bluuebunny/crossref_metadata_2025 huggingface dataset:
A New Method of Measuring Gas Compressibility and Gas Gravity
Authors: Pilcher V. B.
Published: December 2007

Practically all metering devices used in the oilfield today require some correction factor for gas gravity and gas compressibility factor (Z factor) in their calculations. An error in either gas gravity or Z factor could potentially make a significant difference in these calculations. The accepted method of calculating the Z factor uses critical property and gas gravity correlations. The proposed method allows for the calculation of the Z factor by direct field measurements.

A critical flow nozzle can be used in conjunction with a thermometer, turbine meter, and differential and static pressure gauges to allow direct measurements at the wellhead. A simple computer program then uses these measurements to calculate both Z factor and gas gravity. The paper describes the test apparatus and the calculation procedure.
New MWD Applications Using a Slimline Fully Retrievable MWD Tool
Authors: Henderson B. , Cluchey M. O.
Published: December 2007

A new, slimline, fully-retrievable, Directional MWD tool (DMWD®), is finding new applications for and benefits from MWD. Case histories illustrate how compact size and full retrievability are extending MWD into areas of high stuck-pipe risk, small holes, high-temperature drilling, low-budget wells, and remote locations.
Failure Prevention by Selection and Analysis of Drillstem Connections
Authors: Armstrong G.M. , Wadsworth T.M.
Published: December 2007

Connections for drill stem components are routinely selected on an as-available basis or with little regard for the function of the connections. This occurs because most of the effort in drill stem design is usually concentrated on the operating characteristics of the pipe and tools. Dependent upon the type and condition of the connections selected and the drilling conditions encountered, the connections may be a major source of failures and other operating problems. By planning and selecting connections with performance characteristics appropriate for specific drill stem components, the risk of failures can be significantly reduced through more accurate designs which identify and minimize weaknesses.

This paper discusses a systematic method of identifying and analyzing connection characteristics which are pertinent to drill stem design. An understanding of connection characteristics and how to analyze and compare them is provided. Basic characteristics such as bending strength ratio and make-up torque are reviewed. Also included are the effects of machining variations such as stress relief grooves and characteristics such as torsional strength ratio, bearing stress and external load capacity.

Introduction

The design and selection of drill stem components usually occurs after the framework of the drilling programs, such as the directional program, tubular design and hole sizes, have been completed. Consequently, it is often given minimal attention even though the affects can be substantial. Some of the common criteria are:Selection of components based on inside and outside diameter (ID, OD) without regard for the connection.Use of the lowest priced equipment (such as contractor furnished components), the lowest priced rental equipment available or locally available rental tools.Selection of equipment with connections which will minimize the number of crossover subs required.

When selected in this manner, the connections may be inadequate or mismatched and result in higher failure frequencies.

To reduce the risk of failure, the connections should be matched to the component by taking into account the anticipated operating conditions and predominant failure mechanisms. The method described in this paper is:Selection of connection OD based on hole conditions, contractor equipment capacities and equipment availability.Selection of the optimum connection, including size, thread form, ID and special features based on the performance properties of the connections.Development of operational criteria for the connection including make-up torque and dimensions (OD and bevel diameter).

SELECTION OF CONNECTION OD

The selection of component and connection OD's should consider the factors described below. Since the emphasis of each item must be tempered by the anticipated drilling conditions, the priority of each factor must be considered on a well-by-well basis.

P. 207^
A Case History of a Trouble-Free, 20,000-ft Well: Teamwork Pays Off
Authors: Chaney B. P. , Nelson J.
Published: December 2007

Combining the best efforts of operator, drilling contractor, and service company personnel is the goal on any drilling project. This is exactly what happened on Ballard Exploration's Carey and Corolla #1, in Grimes County, Texas.

A partially hydrolyzed polyacrylamide (PHPA) was used as a protective colloid in a low pH, low solids mud system to prevent cuttings dispersion and promote wellbore stability. The optimization of mud properties and a preventative approach to hole problems was responsible for reaching 20,631 feet (6288 m) in a safe and trouble-free manner. The consensus of all concerned parties was that the primary reason for these desirable results was the hole stability achieved with this inhibitive water-based mud. Obviously, there were other factors which played an important part. Teamwork, and careful attention to detail, allowed total depth to be reached in only 119 days, and 2184 rotating hours. Overall drilling performance was improved compared to offsets in the area.
Well Control Insurance: An Overview and Outlook
Authors: Rice W. E. , Burris G. D. , Johnson B. C.
Published: December 2007

Insurance designed strictly for and tailored to risks inherent in oil and gas operations has been available since the 1940's. Originally, this insurance was offered to operators and nonoperators and covered only indemnification for costs incurred to control blowouts, fires, or craters, but over the years, coverage has evolved so as to extend protection to operators, nonoperators and drilling contractors for indemnification for other costs incurred consequent upon the occurrence of events the risks of which are inherent in day to day drilling operations.

The purpose of this paper is to discuss the history of "well control insurance" as well as to touch upon current changes which will shape its future. In addition to generally discussing the duties and responsibilities of operators, nonoperators and drilling contractors in the proper formulation and presentation of an insurance claim consequent upon the occurrence of a loss suffered during the drilling of or other operations concerned with an oil and/or gas well, the recently developed and newly accepted form of control of well insurance wording entitled "Energy Exploration and Development Insurance (8/86)" receives comprehensive treatment.
A Look Ahead: Back to Basics?
Authors: Turrentine R. E.
Published: December 2007

The future status of the offshore drilling contracting business is very uncertain. Assuming that oil and gas will continue to be in demand, it is important to identify and implement steps that can restore the offshore contracting business to a sound footing. Fundamentals of the business must be redefined, understood and applied. Rational pricing for drilling services should be a natural consequence as exploration activity increases over the longer term.
Scientific Approach Leads to Bottomhole Assembly Standards
Authors: Kadjar D. , Delafon H. , Leveque O.
Published: December 2007

Great progress has been made in the understanding of bottom-hole assembly behaviour through computer programmes. However, in the operating company the Drilling Engineer does not yet benefit from this progress. Operating charts should be set up with possible adjustment to field characteristics.

This paper first presents a thorough analysis of the mechanics behind pendulum bottom-hole assemblies. An optimization principle is introduced which allows maximum weight-on-bit. A table recaps the optimized pendulum bottom-hole assemblies for vertical wells.

The second part of this paper deals with directional drilling where, in most cases, a great number of wells have to be drilled in a specific area at various inclinations. Basic designs for lock-up, build-up and dropping bottom-hole assemblies are presented with charts, field recommendations and practical examples. The proposed designs ensure a weak sensitivity of the bottom-hole assembly to variations in drilling conditions. Directional reports for bottom-hole assembly runs must be carefully filled in and stored in a data base. Thus a statistical analysis can be made allowing precise adjustment of the bottom-hole assembly by changing one parameter only.

This application of the bottom-hole assembly models and the use of a data base enable the operating company to define bottom-hole assembly standards to reach the target:

– with the minimum number of bottom-hole assembly runs, – with the optimum drilling parameters, – with the minimum dog-leg severity.
Application of Thermally Stable Polycrystalline Bits/Downhole Motors in West Texas
Authors: Weaver G. E. , Bunch W. D.
Published: December 2007

The use of thermally stable polycrystalline (TSP) bits run on downhole motors has proven to be economical in some West Texas development oil fields. A significant increase in penetration rate and a corresponding decrease in cost-per-foot was achieved with TSP bits and downhole motors in comparison to conventional rock bit performance.

Three different designs of TSP bits were tested successfully at a cost-per-foot less than conventional rock bits. The most successful was a design incorporating a shallow cone profile with a short taper along with reinforced gage protection for motor application.

The TSP bits and motor were also utilized to drill out cement, float collars, and float shoes, thus generating additional savings. A total cost reduction of approximately $350,000 was realized through the use of TSP bits and downhole motors as compared to conventional rock bit drilling.
PDC Bit Development in the Kuparuk River Field, Alaska
Authors: Kappmeyer L. W.
Published: December 2007

Polycrystalline Diamond Compact (PDC) bits have been under development and modification in the Kuparuk River Field since Kuparuk's first PDC run in September 1981. They are currently run in the soft to medium-hard clays and shales encountered between 3500′ and 7200′ MD. The first Kuparuk PDC bit was run at a cost of $59/ft. A typical PDC run for the same interval is currently $22/ft. This savings can be attributed to PDC bit development and other technological advancements.

This paper will document the evolution of the 8½″ PDC bit in the Kuparuk River Unit, including the results of a bit comparison test. This comparison involved six manufacturers and twelve Kuparuk River Unit wells with nearly identical conditions.
Permeability as a Function of Internal Surface of Cores
Authors: Greer F. Conrad , Beeson Carrol M.
Published: December 2007

The methods of Brunauer, Emmett and Teller are used to measure the internal surface area by isothermal nitrogen adsorption. The success of the surface area measurement is evaluated in terms of the criteria set up by these early experimenters. It is concluded that the methods used in the study are satisfactory for the measurement of the internal surface of the sandstone cores under observation.

A sufficient number of sandstone samples are tested to determine that there is a trend of permeability with porosity divided by the square of the surface area. The fact that the trend follows about a 45 degree angle on a log-log scale indicates that the exponents of the variables are approximately correct.

Introduction

The study of the surface properties of a substance is a relatively new concept in the field of chemico-physics, and the explanations for surface behavior are still in an unproved, conjectural stage. An understanding of many of the basic principles of surface chemistry, however, has been developed to the point where scientific applications can be made with considerable confidence. In the industrial field, dye adsorption and color removal, catalytic cracking of complex hydrocarbons, and other organic segregational processes are all phenomena of surface properties. The mechanics of fluid flow often involve the surface effects of conducting media, because resistance to flow is largely dependent on surface area. A particular branch of surface chemistry [or surface physics] which is especially pertinent is the adsorption of gases on solids. This paper is particularly concerned with that branch, and the following discussion deals with the adsorption of gases on solids for the purpose of measuring surface area.
Nitrided 410 Stainless Steel Valve Internals: Where They Are Acceptable for Use in the Oil Patch
Authors: Hartmann M. P. , Bednarowicz T. A.
Published: December 2007

The performance of nitrided 410 stainless steel for oil patch corrosive service applications has been found to be dependent on the type of nitriding process employed and a function of test environment. In general, the nitriding of the 410 produces a metallurgical structure that is more susceptible than 410 to corrosive degradation.
Slant Drilling in the Morecambe Field, Irish Sea, U.K.
Authors: White S. M. , Barile M. F.
Published: December 2007

The Morecambe Gas Field was discovered by Hydrocarbons Great Britain Limited (HGB) following the re-evaluation of logs from two wells drilled in 1969 by a company who subsequently relinquished the acreage. The first well to test gas was drilled by HGB in 1974 and proved the presence of a major gas field in the Irish Sea.

The field consists of two reservoirs separated by a major fault running East/West. The development has been split into two phases with the first phase concerning only South Morecambe – (figure 1). This paper concerns the drilling operations conducted during Stage I, the development of the south eastern portion of South Morecambe.

South Morecambe is a shallow reservoir with minimum depth 2300 ft. and a gas column down to the Gas Water Contact at 3750 ft. This results in exposed reservoir intervals of in excess of 2000 ft. in deviated wells.
A Real-Time Normalized Rate of Penetration Aids in Lithology and Pore Pressure Prediction
Authors: Provost C. E.
Published: December 2007

Mobil plots normalized rates of penetration in real-time using its Drilling Data Center. Field results indicate that this technique reveals changes in lithology and pore pressure. It illustrates one way that the Drilling Data Center integrates computer based drilling technology into field operations.

This technique differs from those previously reported in that: (1) A departmental computer collects, calculates, and displays real-time drilling information; (2) Normalized rate of penetration is correlated with conductivity for pore pressure prediction.

Prudent use of this tool directly reduces cost per foot. Confidence that pore pressure changes will be quickly noticed encourges the operator to drill near-balance, which yields faster rates of penetration. This tool also provides the geologist with an excellent correlation tool when wireline logs are not run.

This paper: (1) reviews normalized rate of penetration theory and its application with field results; (2) illustrates how the plot is obtained; (3) discusses predictions of lithology and pore pressure; and (4) discusses development plans.
Experience with CO2-Laden Fracturing Fluid for Stimulating Water-Sensitive Formations
Authors: Deysarkar A. K. , Dawson J. C. , Acharya A. R.
Published: December 2007

Over the last two decades, liquid CO2 has been conmonly used in well stimulation, work over operations and enhanced oil recovery. There are several advantages for using CO2 in the recovery of hydrocarbons including: (i) minimizing damage of highly water sensitive, clay bearing formations, (ii) helping to clean up the well without swabbing, and thus, resulting in better recovery of fracturing fluids along with fines and silts lost during drilling and, (iii) providing a long sustained solution-gas drive due to high solubility of CO2 with reservoir fluids.

This paper will describe the properties of a unique cross-linked fracturing fluid containing up to 50% vol CO2 at surface conditions, up to 38% vol methanol – another component which minimizes damage to. water sensitive formations, and 12% vol water. The laboratory studies include rheological measurements of the CO2 laden fluids in a high pressure/high temperature rheometer and the measurement of fluid-loss coefficients. Data are also presented correlating the rheological behavior of the fluid to the CO2 concentration, the temperature of fluid, and to various mixing techniques of the fluid prior to measuring the rheological properties.

The other part of this paper will be devoted to actual case histories using the CO2 laden fracturing fluid. Several treatments were performed on both shallow gas wells in Canada and in deeper, hotter gas wells in south Texas. Production results indicate that the treatments have been successful. The fluid is designed to treat either low pressure formations or water sensitive formations with temperatures up to 280°F (138°C) and based on the case histories, it is concluded that this CO2 laden cross-linked fluid can be successfully pumped with up to 50% vol CO2 and contain a maximum sand concentration of 7.5 lb/gal (900 kg/m3).
Effects of a Cushioning Device on Dynamic Forces Exerted on Conventional Sucker Rod Pumping Systems
Authors: Tsuru F. D.
Published: December 2007

A cushioning device composed of a series of synthetic elastomeric compounds will eliminate the metal to metal contact that exists between the pump and the surface pumping equipment. The installation of this cushioning device acts as a buffer in the rod string that suppresses the detrimental dynamic effects regularly experienced in a conventional rod pumping system.
Chemical Control of Biogenic H2S in Producing Formations
Authors: Littmann E. S. , McLean T. L.
Published: December 2007

Waterflooding has presented many unique problems to oil producers since the practice was developed. One problem in many waterfloods has been that of increasing levels of hydrogen sulfide in produced fluids, where either none or only small amounts existed prior to waterflooding. The biogenic production of H2S is certainly a cause of this problem in many of these reservoirs. The problems associated with sour production are well known: corrosion, excess solids, emulsion and surface equipment problems, and the necessity to remove H2S from gas prior to sale.

Attempts to solve the problem at the source, i.e., bacteria in the reservoir, have usually failed. Conventional biocides that are effective when applied at the surface have various limitations and compromises when injected into a reservoir. A new biocide was introduced to the oil field in 1983 that was unique and had none of the limitations and compromises of conventional biocides. The new biocide possessed the necessary chemical properties to allow it to easily pass through a reservoir with the injected water. Case histories are provided that show the effectiveness of the new biocide in reducing biogenic H2S problems by treatment in the reservoir.
The Simultaneous Determination of Formation Compressibility and Gas-in-Place in Abnormally Pressured Reservoirs
Authors: Poston S. W. , Chen H. Y.
Published: December 2007

Geopressured gas reservoirs are commonly found along the Gulf Coast of the United States. The results of material balance, reserves calculations from these reservoir types is predicated on the accuracy of a single-valued formation compressibility function. This term in most cases is very difficult if not impossible to measure. A little used technique has been found in the literature which simultaneously determines the gas in place and formation compressibility.

Formation compressibility calculations during the analysis of available case histories disclose the presence of a low value at and near initial conditions and an increase to a constant and greater value at high to moderate pressure gradients. A final low compressibility value after a normal pressure gradient is again attained.

These variable compressibility phenomena may be readily explained by applying known geological concepts concerning the formation of geopressured oil and gas reservoirs.
Test and Evaluation Methodology for Scale Inhibitor Evaluations
Authors: Vetter O. J. , Kandarpa V. , Schaige A. L. , Stratton M. , Veith E.
Published: December 2007

This paper deals with an evaluation of scale inhibitor test methods used in the oil, gas and geothermal industries. To our knowledge there exists no other publication dealing with this subject of evaluating and analyzing the various test methods related to scale inhibitor evaluations.

There are basically two different types of inhibitor test methods:

Test methods aimed at solving a scale problem for routine, day-to-day field operations. Test methods aimed at solving a scale problem for temporary or intermittent field operations.

Only the first type of test methods is described in this paper.

Laboratory test procedures are used to evaluate and to rank scale inhibitors for field operations. Many of the tests use arbitrarily selected test conditions and many are based on unvarying test conditions. Others evaluate only the inhibitor efficiency without regarding other and simultaneously occuring problems that may dictate the application and usefulness of scale inhibitors in the field. Slight changes in test conditions will usually result in significant changes in the subsequent rankings of scale inhibitors. Each "standard" test may yield inhibitor data and rankings that are completely different from the data and rankings based on other "standard" tests.

Any test procedure aimed at selecting an inhibitor for actual field use must consider actually encountered field conditions. Any test matrix should, as a minimum, include all the possible thermodynamic and at least some kinetic and hydro-dynamic conditions encountered by the inhibitor in an actual field.

The present paper discusses the advantages and disadvantages of the various scale inhibitor evaluation methodologies suited for the field operator. The relevancy of various evaluation methods for field applications is described. The paper is not oriented toward data obtained through previously or newly conducted inhibitor evaluations or evaluating of specific chemicals. The object is to evaluate and compare known or newly tried inhibitor test methods for field applications.
A Mathematical Model for Analysing Drilling Performance and Estimating Well Times
Authors: Thorogood J. L.
Published: December 2007

Drilling progress rates for individual sections of hole were obtained from the depth-time curves of a number of deviated wells in the North Sea. Within each field there was seen to be a good correlation between drilling progress rate and the average inclination for the section. This observation forms the basis of a mathematical model for estimating drilling times of deviated wells. The method requires that a standard design can be specified for all wells in a field. Casing points are defined with respect to the Geology and the drilling programme is set up as a sequence of unit operations, casing jobs and drilling intervals. The model can be calibrated from wells already drilled to provide a yardstick against which future performance can be judged. Alternatively it can be initialised with the performance of exploration wells and then be used to estimate the drilling times for a field development. The model has been used routinely for three years and has proved to be a cheap but powerful tool. Furthermore, it has provided insights into the potential for computer applications in drilling operations performance analysis and simulation.
Single Cutter Testing – A Key for Pdc Bit Development
Authors: Zijsling D. H.
Published: December 2007

A description is given of a single-cutter tester for studying the cutting process of PDCs in rock under simulated downhole conditions. The use of the tester is illustrated by a study of the effect of downhole pressures on the cutting process in shales. Prior to the tests the Pierre shale and Mancos shale outcrop samples used for the study were conditioned to enable proper downhole pressures to be simulated during the tests.

The total bottomhole pressure only was found to govern the cutting process in Mancos shale, whereas both the pore pressure and the total bottomhole pressure govern the cutting process in Pierre shale. The dilatancy characteristics of the rocks are shown to be responsible for this behaviour. In addition the tests unveiled the balling mechanism of the outcrop shales in water-based and oil-based mud environments.

On the basis of the insight gained from single-cutter tests, the paper discusses drilling characteristics of PDC bits in shales and bit and cutter design aspects that facilitate mechanical bit cleaning as a means of improving PDC bit performance in various shales.
A New Multiphase Flow Model Predicts Pressure and Temperature Profiles in Wells
Authors: Ozon P. M. , Ferschneider G. , Chwetzoff A.
Published: December 2007

Since 1981, Elf Aquitaine, IFP and Total-CFP have been collaborating to establish a new calculation method predicting multiphase flow pressure drop in wells able to cope with any case of oil or gas production. A flow model has been developed by using fundamental equations of two-phase fluid mechanics. The mass and momentum balances for each phase are considered as well as interactions between phases related to every flow regime. The main flow patterns are taken into account and mechanistically – based relations determine transitions.

The physical basis of this model has been provided by experiments carried out on test facilities generating fluid flow conditions similar to those encountered in production wells. The test loop consists of two 30 meter long flowlines (diameter 3 and 6 in), which can take any inclination from 0 to 90 degrees. The fluids used were condensate, heavy gas-oil, water and natural gas with pressure ranging from 5 to 50 bar.

Experimentation and modelling resulted in the development of the program WELLSIM, which performs calculations of pressure and temperature profiles in vertical or deviated wells. Comparison with data gathered from wells offering widely different production characteristics shows good agreement over the whole range of parameters and the accuracy of the results is significantly better than with conventional methods.
SHALLOW GAS KICKS, Safety Aspects Related to Diverter System
Authors: Nøkleberg L. , Schüller R. B. , Søntvedt T.
Published: December 2007

Drilling through shallow gas pockets in the North Sea and in other areas represent a risk for loss of control with subsequent uncontrolled gas blowouts. The diverter system is intended to convey this gas to lee side of the platform.

Statistics show that the diverter system fail in about 50 % of the cases they are used to handle shallow gas kicks. The flow conditions in diverter systems currently employed in the North Sea are so severe that it cannot be expected that the diverter systems can withstand a shallow gas kick in more than a few minutes. The erosion rate can be as high as 1-2 mm/min, and this is an alarming figure.

Veritec has investigated various forms of severe damages to a diverter system which failed under a gas blowout in the North Sea. The damages were caused by erosion of sand particles at high velocity and malfunction of valves. Calculations indicated high gas velocity (near sonic) in the diverter during the blowout.

Velocity in the diverter system can be reduced by increasing diameter of the diverter lines and throttling (a choke) at outlet. By this combination erosion rates may be reduced with a factor of several thousand. The downhole pressure will not be affected by this improved diverter design.
Analysis of a Polymer Well Treatment in the Beatrice Field
Authors: Clifford P J , Duthie A
Published: December 2007

A polymer injection treatment was carried out in the Beatrice field in 1985. The object of the treatment was to improve vertical sweep in the heterogeneous sands between an injector/producer pair. The process was closely monitored using a variety of standard and non-standard techniques: tracer tests, production logging, pressure interference tests before and after polymer injection, and polymer chemical analysis in produced and backflowed brine. Subsequently, a chemical simulation model was constructed and compared with the field data. It was demonstrated from the field measurements that the polymer had a clear effect on fluid flow patterns in the reservoir. However, the simulations showed that there had been a shorter distance of polymer penetration than assumed in planning the treatment, so that the watercut changes were too small to be observed. The project is significant in giving an informed picture of polymer behaviour in heterogeneous North Sea fields. It also successfully demonstrates the array of measurements needed to predict, monitor and reduce risk in polymer field applications.
Troll High Rate Production Test, Planning and Execution
Authors: Nilssen B. H.
Published: December 2007

The high rate production test performed by Norsk Hydro on the Troll East structure during the summer of 1985 with the semi submersible drilling rig Treasure Seeker required that a large number of specially designed, modified or adapted equipment items were used in order to fulfil the test objectives and maintain safe operations. These were: -Jetting tool for casing cleaning.-Gravel pack floor manifold to ease operations.-Surface read out of downhole pressure and temperature through cable on the outside of the tubing.-3 inch I.D. tester valve.-3.7 inch I.D. annulus pressure operated kill valve.-Full bore double gauge carrier.-5 inch I.D. sub-sea test valve.-5 inch I.D. lubricator valve.-5 1/8 inch bore flowhead.-Vertical high capacity separator.-32 channel data logger.

The use of this equipment together with other more commonly used equipment made the test a success.
Netherlands Q/8 – A Development Europe's Smallest Offshore Gas Field
Authors: Petterson M. E. , Tibbitt N. C. T.
Published: December 2007

BP brought the Q/8-A offshore gas field on stream in October 1986. Q/8-A is the first fully integrated unmanned offshore development in the North Sea. Estimated reserves of only 37 bcf make the field the smallest offshore gas development in Europe.

Economic development of such a small reserve demanded the innovative use of proven technology. Minimum facilities compatible with safe and efficient operations were designed. An unmanned platform with free water knock-out, glycol injection and a sphere launcher, feeds gas via a pipeline beneath the coastal dunes to a dedicated onshore processing terminal.

A rigorous search for cost reductions during pre-project and project engineering, coupled with the favourable economic climate which the Netherlands provides, led to the viability of this most marginal of field developments.

Several lessons were learned from the Q/8-A development project. A minimum cost development with a short project schedule demands a tightly defined technical statement of requirements. Do not underestimate the level of detailed effort necessary to develop and to operate the smallest of reserves.
Alternative Drainhole Drilling System – Theoretical Background and Practical Experience
Authors: Steenbock A. , Müller-Link D.
Published: December 2007

Increasing the formation flow area is one important way to improve the downhole flow conditions. Drilling drainholes by means of conventional drilling technique can already be seen as state of the art. Beside this conception, the lateral drilling, or the "short radius kick-off"-version, has already proved to be feasable, although predicting angle building and controlling inclination and direction was critical. One big step forward was now done by developing the Articulated Drill String (ADS).

Its principle results in a very good control of the well course and will be described in the paper. Depending on the geometrical layout, build-up-rates up to 90 deg./ l0 m are possible. Steering the bit is achieved by means of a special configuration of stabilizers.

Three field tests have already been performed. The first prototype was tested in a quarry. This hole was surveyed with conventional mine surveying equipment. The accuracy of the predetermined well course was found to be very satisfactory. Two other field tests have been performed in a German oilfield. The depth was approx. 1000 m. Angle was build up to 110 deg. followed by a straight hole section of 40 m in order to reach the attic oil in the reservoir. The well was completed with a slotted liner.

Typical procedures of handling the ADS, drilling, surveying and logging as well as casing and cementing are described in the paper.
Design, Operation and Economic Viability of the First Tripod Tower Platform
Authors: Duncan D. A. , van der Heyden H.
Published: December 2007

The Tripod Tower Platform (TTP) is a simple, fixed steel offshore platform suitable for use in water depths from 10 to 350 metres. The first TTP was designed, fabricated and installed by Heerema in July 1986 for Unocal Netherlands, Inc. Installation of the Unocal Helder ‘B’ platform was accomplished as a single lift and complete offshore installation including hook up took just six days.

The TTP concept can be applied to wellhead and production platforms, as well as accommodation, riser, utility or loading platforms. For shallow waters the TTP can be easily removed after the field lifetime and re-used in other locations.

This paper describes the Helder ‘B’ project and also contains a comparison of the actual cost of this TTP with the cost of a conventional jacket structure for similar duty. The savings in steel weight, fabrication cost, installation and expected long term structural maintenance compared with braced jackets are highlighted to document the cost effectiveness of the Tripod Tower Platform.
Commissioning A Multi-Diameter Subsea Gas Lift System
Authors: Evett Alan , Fuller Joseph
Published: December 2007

This paper describes a dewatering operation on the Texaco Highlander Subsea Production Facility located in the North Sea approximately eight miles north-west of the Texaco Tartan platform.

Difficulties in commissioning gaslift operations on remote subsea wells were attributed to hydrate formation and unsuccessful dewatering after pressure testing. The geometry and changing diameters of the gaslift line were complicating factors.

A new application of foam technology was made and this paper describes the background to the task and gives a record of the practical operations undertaken. The job was successful and the various further applications of this type of technology are discussed.
Petrojarl I – Subsea Systems Installation Experience
Authors: Hewlett Clyde , Shaw Gary , Glorstad T. , Tennoy O.
Published: December 2007

The Petrojarl I is the first purpose-built floating production and extended well test ship designed for worldwide application under the same type of leasing arrangement as a floating drilling rig. All other floating production systems in operation today are designed for site-specific conditions and would require significant modification for other applications. In its present configuration this turret-moored process plant/storage tanker receives production from a single subsea well via either rigid or flexible risers. Stabilized crude is exported by an off-loading system to a shuttle tanker.

This paper reviews the manufacture, testing, installation and early operating experience for the subsea production equipment associated with the Petrojarl I Production/Test Ship (PTS). It provides an overview of the system together with some of the more important design parameters. It also recounts the actual manufacturing, testing, installation and early operating experience for the subsea and other critical systems.

This new type of production system is seen to be technically feasible and is also proving to be an economic success even in current depressed market conditions.
A Complete Subsea Wireline System
Authors: Manzi Brian , Dines Chris , Headworth Colin
Published: December 2007

At the present time there are around 400 subsea completions worldwide and even the most conservative surveys predict a doubling of this number within the next decade.

This paper discusses the evolution and operation of a flexible, self-contained system which makes optimum use of existing technology thereby offering a safe, reliable and economical system for riserless re-entry into any subsea well.
Rotary Cyclone Will Improve Oily Water Treatment and Reduce Space Requirement/Weight On Offshore Platforms
Authors: Gay J. C. , Triponey G. , Bezard C. , Schummer P.
Published: December 2007

A rotary hydrocyclone was developed for the treatment of the produced oily water on offshore platforms. The main advantages of this type of equipment consist in :

– a few second residence time resulting in a dramatic reduction in weight and volume. – higher efficiency when comparing with conventional settling tanks or static cyclones. – insensitivity to the platform motion, – large flexibility in flow rate and in oil concentration in the treated water, – low pressure drop requirement, – easily adaptable to changing field operating conditions, – modular conception facilitating the offshore installation, – reduced maintenance and power consumption resulting in a low operating cost.

This paper outlines the results of laboratory work conducted initially on a static hydrocyclone and on a rotary cyclone scale model, with the reasons for the differences in performance of the both type of equipment.

A field test of a 2 × 25 m3/h industrial rotary cyclone skid is presented and the field performance analysed

Finally main features of the industrial units are presented and a comparison with a conventional treatment is made.
On-Line Current Monitoring Fault Diagnosis in Hv Induction Motors – Cask Histories and Cost Savings in Offshore Installations
Authors: Thomson W T , Chalmers S J , Rankin D
Published: December 2007

This paper presents an on-line current monitoring system for detecting rotor faults in large high voltage 3-phase induction motors. The philosophy and practical advantages of current monitoring are discussed and samples of on-site case histories will verify the effectiveness of the method for detecting broken rotor bars and air-gap eccentricity in the industrial environment. A new computerised diagnostic system with expert system capability will also be described.
Partial Turn Threaded Connector for Offshore Casing, Conductor, and Pile Joints
Authors: Pallini J. W. , Danner L. , Maa T-J.
Published: December 2007

This paper presents a new, patented system for threaded connectors which provides a stable, preloaded, high strength connection for tubular joints. The system consists of a group of design features including special thread contour, multiple start threads, and thread cone taper. The system is substantiated by considerable testing and field experience, which is presented.

Also discussed in this paper are some characteristics of connections which make use of this thread system.
Conventional and Unconventional Kill Techniques for Wild Wells
Authors: Ely J. W. , Holditch S. A.
Published: December 2007

Every year tens of thousands of wells are successfully drilled all over the world. The overall safety record of the drilling industry is quite satisfactory. On occasion, however, problems can arise during drilling where the control of a well is lost. Whenever a well begins to produce uncontrollably, the well is termed a blowout.

Drilling hazards other than blowouts can also occur. It is not uncommon to lose circulation or to have a drill string become stuck. During a completion attempt, mechanical problems can cause the loss of the wellbore. Whenever any of these problems exist, the usual worst case scenario is loss of the well. When a blowout occurs, however, the worst case scenario can be much more serious. It is not uncommon to have loss of life, loss of property, and large volumes of oil and gas produced to the environment. It is quite important, therefore, to minimize the chances of a blowout occurring on any given well.

Even with utmost care, accidents occur and blowouts will result. The first step usually taken by an operator after a blowout has occurred is to call one of the companies that specializes in killing blowouts. After an initial inspection of the wellsite, the blowout control specialist can usually recommend whether a surface kill technique can be used or whether directional wells must be drilled to intersect the blowout well and attempt a kill from the reservoir. Numerous papers have been published that can assist one in understanding what can occur and how to prepare for a typical kill operation.
Case Studies of BHA Vibration Failure
Authors: Mitchell R. F. , Allen M. B.
Published: December 2007

Predicting bottom hole assembly (BHA) vibrations is a complicated problem. Axial, lateral, and torsional vibrations can be coupled and effects such as stick-slip and whirl can magnify the loads. Fatigue, pipe bouncing, and tool joint washouts demonstrate the complexity of the problem.

One type of vibration that can be isolated and analyzed is the rapid destruction of the BHA caused by operating at or close to resonance. At rotating speeds that reinforce the natural vibration of the BHA, the destructive harmonics generate high stresses resulting in very short fatigue life. While other factors may cause BHA failure, a significant percentage of field failures appear to be associated with harmonic vibration, particularly lateral vibration.

A simplified model based on harmonic analysis using finite elements has been found to agree well with field experience. The influence of stabilizer placement, drill string forces, and mass of the drilling mud are included in the finite element vibration model.

This paper consists of 8 case studies involving actual BHA failures. The model predicted lateral vibrations with critical rotation speeds that correspond closely to operating conditions at the time of failure in all of the BHA's studied. In addition, the reversing stress computed for the critical operating speeds exceeded the endurance limits of the connections and occurred at the locations in the BHA's where failures were observed.

These comparisons to field data are the first steps in establishing model reliability, so that it can be confidently used as a tool to select operating speeds or evaluate BHA designs.
Cementing of Liners in Horizontal and High-Angle Wells at Prudhoe Bay, Alaska
Authors: Reiley R. H. , Black J. W. , Stagg T. O. , Walters D. A. , Atol G. R.
Published: December 2007

Standard Alaska Production Company has cemented liners in three horizontal and four high angle (inclination greater than 75°) wells at Prudhoe Bay, Alaska. Cementing techniques which have evolved during the drilling of these wells include off bottom cementing of 7 inch [17.8 cm] liners for gas cap isolation; simultaneous rotation and reciprocation of liners while cementing; and strategic placement of a cement filled formation packer between the gas/oil contact and the oil production interval. This paper describes the development of these cementing techniques and gives details of field operations.
Mobilizing Bitumen Under Reservoir Conditions
Authors: Kaleli M. K. , Farouq Ali S. M.
Published: December 2007

An experimental and theoretical study was conducted of bitumen/heavy oil mobilization under cold conditions, using a solvent, carbon dioxide, and surfactant, to investigate ways of mobilizing bitumen or heavy oil ahead of a displacing thermal front. A rectangular cross-section model was used to carry out experiments simulating a bottom water layer underneath an oil zone. Results showed a strong dependence on solvent slug size, as well as the thickness and permeability of the water zone. Of the methods used, a combination of surfactant and carbon dioxide showed the best performance. Water zone thickness is important, because too thin a water zone leads to high injection pressures, while a thick water zone causes dissipation of the solvent. An optimal thickness seems to be about one-fifth of the oil zone thickness.

A miscible displacement/leaching simulator was extended to include a number of additional effects, notably bitumen transport in the water layer. The efficiency of the leaching process was found to depend on the flow rate, solvent slug size, location of the injection/production points, and the relative thickness of the bottom water zone. A good match of the experimental results was obtained. It was found that a thin bottom water zone is helpful for obtaining initial injectivity, yet not detrimental to bitumen recovery. As in the experiments, a bitumen-to-water zone thickness ratio of 5.0 gave optimal results. The concentration profiles showed that the bottom water zone served as a transport layer for the mobilized bitumen. Upon the injection of a large solvent volume, the leaching process became very inefficient, shown by a sharp drop in the bitumen concentration in the effluent. As much as 85% of the bitumen and 68% of the solvent were recovered in the process.
Hysteresis Effects for Gas Condensate Wells Undergoing Buildup Tests below the Dew Point Pressure
Authors: Economides M. J. , Dehghani K. , Ogbe D. O. , Ostermann R. D.
Published: December 2007

An increasing liquid saturation is observed in gas condensate reservoirs when they undergo drawdown. This liquid saturation is not reversible when the well is subjected to a pressure buildup thus resulting in a hysteresis effect. Hence, once reduced, the effective reservoir permeability does not recover and in a subsequent drawdown, the flow rate remains at largely the same level as before the shut in.

This hysteresis effect is examined and quantified. An existing method to interpret the pressure behavior of gas condensate reservoirs is critiqued and is found appropriate for the time when "steady-state" saturation emerges and as long as relative permeability data are available.

A new method allows the calculation of the "apparent" reservoir permeability at steady state and when employing a step-pressure test then relative permeability data may be obtained from the interpretation.
Environmental Parameters Affecting Neutron Porosity, Gamma Ray, and Resistivity Measurements Made While Drilling
Authors: Koopersmith C. A. , Barnett W. C.
Published: December 2007

Recent technological advances have resulted in development of formation logging sensors contained within drill collars. Environmental parameters affecting natural gamma ray, resistivity, and neutron porosity measurements while drilling (MWD) include borehole size, invasion, drilling rate, and formation exposure time. MWD logs, in many cases, can provide superior quality data as compared with comparable wireline sensors.