bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding Field-Scale Hydrogen Storage Performance in Saline Aquifer Using Experimentally Measured History-Dependent Saturation Function and Numerical Simulation
Authors: Omeke J. , Siddharth M. , Retnanto A. 
Published: February 2024

Abstract
Surpassing natural gas in energy density, underground hydrogen storage (UHS) and its subsequent utilization offer a pivotal advancement in large-scale energy strategies, countering renewable energy fluctuations and reducing anthropogenic emissions. Like other storage systems, UHS is still in its infancy, with limited experiments characterizing the multiphase flow of hydrogen in aquifers. These flows are described using saturation functions (curves in reservoir simulation representing the relationship between relative permeability and capillary pressure). Given the periodic injection and production of hydrogen, saturation functions don't rely solely on current saturation; they also consider the path or history the saturation has taken, facilitating transitions between drainage and imbibition also known as hysteresis. Recent publications underscore the significant influence of hysteresis on recovery factors, and neglecting these effects can introduce substantial uncertainties in cumulative hydrogen recovery.
While many UHS simulations have used individual saturation functions (With or without hysteresis), results vary depending on the experimental curve selected. In this study, we take a more holistic approach. We've combined the four most recent and improved hysteresis-based saturation function measured directly from hydrogen-brine experiments. Simulating under specific reservoir conditions, we are assessing how these combined curves influence hydrogen storage and recovery. To provide a tangible perspective on potential field-scale effects, we demonstrated our findings using a simulation based on actual field data. Through this method, we aim to offer a more cohesive insight into recovery outcomes across these different experiments.
In this study, when applying various experimental curves to the reservoir model, a mere 9% difference in recovery was observed. This indicates a relatively minimal variability in recovery outcomes across different saturation function experiments and injection-production schemes. Moreover, overlooking hysteresis might result in recovery overestimations ranging from 3% to 16%.
Use of Ranking and Clustering Analysis for Robust Well Placement and Efficient Reservoir Sweep
Authors: Al-Ismael M. A. , Abouheit F. F. , BuKhamseen N. Y. 
Published: February 2024

Abstract
With the advancement in technology and the growing availability of data sources, the size of data in the oil and gas industry is increasing at an exponential rate. While large subsurface datasets present more opportunities for field development planning, they also present some challenges in data mining and analysis. This work presents methodologies that can help unlocking the potential of reservoir models to drive insightful field development planning activities more efficiently. A simulation model of a synthetic heterogeneous reservoir is used in this work to evaluate reservoir opportunities for placing new wells. A 3D map of an opportunity index is first prepared using dynamic reservoir properties. Ten clustering analysis methods are then used to group the 3D map grid cells into different target regions. The generated regions are ranked based on their average reservoir opportunity index and hydrocarbon volumes. Ten new wells are then designed and placed in the highly ranked regions and then evaluated using numerical simulation. Results from the ten clustering methods are compared. Each clustering method resulted in a unique set of regions and hence, different locations and designs of wells. The comparison is performed by measuring the overall performance using cumulative oil production as well as by analyzing the clustering quality using silhouette score. The regional-based ranking resulted in an improved reservoir sweep. However, it may not be the optimal due to rig scheduling constraints since the selected regions are scattered. The analysis shows the impact of tuning the hyperparameters of the clustering methods and their significance on generating optimum target regions. This work highlights potential opportunities to improve the sweep efficiency in hydrocarbon reservoirs by capitalizing on data analysis techniques that complement conventional metrics and methodologies. It demonstrates an integration between clustering analysis and reservoir opportunity workflows which can lead to optimum field development planning.
Experimental Study on Stuck Pipe Release by BHA Whirling
Authors: Machocki K. , Aljohar A. , Nazzari I. , Vaziri V. , Wiercigroch M. 
Published: February 2024

Differential pressure sticking (DPS) is one of the most common causes of pipe sticking when a drill-string rests on a borehole wall or even is submerged into a mud cake [1]. Differential sticking can significantly impact the cost of wells and non-productive time for the rig and usually harms the environment, particularly if the BHA has to be abandoned downhole. Failure to free a drill-string leads to significant financial losses due to contractual charges, time-consuming interventions, hole abandonment, side track requirements, environmental problems and others. The existing technology can apply only a limited axial force and jarring load to the stuck object. Thus, a new method should be developed and employed to release differentially stuck pipe problems.
To overcome DPS, a concept of the "Advanced Shock Tool" was proposed by Saudi Aramco in the patent US2019368295 [2]. The idea of this tool stems from generating periodic or chaotic lateral loads on the stuck point rather than applying conventional methods, subjecting the stuck point to axial impact loading only. The expectation is to generate these additional forces by applying torque on the asymmetric pipe section above the stuck point, with under-gauged stabilisers and a rotary tool disconnecting torque transmission from the stuck point.
To address the above-discussed challenge of a differentially stuck pipe, a large-scale experimental rig was designed, manufactured, installed and instrumented to investigate the whirling motion of a shaft interacting with housing to mimic the new jarring method introduced earlier. This experimental study focuses on generating large lateral vibration by developing a robust backward whirling motion, examining the possibility of generating and sustaining such dynamical responses for a wide range of parameters, and ultimately proving the concept of the Advanced Shock Tool in a large-scale experimental setup. The following sections describe the developed experimental setup, experimental strategy and the main results.
New Technology Enables Effective Geosteering Optimization in Low Resistivity Pay – Case Study from Offshore China
Authors: Yang Yong , Hu Wenli , Feng Jin , Xie Xiong , Wang Haifeng , Wang Fei , Wang Chao , Chang Botao , Li Tong 
Published: February 2024

Abstract
Field X in offshore China has a target reservoir with characteristic of low resistivity and low permeability. Resistivity of the target zone is as low as 1 Ohm.m to 3 Ohm.m, while the surrounding calcareous interbeds have only slightly elevated resistivity of 2 to 5 Ohm.m. Besides this, the thickness of the target zone can be as thin as 1 m. Conventional resistivity based geosteering tool usually could not map these boundaries clearly, which often resulted in poor geosteering performance and sometimes sidetracks.
A new directional resistivity tool with new sensor and newly invented measurements, along with a novel inversion process, brings hope to tackling the geosteering challenges in this type of environment. In addition to the axial and titled antennas that were already in the conventional tool, this new tool has introduced a transverse antenna that could better measure formation anisotropy and hence help delineating thin layers. A new family of deep resistivity measurements are also added to increase the detection range of the tool and the mapping capability for low resistivity environment. Finally, a new multi-layer deterministic parametric inversion method is designed and can take full advantage of the new measurements, to achieve higher resolution and larger depth of detection at the same time.
The new tool was utilized in a recent infill campaign for the field X to place horizontal sections in this low resistivity payzone. With the improved mapping capability of the tool, the operator was able to geosteer within the thin and low resistivity target zone with high net-to-gross (NTG) and success rate. In one of the examples illustrated in this paper, the target zone was only 1.3m thick, with calcareous interbed above and below. The resistivity contrast was very limited, with resistivity of the target zone and the calcareous interbed less than 2 Ohm.m and 4 Ohm.m respectively. Under this very challenging environment, the operator achieved 861 m horizontal section with 100% NTG. The calcareous interbed below was mapped clearly which enabled the operator to make informed geosteering decisions to maximize reservoir exposure for horizontal sections.
This new technology opened the door for developing the low resistivity pay in this field effectively. With the enhanced remote mapping capability, the operator now is able to drill longer horizontal sections with better NTG which ultimately helps achieve increased production.
Preventing Drill String Twist Offs Due to HFTO coupled with High Stick-Slip RPM for RSS BHAs
Authors: Singh Varun 
Published: February 2024

Abstract
All drilling dysfunctions or vibrations including High Frequency Torsional Oscillation (HFTO) are monitored in real time with current technology of Drilling Bottom Hole Assembly (BHA). There are certain limits set for each kind of vibration and drilling parameters are optimized while drilling to overcome these dysfunctions. The main objective of this paper is to present a detailed case study of showing the impact of HFTO within the permissible limits which can be monitored in real time, combined with lower to moderate levels of stick slip leading to twisting off Rotary Steerable System (RSS) drilling BHAs. This paper covers the implementation of a new strategy to eliminate twisting off BHAs due to HFTO thereby avoiding Non-Productive Time (NPT) and any additional costs that could be incurred due to an incident such as fishing, unplanned sidetracks etc.
Drilling with PDC bits across Anhydrites always generates HFTO. However, frequency and amplitude of HFTO depends on the type of Bit, rock strength, BHA configuration and drilling parameters. Historically, in the majority of BHA twist off incidents, real time vibrations and drilling parameters are within the maximum allowable tool limits. Monitoring HFTO in real time (RT) is limited due to high sampling rate of vibration data which cannot be transmitted in real time. With the advancement of technology in RSS all high frequency vibration data is stored while drilling and can be analyzed after the run. Memory analysis along with HFTO modelling were carried out for multiple runs to evaluate the impact of torsional loads. Detailed analysis of this high frequency memory, formation behavior, drilling parameters and bit features was done to compare between good and failed runs. Based on the analysis, new guidelines and corrective actions were implemented to eliminate BHA twist offs.
Based on the memory analysis and modeling, torsional loads were higher during stick slip events exceeding tool's limits leading to twist off and it was found to be common in all twist off incidents. New corrective actions were implemented on subsequent runs that resulted in avoiding twist offs by 100%. This translated to reduced trips for failure, tool maintenance cost and improved overall efficiency. In certain applications, depending on the above-mentioned factors HFTO will trigger, however with an optimized well program, drill string twist-off can be avoided.
The methods and processes presented in this paper can be applied globally in the areas with similar challenges. This would result in delivering the wells in the most efficient way by reducing lost time and improving efficiency.
Advanced Techniques for Mapping Oil-Water Contacts
Authors: Taher A. , Fouda M. , Osman H. , Alotaibi A. 
Published: February 2024

Abstract
Lateral variation of water levels can pose a great challenge to successful placement of horizontal production wells. Continuous identification of water levels has been traditionally achieved by logging old vertical or deviated wells drilled in the area, or by drilling new ones for evaluation purposes. This process is usually costly, time-consuming, and does not resolve the lateral uncertainty between those wells. This paper discusses the effectiveness of traditional and advanced modern techniques for identifying varying water levels, for successfully placing horizontal wells in the reservoir.
Traditional techniques to identify water levels based on vertical or deviated well logs utilize resistivity data from logging-while-drilling (LWD) or wireline tools. The results of using different types and frequencies of LWD and wireline resistivity measurements were analyzed. In addition, LWD formation testing data were used for calculating pressure gradients to confirm fluid type and density, as well as estimate formation water salinity. While drilling horizontal sections, evaluation of the oil-water contact (OWC) can be achieved using 1D and 3D inversion from deep and ultra-deep resistivity tool measurements. This technique, using real-time data, provided good estimates of fluid boundary positions. Advanced 3D inversion techniques were also examined to distinguish between the lithology of layers with similar resistivity values.
Comparing the different modes and frequencies of LWD propagation resistivity has shown how evaluating water zones in deviated wellbores has several challenges, depending on which resistivity response is used for the evaluation. Calculating pressure gradients with LWD formation testers is shown to be a successful approach although challenges can be faced due to using different drawdown rates compared to wireline testers. For horizontal wells, real-time fluid mapping using deep and ultra-deep resistivity allowed the assessment of lateral variations of the OWC, making it possible to maintain a distance from the water contacts while drilling. The utilization of 3D inversion for resistivity and anisotropy helped to determine the fluid type and lithology at a distance, where anisotropy evaluation was the differentiator for situations where shale and water-bearing sand zones had very similar resistivities. Integrated data from multiple wells allowed mapping of the water level as a three-dimensional surface at a wide multi-well scale.
This paper presents an integrated approach to mapping OWCs using traditional and advanced techniques. The data used for single-well and multi-well analysis enabled proactive well placement as well as better planning of future wells.
Study on 4D Geomechanical Modelling for Fault Critical Re-Active Stress Evaluation in Underground Gas Storage
Authors: Zhou Daiyu. , Tang Yongliang. , Zhou Wei. , Wu Zangyuan. , Wu Yiming. , Yan Gengping. , Huang Zhaoting. , Wang Haiying. , Li Zheng. , Li Yang. , Lian Liming. , Zhang Liang. , Fu Ying. , Huang Xingning. 
Published: February 2024

Abstract
During the high-speed injection and extraction cycle of an underground gas storage reservoir, the pool's pore pressure, effective stress, and faults change periodically, which may cause formation damage and natural gas leakage, thus affecting the sealing of the entire reservoir. At the same time, the non-homogeneity easily causes local pressure accumulation, which makes the pore pressure and effective stress distribution extremely unbalanced, and the local pressure accumulation in the formation is a potential threat to the operation of the gas storage reservoir. At the same time, clarifying the fault stress field evolution can provide theoretical support for raising the upper limit pressure at a later stage. Therefore, the study of four-dimensional stress field evolution characteristics of the gas storage reservoir geologic body is directly related to the safe operation and efficient use of the gas storage reservoir. This paper investigates the evolution characteristics of fault stress fields in light of the characteristics of multi-cycle high-flow injection and extraction cycles in gas storage reservoirs. In this paper, numerical simulation is used to analyze the factors affecting the integrity of the fault. At the same time, gas-water two-phase seepage and flow-solid coupling principles are used to analyze the seepage mechanics and geomechanics of the conceptual model by combining with the integrated software of geoengineering. According to the simulation results, the pressure and stress fields with time and space changes and distribution characteristics were carried out, and the destructive prediction was carried out to find the submerged destabilized parts. A large-scale seepage-stress coupling field model was established based on the field data, and the model's accuracy was verified by simulation. Finally, seepage mechanics and geomechanical analysis were carried out for the actual model, and the results can provide theoretical support for the construction of the project and the adjustment of the injection and mining program in the later stage to improve the upper limit pressure.
Research on Intelligent Optimization of Intermittent Lift Systems for Low Production Oil Wells
Authors: Ma Gaoqiang , Yu Yanwen , Zhao Ruidong , Shi Junfeng , Wang Jianyu , Zhang Xishun , Chen Shiwen , Chen Guanhong 
Published: February 2024

Abstract
In later stages of production, the depletion of formation energy can lead to a severe shortage of fluid supply, causing oil wells to operate at suboptimal production levels and reduced efficiency. Intermittent lift, as an effective solution, can enhance pumping efficiency and reduce wear and tear on both surface and downhole equipment. To establish a practical intermittent lift system, it is crucial to have a precise understanding of the dynamic fluid level and its evolution. This paper addresses the fluid level and its relationship with time-series indicator diagrams, accounting for factors like changes in inertia, friction, vibration, pressure, and fluid properties. Based on this fluid level recovery/decline law, a self-learning and self-optimizing intermittent lift system is introduced, with the goal of maintaining the liquid level within a predetermined range while maximizing daily oil production per energy consumption. The optimal design of the intermittent lift system is centered on the fluid level. Comparative analysis with existing models, such as Zhang's and Li's models, reveals a significant reduction in the average error, from 30% to 11.6%, with the implementation of this new model. Following a thorough on-site analysis, a manual intermittent lift well is selected for the implementation of intelligent design. A comparison with the manual intermittent lift system demonstrates significant improvements. The duration of switching the well on and off is reduced from days to minutes, resulting in a 4.1% increase in system efficiency, a 36% reduction in power consumption, and a 0.16t increase in oil production. This paper introduces an intelligent intermittent lift system, facilitating the transition from manual to intelligent operations while ensuring consistent fluid level adjustments. Furthermore, the system can be optimized to align with electricity pricing fluctuations, leading to cost savings and increased operational efficiency, which has practical significance in enhancing intelligent manufacturing and refining management.
Using AHP and Stochastic TOPSIS for Carbon Storage Screening and Ranking with Uncertainty Analysis
Authors: Ma J. , Gennaro V. D. , Tan B. 
Published: February 2024

Abstract
A methodology is presented for screening and ranking potential carbon dioxide (CO2) geological storage sites, based on the classical carbon sequestration performance factors - capacity, injectivity, and containment. Other nontechnical criteria, such as cost and public acceptance, are also considered. The various criteria are not always quantitative, sometimes conflict, and can address different risks. Their relative importance may depend on the context.
The Analytic Hierarchy Process (AHP) is used to determine the relative weights of different decision criteria. It has the ability for quantitative and qualitative evaluation of attributes, enabling simple and effective determination of relative weights by comparing attributes in pairs. Next, the intuitive Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is applied to calculate site scores and rank sites by comparing each weighted criterion simultaneously for all sites. Monte Carlo simulation is used for uncertainty analysis of results. Finally, sensitivity analysis is provided to show how the ranking results will change when inputs vary.
The workflow was applied to field data from an existing project for carbon capture and storage (CCS) site screening and selection, which had ranked nine sites, using Excel-based score cards and 31 criteria that were chosen based on data availability. After weighting the criteria via AHP, a stochastic version of TOPSIS was used to score and rank the sites, as well as provide an uncertainty analysis. Comparison with the previous unweighted user-dependent approach revealed that the new workflow improved site ranking because the various criteria are assigned weights, and site properties are evaluated based on precise numerical values instead of a range of values. Moreover, the impact of each site property on different aspects of the project (e.g., economics, safety) can be examined. Unlike Excel score cards, where confidence and score are not correlated, uncertainty and sensitivity analyses in the new workflow indicate overall uncertainty of the results.
This novel integration of AHP for criteria weighting and TOPSIS for sites scoring improves the accuracy and efficiency of carbon storage sites selection. Introduction of Monte Carlo simulation assists the analysis of site properties uncertainty influence on final ranking results, which increases confidence in the final choice. Sensitivity analysis provides information on how ranking results will change when inputs vary, consequently guiding data collection next steps to reduce uncertainty and risk.