bluuebunny/crossref_metadata_2025 huggingface dataset:
The Hyde Development: Sharing Risk and Reward
Authors: Rhodes C. P. , Finch D. J. , Mound D. G.
Published: December 2007

The Hyde Gas Field is a relatively small pool to the North of the West Sole Field, some 70 kilometres east of the English coastline.

Whilst advanced technology and best practice have taken the Hyde project to the launchpad of success, a shared risk and reward strategy has propelled the field beyond the standard orbit of performance for marginal developments.

In 1989, the Hyde project was going nowhere fast.
Propped Fracture Stimulation in Deviated North Sea Gas Wells
Authors: de Pater C. J. , Hagoort J. J. , Abou Sayed I. S. , Donders R. S.
Published: December 2007

We analysed the influence of well deviation on hydraulic fracture treatments in gas bearing Bunter formations, offshore Holland. The reservoir permeability ranged from 2 to 20 mD, which was relatively high for stimulation. Analysis of the pressure records of injection tests and treatments indicated low net fracture pressure and contained fractures. Most treatments ended in wellbore screen-out, giving a high fracture conductivity, especially near the wellbore. The success of the treatments was due to by-passing of a severe skin as well as stimulation of the formation. Also, the well was connected to additional flow units, evidenced by a substantial increase of the permeability (obtained from well tests) after the treatments. In a deviated well we observed gas entry into a small section of the perforated interval. However, there was no indication for a reduced performance of wells with a large deviation compared to the performance of vertical wells.
Effects of Tortuosity in Fracture Stimulation of Horizontal Wells – A Case Study of the Dan Field
Authors: Kogsbøll H. H. , Pitts M. J. , Owens K. A.
Published: December 2007

The horizontal wells, drilled in the Dan field of the Danish sector were initially stimulated with acid fracture treatments, the industry standard for a chalk reservoir. The placement of these treatments proved effective, however, the long term production was limited due to the low formation integrity and consequent collapse of the induced fracture system.

Propped fracture treatments replaced the acid treatments and the benefits to productivity were quickly seen. However, the placement of proppant in some of the Dan horizontal wells was difficult, and in some cases impossible using conventional techniques.

The difficulties in placement of proppant in the Dan field have been attributed to near wellbore tortuosity. This phenomenum occurs due to a variety of situations, namely when well trajectory is not in line with fracture direction, poor cement integrity in the perforated region, and perforation dominated creation of complex fracture patterns in the near wellbore vicinity.

This paper describes the mechanism of tortuosity and its effect on fracture stimulation treatment placement by reviewing several field examples of this phenomenon. The paper also reports modelling procedures utilized to predict the effect of tortuosity. Practical guidelines for removing tortuosity are provided, which have greatly increased the probability of successful proppant placement.

Through better understanding of tortuosity, modifications to completions and stimulation procedures have been implemented which have resulted in over 200 propped fracture treatments being successfully placed from horizontal wells in the Dan field.
Pressure Transient Test Using Mathematical Properties of Type Curve Models
Authors: Alvarado D. A.
Published: December 2007

By taking the derivative of the Bourdet et. al.1 derivative type curve in the Laplace space, using Laplace Transform properties and the Stehfest algorithm the maxima of the curves were found. By inspecting these results it was found that for damaged wells (CDe2S>103), the locus follows a straight line at 45 degrees to the horizontal and parallel to the line Pure Wellbore Storage. The intersection of the extrapolation of this line with the line of zero slope corresponding to radial infinite behavior, defines a unique point over the Bourdet et. al.1 type curve. This point is used as a matching point and that is enough to perform type curve analysis without the use of the type curve.

The method has been extended to analize interference tests, hidrauhc fractured reservoirs well tests and naturally fractured reservoirs well test. Several field examples are presented to illustrate the aplication of the method.
A Muitidisciplinary Study of the Complex Northern Monagas Oil Field, Eastern Venezuela
Authors: Robinson A. C. , Diamond L. F. , de Salazar A.
Published: December 2007

The Geology of Production Study of The Northern of Monagas Oil Fields was done with the participation of a muitidisciplinary team of Geologist, Geophisicists, Petrophisical and Reservoir Engineers. Being the main objective to elaborate the best geological model for the known reservoirs in the area by means of new geological, seismical and engineering techniques. AJ] this was valuable to cuantify reserves as well as to optimize the explotaition schemes proposed for the medium and long term planning.
How to Prevent Gas Lock in Sucker Rod Pumps
Authors: Dottore E. J.
Published: December 2007

This paper contains basic knowledge and formulas that govern fluid production with sucker rod pumps and emphasizes the importance of the parameters that affect the production rate while pumping with a gas phase. The material presented is supported by field experience performed by using special operating conditions and/or special devices acting upon those parameters.
Sand Production as a Viscoplastic Granular Flow
Authors: Geilikman M. B. , Dusseault M. B. , Dullien F. A.
Published: December 2007

A continuum model for sand production is developed by considering coupling of fluid flow and rate-sensitive plastic flow of granular matrix. Initial granular matrix yielding is reached as a result of wellbore fluid pressure reduction (drawdown) below some critical level. The model provides a physical mechanism of yielding front propagation away from the wellbore as the process of sand production continues. Mass balance analysis leads to a relation between cumulative sand production and the current yielding front location. Different regimes of sand production, limited and unstable, are considered. Fluid production enhancement because of simultaneous sand production turns out to be dependent not only on instantaneous sand flux, but also on the current radius of the yielded zone around wellbore, that is, the history of sand production for the well.
Mudcake Cleanup To Enhance Productivity of High-Angle Wells
Authors: Browne S. V. , Smith P. S.
Published: December 2007

The productivity of wells with non-perforated completions can be impaired by both mud filtrate invasion and incomplete mud filter cake removal. Well inflow modelling illustrates that the percentage of the interval flowing and the distribution of the flowing intervals, are more important than the filtrate induced permeability reduction around the wellbore. Therefore adequate filter cake removal is essential for optimum well performance. This paper addresses both physical and chemical methods of mud filter cake removal.
Development of Advanced Drilling, Completion, and Stimulation Systems for Minimum Formation Damage and Improved Efficiency: A Program Overview
Authors: Layne A. W. , Yost A. B.
Published: December 2007

The Department of Energy's (DOE) Natural Gas Resource and Extraction Program consists of industry/government co-sponsored research, development, and demonstration (RDfiD) projects, which focus on gas recovery from both conventional and nonconventional resources. The Drilling, Completion, and Stimulation (DCS) Project focuses on advanced, non-damaging technology systems and equipment for improving gas recovery from conventional and nonconventional reservoirs. As operators move from development of current day economically attractive gas-field development to the lower permeability geologic regions of domestic onshore plays, increasing the emphasis on minimum formation damage DCS will permit economic development of gas reserves. The objective of the Project is to develop and demonstrate cost-effective, advanced technology to accelerate widespread use and acceptance of minimum formation damage DCS systems. The goal of this product development effort is to reduce costs and improve the overall efficiency of vertical, directional, and horizontally drilled wells in gas formations throughout the U.S.

The current focus of the Project is on the development of underbalanced drilling technology and minimum formation damage stimulation technology concurrently with the appropriate completion hardware to improve the economics of domestic natural gas field development. Ongoing drilling technology projects to be discussed include development of an electromagnetic measurement while drilling system for directional and horizontal drilling in underbalanced drilling applications and . the development of a steerable air percussion drilling system for hard formation drilling and improved penetration rates. Ongoing stimulation technology projects to be discussed include introduction of carbon dioxide/sand fracturing technology for minimal formation damage.
Formation Damage in Gravel Packed and Non-Gravel Packed Completions: A Comprehensive Case Study
Authors: Chuah Beng-Swee , Hasumi A. R. , Samsudin Noren , Matzain Ahmadbazlee
Published: December 2007

A comprehensive formation damage study was undertaken on selected fields in the Baram Delta acreage, offshore East Malaysia, to determine the extent and main causes of formation damage in the area. This was due to the high skin factor values interpreted from most transient well tests conducted throughout the years. A total of 70 gravel packed and 60 non-gravel packed wells (involving 220 completion zones) in 6 fields were covered in the study.

Based on statistical and pressure transient data analysis as well as an in-depth review of drilling and completion activities, it was found that the majority of non-gravel packed wells have low or negligible formation damage. Between 60 and 70% of the non-gravel packed wells have skin factors of less than 10. Most of these wells have constant skin factors as a function of time indicating that the damage, if any, did not increase with oil production.

On the other hand, the majority of gravel packed wells were damaged. As much as 70% of these wells have skin factors varying between 10 and 40. About half of these gravel packed wells have skin factors which increased with time indicating that the damage worsened with oil production. Formation damage in these gravel packed wells may be attributed to the gravel packing operations. This was further substantiated by well test results which showed that skin factors immediately after perforating were essentially zero while those determined from pressure build-up tests carried out at a later date after gravel packing operations were in the order of 10 to 100. It was also observed that although improvements in gravel packing and perforating practices were implemented through the years, no significant enhancement of flow efficiencies had resulted.
Productivity Comparison Of Sand Control Techniques Used for Completions in the Vermilion 331 Field
Authors: Mullen M. E. , Norman W. D. , Granger J. C.
Published: December 2007

This case history covers three different types of sand control completion techniques used to complete the Ang B and Lentic reservoir sand series. This paper makes a comparison of the following techniques: Slurry packs, Water packs and Frac packs on 16 completions. This paper includes a rudimentary description of the techniques covered. It includes a brief review of the data evaluated for design considerations in selecting the different techniques used in each case. A review of execution considerations, procedural requirements and an evaluation of the completion performance is also included.

The evaluation of completion techniques for optimum reserve recovery is a controversial topic. Case histories help to separate fact from presumption when fairly evaluated. In an effort to fairly evaluate these completions, a normalized productivity index was developed and used. This paper evaluates the old and new completion techniques employed in the Vermilion 331 field.
Formation Damage and Skin Factor Due to Filter Cake Formation and Fines Migration in the Near-Wellbore Region
Authors: Liu Xinghui , Civan Faruk
Published: December 2007

Particle invasion and fines migration are among the major factors causing formation damage. Extensive studies of formation damage in laboratory and several modeling efforts for prediction of formation damage have been reported in the literature. However, a satisfactory model to simulate the near-wellbore formation damage in field conditions is still not available. In this paper, the linear flow core-scale model presented previously by Liu and Civan is converted into a radial flow field-scale model to simulate the formation damage near wellbore regions in actual field conditions. The radial flow field-scale model utilizes the values of model parameters obtained by a model assisted analysis of the laboratory core tests to determine the temporal and spatial variation of formation damage and the associated skin factor. Simulation results indicate that the overbalance pressure of drilling fluids is an important factor for formation damage control and that the formation damage due to constant-pressure mud filtration is less severe in two-phase flow of oil and water than single-phase flow of water in the formation.
Ultrasonic Treatment for Removal of Asphaltene Deposits During Petroleum Production
Authors: Gollapudi U. K. , Bang S. S. , Islam M. R.
Published: December 2007

Crude oils produced in many parts of the world contain asphaltenes. Asphaltenes are known to deposit in the vicinity of production wells during miscible floods or during thermodynamic changes. Asphaltene deposition leads to production loss and involves expensive corrective measures. This study proposes a new technique for cleaning asphaltenes with an ultrasonic device. A laboratory ultrasonic disruption device was used in this study to carry out experiments. A thin layer of asphaltene was applied to small glass beakers and the beakers were ultrasonically treated for different time periods at different amplitudes in aqueous and kerosene media, separately. Subsequent to ultrasonic treatment, the weight loss fractions were calculated. In a second series of experiments, a two inch long column of asphaltene/sand mixture was placed on top of a sand column in a flow cell, and the flow rates were measured before and after the ultrasonic treatment. The flow rates were correlated with those of sand packed columns in absence of asphaltenes.

Experimental results indicated that the asphaltenes get disrupted effectively after a minimum exposure of one and a half minutes to ultrasonic radiation. However, the maximum amount of cleaning was noticed after an exposure of two minutes and at higher cycles that affect amplitude of the ultrasonic radiation. The increased flow rates measured after the treatment indicated that the technique can be used in an oil-field to disrupt, or desegregate asphaltenes from the vicinity of producing oil-wells. However, simultaneous pumping is recommended during the ultrasonic irradiation, to avoid the reprecipitation of the disrupted asphaltenes. The ultrasonic cleaning appears to be disrupting the maltenes that form a continuous phase to provide adhesive and ductile properties to the dispersed asphaltenes. If this technique is used, following scaled studies, in a field with a modified device, it can reduce the expenditure of taking corrective measures, and can provide technological breakthrough to petroleum industry.
Experiences Gained in the Use of Frac-Packs in Ultralow BHP Wells, U.S. Gulf of Mexico
Authors: DeBonis V. M. , Rudolph D. A. , Kennedy R. D.
Published: December 2007

Four wells in the U.S. Gulf of Mexico were worked over in reservoirs with bottomhole pressures (BHPs) ranging from 0.17- to 0.23-psi/ft gradients using the frac-pack technique. The purpose of the paper is to detail the chronology and expose the learning curve which led to the successful completions. Treatment tools, tubulars, design, rate, and fluid selection are discussed as they were applied in the implementation of each successive treatment.
Effect of the Perforation Damage on Well Productivity
Authors: Asadi Mahmoud , Preston F. W. , Green D. W. , Ghalambor Ali
Published: December 2007

This paper reveals new information on the reduction in productivity caused by the crushed zone surrounding a jet perforation tunnel. A Berea sandstone sample was perforated according to a slightly modified API RP 43 Recommended Practice Standard Procedure for perforation, using a 3.5 gr. RDX type charge. The crushed zone was identified using a scanning electron microscope, SEM. The crushed zone was divided into a number of cells both radially (away from the shot center) and longitudinally (along the perforation tunnel). Porosity and permeability of each cell were obtained using image analysis. The permeability value of each cell was arranged around the perforation tunnel according to their original orientations. Using a black oil simulator, productivity of a well was found and compared to one where no permeability reduction was assumed for the crushed zone. In addition, the Dykstra-Parsons relation was employed to estimate permeability values for a suite of 20 cells. The estimated values were then oriented around the perforation tunnel in ascending, descending, and randomly orders. Productivity of the well was obtained for each permeability orientation. A 55% permeability reduction around the perforation tunnel, as the result of the perforation process, led to a 60% reduction in well productivity. Also, ascending orientation of the permeability around the perforation tunnel resulted in a higher well productivity than descending or random orientation.
A Current Look at Thermal Recovery
Authors: Ramey Henry J.
Published: December 2007

Modern interest in thermal recovery began in the early 1950's with discovery of the insitu combustion process. By the end of the 50's, the first commercial installations of insitu combustion had been made and are still operating today. But there are only a handful of commercial insitu combustion operations, most of which are located in California. In the early 1960's, the main interest in thermal recovery shifted to cyclic steam injection and production of oil. Where applicable the cyclic process has been very successful and many California operators feel they have fully-developed their cyclic steam injection potential. Currently, interest appears to be shifting toward operations involving continuous injection coupled with cyclic steam injection stimulation of producing wells. Cyclic steam injection is one important factor credited with arresting declining oil production rate in California.

Economically successful thermal oil recovery operations of all three major types: insitu combustion, continuous steam injection, and cyclic steam injection, are or have been conducted in many portions of the world.

Introduction

The start of modern interest in thermal recovery dates from publications on insitu combustion in the early 1950's. It was evident from the beginning that there were a large variety of ways to introduce heat into an oil reservoir. Many publications and patents concerning hot fluid injection and patents concerning hot fluid injection and variations on insitu combustion appeared throughout the 1950's. By the end of the decade, the important features of continuous drive thermal methods such as combustion, steam, and hot water injection were thoroughly documented in the literature. In regard to field operations, a number of pilot tests of insitu combustion had been conducted and described, but very little was known regarding field results of hot fluid injection. It was evident that insitu combustion was not economically feasible in all heavy oil reservoirs, and thus a growing interest in hot fluid injection was appearing.
Novel Rheological Equipment for the Characterisation of Hydraulic Fracturing Fluids
Authors: de Kruijf Alexander , Davies D. R. , Fokker P. A.
Published: December 2007

Two novel rheological devices for measurements on hydraulic fracturing fluids have been developed. The helical screw viscometer (HSV) can be used to study the rheology of fracturing fluids such as crosslinked gels and proppant-laden slurries. The dynamic settling tester (DST) has been designed to measure proppant settling velocities in flowing hydraulic fracturing fluids. This paper will discuss the principles of the new equipment and its applications in the field of hydraulic fracturing. The HSV can be used e.g. to study the slurry rheology of fracturing fluids, the relation between the chemistry and flow mechanics of borate-crosslinked gels and the compatibility of resin-coated proppants and fracturing fluids. The DST has proved highly effective for studying the fundamental properties of the complex fluids typically used for hydraulic fracturing treatments. Completely unexpected phenomena - such as a decrease in proppant settling rates due to shear of a shear-thinning fluid — have been identified.
Acidization-Induced Formation Damage: Experimental and Modeling Studies
Authors: Gadiyar B. R. , Civan Faruk
Published: December 2007

The results of laboratory experiments conducted to investigate the effect of matrix acidization on long berea sandstone cores (6"-12") and their theoretical analysis are presented. Both damaged and undamaged core samples were treated with different concentrations of HCl/HF acids (4%HCl/1.5%HF and 12%HCl/3%HF). One undamaged core sample was treated with 6%HF acid. The effect of spent acid on permeability was investigated. The treated cores were cut into four sections each and the mineralogy of each section was analyzed using an X-Ray Diffraction (XRD).

A simplified model for matrix acidization induced formation damage was developed and facilitated to analyze the laboratory test data and to determine the relative affects of adverse processes in matrix acidization. The model developed takes into account the change in concentrations of both acid and minerals, thereby predicting the change in permeability.

The results indicated that higher concentration of acid causes more formation damage due to the precipitation of silicates and/or iron oxides. In addition, when the spent acid resides in the core for a longer time it causes a severe formation damage.

It is shown that the experimental and simulation results agree well within the accuracy of the simplified model.
The Miller Field: Appraisal and Development Formation Damage Experiences
Authors: Adair Paul , Smith P. S.
Published: December 2007

The Miller field lies in blocks 16/7b and 16/8b of the UKCS and was discovered in 1982. The Miller reservoir is an Upper Jurassic submarine-fan sandstone with a typical true vertical depth of 13,200 feet (4000m). The field currently produces circa 125mbpd from seven wells. The oil contains 11% by weight of carbon dioxide and the gas typically contains 200 ppm (vol/vol) of hydrogen sulphide. General reservoir fluid parameters are listed in Table 1.
Coiled-Tubing Case Histories
Authors: Leising L. J. , Rike E. A.
Published: December 2007

The total number of coiled tubing drilling (CTD) jobs worldwide has grown from 4 in 1991 to 11 in 1992 and will probably exceed 25 in 1993. While CTD still represents only a small fraction of the worldwide drilling market, the growth rate indicates CTD is a technology that is rapidly coming of age. This paper summarizes the jobs performed to date and charts the applications in an effort to predict future trends.

In addition, one specific case study is presented for a well in Alaska. This well was drilled through tubing and underbalanced, thus saving the cost of pulling the completion tubing and preventing formation invasion damage. Coiled tubing is routinely used for live well intervention; its use allows an accepted, safe method for underbalanced drilling.

Underbalanced drilling is appropriate for many mature and depleted field re-entry projects and offers a method of both preventing invasion and increasing productivity while enhancing natural flow and ultimate recovery. In addition, differential sticking is eliminated and penetration rate is greatly increased.
Installation of Monopod Production Structures Using Jackup MODU's
Authors: McRae L. D. , Montoya A. C. , Keaton C. P. , Ettle R. E.
Published: December 2007

Jack-up Mobile Offshore Drilling Units have been used to set monopod production structures in the offshore waters of the Gulf of Mexico. The monopod caisson is towed to the site, picked up with the traveling gear, ballasted with salt water, uprighted and driven with a diesel hammer. This procedure obviates the need for a derrick barge to set a jacket thus eliminating scheduling problems and reducing costs.
The Alliance: An Alternative Approach to Integrated Drilling Services
Authors: Carr A. J. , Howell P. D.
Published: December 2007

Lead Contractor and Alliance contract models provide a template for managing operations cost effectively, safely and in a quality manner. The models are contrasted and the relative benefits examined. The experience of establishing an operating Alliance is described for a North Sea platform drilling and workover programme.
Solution of Common Stuck Pipe Problems Through the Adaptation of Torque/Drag Calculations
Authors: Haduch G. A. , Procter R. L. , Samuels D. A.
Published: December 2007

Stuck pipe conditions require fast and effective response. This paper describes a method through which torque/drag calculations can be adapted to quickly and accurately answer the three most often asked questions associated with stuck pipe situations. This approach is used to determine:

the force at the stuck point given any measured weight the measured weights required to set and trip a jar the measured weight required for backing off at a given depth

The method correctly accounts for the critical role which drag forces play in these calculations. Further significant enhancements over previous methods are provided by taking into account both the operating condition at the time of sticking and any subsequent surface action taken by the driller before stopping operations. The integration of this methodology with currently available torque/drag analysis software, provides the drilling engineer with a wider range of solutions for problems associated with day-to-day operations.

The theoretical basis for this method is summarized, and drillstring behavior prior to, during, and after sticking is explained. An understanding of friction effects and their impact on the final solution is emphasized. A wide range of operational cases are presented, and comparisons showing important benefits over other calculation methods are included.
Mud-Gas Separator Response to Well Control Procedure
Authors: Williamson M. D. , Dawe R. A.
Published: December 2007

A gas kick is removed from a wellbore by applying well control procedure. The large volume of flammable gas brought to the surface is directed toward the mud-gas separator, MGS, where it is separated from the mud and safely disposed of. However, the gas flow rate may become so large that the MGS overloads. Under these circumstances, significant amounts of hydrocarbon will be released onto the rig floor causing a risk of explosion. This situation poses a serious danger to rig personnel and equipment.

Advanced gas kick simulators are now available that can predict the flow properties of the fluids entering the MGS as functions of time during the well control procedure. The availability of such detailed information presents an opportunity to understand the response of the MGS to well control procedure. This detailed information allows the development of models of the MGS that predict MGS parameters with greater precision than existing methods will allow.

In this paper, models of the physical processes that occur at the MGS are developed. These models have been combined to produce an algorithm which, together with simulated well control data, can estimate MGS parameters as functions of time during the well control procedure. This algorithm will be useful to office based drilling engineers preparing rig safety cases during the well planning stage of drilling a well. The use of this algorithm will result in better selection of well control procedure, MGS operation and sizing, and better contingency plans for altering the well control procedure or MGS operation should the need arise.
A Discussion on Casing Settling During Shallow Gas Blowouts
Authors: Adams N. J. , Kuhlman L. G.
Published: December 2007

This paper discusses an aspect of shallow gas blowouts not previously addressed in prior published works. The topic considered is the effect of blowouts on settling of casing strings. Some field cases have resulted in complete loss of the pipe in underground caverns while others have shown no settling, in some cases, subsea BOP stacks were lost with the casing. Deep blowouts and casing settling will be discussed also.

This paper will consider 7 field cases as examples of the event. Some cases had settled or lost casing while others remained undisturbed and intact. The paper presents hypotheses on settling causes.

Recommendations will be given on procedures to diagnose the probability that pipe will settle and give some field procedures on how to prevent or control pipe settling.

Shallow gas flows on production platforms have resulted in settling of the blowing well and also settling in other producing wells on the platform. Examples will be given. Control problems will be discussed.
The First 12 Snorre Field Wells: Accelerating the Learning Process
Authors: Oftedal T. O. , Ledsaak J. P. , Pollard M. G. , Hjellen A. P. , Elks W. C. , Haut R. C.
Published: December 2007

This paper discusses the experience gained by Saga Petroleum during the drilling and completion of the first 12 wells at the Snorre Field as well as the systems developed to help maximize the learning curve. Included in the paper are specific examples of how the drilling and completion times at Snorre have been reduced.
Reducing Downtime Due to Top Drive: The $1000 Bet
Authors: Ogidan Biodun
Published: December 2007

From 1982 when the first TDS (Top Drive System) was introduced to drilling to 1993 when over 350 units were operating worldwide, there have been over 100 service bulletins issued by Varco (the TDS main supplier). These bulletins in conjunction with 5 major upgrades to the equipment have contributed to improvements in its operating performance and safety in operations. The bulletins and upgrades (= improvements) have been driven by continous feedback from TDS users worldwide.

Inspite of the improvements haven been made, the tool remains a significant cause of rig downtime if not well managed.

Sedco Forex, was the first drilling contractor to install a Top Drive on its rig (the Sedneth 201 & 202 in 1982) and has the highest number of Top Drives in use worldwide. Consequently, there was a need by the drilling contractor to develop and monitor a program to reduce TDS downtime. Analysis showed that 20% of rig downtime was accountable to this equipment. This analysis was conducted using performance data taken from 36 rigs over a period of 3 years. Half of these rigs were fitted with Top Drives.

This downtime coupled with high maintenance cost and expensive upgrades of the equipment translate into over $200,000 cost per TDS unit per year. To address this issue, as an incentive, Sedco Foiex and Varco each pledged a nominal $1,000 lumpsum bonus/malus per TDS unit, payable by either party to the other, dependent upon improvements being made to Top Drive related downtime. The goal was to reduce TDS downtime by 30% within a year. Varco would earn the bonus / incur the malus if the goal was / was not achieved.

During the first 5 months of the incentive agreement, it was observed that both parties profited to a degree far greater than the original pledge.

This paper explains the virtual approach taken by the two companies to achieve a true win-win situation, and demonstrates the benefits to be gained through a simple and practical contractor - supplier alliance.

The paper concludes that there is a potential saving to the oil industry of several million dollars by reduction of TDS related downtime.
Complete System for Continuous Coring With Retrievable Tools in Deep Water
Authors: Gelfgat Michael , Gamsakhurdia George , Geise Joost , Spierings Henk
Published: December 2007

Drilling shallow stratigraphic boreholes in deep water is an important component leading to reduction of exploratory costs. The Complete Coring System (CCS), using special retrievable tools and large diameter aluminium drill pipes has proved to be a possible way to perform this task. CCS combines experience of Russian continental scientific drilling techniques with ODP research efforts and is represented by several coring methods along with sequential drilling using a retractable bit and logging without tripping of the drillstring. Separate units of the system have been used both onshore and offshore in different geological conditions. In 1993 CCS has been utilized for drilling in 1500 m water depth offshore Norway.
A Computer Programme for Drilling Hydraulics Optimisation Considering Realistic Rheological Models
Authors: De Sá C. H. M. , Martins A. L. , Amaral M. S.
Published: December 2007

Drilling fluids while circulating in oilwells are submitted to a wide range of shear rates, varying from very low values (in the mud tank or in riser/drill pipe annular region) to very high ones (through the bit nozzles).

It is common sense among rheologists involved in the area, that the conventional rheological models (Bingham and Ostwald de Waele) do not represent adequately the behaviour of drilling fluids in such a wide range of shear rates. Other rheological models have been proposed to characterize drilling fluids. However, their current use in the design and supervision of drilling operations is not overspread yet.

Since most drilling rigs today have computational facilities, there is no longer necessity to use inaccurate models for engineering calculations. Adequate rheological characterization is an essential starting point for several calculations, such as hydraulics, cutting transport, kick control, etc.

This paper presents a procedure for drilling hydraulics calculation based on dial readings at the six available rotation speeds of the conventional oilfield viscometer, calculation of five rheological models and use of specific friction loss correlations for each model. An user friendly computer program was developed for optimum flow rate calculations based on this procedure and validated with data obtained from a real scale well. The program was developed based on the requirements of several drilling activities such as offshore operations, compressible fluids, high angle wells, etc.
Interactive Modelling of Multiphase Inflow Performance of Horizontal and Highly Deviated Wells
Authors: Alvestad Jostein , Holing Kent , Christoffersen Kjell , Langeland Ole , Stava Ole
Published: December 2007

An interactive system for modelling of multiphase inflow performance of long, highly deviated and horizontal wells is presented. It's prime areas of use are design of well trajectories and completions, and evaluation of wells inflow performance including calculation of well indices for full reservoir simulation. Further, the system provides a basis for improved integration of the reservoir engineering and the well completion design. The reservoir pressure and multiphase flow distribution is modelled accurately using a finite element method combined with automatic local grid refinement around wells. A comprehensive multiphase wellbore flow model is available for accurate flow modelling in the wellbore. A well inflow model including a generalized formula for calculation of well indicies of wells in arbitrary directions is proposed. Examples are given showing improved inflow performance calculations using the new well indices.
Downhole Material Selection for Clyde Production Wells: Theory and Practice
Authors: Blackburn N. A
Published: December 2007

The Clyde oilfield lies within North Sea block 30/17b. First oil was produced from the field in March 1987.

Wells drilled during field appraisal indicated a potentially, highly corrosive downhole environment. Although high chromium content (Duplex) steels appeared to be the technically preferred completion material a decision was taken to use carbon steel tubulars.

Historical data has shown that carbon steel gives acceptable performance in the large majority of production wells. Failures have occurred but these have been highly specific and related to high fluid velocities and increasing watercuts. A "mixed" string completion employing carbon steel, 13 Cr and plastic coated tubing has been successful in controlling downhole corrosion in these few problem wells.

This paper reviews the downhole corrosion control strategy used on the field and shows how carbon steel may be used successfully in a severe downhole environment.
New Polymer Gels for Reducing Water Production in High-Temperature Reservoirs
Authors: Albonico Paola , Bartosek Martin , Lockhart T. P. , Causin Emilio
Published: December 2007

Selected complexing agents are used to achieve the delayed gelation of Cr(III) crosslinked acrylamide polymer compositions to temperatures as high as 150°C. With these retarding agents formulations based entirely on inexpensive, commercially available materials have been developed that display gelation characteristics suitable for a wide range of reservoir treatments at elevated temperature. Studies on Cr(III) acetate show that Cr(III) propagation in porous media degrades sharply at elevated temperature. The presence of the retarding agents significantly reduces Cr(III) retention and enhances the stability of Cr(III) in solution. The mechanisms underlying this behavior and the implications for gel treatments in reservoirs at elevated temperature are discussed.
Using Simulation To Assess Manning, Skills and Logistics Requirements for High Productivity and Low Life Cycle Cost
Authors: Gray C. G. , Aase B. K.
Published: December 2007

Statoil has cooperated with Hunting Engineering Ltd. to establish a simulation software tool applicable to offshore industry needs. The software has been named AIMLO (Analysis of Installation Manning, Logistics and Operations).

The purpose of this paper is to show that a simulation model of this type can be used to determine how manpower and installation productivity are affected by:

Installation characteristics, including:

Type of equipment installed

Criticality of main functions

Failure modes and Mean Time Between Failures

Events/Failures that require an immediate visit

Maximum number of men allowed on the platform

Manpower characteristics, including:

Location of the maintenance crew

Each man’s skills

Shift patterns

Logistics support levels, including:

Alternative transportation routes and times

Availability of a helicopter

Operating and maintenance policies, including:

Maintenance strategy

Type, amount and frequency of workload activities

Required skills and seniorities

Other activities

Control philosophy

Intervention philosophy

The model results can make a significant contribution to the design and policy decisions which impact on the operational availability and whole life cost of an installation.

The paper is presented in two parts. The first part describes the application of the model to a specific project. For commercial reasons the quantitative information derived during this study is omitted from the paper. The second part describes the origins and nature of the simulation technique, and how it may be developed in the future.
Critical Issues in Hydraulic Fracturing of High-Permeability Reservoirs
Authors: Cleary M. P.
Published: December 2007

The paper focuses on the sub-class of issues which can affect/dominate the performance of hydraulic fracturing in (gas or oil) reservoirs with higher-permeability, of order lmD (10mD) or more in gas (oil) reservoirs. These issues are placed in the broader context of five major aspects which have been newly extracted from data-analysis over the past five years and which have greatly polarized/reversed industry thinking on hydraulic fracturing: heretofore, primary implications have been for lower-permeability reservoirs, where convection and tortuosity constraints impose a narrow (or non-existent) window for successful design of fracture treatments, especially in light of properly-interpreted higher net fracturing pressures (than conventional industry models) induced by nonlinear rock response to (multiple) fractures. A much wider design window has made successful stimulation of higher-permeability reservoirs relatively easy and economically more rewarding, a result surprising to some. Perhaps more surprising are conclusions that appropriate proppant concentration may vary somewhat inversely with reservoir permeability and that fractures may preferentially grow (vs. initiate) in lower- permeability strata/sections, the main theme of this paper. Fluid rheology also plays a much more important role in (leak-off behavior during) fracturing of high-permeability reservoirs vs. a lower-permeability role limited to near-wellbore (tortuosity) response. Some issues are illustrated with simulations performed by a unique computerized system, which allows credible matching of (treatments and production) data over a wide range of reservoir, fluid and job parameters - thereby allowing establishment of conclusions with case-histories, supported by some careful laboratory experiments. With the aid of this computerized capability, dramatic results have been achieved in reducing job costs and improving production, especially for low- to medium-permeability reservoirs, but many of the implications can be carried over to high-permeability reservoirs.
Asphaltene Deposition Monitoring and Removal Treatments: An Experience in Ultra Deep Wells
Authors: Galoppini Maurizio , Tambini Mauro
Published: December 2007

An anomalous decline in production parameters has been observed since the beginning of the productive life of wells in the ultradeep Villafortuna-Trecate (VF-TR) field in northern Italy owing to the deposition of asphaltenes within the formation and tubing string.

This paper discusses the procedures that have been developed for monitoring well productivity performance based on the measured surface production parameters. These data are processed by means of well performance analysis in order to obtain a so-called Equivalent Productivity Index which is correlated with the Cumulative Production and has been used to determine when and if to carry out remedial solvent treatments, and to optimize the volumes and field treatment procedures.

Case histories of the most significant experiences are reported, including the results of production logs. These clearly show the progressive plugging of perforations owing to asphaltene deposition and the subsequent action of the solvent/acid treatments.
Use of Transient Rate and Pressure Data To Determine Drainage Area Average Reservoir Pressure Without Shutting In the Well
Authors: Ahmed Usman , Hendrix J. L. , Schwanitz B. J.
Published: December 2007

Drainage area average reservoir pressure , p¯, is an important reservoir parameter needed to define reservoir potential and also to plan and evaluate performance of various flooding processes. In certain countries and states, Alaska for one, the state oil and gas department requires the measurement of p¯ annually on designated wells. Typically, p¯ is estimated by shutting in a well and performing either a conventional pressure build-up test or taking static pressure measurements at designated intervals. In both the scenarios, test times can be days to weeks depending on the formation permeability. In the case of static pressure test, error bounds can be significant.

In this paper we present an alternate technique that allow the estimation of p¯ without shutting in the well and performed in a relatively short period of time. The technique was developed in conjunction with BP Exploration in Alaska by modifying Schlumberger’s existing Transient Rate and Pressure (TRAP) testing analysis. The technique involves imposing a transient on the formation; and the rate convolved pressure is used in conjunction with the Mathews-Brons- Hazenbroek (MBH) method to calculatep¯.

The project described in the paper consist of developing the technique and applying to six wells. In several cases long term build-up data was available for comparison. The comparison was very good and following a review by the State of Alaska regulatory board the technique was approved as a replacement for long term shut-in tests.
Slim-Hole and Coiled-Tubing Window Cutting Systems
Authors: Faure Alban , van Elst Herman , Burge P. M. , Jürgens Rainer
Published: December 2007

With re-entry drilling systems available for hole sizes as small as 3-7/8", slimhole re-entry horizontal drilling offers operators an opportunity to improve field recovery and revitalize wells suffering from gas or water coning by infill drilling. In particular, the potential for coiled tubing drilling has created significant industry interest over the last 18 months. Offshore where there is no derrick in place, use of a coiled tubing drilling system makes it possible to redrill old wells and perform horizontal re-entries.

To date, coiled tubing re-entry wells have used a conventional rig to cut the window, adding unnecessary costs and time to the program. It was recognized that a coiled tubing conveyed window cutting system will enhance the capabilities of coiled tubing drilling by eliminated the need to cut the window with a conventional rig.

The problems of slimhole window cutting include controlling weight on bit while starting the window, and reducing torque while milling to prevent drillpipe failure.

In the coiled tubing application, rotation is supplied by a downhole motor, which presents additional problems with respect to controlling weight on bit.

A milling system that combines downhole motors with hydraulic thrusters to supply constant weight on bit has been bench-tested and field proven. While the prototype system required three milling runs after setting and orienting the packer, subsequent systems are in testing to reduce the number of milling runs to one.

A description of the applications and requirements of the window cutting system is provided, along with bench test and field test results.
Potential of the Cyclic CO2 Process in a Waterflooded, Light Oil, Shallow Shelf Carbonate Reservoir
Authors: Wehner S. C.
Published: December 2007

The goal of this Central Vacuum Unit Project is to demonstrate the CO2 Huff-n-Puff process in a light oil, shallow shelf carbonate reservoir within the Permian Basin. The CO2 Huff-n-Puff process is a proven enhanced oil recovery (EOR) technology for Louisiana­ Texas gulf coast sandstone reservoirs. The reader is referred to three Society of Petroleum Engineers (SPE) papers, No. 15502, 16720 & 20208 for a review of the theory, mechanics and case histories of the process. The process has even been shown to be moderately effective in conjunction with steam on heavy California crude oils. Although the technology is proven in sandstones, it continues to be a very underutilized EOR option for carbonates.
Application of Integrated Reservoir Management and Reservoir Characterization to Optimize Infill Drilling
Authors: Pande P. K. , Clark M. B. , Blasingame T. A. , Kelkar Mohan , Vessell R. K. , Hunt P. E.
Published: December 2007

This project demonstrates the application of Advanced Secondary Recovery (ASR) technologies to remedy producibility problems at the North Robertson (Clearfork) Unit, in Gaines County, Texas. The North Robertson (Clearfork) Unit is a Shallow Shelf Carbonate (SSC) reservoir of Permian-Leonardian age operated by Fina Oil and Chemical Company. The Department of Energy (DOE) has selected the Unit as a Mid-Term Field Demonstration under the DOE Class II Oil Program.