bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Cemented Casing Test Cells with an Ultrasonic Phased Array Transducer for Cement Bond and Corrosion Logging
Authors: Guedes Orland , Van Os Roel , Titton Izabela , Li Zheng , Hori Hiroshi , Ishberdina Gulnara , Singh Kamaljeet , Gardner David , Simensen Per 
Published: February 2025

Abstract
Pulse-echo ultrasonic measurement techniques are used in the oil and gas industry for imaging casings and tubings for cement bond and corrosion evaluation. Conventional downhole ultrasonic measurement tools typically consist of one or multiple ultrasonic transducers, that probes inner surface and are rotated to provide full azimuthal coverage. This paper proposes a method of achieving this using phased array transducers.
Phased array pulse-echo methods are widely used in non-destructive testing and medical applications. In a typical operation, multiple elements are activated in collaborative fashion to transmit and receive the ultrasonic waves. By introducing de-phasing among the elements, the ultrasonic beam can be shaped and directed onto regions of interest to target. The main advantage of this technique for cased hole imaging is the versatility thanks to a high number of emitting and receiving elements that are placed around the circumference of the tool; electronic scanning can replace the mechanical rotation that requires complex mechanical systems.
SLB has developed such a phased array ultrasonic transducer integrated into an experimental prototype tool and conducted logging in test cells at the NORCE Norwegian Research Centre facility. The test cells are made of a variety of pipes with designed cementing defects. In this paper, we will introduce an overview of downhole phased array measurements and present test cell logs in comparison to the reference logs from commercial tools. The results show a good agreement between images obtained from the legacy and new phased array sensors in the tested conditions.
This paper reports one of the first well integrity measurements performed with an ultrasonic phased array for azimuthal cement bond and pipe thickness imaging. On the other hand, the simplification of the tool architecture allows a reduction of the outer diameter and unlocks the possibility to deploy such a tool on monocable in diameters starting from 3.5 in. casing/tubing, which was not available before.
Gas Tight Cementing Valves and Casing Annular Packer Prove Successful in Achieving Multiple Isolation Objectives Across a 10,200ft Interval in a Single Trip
Authors: Hrabovsky B. W. , Bermudez F. Z. , Bamber J. 
Published: February 2025

Abstract
Working in an offshore field, recognized as one of the world’s largest natural gas reserves, with a unique geological composition presents multiple challenges for oil and gas operations. The formations within the field are characterized by high porosity and varying permeability, which contribute to their potential for instability during cementing operations. The integrity of cement barriers is paramount, as failures can lead to gas migration, loss of hydrocarbon resources, and environmental hazards.
The geological landscape of the field includes a variety of formations, each with distinct characteristics that influence cementing operations. These formations often exhibit high-pressure zones interspersed with permeable intervals, making them particularly susceptible to breakdown during conventional cementing processes. The variability in formation properties complicates the cementing process. Traditional methods often struggle to maintain cement integrity in these environments, leading to issues such as loss of circulation, inadequate zonal isolation, and the risk of sustained casing pressure. Each of these challenges necessitates a tailored approach to cementing that considers the unique conditions encountered in this field.
Cementing is a critical process in well construction, as it establishes a secure barrier between the wellbore and surrounding formations. The ability to achieve zonal isolation and maintain pressure integrity is essential, especially in the presence of high-risk formations. This paper aims to explore the innovative cementing strategies employed in this operation, focusing on the integration of advanced technologies that enhance annular seal integrity, reduce operational complexities, and optimize well design.
Assessment of High-Magnesium Brine Resistance in Various Well Barrier Systems
Authors: Binns Matthew , Johnson Carl R. , Ficetti Silvina 
Published: February 2025

Abstract
Identifying effective well barrier materials for new energy applications such as carbon capture and sequestration (CCS), critical mineral mining and geothermal wells has become increasingly important in the energy industry. Laboratory testing was conducted to compare the brine resistance of various cement systems to a specific high-magnesium content brine under low and high-temperature/pressure conditions. This study was initiated due to the increased availability of pozzolanic blend components and the lack of recent studies using these new blend components.
Testing was conducted at low and high temperatures and pressures (60°C/121°C and 14.7 psi/5000 psi, respectively). Each sample was prepared from cured material and subsequently cored. Low and high-temperature testing involved curing cores for a minimum of seven days, with several cores at each temperature and pressure being tested prebrine exposure to provide reference data. Additionally, computerized tomography (CT) analysis was conducted on a single core in each system. For brine-exposure cores at low temperatures, each core was placed in an individual sample bottle containing a specific synthetic brine for 30 days. For brine-exposed cores at high temperatures, cores were submerged in the same brine inside a high-pressure high-temperature (HP/HT) curing chamber for 42 days.
The post-curing properties of the brine-exposed core samples revealed multiple effects relative to the type of barrier material being evaluated. Depending on the system, visual effects (cracking, precipitation, crumbling, flaking) and internal effects (reaction front, strength loss, mass changes) were quite distinguishable in some cases. All systems tested experienced brine attack to some degree, with several systems showing significant attack and integrity degradation. In one case, a thick gel precipitate formed, which, after X-ray diffraction analysis, was found to be a mixture of bischofite (hydrous magnesium chloride), tachyhydrite (hydrous chloride of calcium and magnesium), and levyne-Ca (hydrated calcium silicate mineral). The same sample had expanded, cracked, and was crumbling. CT analysis revealed there was an impact on the development of the reaction front depending on the slurry additives and fillers used, some beneficial and some detrimental, i.e., change in compressive strength. Test results and the varying degrees of resistance to the brine for all the systems are discussed.
New data are presented on barrier materials that use non-API (American petroleum institute) cements in the presence of certain pozzolanic materials. These materials enhance the set properties of the barrier material in an aggressive magnesium brine environment. Additionally, the impact of specific commercially available additives is discussed with recommendations. Overall, this work aims to support improvements in well integrity in wells such as geothermal producers, where aggressive brines can be common.
Novel Spacer Technology Improves Well Integrity in Complex Cementing Scenarios in the North Sea
Authors: Kaastad A. , Nascimento F. , Yasser H. , Lo R. , Bermudez F. 
Published: February 2025

Abstract
North Sea lithologies are often complex, creating challenging environments during cementing operations. Ensuring wellbore stability and zonal isolation are pivotal throughout a well's lifecycle and to achieve an optimal top of cement, therefore preventing lost circulation is imperative during the primary cementing operation. The deployment of this novel spacer technology has enabled superior cementing jobs, which not only helps operators in minimizing downtime but also enhances their environmental stewardship by avoiding remedial work, and reducing additional cement use.
In modern upstream activities, economics are key to any drilling and completion operations. Lost circulation is a costly problem for drillers, causing non-productive time, wasted material, additional trips, unplanned casing strings, and can even cause additional problems later in the life of the well if proper zonal isolation is not achieved. The cementing operation, while a small portion of an operator's overall drilling budget, is a key component of ensuring a well is constructed with the necessary annular barriers. This paper discusses a novel lost circulation spacer, showcasing its performance, and results from case histories.
Engineered Drill Bit Cutting Structures for Interbedded Applications Suppressing Lateral and Torsional Excitation at High Performance and Durability
Authors: Hanafy A. , Kueck A. , Duffy S. , Benzaoui T. , Fankhauser E. , Evans K. , Doster M. , Bomidi John 
Published: February 2025

Abstract
Drilling dysfunctions are big challenges while drilling interbedded formations. Adding to the excessive loads on cutters during soft to hard transitions, the lateral and torsional dysfunctions can be detrimental for the bit and BHA. Recent research proved that the excitation of these vibrations happens at the cutter/rock/fluid level (Jain et. al. 2014, Kueck et. al. 2023). This work evaluates the excitation of dysfunction by current cutting structures of drill bits and showcases the capability of a novel cutting structure that promotes stability, performance, and durability.
This work integrates modeling and simulation data with a full-scale drilling simulator and in-bit sensing to deepen the understanding of lateral and torsional excitation and drilling interbedded formations. Moreover, it lays out a framework to iterate on cutting structures to enable drilling stability without jeopardizing bit performance and durability. This iterative design tool is implemented to deliver a cutting structure that suppresses the excitation extent and enables performance and durability gains. The final cutting structure is benchmarked against the application established structure in a high-pressure drilling simulator. The potential stability and performance gains are validated in the field.
The design framework shows the capability to predict the different cutting structures responses with simulation validated by their performance in the lab and field. The newly developed cutting structure shows a significantly different excitation of High-Frequency Torsional Oscillations (HFTO) in simulations and lab drilling. Furthermore, the cutting structure enhances ROP response to applied WOB and helps distributing the cutting loads on the cutters to avoid shear failures due to overloading. The lab scale drilling simulator shows vibration reduction nearing 25% without HFTO or lateral vibration and performance gains up to 25% in ROP. The application in the field showed positive results with better bit dull grade and fewer bit and BHA failures.
Finally, this approach targeting challenging applications has proven the capability to shorten the number of bit design iterations. The coupling of modeling and lab simulation generating a better understanding of the bit response enabled guided cutting structure conceptualization and an efficient iterative design approach. Providing stable bits enables faster drilling and fewer bit and BHA related failures.
Enhancing Wellbore Integrity: The Impact of Fine Particle Mudcake on Fracture Initiation Pressure
Authors: Hamidov E. , Baldino S. , Ozbayoglu E. , Zhang J. , Chellappah K. , Routh A. 
Published: February 2025

Abstract
Wellbore integrity is essential for preventing lost circulation and ensuring drilling operations remain productive and cost-effective. This study explores the role of fine particle mudcake in enhancing fracture initiation pressure, building upon previous research to provide a deeper understanding of how fine particles contribute to wellbore strengthening. Utilizing an advanced true triaxial testing setup, this investigation evaluates the impact of various drilling fluid formulations on mudcake formation and wellbore stability. The effects of mudcakes, as well as scenarios without mudcake were examined. In addition, a series of modified API filter tests have been utilized using different mud formulations such as MgO, Latex and Ultrafine Barite. Our results reveal that both mudcake and fine particles can contribute to wellbore strengthening through a combination of fracture plugging, stress redistribution, and fracture propagation resistance. The results demonstrate the potential for optimized drilling fluids incorporating mudcake and fine particles to improve wellbore stability and mitigate lost circulation events, offering a promising alternative to conventional wellbore strengthening methods. This research underscores the importance of considering both mudcake and fine particles in drilling fluid design and provides a foundation for further exploration of their combined role in enhancing wellbore integrity and lost circulation management.
Re-Defining the Limiter in LWD NMR - Unique Case of Designing the BHA for Specific Objectives
Authors: Ijasan O. , Story S. , Jing I. , Fazal A. I. , Ramadan Z. , Seitz J. , Shrivastava C. 
Published: February 2025

Abstract
An innovative logging-while-drilling (LWD) Nuclear Magnetic Resonance (NMR) acquisition program was designed, tested, validated, and deployed to accurately measure bound-fluid pore volumes in siliciclastic formations. Field development in deepwater operations required bound-fluid logging in horizontal wells to reliably interpret water saturation, properly characterize reservoir quality, and improve rock physics modeling. However, LWD NMR has always been considered a limiter in the drilling bottom-hole assembly (BHA) due to low drilling rates required to avoid spin over-polarization and acquire measurement with optimal vertical resolution of formations in the subsurface. This often results in slower rates of penetration (ROP) which hinders operational efficiency in high cost deepwater environments.
A recent NMR acquisition sequence, with a 10-second acquisition cycle at 200 ft/hr, focusing on bound-fluid has redefined this limiting factor with deployment in deepwater operations. This lead to acquisition of high-quality NMR data for specific fit-for-purpose applications while doubling the ROP. Forward modeling was performed to evaluate strengths and limitations of this 10-second acquisition configuration. Furthermore, this robust bound-fluid sequence was extensively verified and validated with tool architecture, electronics, and hardware while all withstanding heavy duty cycles. Additional modeling was performed using known formation properties and the new 10-second sequence provided better vertical resolution of 2.8 ft while responding to facies variations in the wells of study. This is compared to 8.3 ft at 200 ft/hr with a standard 30-second sequence. The sequence was implemented in successful field deployment, thereby redefining the limiting factor of slow ROP for LWD NMR acquisition. This advancement achieves logging objectives while enhancing the overall efficiency of deepwater drilling operations.
Fatigue Strength Evaluation of a Variety of Drill Pipes for Challenging Drilling in 7000 m Water Depths, IODP Expedition "JTRACK"
Authors: Inoue T. , Sakurai N. , Santus C. , Romanelli L. , Bhukya S. 
Published: February 2025

Abstract
The fatigue resistance of a drill pipe is a critical factor affecting the performance of deep drillings. This study focused on the determination of fatigue strength, through full scale tests, on a selection of actual drill pipes, and the evaluation of the entire drill string fatigue resistance after the analysis of these test results. The fatigue tests cover a variety of drill pipes such as 165, 150 and 140 ksi grades with Delta, GPDS or DSTJ connection, new and used pipes. A resonant fatigue test machine was used to perform rotating fatigue tests on full scale drill pipe sections (or specimens) with dual measurements combined with a control software to keep stress amplitude constant. After these tests, the numbers of cycles to failure were experimentally evaluated along with the observation of the crack initiation locations that resulted to be dependent on several factors as discussed in the paper. Using these test results, the fatigue evaluation of drill string, planned for International Ocean Discovery Program (IODP) expedition 405 JTRACK operations, was examined by calculating the cumulative damage ratio to find the possible endurance of the operation. It was found that a specific type of drill pipe has higher fatigue strength than others, so the use of that drill pipe will contribute significantly to the prevention of fatigue failure during the offshore drilling expedition.
Real-Time Downhole RPM Range Prediction for Improved Stick-Slip Detection Using Ensemble Machine Learning
Authors: Zhang M. , Kaya M. E. , Habib N. , Groh A. , Small A. , Xue Y. , Walthall J. 
Published: February 2025

Abstract
Understanding downhole dysfunction, such as stick-slip, is critical for preventing downhole tool damage and reducing non-productive time during drilling. Common methods for quantifying dysfunction intensity, such as a surface Stick-Slip Index (SSI), often fail to capture the complex relationships between surface measurements and downhole behavior. This can lead to improper evaluation of actual downhole conditions and driller response. This paper presents a machine learning model for real-time downhole rotations per minute (RPM) range prediction with surface data which is coupled with an ensemble framework for more robust stick-slip detection and quantification.
This method utilizes a combination of models to blend machine learning with subject matter expertise and physics-based features to improve real-time detection of downhole stick-slip and to quantify its severity. In contrast to surface SSI, which focuses exclusively on surface torque, this method combines additional traces into a downhole RPM prediction model using gradient-boosted trees. Downhole data from 84 runs were used to train and validate the downhole RPM prediction model with eight runs being used as hold-out test data. This prediction was evaluated in combination with wavelet transforms to quantify the severity of stick-slip. Next, the model was deployed across the fleet to enable collection of data in real-time. The output is then linked to bit dull grade data for damage analysis.
When evaluating the model's predictions for downhole RPM range, we achieved good performance on the validation set, with over 50% RMS (root-mean-squared) error reduction from both the naïve predictor (average RPM range), and a surface SSI-based regression tree model. Similar improved performance was observed when evaluating the hold-out bit runs from the same region. The model's ability to generalize to other regions is an area for future study, but we hypothesize that the training dataset may need to be expanded with representative wells to achieve similar performance in new regions. Finally, timeseries data for 1,270 additional runs from 496 wells have been processed utilizing the full ensemble model. The results are compared with their associated bit dull grade records to understand the correlations between stick-slip metrics and bit damage.
This study presents a better approach for determining downhole stick-slip risk in real-time, using a data-driven approach to minimize the requirement for detailed engineering input to run the model. Additionally, it highlights that surface SSI is poorly correlated with actual downhole RPM behavior, only marginally outperforming the naïve estimator. This implies that surface SSI alone is not enough for identifying damaging stick-slip. Interestingly, the surface SSI ranked highly in feature selection, suggesting that there is meaningful information stored within the metric itself but that it loses value without additional context.
Low Thermal Conductivity Coating Extends BHA Life and Improves Drillstring Performance in Challenging High-Temperature Environments
Authors: Fard Reza S. 
Published: February 2025

Abstract
In shale plays like the Haynesville in the US, elevated formation temperatures and abrasive, high-weight drilling muds shorten the working life of bottomhole assemblies (BHAs) and surface equipment. The result is more trips downhole, increased nonproductive time (NPT), and costly tool repairs. This paper reviews a field study conducted by a major operator to evaluate a novel, low thermal conductivity-coated drillpipe for long-lateral drilling operations in the Haynesville.
The paper reviews the development of the low thermal conductivity coating, built on established coating solutions that protect tubulars in aggressive oil and gas environments from corrosion, wear, and deposit buildup while improving hydraulic efficiencies. Several coating formulations were evaluated for their ability to reduce heat transfer through the tubing to keep drilling fluids and bottomhole assembly (BHA) tools cooler and running longer. The paper also reviews the operator's modeling work to simulate the temperature profile while drilling through the formation, which helped optimize the coating design and drilling plan before going to the field.
The iterative coating development and testing process resulted in a coating system with a thermal conductivity of k=0.1808 W/mK, nearly five times lower than the initial coating formulation and 250 times lower than steel pipe. The temperature profile showed excellent alignment with the model in the first well drilled with the new insulated, coated drillpipe. The coated pipe kept sensitive BHA components cooler and reduced the number of roundtrips for tool repairs and replacements.
Based on these results, the operator estimates that the low thermal conductivity coating saved an average of two BHAs per lateral across the entire drilling area, with some of the hottest areas of the Haynesville basin saving more than four BHAs per well relative to historical performance. This BHA savings translates to significant savings in drilling costs and nonproductive time. It also minimizes the number of trips to retrieve heat-damaged BHAs, a significant saving considering that each trip costs several hundred thousand dollars. Drilling operations in other high-temperature, harsh downhole drilling environments, including geothermal and deepwater HP/HT wells, will likely see similar cost, time, and carbon footprint reductions with this low thermal conductivity-coating.