bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analyses and Procedures for Kick Detection in Subsea Mudlift Drilling
Authors: Choe Jonggeun , Schubert Jerome J. , Juvkam-Wold Hans C. 
Published: December 2007

Abstract
In deepwater drilling a conventional large diameter riser requires drilling vessels with huge weight and space capacities, large mud volume to circulate through a riser, and many casing points because of narrow gap between pore and fracture pressures. A large number of casing points also require a larger wellhead and a larger marine riser. These problems are inter-related and intensify as the water depth increases. Although there are some successes to set a new drilling record on water depth, it is impractical to extrapolate current technology with a marine riser to 10,000 ft water depth.
Subsea mudlift drilling(SMD) is a term used to describe an unconventional technique using a relatively small diameter pipe as a mud return line from the sea floor instead of a large diameter marine riser. The scheme also balances internal and external pressures at the sea floor by reducing the internal pressure to make a dual pressure gradient possible. It has potential advantages of cost and time savings and rig upgrades for deepwater applications.
Kick detection and well control will not be hurdles for field applications of SMD. If the circulation rate is less than the maximum free fall rate, there will be a severe delay in kick detection. In this case, we may need to increase the circulation rate or use a drill string valve that provides a positive surface pump pressure. In case of transient U-tubing or fill up, we should avoid other operations for easy kick detection and well control, unless we have an accurate prediction and monitoring tool.
Delivering the Limit without Compromise: Understanding a True Operator/Contractor Value Partnership
Authors: Quintero Alan , Cockram Mark 
Published: December 2007

Abstract
This paper will outline how a long term relationship between a contractor and operator that integrates their safety cultures, provides incentives to the parties, and looks for ways to continually improve performance can lead to results that benefit both parties.
British Gas (BG) began an exploration program in the West Delta Deep Marine concession offshore Egypt in 1998, and hired the Atwood Oceanics rig Atwood Eagle to drill this initial program. The early exploration program was a success, and led to an exploration, appraisal and development program lasting 4.5 years and consisting of 36 wells drilled and eight wells completed with Atwood Oceanics rigs. The Atwood Eagle drilled 19 wells, the Atwood Southern Cross one, and the Atwood Hunter drilled 16 and completed eight wells.
HS&E performance was held in the forefront of the planning and execution of this program, and approximately 1.5 million man hours of rig operations were accomplished without a lost time incident (LTI). Details of how the safety cultures of the companies were seamlessly integrated will be discussed.
Also, as part of the drive to improve performance, BG's Total Value Drilling (TVD) initiative was executed for the Scarab Saffron eight-well completion program, the culmination of the entire rig campaign. The teamwork approach to operational improvement gained through the TVD process will be outlined.
The cooperation between Atwood Oceanics and BG led to excellent results that included:
A combined 1.5 million man hours achieved with three rigs on contract with BG, Rashpetco and Burullus (BG companies) in a challenging deep water drilling and completion environment. Drilling the first deep water exploration well in the area. The campaign included wells in water depths up to 3,430 feet. Best in class drilling performance compared to other operations in the area over 4.5 years without compromising safety. Operations that approached or surpassed the expected technical limit. Hiring and training of local employees into a world class safety program. No damage to the environment.
Invert Emulsion Fluids for Drilling Through Narrow Hydraulic Windows
Authors: Fimreite Gunnar , Asko Arne , Massam Jarrod , Taugbol Knut , Omland Tor Henry , Svanes Kaare , Kroken Wenche , Andreassen Espen , Saasen Arild 
Published: December 2007

Abstract
In mature fields the difference between the pore pressure and fracture pressure, expressed as the hydraulic window, is reduced. Underbalanced drilling and the use of low-viscosity drilling fluids are but a few of the many approaches that have addressed this challenge. While low-viscosity fluids severely reduce frictional pressure loss when compared to more viscous fluids, there is a limit to how much viscosity can be reduced before conventional weight material begins to settle.
This paper describes the development and application of novel technology that has resulted in a ten-fold reduction in the particle size of the weighting agent. With this development, invert emulsion drilling fluids can be designed with low viscosity with minimal settling potential of the weight material.
The authors will explain in detail the first field applications of this polymer-coated, micron-sized weighting agent in an oil-based drilling fluid. The system was used to drill two wells offshore Norway. These reservoir wells included an 8½-in. section and a 5⅞-in. thru-tubing section.
This novel drilling fluid technology delivers a low-rheology, low-sag fluid offering a number of performance benefits over conventional technology. Performance data from offset wells will be presented that show the benefits of this unique approach. Equivalent circulating densities (ECD) and torque values were significantly lower than comparable wells and no instances of particle settlement were observed.
Silicate-Based Drilling Fluids Deliver Optimum Shale Inhibition and Wellbore Stability
Authors: Soric Tomislav , Marinescu Pavel , Huelke Robert 
Published: December 2007

Abstract
Along with exorbitant costs and safety considerations, drilling an exploratory well where conventional mud systems could not maintain wellbore stability and trouble-free drilling, also posed the additionally difficult challenge of selecting a fluid system stable against multiple contaminants and flexible for a broad range of densities. The demands are compounded dramatically when designing the system and information to support the decision is poor.
This paper details the design and performance of a silicate-based fluid, which is an inhibitive mud system formulated with a soluble silicate for maximum shale inhibition. The system has been developed to drill water-sensitive reactive shales and dispersible chalk and illite formations. The degree of inhibition provided by the silicate system is significantly greater than any other water-based system, truly approaching the level of an oil-based system.
The authors will discuss the design and the application of the drilling fluid, which was selected to drill a formation containing anhydrite, claystone, dolomite and salt.
The system was formulated to be salt-saturated to avoid dissolution of salt layers; to withstand anhydrite contamination; to be flexible for densities up to more than 2.0 kg/dm3 while maintaining its high level of inhibition. Though comprehensive lab tests were performed, the possible depletion of silicate while drilling the anhydrite-containing formation remained. Nevertheless, this challenge was accepted with tight wellsite engineering planned to maintain the fluid properties.
Six wells have now been drilled with the proposed silicate system, with each showing very good performance and stable behavior in the above mentioned environment. The authors will present its effectiveness, formulation, properties, maintenance and lessons learned, along with the coordination and pre-planning that contributed to its successful application.
Alternative Aphron-Based Drilling Fluid
Authors: Growcock Frederick B. , Simon Gerard A. , Rea Anthony B. , Leonard Russell S. , Noello Eduardo , Castellan Rolando 
Published: December 2007

Abstract
A novel drilling fluid containing specially designed micro-bubbles -- "aphrons" – was recently introduced and has now been employed successfully in various parts of the world to drill through formations which previously had experienced uncontrollable losses and high incidence of differential sticking. The aphron-laden fluid appears to be particularly well suited for drilling through depleted zones. Wellbore stabilization is accomplished by (a) greatly reducing the invasion rate of the base fluid with additives that minimize the thixotropy of the fluid and enhance its shear-thinning character, and (b) reversibly plugging pores and fractures by the aphrons.
A recent innovation has permitted modification of the original fluid design to permit incorporation of selected clays in the fluid for rheology control and stabilization of the aphrons. In addition, the chemistry of the aphron membrane has been altered using a polymer/surfactant package so that the longevity and resistance to pressurization of the bubbles are greatly improved.
The authors will discuss the design and properties of the new Alternative aphron-based drilling fluid and how these characteristics can be used to advantage in a drilling operation.
Benchmark Performance: Zero Barite Sag and Significantly Reduced Downhole Losses with the Industry's First Clay-Free Synthetic-Based Fluid
Authors: Burrows Kim , Carbajal David , Kirsner Jeff , Owen Bobby 
Published: December 2007

ProposalSince the introduction of invert emulsion fluids in the 1960s, oil-based fluids (OBF) and synthetic-based fluids (SBF) have been formulated with a similar group of components: base oil, organophilic clay and lignite, lime, CaCl2 brine, and emulsifier. The family of invert emulsion fluids has remained closely related in terms of mud properties and performance expectations.In 2001, an SBF formulated entirely without commercial clays or lignites was introduced in the Gulf of Mexico (GOM). Rheological properties are controlled through the emulsion characteristics, a radical departure from accepted solids suspension mechanisms. The behavior of this unique fluid has changed perceptions about what constitutes "good mud."The clay-free, emulsion-based fluid (System) has consistently prevented detectable barite sag on 80+ wells drilled with it to date. Based on observed fluid densities after long static periods (an 8-day logging run in one case) and verified by modular dynamic test (MDT) log data on numerous high-angle wells, the fluid's unique emulsion structure and wetting characteristics prevent settling of barite and other solids.Attempts to control barite sag with conventional clay-based SBFs have produced mixed results. A 14.0-lb/gal SBF treated with sag-prevention organophilic clay showed a 0.3-lb/gal density reduction in the initial return flow and a 0.3-lb/gal density increase in the tail flow after a 52-hr logging run. This 0.6-lb/gal variation in density was deemed "manageable." However, the treatment resulted in a 20% increase in the funnel viscosity at 75°F, demonstrating an adverse effect on the rheology after increasing the clay concentration by only 0.2 lb/bbl. At lower temperatures encountered at the sea floor, this effect would be amplified.In addition to preventing barite sag, the System has provided other important field-documented performance advantages: Whole mud losses reduced by an average of 60% while drilling, running casing, and cementing (with 80% reductions reported on several deepwater wells).Significantly lower ECDs, validated by pressure-while-drilling (PWD) data.High, flat gel strengths that break with minimal initiation pressure, validated by PWD data.Highest standard of compliance with environmental regulations governing GOM operations.The System is currently under consideration for use offshore West Africa, offshore Brazil, and the Asia-Pacific region.
Reformulating an Oil-Based Drilling Fluid with Especially Selected Chemicals Lead to Development of a Low-Viscosity High-Sag Stability Drilling Fluid
Authors: Taugbøl Knut , Sandberg Gerd Marit , Cullum Daryl , Dyrkolbotn Erik , Jacob Hans , Grevstad Kvaal 
Published: December 2007

Abstract
A conventional oil-based drilling fluid was determined not to be applicable for drilling narrow hole annuli in a mature field offshore Norway. Drilling these wells with a very narrow hydraulic window required an oil-based drilling fluid with reduced viscosity and improved sag stability.
A totally reformulated drilling fluid system was developed. The combination of base oil and selected products produced a fluid with a flatter rheological profile, resulting in reduced plastic viscosity (PV) and increased low shear rate viscosity (LSRV). This rheological profile reduced equivalent circulating density (ECD) and improved sag stability. This rheological profile also directly impacted pump pressure and hole cleaning capabilities, delivering lower pump pressure and allowing for higher pump rates and improved hole cleaning.
This paper presents the experimental work performed when developing the system for this specific application. The authors also will present field data and compare the performance of the new drilling fluid system with that of conventional systems.
Case Study of a 300-ft Water Depth Jackup in a Class IV Hurricane
Authors: Duhaney Harvey , Keys Harold , Daigle Paul , Laird John 
Published: December 2007

Abstract
This paper examines the ability of a Levingston Class 111-C jackup rig to withstand hurricane winds of 128 knots, which significantly exceeds the rig's 100-knot storm rating. It compares the analytical results of an engineering study focused on predicted rig attitude, areas of failure, and areas of high stress with the actual rig conditions observed.
Details of the shipyard repair show how an innovative chord repair method was used to dramatically decrease the cost of repairs and allow the rig to be returned to service in only 28 days.
Innovative Design for Deepwater Exploratory Wells
Authors: Cunha J. C. 
Published: December 2007

Abstract
Currently, in the southeastern cost of Brazil, a major deepwater exploratory campaign is being carried out. In a period of two years more than 150 wells are expected to be drilled. With water depth varying from 1,000 to 2,800 meters (3,280 to 9,200 ft), these exploratory wells are being designed and drilled taking into account three major points, safety, well data reliability and well cost.
On the design of the wells various innovations were implemented. Casing design is aimed to minimize the number of casing sections and a new improved deepwater wellhead system is being used. The drilling fluid system has been specially planned to improve borehole quality, cuttings transport and drilling efficiency.
The innovative approach adopted to drill the wells significantly reduced the total drilling time, which was very important due to the shortage of deepwater drilling vessels in the current market.
Ultrafast Drilling in the Gulf of Thailand: Putting Science into the Design Process
Authors: Pinto C. J. , Pendleton L. E. , Dick J. L. , Sinor L. A. , Oldham J. , Stauffer B. 
Published: December 2007

Abstract
A novel PDC bit design, the result of high end numerical modeling and laboratory testing set the Gulf of Thailand field record for rate of penetration during its first run by averaging 840 ft/hr over the 5,040 ft section. This was accomplished while building inclination from 26° up to 56° before dropping back to 37° at total depth. The bit also made the planned azimuth turn from 305° to 258°. The same design later pushed the performance record further by averaging 1,023 ft/hr over a 6,144 ft. section. Instantaneous rates in excess of 2,000 ft/hr were documented over a 1,000 ft section of this hole. Designing a bit that maximizes rate of penetration while maintaining a neutral walk tendency in rotate mode is presented in this paper.
Extending the Drilling Operating Window in Brent: Solutions for Infill Drilling in Depleting Reservoirs
Authors: Davison J. M. , Leaper R. , Cauley M. B. , Bennett B. , Mackenzie A. , Higgins C. J. , Shuttleworth N. , Wilkinson D. 
Published: December 2007

Abstract
The Brent field is located in the Viking Graben of the northern North Sea and produces from the Brent Formation and the deeper Statfjord Formation. Virgin reservoir datum pressure in 1976 was approximately 5,655 psi at 8,700 ft TVDSS. Pressure support was maintained until the 1998 since when reservoir pressure has been depleting at about 500 psi per year. The current datum pressure in the Brent units is approximately 1600-1700 psi.
Significant lost circulation problems started to be experienced in the late 90's and a study identified the cause as the narrowing of the mud weight window as reservoir depletion gradually lowered the fracture gradient [ref 1]. Mud weights have been lowered to mitigate against the costly lost circulation events. The mud weights currently used are typically 700-900 psi less than the shale pore pressure (i.e. underbalance). Two case histories from sub-horizontal wells last year illustrated that the shales can be drilled over 900 psi underbalanced with no indication of shale failure, however, when running in liners they both hung-up where shales had collapsed. Based on this experience, the minimum mud weight for drilling the sub-horizontal reservoir sections has been set at 700 psi underbalance relative to the interbedded shale pore pressure.
Reservoir depletion has reached the point where the (static) minimum mud weight for shale stability is almost equal to the fracture propagation pressure (FPP) for the reservoir sands. In the first half of 2002, 5 of the 7 wells drilled experienced lost circulation. The average losses volume per well was over 5,000 bbls with nearly 19,000 bbls being lost on one well. Of more significance is the NPT associated with the losses, this averaged over 300 hours per well. The average monetary cost of the lost time and mud volume was close to £1 MM per well. In an environment drilling low cost sidetracks, accessing reserves of 1-2 MM boe, this situation was unsustainable.
A task force set about finding possible solutions to combat the lost circulation problems. After technical review, including laboratory testing, a recommendation was made for a size and concentration of graphite to be added to the OBM. In 10 field trials to date all the sections reached TD without inducing lost circulation, however, 4 of the 10 sections did experience losses when running the liner and/or circulating prior to cementing. With the addition of the graphite the average losses per well has dropped from 5,238 bbls to 621 bbls and the associated NPT has dropped from 302 hours to less than 1 hour per well. Recent field data suggest that the graphite could add approximately 1000 psi to the fracture breakdown pressure. This opens a host of possibilities for future infill drilling in depleting reservoirs.
Surge Pressures in Low-Clearance Liners
Authors: Mitchell Robert F. 
Published: December 2007

Abstract
Pressure surges have long been known to cause well-control problems. As early as 1934, pressure surges resulting from pipe swabbing were identified as a possible cause of fluid influx, and in extreme cases, blowouts, and lost-circulation problems.
In most wells, the magnitude of the pressure surges is not critical became proper casing design and mud programs leave large enough margins between fracture pressures and formation-fluid pressures. A certain fraction of wells, however, cannot be designed with large surge-pressure margins, and some operations are particularly prone to large pressure surges, in particular, the running of low-clearance liners in deep wells.
Low clearance liners have several characteristics not present in the usual surge/swab situation. First, the low clearance produces large fluid friction effects, slowing the liner's speed relative to the surface speed. The moving liner "scrubs" fluid from the wellbore wall, producing lower than expected pressures and allowing fluid influx from the formation. Because fluid ahead of the liner cannot easily penetrate the low clearance annulus, fluid swabbing occurs behind the liner, while larger than normal surge pressures are produced ahead of the liner.
Typically, pressure surges in critical wells are estimated by "steady-flow" fluid models. These models consider the complexities of the non-Newtonian flow of drilling muds, but usually neglect fluid inertia and the compressibility of the fluid and wellbore. The lack of fluid compressibility is considered a conservative assumption because it overpredicts flow rate, while the neglect of fluid inertia is not considered a conservative assumption, because pressure is needed to accelerate the mud when the pipe is run.
Calculating dynamic surges with high fluid friction also presents technical difficulties. Because the fluid flow is overdamped, care must be taken to avoid unstable behavior of the fluid system. Pipe elasticity also needs to be considered, because of the high axial forces developed by the fluid friction at the liner.
This paper fully describes the technical details for calculating dynamic surge pressures with high viscous forces in the low clearance liner annulus. Several sample problems of realistic low clearance liner runs are used to show the unusual pressure distributions developed by these cases. The potential problems running low clearance liners are examined, and possible solutions are presented.
2,000,000 lb. Landing String Developments: Novel Slipless Technology Extends the Deepwater Operating Envelope
Authors: Simpson Burnie , Payne Michael L. , Jellison Michael J. , Adams Burt A. 
Published: December 2007

Abstract
This paper pertains to the technological development of a completely integrated landing system that provides the ability to extend the deepwater drilling and completion envelope. This system is comprised of an elevator, slipless spider, and landing string all specifically designed to land heavy casing strings in deepwater wells thus overcoming the load limitations of conventional equipment. All stages of evolution are analyzed including research, development, design, verification testing, manufacturing, proof testing, running, handling, and actual case histories detailing field use. Actual verification testing loads were over 5,200,000 lbs and proof testing loads were 3,000,000 lbs. Unique manufacturing challenges and solutions associated with the production of ultra-thick wall landing strings with 2,000,000 lbs super premium yield ratings1 (90% remaining body wall) are presented in detail.