bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defining and Improving Process Safety for Drilling and Well Services Operations
Authors: Chajai Hicham , Smith Clive 
Published: June 2014

Abstract
In 2007 Maersk Oil actively engaged in quantifying how Process Safety could effectively be implemented in drilling and well services operations. For years the term ‘Process Safety’ had been effectively embedded and understood in our production operations, whereas it was lesser known in the drilling community, where ‘well control’, ‘barrier philosophy’ and ‘Safety First’ were the phrases heard on the rigs.
Initial efforts were exerted in order to establish the right framework and terms of reference that would be suitable for drilling and well services. Likewise it was important to establish a baseline in terms of effectiveness of its management of Process Safety. Thus, the Company looked to create relevant tools in order to qualitatively measure its performance and enable continuous improvement.
The objective of this paper is to present a case story, as to how the broad definition of Process Safety has been successfully implemented within the drilling and well services discipline and how we are able to measure effective embedment as well as continuous improvement.
The Company adopted the Risk Based Process Safety (RBPS) (based on 4 main ‘pillars’ and 20 key elements) approach, originally developed by the petrochemical industry, but now also a recognized approach in the oil industry, to ensure effective management of Process safety.
This paper describes the development of a questionnaire, now available as a web-based self-assessment tool that evaluates and measures the maturity of Process Safety understanding, commitment and implementation across locations and also across disciplines. It also describes how the assessment is being used for continuous improvement and management review.
As part of the process, a discipline specific information booklet and a tailored training program were developed and rolled out to all drilling & well services technical personnel, thus providing enhanced knowledge and understanding of the principles of Process Safety.
This paper describes the methodology employed to select Global KPIs.
Finally, the paper will explain how the management system is already applying Process Safety, thus supporting Company's ambition of an "Incident-Free" operation.
Complex Wells: New Perspective on the Selection of Optimal Drillpipe
Authors: Mehrabi Mehran , Miska Stefan , Merlo Antonino 
Published: June 2014

Abstract
Drilling of extended reach wells (ERW) and ultra-deep HPHT wells is the most compelling reason for drilling companies to look for alternative drill pipes that meet their requirements. Currently, with the emergence of drill pipes made of materials other than steel, a thorough study of their advantages and disadvantages compared with conventional drill pipes is needed. In this study the main focus is on the comparison of fatigue performance of Steel Drillpipe (SDP), Aluminum Drillpipe (ADP), and Titanium Drillpipe (TDP) in mild and severe doglegs. Fatigue performances of different drillpipes are compared and it is shown that depending on the drillpipe specification, applied torque, axial load and Dogleg Severity (DLS) of the wellbore, one type can function better than others and a one-size-fits-all is not an appropriate approach on the selection of drillpipe material. Generated contact forces at the tool-joints and pipe body adds more complexity to the decision of which type of drillpipe is more appropriate for drilling a severe dogleg. The contact forces at the tool-joints and pipe body could be an extremely important factor owing to their direct impact on wellbore stability, casing and pipe body wear and the heat checking of the tool-joints. Large contact forces at the pipe body can make relatively major scratches on the surface of the pipe tube of ADP and TDP, which can render their corrosion resistance features insignificant. Based on the conducted study, TDP has a significantly good fatigue resistance even at the simultaneous presence of high applied torque and axial load, and severe doglegs, which makes the use of other options (SDP and ADP) impractical from the fatigue failure standpoint. It is shown that the limiting factor for using TDP in such severe conditions is not the fatigue resistance of the material that the pipe is made of, but the high contact forces between the wellbore/casing wall and tool-joints/pipe-tube. The fatigue envelopes and calculated contact forces for each category of drillpipe reveal the practical range of the applied torque and axial load, to avoid both suffering from fatigue failure as well as detrimental effects to the wellbore integrity. This paper can help drilling engineers design an optimal drillstring for ERD and complex wells.
Successful Cementing Based on New Design Methodology for Displacement of Non-aqueous Drilling Fluid
Authors: Kefi Slaheddine , Pershikova Elena , Docherty Kevin , Barral Quentin , Droger Nicolas , de la Mothe Loic Regnault , Khalfallah Inès 
Published: June 2014

Abstract
Drilling fluid removal by spacer fluids is an important step in ensuring proper cementing and therefore adequate zonal isolation, especially when non-aqueous fluids (NAF) are used. In addition to the fluid mechanics aspect of displacement, a tensioactive package containing surfactant(s) and solvent(s) is typically added to the spacer base fluid to clean all surfaces, including the casing. However, current surfactants and solvents on the market have limited application in terms of temperature and type of drilling fluids.
API and ISO standards recommend practices for evaluating the suitability of a spacer. The viscosity of NAF, spacer, and cement mixtures at various fixed ratios determines their rheological compatibility. The reverse-emulsion test or spacer-surfactant screening test (SSST) determines the percentage of spacer for inverting the NAF emulsion. Other non-standardized tests such as bottle tests or grid tests determine the efficiency of a surfactant/solvent aqueous solution to remove NAF from metallic or glass surfaces. But all these tests suffer from lack of reproducibility and limited automation.
Improved alternative laboratory procedures have already been proposed. They include measuring rheology during SSST, which clearly shows the positive impact of early emulsion inversion on viscosity of NAF/spacer mixtures. In addition, proper preparation of metal surfaces clearly improves repeatability of the cleaning test, which now is performed with weighted spacer under temperature and pressure.
Using these improved experimental methods, we performed more than 3,000 different tests on more than 200 tensioactive blends. Statistical analysis helped in selecting the optimum chemistry as a function of the conditions (type of base oil, salinity, and temperature). This allowed developing both guidelines and a tensioactive package comprising a limited number of chemicals (surfactants and solvents), from which the field user would select the ones to combine for the application. Only a few confirmation tests would be necessary at the location for planning a given cement operation.
An advantage of developing a package of chemicals is ease of implementation at field level since it requires having only a few chemicals in inventory to cover all situations and limited local laboratory testing. The new methods have been successfully applied in several wells in which different types of nonaqueous fluids were used at various temperatures.
Improved Model for Tapered Casing Design under Pressure Testing
Authors: Samuel Robello , Wang Zhenying , Kumar Aniket , Gonzales Adolfo 
Published: June 2014

Abstract
The casing program constitutes a significant portion of total well costs and thus calls for an efficient and accurate casing design. One aspect that is very important is accurately calculating the service load in a tapered casing string. Estimating the load when conducting pressure tests in tapered casing in a deviated well is very complex. In addition to the ballooning force, the piston forces acting on cement plugs and cross-sections at casing size changes result in 3D forces. When both the casing hanger and casing shoe are fixed, the casing string becomes a statically complicated indeterminate mechanical system. Thus, the service load distribution in tapered casing in a deviated well is very different from the load distribution in a vertical well or in a single section casing design. Underestimation of the load creates inherent safety issues.
This paper presents a new mathematical model to solve the load for a constrained casing system in a deviated or vertical well, using the Transfer Matrix Method (TMM). The distribution of forces along a tapered casing string in a deviated well are accurately calculated and presented in this paper. Example calculations are presented with details. Calculation results show that the distribution of the service load is greatly affected by the well trajectory, location of cementing plugs, the selection of casing, etc.
The Operational Benefit of Testing HPHT/MPD Procedures Using an Advanced Full Scale Drilling Simulator
Authors: Blikra Harald , Pia Giancarlo , Wessel Just Sverre , Svendsen Morten , Rommetveit Rolv , Ødegård Sven Inge 
Published: June 2014

Abstract
A challenging HPHT well was drilled with Managed Pressure Drilling. In the preparation phase, an advanced dynamic drilling simulator was used by the operator in order to test and verify operational procedures as well as the HPHT & MPD well control manual. This drilling simulator is based on advanced dynamic models developed from first principles, and will respond very realistically on the operators actions when "drilling", "circulating", "managing the well control problems" etc; like a "Drilling Flight Simulator". All relevant HPHT effects are modeled, like mud density, compressibility and rheology as function of Pressure and temperature; gas solubility in Oil Based Muds, transient thermal interaction in the well and surroundings etc. An MPD module has been developed in the simulator, allowing testing and training of all relevant procedures and operations related to MPD. Also, the drilling rig characteristics (pumps, surface lines, choke and BOP, MPD toolkit etc.) are modeled according to the real rig specifications.
The testing lead to several significant changes to the operator's manual and operational procedures. At the same time it allowed the Engineering team to test and rectify the Drilling program prior to deployment of the operation. The MPD technique was tested in the simulator as well, and the various contingency procedures were assessed. It allowed the rig contractor, operator, and the MPD provider to find the operational routine, communication and best practice prior to start operation offshore. The team's decision trees where reviewed and updated during the simulator training.
Since the crews actively had a part in the final revision in the manual, the operator experienced that the crews took an ownership in the making of the manual and the offshore operation.
As a resultant effect, the drilling crew and MPD operators rapidly adapted to the MPD procedures agreed upon during training, when operation started.
This paper will briefly present the advanced drilling simulator, and focus on the testing and verification of procedures and well control manual. The modifications done will be presented, and the operation itself will also be described, highlighting the benefits of utilizing the drilling simulator prior to operation.
Temporary Severe Reduction in Drill Pipe Load Capacity Due to Frictional Heating
Authors: Desrosiers Andrew , Marchman Kellon , Gokhale Samit 
Published: June 2014

Abstract
Numerous cases of drill pipe overload failures have occurred while rotating and reciprocating the drill string under packed off conditions where circulation is either low or lost completely. These failures are typically known as "down-hole heating" failures. The failure mechanism and forensic evidence needed for identification of the failure mode has been presented in a technical paper (SPE/IADC 92429). This failure mechanism occurs when frictional heating, along with poor or no circulation of drilling fluid results in extremely high localized temperatures in the tube. Material temperatures above the steel's austenitic transformation temperature can be reached causing a microstructural transformation and alteration of the material properties. However, when the material temperatures do not exceed the austenitic transformation temperature, the microstructure does not change but the mechanical properties can be drastically altered temporarily, leading to an overload failure. The understanding of failures occurring under this scenario and the supporting forensic evidence is still in the developing stages due to a lack of empirical data.
This paper provides multiple case studies where packed hole conditions with lost circulation were present and drill pipe tubes failed from overload deep in the well with low tensile loads relative to the rated tensile capacity which is consistent with "down-hole heating" overload. In these cases, the failure samples did not provide the physical evidence and microstructural transformation signatures described in the previous work paper SPE/IADC 92429. It was postulated that the failure occurred due to frictional heating but the material temperature did not reach austenitic transformation temperatures required to change the material microstructure. The paper presents experimental data that demonstrates the effect of elevated temperature on material strength for S-135 drill pipe tube materials at temperatures ranging from room temperature to austenitic transformation temperatures. Two separate tensile tests were conducted for each temperature throughout the range: one set of tests were pulled while the samples were at the elevated target temperature, the other set of tests were pulled after the samples had air cooled to room temperature from the target temperature.
The experimental data obtained in this study documents that the yield strength of S-135 drill pipe tubes can be temporarily reduced up to approximately 90% when heated to elevated temperatures below the austenitic transformation temperature with no change of material microstructure. The data provided in this paper provides the industry with valuable information when evaluating down-hole heating failures.
Drilling with Production Liner reduces AFEs per well, brings to early production in Urmanskoye field onshore Russia
Authors: Sidorenko Kirill , Valiyev Gurban , Priymachenko Dmitry , Beattie Scott , Bakhtin Andrey , Dubovsev A. G 
Published: June 2014

Abstract
As an industry segment, drilling with casing and liner is still very much in its infancy. However, a few "early adopters" have been successfully extending the operational envelope and discovering new applications. The fundamental value of drilling with casing lies in improving drilling efficiency by eliminating flat spots in the drilling curve. It also has the capability of extending open hole sections to reach deeper casing points with smaller diameters, thus eliminating contingency intermediate strings. The implications for exploration and production industry are significant. Currently, there are two basic methods of drilling with casing divided as follows: Rotating the casing at surface to transmit torque to the drilling BHA, or having a retrievable BHA latched inside the casing that incorporates a motor that drives a conventional bit and underreamer. Both systems, though operational and technically sound, still have many technical issues to overcome concerning all aspects of well planning to operations on the rig floor. This paper will focus on drilling with liner by rotating the casing without Top Drive. The paper will highlight the significant lessons learned from these experiences. This emerging technology is considered ‘"game-changing" and is seen as complementing the expandable and underbalanced technologies which promise to revolutionize well construction.
Selecting Safe Mud Weight Window for Wellbore in Shale While Drilling Using Numerical Simulation
Authors: Han Yanhui , Meng Fanhong (Frank) 
Published: June 2014

Abstract
In conventional drilling, the lower bound of the safe mud weight window is usually chosen for preventing compressive shear yielding evaluated by applying various failure criteria, such as the Mohr-Coulomb criterion on the elastic stresses, while the upper bound is typically determined by the fracture initiation pressure. For the wellbore drilled in shale formation, however, the lower bound calculated using a conventional method becomes unsafe because of the complications introduced by various shale issues, such as bedding planes. In this paper, two approaches are used for computing the safe mud weight window for wellbore drilled in shale formations. In the first approach, the effect of bedding planes is absorbed in the equivalent rock strength properties in the theoretical analysis. The second approach involves performing direct numerical simulation with bedding planes modeled explicitly in the constitutive model. A case study indicates that the two approaches provide consistent results.
Analysis of Spiraled Borehole Data using a Novel Directional Drilling Model
Authors: Marck J. , Detournay E. , Kuesters A. , Wingate J. 
Published: June 2014

Abstract
This paper describes the application of a directional drilling model to wellbore spiraling and compares it to field data. In this paper, the spiraling tendency of a Bottom Hole Assembly (BHA) is determined from a stability analysis of the delay differential equations that govern the propagation of a borehole. These propagation equations are derived from a novel mathematical model, constructed by combining (1) a bit/rock interaction law, which relates the forces acting on the bit to the penetrations of the bit in the rock per revolution; (2) kinematical relationships, which link the bit motion to the local borehole geometry; and (3) a model for the BHA, which expresses the forces and moments at the bit from the external loads and the deflections imposed by the stabilizers. Spatial delays associated with the positions of the stabilizers account for the feedback of the borehole as the stabilizers interact with the wellbore.
The analytical form of the propagation equations makes it possible to carry out a stability analysis and determine whether borehole spiraling is expected. The coefficients of the propagation equations embody the characteristics of a particular drilling system; these include the BHA configuration, bit properties, and the active weight, Wa, a calculated reduced weight on bit that depends on the actual Weight On Bit (WOB), the cutter wearflats, and the rock strength. If the bit trajectory is unstable, then any perturbation in the borehole geometry is amplified gradually, eventually leading to the generation of a spiraled hole.
The stability of the bit trajectory essentially is controlled by the magnitude of a dimensionless group relative to a critical value that depends on the BHA configuration. This group is a function of the lateral steering resistance of the bit, the bit wear, the rock strength, and the WOB. Thus, a BHA can be either stable or unstable depending on the selected bit, its state of wear, and the WOB.
Predictions of the stability analysis are compared with field data from spiral holes pertaining to eight sections from four wells drilled with different bit types and BHA configurations. The paper shows that the propensity of a BHA to spiral can be predicted by the model by assuming reasonable values for parameters such as the lateral steering resistance and the part of the WOB transmitted by the cutter wearflats. This comparison suggests that the model can be used to optimize BHA designs and critical WOB levels that will mitigate the creation of spiral holes.
An Alternative Systems Approach to the Successful Execution of Deepwater Drilling Programs
Authors: Bouska R. , Jeffery C. , Ramnarace D. , Brinkman C. , Jorgensen J. , Vasylyev S. 
Published: June 2014

Abstract
The increasing complexity of deepwater Bottom Hole Assemblies (BHAs) requires a complete systematic approach to each phase of the drilling process: pre-job planning, execution and evaluation. This approach was successfully applied to a recent multi-well project in the Gulf of Mexico, whose vertical 12¼ in x 13½ in sections were historically plagued by shocks and vibrations while drilling. The root cause of inefficient drilling performance could not be accurately determined based on drilling data, but severe vibrations resulted in multiple downhole tool and BHA component failures.
With the implementation of a complete, holistic approach to the drilling system, the drilling proceeded with no downhole tool failures and a significant reduction in drilling time and costs. The key to these successes were the multistage preparation process that was utilized, which included:
A detailed analysis of all the offset data available for the same field and for fields with similar lithologies and formation properties. A rock strength analysis based on Logging While Drilling (LWD) data and Compressive Confined Strength (CCS) measurements. A bit and reamer matching process taking into account CCS, lithology, directional profile and cutters layout while matching the performance criteria for both drill bit and underreamer.
Advanced tools and technology, including critical speed analysis and asymmetric vibration tool placement, were applied and supported by high-frequency downhole dynamics memory data with corresponding post-run drilling performance and vibration analysis. Some of the major contributors to the successful application were the designed-for-purpose engineered BHA and optimized operational environment.
This approach can be applied to borehole enlargement wells, as well as vertical, directional and horizontal wells. The analyses of the measurements gathered during all phases of the project, including a description of the obtained results, are discussed in detail. The results highlight a consistent improvement in drilling performance for the 12¼ in x 13½ in well section, where vibrations were the main limiting factor. Efficient drilling performance is achieved by implementing this complete approach to the deepwater drilling system and these engineering solutions for vibration mitigation, increasing ROP and improving BHA integrity and wellbore quality.