2020) testing data to assess the fidelity of the rockbolt load development and deformation response. Subsequent model calibration and sensitivity studies are performed, demonstrating considerations for the selection of an appropriate bolt model and bond interface parameters for the design of rebar rockbolts, where pre-yield rockbolt behaviour is of focus.

1. INTRODUCTION
Grouted rebar rockbolts are widely used in civil and mining engineering to control rockmass displacements and improve excavation stability (Kaiser et al. 1996, Hoek 2007). Grouted rebar support is coupled to the rockmass using a cementitious or resin grout material, and generates shear resistance to movement primarily through mechanical interlock between the bolt and the grout, and the grout and the rock. Grouted rebar rockbolts are classified as continuously mechanically coupled support (Windsor 1997).
The numerical simulation of tendon rock support for excavation design can be achieved using material models or structural elements. Structural elements are practical for large-scale problems, as material models require finer mesh that is less computationally feasible for most larger-scale excavation design problems. A multitude of structural elements have been developed across industry numerical modelling programs (e.g. Jalalifar and Aziz 2012, Swoboda and Marence 1991, Marence and Swoboda 1995), incorporating different combinations of parameters to address material and interface strengths and stiffnesses. To properly represent the functioning mechanisms of a rockbolt in a numerical model, an appropriate rockbolt model and appropriate input parameters for the bolt materials and interfaces must be selected. Such parameters control how load is transferred between the rockmass and the modelled support element.
Investigating Mechanical and Acoustic Properties of 3D Printed Materials: A Focus on Printing Orientation
Authors: Ifrene Ghoulem , Pothana Prasad , Egenhoff Sven , Nagel Neal , Hickey James 
Published: August 2024

ABSTRACT:
Stereolithography (SLA) 3D printing technology is increasingly applied in geomechanics, petroleum engineering, geothermal, and CO2 storage research, particularly in fracture flow and mechanics. To understand the mechanical characteristics of 3D printed materials, we conducted laboratory experiments examining the effect of printing orientation on the properties of three specimens. These specimens were printed using a FormLabs (3B+) 3D printer at layering angles of 0°, 45°, and 90°, with a resolution of 100μm, and sized 1-inch in diameter and 2-inches in length. We performed triaxial compressive tests, ultrasonic elastic wave velocity measurements, and unconfined compressive strength (UCS) tests using an Autolab 1500 test frame. Incremental confining pressures from 1 MPa to 20 MPa were applied to explore static and dynamic mechanical properties. The UCS tests showed that all samples exhibited ductile behavior with similar stiffness and yield strength across different layering angles, demonstrating a stiffness of approximately 4 GPa and compressional wave velocities between 2555-2580 m/s at zero confining pressure. The findings confirm the mechanical and acoustic consistency of the samples, supporting their suitability for advanced geomechanical applications.

1. INTRODUCTION
Three-dimensional (3D) printing technology, also known as advanced manufacturing (AM), is a rapidly developing field that has revolutionized manufacturing processes across various industries including aerospace (Richter & Lipson, 2011), automotive (Rahim & Maidin, 2014), healthcare (Logan & Duddy, 1998), petroleum engineering (Li et al., 2021), and geomechanics (Phillips et al., 2021). This technology uses computer-aided design (CAD) to create three-dimensional objects by adding material layer by layer using almost any type of material such as polymers, and ceramics. Thermoplastic urethane and metals can also be employed as raw material (Gopinathan & Noh, 2018).
There are several techniques involved in 3D printing, including Fused Deposition Modeling (FDM), Stereolithography (SLA), Selective Laser Sintering (SLS), Digital Light Processing (DLP), Binder Jetting, and Material Jetting. Each technique has its advantages and disadvantages (Jandyal et al., 2022), and the choice of technique depends on the type of object being printed, the desired resolution, and the available materials. With the increasing popularity and availability of 3D printing technology, it is now relatively easy to create custom objects, prototypes, and even entire structures using 3D printing. Among the available techniques, SLA is known for producing high-resolution objects with smooth surfaces. SLA was first developed in the early 1980s by Kodama, 1981 and called Rapid Prototyping (RP).