bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the Pressure Capacity of Rotary-Shouldered Connections
Authors: Pettit Grant , Lee Kang , Gokhale Samit 
Published: June 2014

Abstract
API rotary-shouldered drill stem connections have a seal surface that is required to carry internal pressure. We assume that this seal will hold the pressure from routine drilling operations, but drill stem tests, stuck pipe, or other special situations can apply much higher differential pressures to the drill string. Currently, there is no analytical solution for predicting the pressure that can be safely contained by one of these industry-standard connections.
This leads to extra cost and logistical difficulties in those instances where significant pressures are expected. Some proprietary connections are designed for this high-pressure service, but these may be unnecessary if the API connection can safely tolerate those pressure loads. Without an accurate predictive equation, however, relying upon the pressure capacity of an API connection injects uncertainty and risk into the drilling process.
This paper addresses that problem by developing a predictive pressure-capacity equation for rotary-shouldered connections.
To cover a broad spectrum of rotary-shouldered connections with the predictive equation, Finite Element Analysis (FEA) was used to model six different connection types with varying dimensions and tensile loads applied. Over 70 distinct models were created to fully describe the effects of internal pressure on a rotary-shouldered connection.
Patterns in those results were associated with physical stress and strain effects to create an analytical equation that accurately describes the stress state at the seal surface under various pressure loads. It is this equation that predicts the pressure capacity of an API rotary-shouldered connection.
In order to put this equation into use, laboratory testing is recommended to both confirm the FEA results and define an actual failure criterion (that is, at what seal stress the connection begins to leak). Possible paths forward are discussed, along with important considerations for obtaining meaningful test data.
Case Histories of Real Time Drilling Optimization Combining Drill String Modeling, Surface Measurements and Down-Hole Measurements
Authors: Frenzel Mark , Wassell Mark , Brown Craig 
Published: June 2014

Abstract
A novel, real time drilling optimization system is shown to improve drilling performance by increasing the rate of penetration (ROP) while extending the length of the bit run. Additionally the optimization system reduces the wear and tear on the drill string realizing additional cost savings by minimizing down-hole equipment failures. The result is lower total cost to drill the well.
The optimization system's new features include combining surface data with down-hole vibration data to get the available results in realtime. Additionally, the method uses mechanical specific energy to determine the drillability through stringers and fractures. While the average mechanical specific energy maybe minimized for a given set of surface parameters, the mechanical specific energy spikes whenever stringers, fractures or any other changes in the formation are encountered. The optimization program combines all of these features to determine the optimal parameter set points.
To date, seven wells have been drilled utilizing this optimization system. Significant cost reductions are achieved whenever the optimization recommendations are followed. The system combines analytical drill string modeling with real time drilling data. The real time drilling data includes surface data from the rig EDR system and down hole MWD data. The optimization system analyzes the data and then determines the optimized drilling set points based on the rate of penetration, mechanical specific energy, down hole vibration and data scatter. The system has the ability to identify and resolve drilling dysfunctions in real time, mitigating damage and avoiding unplanned trips.
In the planning stage, drill string modeling analyzes the proposed drill string to assess the structural integrity of the BHA, predicts the drilling tendencies to ensure the planned BHA is capable of developing the directional plan and identifies critical drilling speeds associated with excitation of the motor, bit and or drill string RPM. The modeling application also analyzes the drill string for torque and drag, stick slip and the planned hydraulics. During the drilling process the model is continuously updated accounting for differences from plan. The system optimizes drilling performance in real time and offers solutions for mitigating drilling dysfunctions that could result in unplanned trips if not addressed in a timely manner.
Several examples are discussed in depth, which illustrate the efficacy and benefits of this new drilling optimization system.
Reliable Technology for Drilling Operations in a High-Pressure/High-Temperature Environment
Authors: Ahmad I. , Akimov O. , Bond P. , Cairns P. , Eide N. , Gregg T. , Heimes T. , Nwosu A. , Wiese F. 
Published: June 2014

Abstract
The development of oil and gas assets is becoming more complex with reserves being found in more challenging environments. Wells are being drilled to greater depths and in areas where the temperature gradient is higher leading to the requirement for downhole equipment to withstand temperatures in excess of 302°F (150°C) and pressures in excess of 30,000 psi. Directional wells require measurement while drilling (MWD) and drilling systems that operate reliably in the challenging environments. The problem of high pressure is solved using seals to isolate the inner equipment from the wellbore fluid, protecting it from variations in material properties and geometrical dimensions. The greater challenge to electronic components is in the high-temperature environment. Conventional electronic components are generally rated to 158°F, 185°F and 257°F (70°C, 85°C and 125°C), respectively, which is far below the rating required to build a high-temperature MWD and rotary steerable system (RSS). New techniques were required in the design of MWD and RSS tools for high-temperature wells. The paper describes the development of high-temperature drilling equipment that can be used in environments up to 350°F (175°C) and at pressures of 30,000 psi.
The authors utilize case histories to demonstrate how the system provides a performance change in the challenging environment.
Advanced Geomechanical Analysis of Wellbore Strengthening for Depleted Reservoir Drilling Applications
Authors: Shahri Mojtaba P. , Oar Trevor , Safari Reza , Karimi Moji , Mutlu Uno 
Published: June 2014

Abstract
Drilling depleted reservoirs is often encountered with a host of problems leading to increase in cost and non-productive time. One of these faced by drillers is lost circulation of drilling fluids which can lead to bigger issues such as differential sticking and well control events. Field applications show that wellbore strengthening effectively helps reduce mud loss volume by increasing the safe mud weight window. Wellbore strengthening applications are usually designed based on induced fracture characteristics (i.e., fracture length, fracture width and plug location within fracture). In general, these fracture characteristics depend on several parameters, e.g., in-situ stress magnitude, in-situ stress anisotropy, mechanical properties, rock texture, wellbore geometry, mud weight, wellbore trajectory, pore pressure, natural fractures, formation anisotropy and among others. Analytical models available in the literature oversimplify fracture initiation and propagation process with assumptions such as: isotropic stress field, no near wellbore stress perturbation effects, vertical or horizontal wells only (no deviation/inclination), constant fracture length and constant pressure within the fracture. For more accurate predictions, different numerical methods, i.e., finite element, boundary element, etc., have been utilized to determine fracture width distribution. However these calculations can be computationally costly or hard to implement in near real time. The aim of this study is to provide a fast running, semi-analytical workflow to accurately predict fracture width distribution and fracture re-initiation pressure (FRIP). The algorithm and workflow can account for near wellbore stress perturbations, far field stress anisotropy, and wellbore inclination/deviation. The semi-analytical algorithm is based on singular integral formulation of stress field and solved using Gauss-Chebyshev polynomials. Proposed model is computationally efficient and accurate. The model also provides a comprehensive perspective on the formation strengthening scenarios; a tool for improved LCM design and how they are applicable during drilling operation (in particular through depleted zones). Sensitivity analysis included in this paper quantifies the effect of different rock property, in-situ stress field/anisotropy and wellbore geometry/deviation on the fracture width distribution and FRIP. Additionally, the case study presented in this paper demonstrates the applicability of the proposed workflow in the field.
Development of On-Line Sensors for Automated Measurement of Drilling Fluid Properties
Authors: Magalhães Sérgio , Scheid Cláudia , Calçada Luís Américo , Folsta Maurício , Martins André Leibsohn , Marques de Sá Carlos Henrique 
Published: June 2014

Abstract
The high costs associated with drilling operations, especially in offshore environments, make it necessary to optimize each step of the job. The drilling mud plays a critical role in the drilling operation, as it is responsible for several functions (solids transport, wellbore mechanical stability, signal sensor transmission, etc.). Besides that, the attention given to the control of drilling mud properties has not changed much from the last 50 years. Downhole and surface online measurements for several drilling parameters are available for anticipated diagnostics of operational problems. Drilling automation is already a reality (automated pipe handling, controlled tripping operations, etc.), but the drilling mud properties continues to be measured manually. The drilling mud sample has to be collected, transported, treated and analyzed to only then the measured property is reported.
This work aims to present the development and result of experiments performed at a large scale drilling fluid loop, aiming the evaluation of commercial and built in property sensors. The following properties were determined: rheological parameters, mud weight, water-oil content, emulsion electrical stability (for oil based muds), fluid conductivity (for water based muds) and particle size distribution.
The use of neural networks (Multi-Layer Perceptron type) allows the connection of the on-line equipment results to increase the reliability of mud properties determination. Comparisons with the results obtained from laboratory equipment were performed to train the neural networks as well validate the developed techniques.
The Latest Generation of Steerable Motor Overcomes Drilling Challenges in the Niobrara Shale Unconventional Play
Authors: Azizov Azar , Lemesany Lane , Augustine Norwood , Loesel Chad 
Published: June 2014

Abstract
Maximizing well productivity and improving drilling efficiency remains a major challenge while drilling horizontal wells in US-land unconventional shale plays in the last few years. Reducing drilling times and eliminating trips for the curve bottomhole assembly (BHA) requires a motor that can be rotated at high RPM in the vertical section while still achieving buildup rate (BUR) in the curve.
The challenges of horizontal well drilling in US land led to the recent introduction of a steerable optimized design motor (ODM) with a short bit-to-bend (BTB) distance. These ODMs achieved higher BUR in the curves than the conventional motors at lower adjustable kick-off (AKO) sub angle.
Although the planned dogleg severities (DLS) stayed at the similar level, drilling vertical and curve sections of the horizontal wells in the Niobrara shale unconventional play posed additional challenges:
– Rotating the BHA in the vertical section with a high AKO angle – Dealing with formation challenges – Holding the toolface to achieve consistent BUR in the curve – Completing the vertical and curve sections in one run
The introduction in 2013 of the latest-generation steerable motors (LGSM) with further reduced short BTB distance design helped the operator overcome these challenges. The new system significantly improved drilling performance with excellent directional control.
This paper will discuss the design, testing and results of horizontal wells drilled using the LGSM in the Niobrara unconventional shale play.
Improving Drilling Operations Efficiency on an Ultra-Narrow Margin HPHT MPD Well with use of a Mud Cap
Authors: Oyovwevotu Joy , Low Eric , Nas Steve 
Published: June 2014

Abstract
As the industry pushes the boundary of technology to drill narrow margin wells, combining safe drilling practices with drilling efficiency is becoming ever more challenging. The practice of drilling with Managed Pressure Drilling (MPD) using statically underbalanced mud weight is gaining increasing acceptance in High Pressure High Temperature (HPHT) well construction. This paper describes the planning and execution of using mud cap fluid in the drilling of an ultra-narrow margin (0.50ppg window at the planning stage) HPHT well from a Jack Up rig.
Drilling Equivalent Circulating Density (ECD) with overbalanced mud weight at acceptable flow rate would have exceeded the formation fracture gradient and resulted in a loss of well integrity. To avoid this outcome, the HPHT section of the well was drilled with statically underbalanced mud weight. Displacing well to kill weight fluid at acceptable flow rates prior to any trip out of hole was not viable. Planning focused on how to maximise operational efficiency by using a cap fluid to trip in and out of hole without compromising open hole integrity and well safety.
In this paper, we discuss the design of the mud cap fluid, selection of Changeover Depth (CoD), risks associated with use of the cap fluid, determination of available window for mud cap placement and removal, planning and execution of mud cap placement and removal, challenges of running and displacing the cap fluid with a liner and, lessons learnt from repeated use of the technique throughout the well construction phase, including coring and wireline logging under MPD conditions.
Significant operational efficiency was gained from the use of cap fluids, making it possible to drill a well which would otherwise have been near impossible to drill with minimum lost time.
Measuring and Improving Land Rig Moves Using Hard Data
Authors: Dunham Thad , Elsik Wayne , Shah Mihir 
Published: June 2014

Abstract
As the shale revolution continues to boom, the industry is facing ever-growing pressure to increase overall efficiency when it comes to drilling operations and rig moves. This paper addresses improvements in pad-to-pad rig moves. The industry is using several different rig moving procedures, but there is a need to determine how each can be improved. Relevant data is in high demand from many players within the land rig market.
Observation and analysis of twelve different rig moves in the study yielded noteworthy data. By utilizing techniques primarily from other industries, the different "steps" of a rig move were quantified. Documentation of the entire rig move process included rig down and rig up sequences, equipment utilization, pad site layouts, as well as potential design improvements.
Through collaboration with a drilling contractor, the results of the study were converted into actual improvements. The improvements both design and process related, saved money and increased the number of wells drilled per year. Studying the entire process of moving a rig resulted in faster, cheaper, and more efficient rig moves. Contractors, operators, and oilfield suppliers throughout the industry can realize the benefits of efficient moves.
Relief Well Drilling Using Surface Seismic While Drilling (SSWD)
Authors: Evensen Kristoffer , Sangesland Sigbjørn , Johansen Ståle Emil , Raknes Espen Birger , Arntsen Børge 
Published: June 2014

Abstract
Magnetic survey methods are used to locate the blowing wellbore when drilling a relief well. If no magnetic material is present in the openhole section of the blowing well, the last set casing shoe is the deepest possible intersection point. A deeper intersection point will increase the hydrostatic head, increase the frictional pressure drop and allow a lower density kill fluid to be used.
A new potential method called surface seismic while drilling (SSWD), could make it possible to intersect the blowing well below the casing shoe. This method is not dependent of any casing or steel tubular present in the well to identify the relative wellbore positions. The SSWD method is based on a surface seismic source generator and a receiver array located on the seabed. Preliminary simulations indicate that it is possible to locate the wellpaths of the two wells on the seismic data. This method will allow real-time seismic monitoring of the well paths without interfering with the drilling operation. This can allow for more precise relative wellbore positioning.
To investigate the benefits of a deeper intersection, a simulation model was prepared. A vertical offshore well consisting of 2000 meters of casing, and a 1000-meter openhole section were used. The well was killed dynamically by circulating seawater at high rates into the blowing wellbore. Compared to a casing shoe intersection, simulations show that a bottom hole intersection would reduce the flow rate and pump pressure by approximately 48% and 55%, respectively. The required kill mud weight was reduced by 24 %.
The seismic method may also be used in conventional well killing operation to provide additional information of the position of the two wellbores and potentially reduce the time needed to drill the relief well. This paper presents the SSWD method and the potential improvements in relief well drilling and well killing.
Innovative Non-Planar Face PDC Cutters Demonstrate 21% Drilling Efficiency Improvement in Interbedded Shales and Sand
Authors: DiGiovanni Anthony , Stockey David , Fuselier Danielle , Gavia David , Zolnowsky Matt , Philips Russell , Ridgway Derek 
Published: June 2014

Abstract
Traditional polycrystalline diamond cutter (PDC) technology has made tremendous gains over the past decade with corresponding footage and rate of penetration (ROP) improvements in drilling performance. The remaining challenge is managing interbedded formations with competent stringers while maintaining drilling efficiency and the highest ROP potential, such as those present in the 6 to 6⅛-in. Pinedale Anticline production hole and the 12¼-in. Cana intermediate section. By modifying the standard planar PDC cutter face geometry with novel shallow recessed features, a demonstrated improvement in drilling efficiency was observed in these applications and an increase in attained footage. Extensive analysis in Pinedale runs indicated this cutter design benefits a lower mechanical specific energy (MSE) in the shale and sand, shorter day curves, and higher average ROP per unit of motor horsepower. Initial runs in the Tonkawa sands of the Cana intermediate have started to show similar trends.
The successful field runs have been supported by in-depth analysis and study of cutting efficiency including, single-point cutter testing in a pressurized vessel, atmospheric vertical turret lathe testing, and full-scale PDC bit laboratory testing in a state-of-the-art downhole drilling simulator. The results of this work improved the understanding of the thermo-mechanical behavior of cuttings formed by the drilling action of a PDC cutter in these applications. This study is part of an innovative approach to manage rock cuttings, cutting efficiency, and thermal loads as it applies to PDC durability in state-of-the-art drill bit designs.
The design changes have improved cutting efficiency and aggressivity, which has improved the ROP of bits in abrasive sand and in the shale sections. This paper provides documentation and visual demonstrations of the features and benefits seen in the single-point test apparatus, the downhole simulator in the laboratory and in the field with case studies compared to offsets of standard bits with planar PDC cutters.
Finite Element Studies of Wellbore Strengthening
Authors: Arlanoglu C. , Feng Y. , Podnos E. , Becker E. , Gray K. E. 
Published: June 2014

Abstract
In drilling deep horizons, the mud weight window between pore pressure gradient and fracture gradient often narrows due to rock properties and underground stress state. Non-productive time (NPT) events such as lost circulation, wellbore instability, kicks, underground cross-flow, and pipe sticking are more likely. Such problems greatly increase drilling costs. Plugging preexisting natural fractures or drilling-induced fractures with lost circulation materials (LCM) is often used to increase fracture gradient and widen the mud weight window. This technique, called ‘wellbore strengthening’, includes several strengthening methods, but there are several factors affecting these procedures are not thoroughly understood.
To reduce the risk of loss circulation while drilling in formations with narrow mud weight windows such as pressure depleted reservoirs and deep-water formations, a good understanding of the mechanisms of wellbore strengthening in different down-hole scenarios helps engineers to optimize the design of drilling fluids and operation procedures.
This paper discusses the mechanism of wellbore strengthening in elastic and pore-elastic models, utilizing the finite element method to evaluate wellbore and near-wellbore stresses during fracture initiation and propagation, and after plugging fractures with LCM. Factors affecting fracture behavior such as formation stress anisotropy, LCM bridging location, initial pore pressure, and fluid leak-off are investigated. A better understanding of the several interacting events local to the wellbore and near-wellbore regions can result in improved operational practices related to lost circulation events.