bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Method for the Estimation of Lost Gas During the Measurement of the Gas Content of Coal
Authors: Lu Meng , Pan Zhejun , Connell Luke D. , Lu Ye 
Published: July 2016

Summary
In this text, the authors present a study on estimating the lost gas during the retrieval process of coal sample within wellbores. A new method is proposed because the traditional ones often give inaccurate predictions. To this end, the major sources of errors with those routine methods are first discussed briefly, and modifications are made accordingly in the present method to improve the accuracy of prediction. This new method takes into account these aspects: (1) Both the advection and diffusion effects are included in the proposed flow equation; (2) the present model uses the actual shape of the core sample (say, a cylinder) rather than a simplified 1D spherical object; and (3) a fully numerical scheme is developed in which the actual retrieval history is used to specify the boundary conditions of the core sample. When the relevant sorption isothermal curve for the coal is known, the proposed model contains three parameters to be determined, which refer to the effective permeability, the effective diffusion coefficient, and the initial gas content or the initial gas pressure. The three parameters are determined through best matching the experimental data with the aid of an artificial-neural-network (ANN) technique. Two application examples are presented in this study. One is with a benchmark laboratory test, and the other is with a standard field case studied by means of an established method. It is shown with the two examples that the present method can give accurate predictions for the lost gas volume concerned, and offers some important advantages that the traditional ones do not have.
Rheology Modification for Safe Cementing of Low-ECD Zones
Authors: Gahlawat Ravinder , Jandhyala Siva Rama , Mishra Vaishali , Patil Sandip 
Published: August 2016

Abstract
Long-term zonal isolation requires effective mud displacement. One best practice for achieving this is to use the highest pumping rates allowable during cementing operations. However, in zones with a narrow pressure window, fracture pressure sometimes does not support higher flow rates. This is because high flow rates result in high friction pressures, which can exceed the fracture pressure of the formation. This is an issue particularly in long horizontal wells. In such cases, fluid rheology is important for achieving better displacement efficiency without inducing fractures.
The current work discusses a procedure in which the rheology of cement slurry can be tuned such that good displacement efficiency is attained at sufficiently low flow rates. The tuning should be such that the shear stress is almost invariant for varying shear rates. This reduces the friction pressures considerably during placement. A hydraulics model was run on an example well configuration with a narrow margin situation. Pressure response and displacement characteristics of two types of slurries were analyzed. These include conventional and modified slurry, the latter of which was tuned for better mud displacement at low flow rates.
The modified slurry showed an increase in yield point with a shear stress profile that was almost invariant for the range of shear rates analyzed. A decrease in equivalent circulating density (ECD) occurred as a result of rheology modification, and this resulted in avoiding ECDs exceeding the fracture gradient at critical locations. Displacement efficiency increased by 10% when using the modified slurry at the same pump rates as those used for the conventional slurry. On the other hand, when targeting the same displacement efficiency as the conventional slurry, the required pump rates for the modified slurry were lower.
This study indicates that better displacement can be attained through rheology modification, even by using relatively low flow rates, thereby maintaining low ECDs to help ensure effective cementing operations.
Appropriate Completion To Prevent Potential Damage of Annular Pressure Buildup in Deepwater Wells
Authors: Zhang Bo , Guan ZhiChuan , Wang Qing , Xuan LingChao , Liu Yongwang , Sheng Yanan 
Published: August 2016

Abstract
Deepwater oil and gas wells will generate annular pressure due to the redistribution of wellbore temperature in production stage when the hyper-thermal fluid is lifted from reservoir formation. Annular pressure threatens casing integrity and well safety. Related accidents have been reported in Mexico Gulf, South China Sea and some other deepwater oilfield. The analysis indicates that annular pressure buildup is so high that deepwater well is in the risk of casing collapse, so it is necessary to take some measures to mitigate annular pressure. Since subsea wellhead is unable to release pressure, appropriate completion measures must be considered. Good understanding of mechanism as well as accurate calculation is prerequisite for appropriate completion, so a model is built based on comprehensive consideration of multi-string interaction and heat transfer process to offer basic pressure data for well completion.
According to Annular Pressure Build-up mechanism, pressure can be controlled by releasing expanded liquid out or getting extra space to accommodate liquid as well as slowing down increasing speed of annular liquid temperature. Some completion technologies can work as mitigation measures. These mitigation methods can be divided into two types: active and passive. Active methods function through increasing heat-transfer resistance or eliminating annulus, including full-height cementing, heat-insulated liquid, thermal-insulated pipes and reducing production rate. Passive methods mitigate pressure build-up by releasing some extra space to contain expanded fluid, including cement shortfall, rupture disc, compressible foam and highly compressible annular fluid. These measures differs at cost, operating difficulty, reliability and working mechanism. Among them, thermal-insulated Pipes, heat-insulated liquid, compressible foam, rupture disc, increase the annular liquid compressibility possess good applicability and have been applied in some wells or tested through experiments. Considering deepwater wells' structure, this paper analyzes the feasible measures and offer design methods.
A Comprehensive Survey Management Workflow
Authors: Schiermeier Pete , Greenwood Jeremy 
Published: August 2016

Abstract
To ensure the highest level of accuracy in wellbore placement, the integration of many survey management techniques is required, which in certain situations includes the integration of relative wellbore position measurements (ranging). The goal is to identify and eliminate all errors and biases that are internal and external to the survey tool to help reduce the positional uncertainty of the wellbore and to determine the relative position of the current wellbore to surrounding wells.
Designing a workflow to achieve the necessary combination of analyses to cover all potential situations required the development of an application that allows an expert user to select and configure the appropriate corrections. It had to be easy to use and provide empirical solutions to the wellsite users in a timely manner to help limit rig interruptions and associated nonproductive time (NPT). Rigorous workflow analysis is required to ensure a high level of quality for the final surveys to meet industry expectations for well positioning and also criteria from governing bodies that demand the final well position be formally recorded.
Current practice involves multiple steps for survey correction, beginning with basic quality assurance and increasing in complexity by identifying instrument biases in accelerometer and magnetometer readings, compensating for local magnetic and gravity anomalies in the subsurface, identifying interference generated by ferromagnetic materials in the drillstring itself and surrounding wells, and compensating for diurnal fluctuations in the earth's magnetic field caused by changes in the intensity of solar radiation. Each of these corrections involves different data sources, from the raw responses of the measurement devices to time-based magnetic observatory data, and the cumulative effect of all of these factors should be determined as accurately as possible to help minimize uncertainty.
The workflow seamlessly combines all of the different correction methodologies currently available and allows the automation of the calculations after they have been configured by the expert. Multiple wells can be assessed concurrently, increasing the amount of time the expert spends on analysis and interpretation and reducing the time required to obtain and manipulate data.
This workflow is unique to the industry because it combines every survey correction methodology available, enabling the analysis of all potential environments and resulting in greater accuracy. Accurate determination of the wellbore position should significantly reduce health, safety, and environment (HSE) risks associated with the potential for wellbore collisions caused by the inherent uncertainty of the wellbore location and can significantly improve reservoir production through optimum placement.
A Semi-Empirical Carbonate Acidizing Model for Chelating-Agent-Based Fluids
Authors: Baghel Vikesh Singh , Pravesh Jag 
Published: August 2016

Abstract
This study investigates, theoretically and experimentally, the effect of conventional and new chelating-agent-based acidizing fluid systems on carbonate formations. An initial assessment showed that an existing semi-empirical model used for hydrochloric (HCl) acid systems was not suitable for predicting wormhole growth and penetration for chelating agents.
With recent advances to acidizing and stringent environmental regulations, chelating agents have begun to replace conventional acid systems for well stimulation. They are more environmentally acceptable and can work in high-temperature wells. One crucial aspect for successful well stimulation of carbonate matrix acidizing is acidizing models. Yet, there have been few attempts to model wormhole growth and penetration for these newer chelating agents.
A semi-empirical mathematical model is proposed for chelating agents based on published experimental data. The results were compared with HCl acid systems.
The predicted wormhole growth was in good agreement with laboratory data for a wide range of temperatures and concentrations. A comparative study with chelating-agent and HCl-acid systems is also discussed. Results showed that pore volume to breakthrough (PVbt) for the chelating-agent-based system increased more steeply compared to the HCl-acid-based system with injection rate. This would translate into higher pumping volumes in the field for a given wormhole penetration if not optimized. This could be attributed to the slower reaction rate of the chelating agent and might require adjustment in transport phenomena for optimized treatment design.
The model developed in this work should help field engineers design treatments with optimum rates and volumes, helping minimize the cost of stimulation treatments. It should also further facilitate understanding of the wormhole formation mechanism for chelating agents.
Using MPD Techniques to Effectively Drill Differently Pressured Layered Sand Reservoirs on Deepwater Development Wells Offshore Malaysia
Authors: Pinkstone H. , Doll R. , Chandra M. , Babcock W. , Tilley V. , Choo B. 
Published: August 2016

Abstract
Previous offset wells drilled in the layered sandstone differentially pressured reservoir formations offshore Malaysia in 1341m water depth, using conventional open system drilling techniques, had experienced lost drilling fluid circulation and hydrocarbon gas kick events, resulting in significant non-productive drilling time, and well control events.
This paper describes how advanced Managed Pressure Drilling (MPD) technology, combined with a drill string conveyed subs based (CCS) continuous circulation system, were deployed on a tender assist semi-submersible rig, and used to effectively and safely drill subsequent development wells. Techniques employed on the project also included Dynamic MPD Well Control and Formation Evaluation procedures, along with dynamic Managed Pressure Cementing (MPC) techniques.
MPD and CCS systems were used, along with MPC, to effectively drill and complete sandstone reservoir layers at various formation pressures depleted from ongoing production, and also over pressured layers charged as a result of water injection activity.
Improving Oil Recovery in Complex Heterogeneous Reservoirs of Highly Mature Oil Fields through Innovative Measurement and Strategies: A Case Study from South China Sea
Authors: Wu Yiming , Zhang Yongjiang , Wang Chao , Chang Botao 
Published: August 2016

Abstract
Located in South China Sea, B oil field has entered into mature development phase. A horizontal drilling campaign was initiated to develop the remaining oil reserve within the heterogeneous reservoirs with multiple laminated layers.
To address the challenges and uncertainties of drilling horizontal wells in these complex reservoirs, an innovative approach and strategy were introduced and employed for optimal well placement in a specific heterogeneous reservoir. This approach includes the advance distance-to-boundary mapping service and the high-definition multiboundary mapping service with the ability to map multiple key boundaries within reservoirs.
Best practices have been developed for using this innovative approach in strategic planning and real-time well placement of horizontal wells in the field for the efficient draining of the reservoir. These include the description of the detailed reservoir profile, the sweet zone identification while drilling, and the lateral placement close to the sweet zone top to minimize the attic oil and extend the well life. The outcomes in two successful wells were: ■Clear identification of multiple boundaries of the reservoir geobodies and their interfaces including the current fluid contact level.■Minimization of attic oil and achieving optimum lateral placement to drain the reservoir.■Exceeding the economic prediction of heterogeneous reservoirs
The successful implementation of the innovative well placement strategy in complex and heterogeneous fields will lead to extended production, optimal well economics, and increased oil recovery. The approach provides an example of using integrated technology solutions to overcome the challenges in complex reservoirs with multiple laminated layers.
An Innovative Pipe Grade to Enhance Reach of Deeper Prospects in Sour Fields
Authors: Plessis Guillaume J. , Uttecht Amie , Pink Tony , Hehn Lucien , Jellison Michael J. , Vinson Barry 
Published: August 2016

Abstract
Moving into the next decade, wells in the Middle East are becoming more challenging as the deeper and more complex plays are exploited. This environment will be challenging from a torsional and tensile loading standpoint, and will be dynamically very active. This type of environment combined with high levels of H2S calls for a new high grade of sour service pipe. The Middle East is also opening up to the idea of high speed telemetry and wired pipe economics that call for a long lasting pipe product.
When using sour service pipe that is traditionally limited to 105 KSI grades, even with an optimized string design, drillers sometimes have no other option than to sacrifice the margin of overpull, risking losing the well if fishing is unsuccessful. Alternatively, they can elect to use drill pipe, which is not suited for use in this corrosive environment, generally using API S135, with a risk of parting the string due to H2S embrittlement. To address these operational limitations, the pipe body, which is the drill pipe limiting member in tension, has to come with higher material strength and at the same time exhibit improved Sulfide Stress Cracking (SSC) resistance compared to API S135 grade.
A novel grade of drill pipe was developed over a period of two years that is the strongest sour service drill pipe the industry has to offer to date and gives drillers an extra 19% of tensile capacity with its 125 KSI material yield strength. This new grade has been ordered for use in various regions of the world and for numerous applications. At this time, it is being used for intervention and stimulation operations in the Gulf of Mexico (GOM), and drilling long, extended reach (ER) wells with wired telemetry drill pipe in the Middle East.
This paper presents the phases of the grade development and discusses testing requirements for the crossover between strength and SSC resistance. It also includes statistical data on the first full scale manufacturing tests. Finally, it outlines the products expectations for field applications.
Employing Process, Benchmark Automation, and Real-Time Analysis to Improve Drilling Efficiency
Authors: Taylor Aimee , Wesley Avinash , Adari Ram , Kurian Lijoy 
Published: August 2016

Abstract
Using the right offset well data to plan the next project is critical, but performance expectations get diluted when metrics are averaged over large depth ranges. Focusing on the rate of penetration (ROP), a benchmarking process was developed to improve drilling efficiencies. The whole process was automated and included a real-time analysis of the well being drilled that was capable of quickly identifying the 1) offset wells based on location, lithology, well type, and performance; 2) sectors within those wells with common formation, wellbore, and tubular characteristics; and 3) the effective technical limit (ETL)—the best drilling performance that realistically can be repeated. The process mentioned in this paper identifies opportunities for operators to reduce inefficiencies while drilling, allowing users to take action while there is still opportunity to mitigate or eliminate the damage.
Using the guided workflow and real-time data to identify and select the appropriate offset wells, multiple ETL sectors are created based on the characteristics they share (formation, wellbore, tubular). During real-time operations, when the same set of characteristics for a particular sector is met, ETL data for that sector are displayed, and users can evaluate performance in real time compared to best historical performance. This paper also presents a case study in which this process was applied to improve an operator's drilling efficiency.
Mechanical Specific Energy for Drilling Optimization in Deepwater Brazilian Salt Environments
Authors: Pinto C. N. , Lima A. L. 
Published: August 2016

Abstract
Operators exploring presalt areas report issues with bottomhole assembly (BHA) wear and failure resulting from factors such as vibrations, stick-slip, and torsional resonance during drilling operations in salt layers. This study presents a new real-time analysis based on geomechanics capability to optimize energy consumption and rate of penetration (ROP) in salt-layer drilling and improve economic results.
A real-time geomechanical analysis based on mechanical specific energy (MSE) was used to optimize drilling and prevent nonproductive time (NPT) when drilling in evaporite intervals. This analysis defined two energy limits as a function of depth. Both maximum and minimum energy limits were calculated in real time based on estimates of confined compressive strength and intrinsic MSE, respectively. The intrinsic MSE calculation depends on the mechanical properties of the rocks [i.e., unconfined compressive strength (UCS), friction angle (θ), and the cutting environment].
When both limits were estimated, a real-time analysis was successfully developed based on measuring and comparing the following: MSE applied during the drilling process, which depends on drilling parameters, such as ROP, rev/min, weight on bit (WOB), and torqueMSE intrinsic valuesConfined compressive strength (CCS) of the evaporate
The analysis identified excessive energy consumption to help reduce and mitigate factors, such as axial/lateral vibrations, stick-slip, torsional resonance, and wear of BHA components in this geological environment. All factors were estimated and analyzed through empirical relations based on logging while drilling (LWD) logs and mud logging parameters.
Results of two case studies show how excess energy results in excessive vibrations and wear of the BHA when this energy analysis is not applied and energy stabilization, ROP efficiency, and mitigated vibrations when the methodology is implemented. A depth versus time plot shows drilling performance optimization with 12 operational days saved and no operational NPT registered. Economic results were also positive.
This study aims to create a methodology that helps optimize the ROP in real time for salt environments based on the estimation of the minimum and the maximum (optimum) values of energy necessary to drill efficiently and avoid BHA failures resulting from excess energy in the drilling system.
Innovative Approach Helps Operator Drill Faster and Achieve Benchmark ROP Over Offset Runs in Southern Kuwait
Authors: Baqer Yousef Ahmed , Eid Khaled , Ebrahim Ebrahim Khalil , Ghoneim Osama , Jokhi Ayomarz , Hassan Said , Nair Prakash , Helal Karim 
Published: August 2016

Abstract
Drilling the 12¼-in hole in southern Kuwait usually starts in a shale formation and continues through interbedded sandstone, limestone, and shale. The unconfined compressive strengths throughout the section vary from 6,000 psi to 10,000 psi. The bit types typically used in this section are six-bladed PDC bits with either 16-mm or 19-mm cutters. Because fields in the area are development fields, the main objective for the operator is to achieve the best rate of penetration (ROP) and complete the section as quickly as possible. A common objective was decided on between the operator and bit provider to design a bit to drill the 12¼-in section in one run with ROP above the current benchmark.
Different design configurations with different blade counts, cutter sizes, and cutting structures were analyzed using dynamic simulation based on finite-element analysis (FEA). The simulations were run in a dynamic environment to arrive at a design suitable to drill the application. The cutters were designed to withstand excessive wear, enabling the cutters to stay sharper for a longer interval and drill faster relative to previously used bits until the end of the run. Once the suitable bit was designed, different parameters were run in the simulation to define a set of parameters to be applied while drilling the actual well.
The offset wells had delivered ROP in the range of 83–93 ft/h. The new design drilled the entire section in one run in 8.7 hours, attaining an ROP of 108.6 ft/h. This represents an ROP improvement of 18% over the benchmark ROP, setting a new benchmark ROP for this application.
A combination of changing the bit configuration and cutter type along with the optimized cutting structure enabled the bit to last longer and drill faster than previous bits, saving the operator the cost for the associated drilling hours.