bluuebunny/crossref_metadata_2025 huggingface dataset:
The Use Of Accurate Pressure Data In A High Permeability Environment
Authors: De Boer Engelbart Theodore
Published: December 2007

The advance of accurate pressure sensors with surface read-out facilities, has enabled a sufficiently accurate definition of both the time and pressure scales to allow for a detailed data analysis. Especially in a high permeability environment reliable information about the continuity and transmissibility of the reservoir and the pressure as a function of time can be obtained. The facility to read-out the measured pressure data instantaneously at surface allows optimisation and modification of test programmes during execution, resulting in a minimum of lost oil production and a maximum of information. Because of the integrity of the data and the reservoir characteristics, it proved possible to quantify the water influx rate into the reservoir with a single early pressure survey within narrow limits.

INTRODUCTION

In offshore deep water environments with a platform development programme the number of wells is strictly limited. Consequently, it becomes very important to extract the maximum amount of information from the reservoir on a per well basis.

For an extremely permeable and continuous reservoir, such as the Piper field, conventional pressure sensors frequently lack the accuracy to allow the determination of basic reservoir parameters. The productivity index and static pressure are often the only data obtainable.

Precision pressure sensors, such as the quartz pressure gauge, with an electronic time measurement device define the pressure and time scales sufficiently for a detailed data analysis. A range of different types of pressure tests can be devised to obtain specific information deemed necessary.

Due to the accuracy of the data, all the results of the analyses should be consistent. An adherence to first principles is required as otherwise wrong conclusions may be drawn from the observed pressure changes. To illustrate this, three pressure tests conducted in the same well will be discussed in detail.

Early evaluation of any water influx is of prime importance for future operations planning. In the particular case of the Piper field, the existence of a water drive appeared to be likely only two months after production started. It proved possible to quantify the aquifer influx rate within narrow limits with a single pressure survey after only four months of production.
Frigg, The First Giant Gas Field In The Northern North Sea
Authors: Dufond R. , Laffont M.
Published: December 2007

The development of the Frigg gas field is unique in many ways:It is the first giant gas field, to be put into production, in the deep and hostile waters of the northern North Sea, and at a considerable distance from the UK coast (360 kilometres).It is situated in both British and Norwegian offshore sectors.Production will be built up gradually to 1.5 billion CFPD of gas, which will represent, 40% of the present gas production of the six British gas fields of the southern part of the North Sea.The development scheme of this huge gas field has been prepared with the safety of the personnel, and the importance of the continuity of gas production in mind:The living quarters-control-platform is separated from the production and treatment platforms.There are two drilling-production platforms and two treatment platforms.

Therefore the consequences of a major accident are reduced: a minimum number of the personnel is exposed to danger and the supply of gas to the British Gas Corporation could be continued in the event of such an accident. This gas supply is vital to British industry.

After a general presentation of the main characteristics of this Field, and the problems related to the unitization between the British and Norwegian Sectors, the concept of this Field as a unique development will be given, as well as the description of each platform.

INTRODUCTION

The Frigg Field is the largest natural gas structure in the northern part of the North Sea and one of the giant offshore gas fields in the world. It was discovered in Norwegian waters, block 25/1, by Elf-Aquitaine Norge in June 1971, and the following year Total Oil Marine drilled the first well on its adjoining block 10/1 in the UK sector and confirmed the extension of the structure into British waters.
Drilling Without Conductors Piper Field Development
Authors: Trendall T.
Published: December 2007

Trendall, T., Occidental Petroleum (Caledonia) Ltd. UK

Occidental discovered the Piper field in the UK of the North Sea, 100 miles east of Wick on block 15/17 in January 1973. After the discovery well, another six wells were drilled to delineate the field. Early on in the appraisal drilling programme, it was decided a single steel platform with twin drilling rigs would effectively develop the field. The size of the platform (one of the largest steel platforms set in the deepest water at the time of setting) caused Occidental to develop a unique concept to help decrease the live loading on the platform construction and development drilling and helping speed initial production start-up. Experience gained from the exploration programme helped Occidental decide that it would be possible to develop Piper, utilizing a redesigned 20 in. string as conductor and doing away with the 30 in. string altogether. This concept was then incorporated into the final design of the platform.

PIPER DEVELOPMENT HISTORY PIPER DEVELOPMENT HISTORY The Occidental consortium's interest in the British sector of the North Sea shifted to activate exploration in 1970 following the Ekofish discovery in the Norwegian sector. On the basis of 20,000 miles of seismic data. Occidental placed application for British North Sea blocks with the government in 19712. In March 1972, the government awarded Occidental a petroleum licence for six blocks covering approximately 316,000 acres. Two months after the award. Occidental spudded its first well block 15/11. It was dry. The second well was drilled on 14/19 (Claymore) this was also a failure although shows were encountered. The third well was spudded on 15/17 (Piper). This well had to be abandoned at 750 ft due to weather conditions getting the better of the drill ship used. A new semi-submersible rig. The Ocean Victory, was acquired and this rig spudded 15/17-la in November 1972. This well flowed at a combined rate of about 90,000 bopd and the field was designated Piper field.
Underwater Repair Of Concrete
Authors: Humphrys B.G.
Published: December 2007

Introduction

To carry out a satisfactory repair it is essential to obtain accurate details of the damage and establish the cause of the failure; with this information it is possible to develop a method of repair to prevent or delay future damage. In this paper consideration of methods of repair of concrete paper consideration of methods of repair of concrete permanently underwater and in the splash zone is related permanently underwater and in the splash zone is related to offshore gravity platforms and the damage that may occur on such structures; however, the repair materials and techniques can be used for any underwater concrete construction.

DAMAGE

Damage may be caused by accident, unexpected structural movement, failure or inadequacy of materials or workmanship in conjunction with hostile environmental conditions. The repair of such damage will have to fulfil one or more of the following tasks:Prevent corrosionRestore full structural strengthPrevent leakageMaintain or improve durability

which must be defined for developing the method of repair. The word 'cosmetic' is used loosely to describe a repair which does not restore full structural strength of the damaged area; the use of the word should be avoided because it is inappropriate and it is simple to properly define the particular requirements of a repair. The construction contractors and operators of platforms are naturally reluctant to make known details of platforms are naturally reluctant to make known details of repairs which may be needed to their concrete structures, Such information as can be gained indicates there have been some impact accidents which have reduced or removed the concrete cover to the rebars. It is known that there have been some problems of leakage through cracks during construction and installation stages. However, little has been heard of the type of damage most frequently observed on inshore construction which is the spalling of the concrete cover to rebars due to failure or inadequacy of materials and/or workmanship: no doubt this is due to the very high quality of the concrete and the attention given to this particular problem during the design and construction.
On Stream Inspection Of Pipelines
Authors: Osborn C.W.
Published: December 2007

Introduction

'They don't make it the way they used to,' or words to that effect are often heard these days and invariably reflect sadness (or frustration) that the high standards of a bygone age are no longer applicable. The pipeline industry could perhaps use the same expression but the meaning would very different. The modern pipeline embodies a higher degree of technology and, in consequences, of safety, than ever before.

A glance at a map showing major pipeline systems gives some idea of the degree to which industry is committed to transporting an ever-widening range of raw materials and products. There are, however, a number of facets to this growth pattern which are under regular review.

Firstly, over the last 25 years standards have changed considerably. Pipelines built in this period have progressively taken advantage of the availability of new steels and new technology.

Secondly, fatigue stresses leading to brittle and ductile fractures have been closely studied along with many other operational factors affecting pipeline integrity.

Thirdly, the growing proximity of one pipeline service to another, in some cases involving use of a common wayleave, places a responsibility on each occupier with reference to the security of the other.

Fourthly, increased speeds and density of road, rail and air travel present a potential hazard to buried services.

Finally, expanding population and the decentralization of industry lessens the distance between major pipeline systems and populated areas.

So to some extent there is a conflicting situation - pipelines are designed and built to a better standard than ever before but may be subject to a greater hazard than previously envisaged. The pipeline industry is very aware of the problems and this paper is intended to cover only one aspect, that of irregularities in pipeline diameter.
Multifunction Support Vessel For North Sea Construction, Maintenance And Emergency Operations
Authors: Edwards W.R. , Jacquet E.K.
Published: December 2007

The basic requirements of marine vessels as stable working platforms in the North Sea has existed since commencement of exploratory drilling. This requirement has now expanded to include year round construction and maintenance for associated oil and gas producing platforms, and lately for emergency disaster and blowout control. During the development of the Occidental Petroleum Consortium's Piper and Claymoe fields, Petroleum Consortium's Piper and Claymoe fields, based on 56 vessel-months of construction support anchored adjacent to platforms, an on-going need was realized for a comprehensive marine vessel, outfitted to support these developments. The additional requirement of fire-fighting and disaster control resulted in the emergence of a uniquely designed semi-submersible multifunction support vessel (MSV). Occidental has now placed a keel-up order in a Japanese shipyard for 1979 delivery of this special unit. The specifications for the unit have been developed in conjunction with Redco Inc., and Earl and Wright, a subsidiary of Sedco Inc.

The requirements for such a multifunction support vessel are unique to the individual operations to be carried out, and specifications include those necessary for dynamic positioning, fire-fighting cranage and a comprehensive saturation diving system. Development of these specifications resulted in a dynamically positioned column stabilized semi-submersible vessel equipped with the following unique features:Extensive on board maintenance facilities for support of platform production and maintenance operations:A dynamic positioning system suitable to D.P.on all sides of a burning platform in Beaufortstate 10 while effectively fire-fighting.Fire-fighting equipment to provide for fire control platform abandonment, and remote manipulation and removal of debris associated with such disasters.A sixteen man saturation diving system, featuring a tethered and manned Mobil Diving Unit.
The Effect Of Confining Stress And Fluid Properties On Arch Stability In Unconsolidated Sands
Authors: Clearly Michael P. , Melvan Joseph J. , Kohlhaas Charles A.
Published: December 2007

A cylindrical sand pack, 52.75 inches long by 16 inches in diameter, was used to study the stability of unconsolidated sands across casing perforations. Bottom-hole producing conditions perforations. Bottom-hole producing conditions were approximated with overburden stresses of 250, 750, 1500, 2250 and 3000 psig. Fluid saturations consisted of an irreducible water phase and liquid hydrocarbons. The sand used phase and liquid hydrocarbons. The sand used was Gopher State 20/40 frac. sand, and the different hydrocarbon fluids investigated were kerosene and mineral spirits.

The observed mechanism of sand stabilization around a wellbore was the formation of sand arches across a perforation opening— an observation consistent with those instability was recorded at the moment of failure of sand arches.

Arch structure is a function of the stress distribution in a sand pack. Maximum arch size and stability were also found to be a function of confining stress. The effect of different hydrocarbons on arch stability manifests itself in the cohesive forces in the pendular saturation of the wetting phase at the arch wall. Dilatant restabilization of arches is accommodated at higher stress levels and it is greatly enhanced by the cohesiveness of the sand in the arch itself. The conclusions from this study both strengthen and extend knowledge of unconsolidated sand behavior.

Introduction

The ability to control sand production has been measured by the success of mechanical and chemical processes and devices; however, well productivity is severely reduced with each productivity is severely reduced with each measure taken to control sand production.

An alternative method of sand control is based on the premise that stable sand arches can be formed under the conditions present in an unconsolidated reservoir. Field observations verify that in several cases, a producing oil well in an undersaturated reservoir will initially produce small amounts of sand when it is placed on steam. Initial sand production then ceases, and sand-free oil production is maintained until wellbore parameters are altered.

Sand flow into the wellbore is generally thought to be a function of one or more of the following factors:Fluid drag associated with high oilviscosities.Fluid drag due to high fluidvelocity.Skin buildup around the wellbore.Rate surges.Changing loading conditions around the wellbore due to pore pressure around the wellbore.

In the past decade, several investigations have been made to understand sand arching more fully. Hall and Harrisberger observed that under a confining stress dry angular sand would readily form an arch. They also observed that a cohesive force resulting from a residual fluid saturation was necessary in a well-rounded sand to allow an arch to form.
Large-scale Application of (Anisotropic) Pre-stack Depth Migration in the Foothills
Authors: Johnson Peter , Doyle-Linden Andrew , Miller Susan L. M. , Martin Brian
Published: December 2007

Introduction

Shell Canada Limited is routinely applying full (anisotropic) Pre-Stack Depth Migration (PSDM) to 2D and 3D seismic surveys in the Foothills of Western Canada. In this paper we will show data examples which illustrate the practical application of these techniques. This technology can contribute to drilling success though proper well positioning and thus has important business implications.

Anisotropic 3D PSDM

In the highly structured fold and thrust belt of the Foothills, anisotropic clastic beds which are steeply dipping often overlay deeper carbonate targets. This can result in poor focussing and mispositioning of structures on the seismic section unless these effects are correctly accounted for in processing. The Shell Group has developed algorithms for anisotropic prestack depth migration which are being effectively applied by Shell Canada on both 2D and 3D Foothills data. Structures show improved focussing and, in some cases, lateral shifts on the order of 100 - 300 metres. The formulation of the Shell proprietary anisotropic PSDM is such that it is able to handle any symmetry of anisotropy. However, current experience is limited to working with the TI assumption, though also accommodating a laterally varying tilted axis of symmetry.

Practical considerations for PSDM

Shell's proprietary state-of-the-art processing management software (used worldwide by the Shell Group) deals with many of the logistical requirements for processing large amounts of data on a network of workstations. This has had significant impact on the turnaround achievable for 3D PSDM projects. It also frees up geophysicists to concentrate on geophysical issues, including velocity model building and updating, as opposed to administering jobs through the system. Thus quality PSDM processing is accomplished in a timely, efficient manner which is suitable not only for Development but also for Exploration needs. Though expertise is required to oversee the correct application of the technology, the whole system facilitates a staged progression of learning for personnel new to 3D PSDM, allowing them to quickly become productive.

Our PSDM processing software is tightly linked into Shell's proprietary 3D interpretation software (123DI) which provides a communication vehicle for processor/interpreter interaction on an ongoing basis from initial model development to intermediate results and model updates, to final product. This is a crucial link, the impact of which should not be underestimated.
Recommended Procedures for Utilizing High Cost, Non-Damaging Fluids
Authors: Ilfrey William T.
Published: December 2007

Over the last six years nondamaging fluids, primarily inorganic salt blends, have proved to be very cost effective in numerous applications to drilling and production operations. A natural progression to high density, high cost non-damaging fluids has occurred. Successful application of these high cost fluids requires better planning and improved operational procedures, a better understanding of the physical properties of the fluids, and an evaluation of the optimum economic benefit of the fluid at project termination. The aim of the present discussion is to recommend a pre-operation planning procedure. A discussion of the physical properties of the fluids is presented to maximize the number of economic alternatives. The considerations governing whether fluid will be disposed, sold, or stored and reused are reviewed.
Selection of Polymers for the Control of Mobility and Permeability Variation at Richfield East Dome Unit, Orange County, California
Authors: Bolton Helen P. , Carter Walter H. , Kamdar Ruby S. , Nute A. J.
Published: December 2007

Richfield East Dome Unit (REDU) is located in Orange County, California, southeast of Los Angeles. The East Dome Unit contains several massive unconsolidated sand zones which were produced by depletion drive from 1920 to 1974. In 1974, a water-flood was initiated in the Chapman Zone. The performance of the waterflood has been reduced by the highly hetergeneous nature of the Chapman sand and by the adverse water-oil mobility ratio resulting from the high viscosity crude oil present. Preliminary evaluation of various enhanced recovery processes indicated that the application of mobility control polymer, coupled with selective permeability variation control treatment of certain injection wells, could improve the oil recovery efficiency of the waterflood.

Extensive laboratory testing was conducted in Chapman cores and sand packs to select the most applicable mobility control polymer and the most effective permeability variation control process.

Five commercially available mobility control polyacrylamide polymers were screened to determine their suitability to REDU reservoir rock and fluids. Selection criteria included the oil recovery efficiency, polymer retention, polymer solution viscosity, and residual resistance factor. As a result of the laboratory tests, Cyanatrol WF-940S was selected for additional field testing.

Three commercially available polymer permeability variation control processes were also evaluated in the laboratory. The ability of each process to improve the dimensionless flow rate ratio in parallel sand pack tests was used as the main selection criterion. A polyacrylamide treatment utilizing aluminum cross-linking was selected for additional field testing.

Field tests of both the mobility control polymer and the permeability variation control polymer process have been initiated in the Chapman Zone of the Richfield East Dome Unit.
Calculation of Unsteady State Heat Loss for Steam Insection Wells Using a Ti-59 Programmable Calculator
Authors: Smith David D. , Weinbrandt Richard M.
Published: December 2007

A TI 59 program is presented which calculates downhole steam quality, steam enthalpy, and heat injection rate as a function of time. The basic calculation technique used in the program is taken from the available literature with modifications to permit use of the programmable calculator. Both concentric and eccentric tubing cases are considered. The program has been validated against several other computer simulations and checks quite favorably in all cases.
Preliminary Methane Resource Assessment of Coalbeds in the Akroma Basin
Authors: Rieke Herman H.
Published: December 2007

Potentially recoverable quantities of methane from unconventional sources such as coalbeds have been largely excluded from potential gas supply surveys. This is attributable to the lack of data about the resource, technology and economics of its recovery. In order to provide answers, DOE initiated the Methane Recovery from Coalbeds Project (MRCP) to characterize the gas-in-place for various coalbeds and associated sediments. After the 1977 initiation of the MRCP, several other interested groups have supported various aspects of the project.

Results are presented from the first phase of a joint effort between DOE (METC), TRW, GRI, and Industry to investigate the coalbed methane resource in the Arkoma basin. This elongated narrow east-west sedimentary basin is located in east-central Oklahoma and in west-central Arkansas and contains extensive gaseous bituminous coal reserves of Pennsylvanian age. Preliminary gas-in-place resource estimates were made based on the volume of coal in-place and on direct methane desorption data. It has been conservatively estimated that the total coal resource of the basin is about 7.9 billion tons. Seven individual coal seams have been identified as being the most likely candidates to contain potential coalbed gas reservoirs. The majority of these coalbeds are continuous, but these beds do not maintain a constant thickness throughout the basin. Total gas contents, as determined by desorption tests on coal cores, range from 73 cubic feet per ton to 576 cubic feet per ton. The estimated unsealed in-place methane resource is 1.6 Tcf and is considered a low volumetric assessment for the basin. The estimated depth scaled in-place methane resource is 2.7 Tcf, 82 percent of which is contained in the Hartshorne coalbeds. Analyses of gas produced from the Hartshorne coals/Hartshorne Formation show a range of Btu values from 993 to 1118 in the western part of the basin.

A viable exploration rationale has been established for the Arkoma basin, based on various geological aspects, such as stratigraphy and structure, the depth of the coalbeds and the recent MRCP well tests. The described methodology of methane exploration is present along with the results. Redefined target-test areas in the basin have been delineated and are discussed.
Evaluation of Fractured Reservoir Rocks Using Geophysical Well Logs
Authors: Fertl Walter H.
Published: December 2007

Recent economic forecasts place recoverable crude oil reserves from fractured reservoir rocks in excess of 40 billion stock tank barrels. Hence, over the past few years the petroleum industry has exhibited an ever increasing interest in fractured reservoirs.

The present discussion summarizes wireline logging techniques applicable in the detection of fractured reservoir rocks and reviews their advantages and possible limitations.
Economics of Devonian Shale, Coal Seam and Similar Special Appalachian Gas Sources
Authors: Miller Richard M. , Mutchler Norman E.
Published: December 2007

The natural gas curtailments during the winter of 1976-77 and the threat that gas interruptions would become a permanent way of industrial life sparked widespread interest in the investigation of local, higher-cost gas sources. Analyses of the technical, institutional, legal and economic constraints and opportunities associated with these gas sources located in the Appalachian Region were undertaken for the Appalachian Regional Commission. The economic potentials appeared encouraging providing certain constraints are removed and/or relaxed.
Waynesburg College Multiple Coal Seam Methane Extraction Well
Authors: Kirr James N. , Eddy Greg E. , Rahsman Robert , McGinnis Norman F.
Published: December 2007

Waynesburg College, in cooperation with TRW, Inc. and the Department of Energy, is in the process of completing the drilling of a well through the Upper Pennsylvanian coals near Waynesburg, Greene County in southwestern Pennsylvania. The primary objective of this well was to determine the optimum method for the extraction of methane gas from a multiple number of coal seams, and secondly, to provide Waynesburg College with an alternate source of energy to heat the buildings on the campus. It is anticipated that the gas produced will replace 60 to 70 percent of the peak demand of the College.

The well was drilled to a total depth of 442 meters using rotary percussion with air. After setting a water string of 22 cm casing, a 20 cm hole was drilled to the total depth. Production casing measuring 14 cm was cemented to the surface in a single stage.

Perforation and fracturing were done on an incremental basis using a retrievable bridge plug. Data from the coring and logging operations indicated that only seven of the coal seams present at the site would be suitable for fracturing and gas production. The coals were divided into three zones and perforated and fractured in turn to allow for maximum stimulation. The retrievable bridge plug was used to isolate the lower fractured seams from those above that were to be fractured. Fracturing was done with foam injected at a maximum rate of .03 m3/s using a sand proppant to maintain the openings in the coal.

The well, when completed, will be topped with a standard well head. A downhole positive displacement pump will be used to remove the water produced from the coals. The well is presently undergoing testing to determine its production potential. The gas produced will be run through a separator and dessicator before it is metered into a nearby existing commercial gas line for transportation to the Waynesburg College campus.
Polymer-Polymer And Polymer-Solid Interaction And Their Relevance For Polymer Application In Enhanced Oil Recovery
Authors: Klein J. , Kulicke W. M.
Published: December 2007

A variety of vinyl type polymers has been prepared and characterized to compare their viscosity behaviour with "established" technical polymers. Special emphasis is given to fundamental aspects of solution structure with regard to the conformation of a single chain and of chain to chain interaction. This will be examplified by studying homopolymers, copolymers and polymer mixtures of nonionic and ionic charakter.

Chain stiffening, based on intramolecular energetic and steric interaction and hydrogen bonding are considered as important structural parameters to describe the static and dynamic (time dependent) solution structure.

Polymer adsorption on quarz sand shows considerable differences for polyacrylamide (PAAm) and polysaccharide in their dependence on salinity. Polymer retention - in addition to adsorption - can be made visible by scanning electron microscopy in combination with energy dispersive X-Ray analysis.
The Economic Aspects of Marginal Field Development in An Offshore Environment
Authors: Cox T. F.
Published: December 2007

With the current demand for hydrocarbons, the constraints on the development of offshore oil and gas fields are attracting more and more attention. In the North Sea for example some 15% of the reserves could lie in reservoirs containing 100 million barrels or less. The discoveries which are restrained from development by economic factors can therefore be a significant percentage of the total basin reserves. In this paper the constraints are examined and their significance in economic terms is considered. It is concluded that in an environment such as the United Kingdom Continental Shelf, major problems can be expected with justification of the development of a field containing reserves of less than 50 million barrels. At this level of reserve the importance of the range of uncertainty in reserve, deliverability and cost estimates must be clearly understood. Where uncertainty prevents development decisions, government incentives must be considered.
Design Aspects of A 1.5 MWe Exhaust Fired Gas Turbine
Authors: Lowder J. R. A.
Published: December 2007

The paper presents some of the engineering details of the Ruston-Hague Exhaust Fired Gas Turbine (EFGT) and gives a record of recent advances made in developing the ceramic heater for this system. It is proposed to demonstrate this powerplant in a heavy crude oil, coal-oil or fully coal fired application when the current program of laboratory testing has been completed.

In this cooperative venture, Hague International of South Portland, Maine, will provide the ceramic heater and combustion equipment and Ruston Gas Turbines of Houston, Texas (also Lincoln, England) will supply the gas turbine, power takeoff and control equipment. The system will be used to supply shaft power or electricity, in addition to process steam, at an estimated overall fuel efficiency close to 80%.

The project has evolved from international pressure to utilize cheaper indigenous fuels in machines hitherto designed for power generation on distillate oils. Because the system incorporates an externally fired ceramic heater, many of the fundamental problems associated with internally firing a small industrial gas turbine on ash laden and often corrosive fuels are completely avoided. Problems associated with particulate, NOx and SOx emissions remain a serious consideration but these render themselves more amenable to traditional treatment once the decision to opt for external firing has been taken.

The paper examines the economic and technical merits of the Ruston-Hague system using a generalized economic calculation. The broader implications and scale up potential of this technology are then covered and the relevence of this technology to the Petroleum industry briefly discussed.
Downhole Corrosion - Prevention and Treatment
Authors: Weeter Robert F.
Published: December 2007

Corrosion control planning should begin before any well is drilled. The means of controlling corrosion in oil and gas wells are outlined in some detail in this paper. Primary cause of corrosion of metals is contact of metal with corrosive gases in well fluids in the presence of liquid water. Corrosion can be controlled by removing the contact, the corrosive gases or the water. Means for doing this are metallurgy, control of the well environment, separation of the metal of the pipe from the well environment, and cathodic protection. Each should be evaluated for use separately or in combination to obtain the most cost-effective control. Corrosion rates can be monitored by one or several devices which are commonly used for that purpose. The monitoring is especially effective in evaluating the results of corrosion control measures.
Computer Simulation of the Directional Drilling Process
Authors: Millheim Keith K.
Published: December 2007

This paper is the first reporting of a directional drilling simulation computer program that converts side force values, generated by a three-dimensional bottom-hole assembly algorithm, to actual displacements in the x and y planes. The program can be used to simulate directional wells that have been drilled, or to predict the actual trajectory for a given bottom-hole assembly, geology, and operating conditions.

The logic for the simulation program is presented, discussing how the bottom-hole assembly program, and the bit and stabilizer side cutting data were merged to form the basis of the program. Various inputs for a simulation or prediction, and the sensitivity of each input, are discussed. Mechanisms that are not included in the algorithm are cited, explaining how the lack of these mechanisms precluded the simulation of a certain variety of directional wells.

Results from the simulation of a directional well drilled in Holland are presented. Matching of actual inclination and direction data provided the basis of showing how the program could be used in a predictive mode for the selection and operation of other bottom-hole assemblies for drilling another directional well in the same area.

A final section discusses some of the problems encountered in running simulations and how these problems equate to actual field conditions. Mechanisms that need to be added to the algorithm to increase the fidelity and the breath of the simulation are mentioned.

The existing program has been used successfully to match wellbore trajectories in areas where the geological effects are nil to moderate and the wellbore conditions can be accurately described. With further refinements and enhancements to the program, it will only be a matter of time before any directional or deviation control well can be simulated. This ultimately means a computer program can be used to aid the drilling person in making sound engineering decisions on how to drill a directional well.
Breeding for Striga Resistance in Sorghum: Exploitation of an Intricate Host–Parasite Biology
Authors: Ejeta Gebisa
Published: December 2007

The parasitic weed Striga Lour. has been one of the more intractable agricultural problems seriously limiting productivity of cereal and legume crops in sub‐Saharan Africa. The development of crop plants with resistance to Striga has been limited because of the complexity of interactions between host, parasite, and the physical environment. We formulated a novel approach based on developing and exploiting a thorough understanding of the biology of this intricate association. We employed this knowledge‐based approach to develop powerful selection assays, to conduct genetic analyses, and to characterize the range of mechanism involved in host plant resistance to Striga Information thus generated has been used to identify unique sources of resistance to Striga, introgress these genes into selected cultivars, and deploy sorghum [Sorghum bicolor (L.) Moench] cultivars with known sources of Striga resistance either independently or in tandem as genotypes with multiple mechanisms of resistance. High yielding sorghum cultivars with Striga resistance and evident grain quality characteristics have been developed and deployed in a number of African countries to be used as cultivars per se or as a central component of an integrated Striga management program.
Translational Bioinformatics: At the Interface of Genomics and Quantitative Genetics
Authors: Beavis William D. , Schilkey Faye D. , Baxter Susan M.
Published: December 2007

Genomics and bioinformatics are expected to revolutionize crop improvement. We have to admit, however, that while information from the various “omics” is being used by developmental and evolutionary biologists, the information is not being used routinely by translational plant biologists or applied plant breeders. This is due to a failure to provide information from omics technologies in formats that can be used to develop more effective and efficient assays that the breeder can use for selection. A similar situation exists in biomedical research where more efficacious therapies will be realized if omics information is translated into biomarker‐based diagnostics. Because data are still lacking in plant science, herein we describe the development of an integrated web‐based system that supports translational research using a biomedical example that can serve as a model for translational plant research. We also discuss how the bioinformatic system is agnostic with respect to data content and is capable of accepting omics data that eventually will be generated by plant biologists for use by plant breeders to develop diagnostic biomarkers for use in selection.
Varied Properties of Hepatitis-Delta Virus-like Particles Produced by
Baculovirus-Transduced Mammalian Cells
Authors: Chiang Ying-Wei , Wu Jaw-Chin , Wang Kuei-Chun , Chou Szu-Ting , Hu Yu-Chen
Published: December 2007

Hepatitis delta virus (HDV) is a defective virus that requires the supply of hepatitis B virus surface antigen
(HBsAg) for replication and transmission. We have previously demonstrated that co-transduction of BHK cells with Bac-
GD, a recombinant baculovirus expressing large hepatitis delta antigen (L-HDAg), and Bac-GS2, another recombinant
baculovirus expressing HBsAg, gives rise to the assembly and secretion of 22 nm HBsAg subviral particles and 35-37 nm
HDV-like particles (HDV VLP). In this study we uncovered oversize particles (>50 nm in diameter) comprised of HBsAg
and L-HDAg and the particle properties varied with the relative dosages of Bac-GD and Bac-GS2, as demonstrated by
Western blot, transmission electron microscopy and immunogold labeling. At a given Bac-GS2 dosage, decreasing the
Bac-GD dosage resulted in the expression of more HBsAg, elevated secretion of HBsAg subviral particles, incorporation
of more HBsAg into the HDV VLP, narrower particle size distribution and lower particle density. These data collectively
demonstrated that the composition, and hence the properties, of HDV VLPs could be manipulated by altering the relative
expression levels of structure proteins.
Two Heat Pipe Type High Efficient Adsorption Icemakers for Fishing Boats
Authors: Xia Z.Z. , Wang R.Z. , Lu Z.S. , Wang L.W.
Published: December 2007

The adsorption performances of compound adsorbent (the mixing of activated carbon and CaCl2 by proper
technology)-ammonia are studied, which shows the obviously improvement for long term stable operation of adsorption/
desorption, and also the large adsorption cooling density. A multifunction heat pipe for heat transfer design in adsorber
is invented to use waste heat for heating and sea water for cooling effectively and reliably. An adsorption icemaker
experimental system driven by the exhausted heat from the diesel engine of fishing boats are studied, which shows
the optimum average SCP (specific cooling power) and COP (coefficient of performance) for the refrigerator have
reached to 770.4W/kg and 0.39 respectively at about -20°C evaporating temperature. Based upon the studies above, a real
multifunction heat pipe adsorption icemaker is then designed and built, the system is fully automatic controlled by Programmable
Logic Controller (PLC). The system operation shows the capability to make flake ice for more than 20 kg/hr.
Capillary Electrophoresis Coupled To Mass Spectrometry for Forensic Analysis
Authors: Huck Christian W. , Huck-Pezzei Verena , Bakry Rania , Bachmann Stefan , Najam-ul-Haq Muhammad , Rainer Matthias , Bonn Günther K.
Published: December 2007

In this review the most important techniques, which are developed to hyphenate capillary electrophoresis to
mass spectrometry (CE-MS), suitable for forensic analysis, are summarized. Analytes of interest are divided into four
main parts, namely, compounds with amine containing side chains, compounds with N-containing saturated ring structures,
other heterocycles and peptides. Sample pre-treatments and direct injection modes used in CE-MS for forensic
analysis are briefly discussed from critical point of view. Special emphasis is placed to point out the advantages of mass
spectrometric detection compared to UV- and laser- induced fluorescence (LIF) detections.
Reducts of stable, CM-trivial theories
Authors: Nübling Herwig
Published: December 2007

We show that every reduct of a stable. CM-trivial theory of finite U-rank is CM-trivial.
Club guessing sequences and filters
Authors: Ishiu Tetsuya
Published: December 2007

We investigate club guessing sequences and filters. We prove that assumingV=L, there exists a strong club guessing sequence on μ if and only if μ is not ineffable for every uncountable regular cardinal μ. We also prove that for every uncountable regular cardinal μ, relative to the existence of a Woodin cardinal above μ, it is consistent that every tail club guessing ideal on μ is precipitous.
An exploration of the partial respects in which an axiom system recognizing solely addition as a total function can verify its own consistency
Authors: Willard Dan E.
Published: December 2007

This article will study a class of deduction systems that allow for a limited use of the modus ponens method of deduction. We will show that it is possible to devise axiom systems α that can recognize their consistency under a deduction systemD provided that: (1) α treats multiplication as a 3-way relation (rather than as a total function), and that (2)Ddoes not allow for the use of a modus ponens methodology above essentially the levels of Π1and Σ1formulae.

Part of what will make this boundary-case exception to the Second Incompleteness Theorem interesting is that we will also characterize generalizations of the Second Incompleteness Theorem that take force when we only slightly weaken the assumptions of our boundary-case exceptions in any of several further directions.
ω-powers and descriptive set theory
Authors: Lecomte Dominique
Published: December 2007

We study the sets of the infinite sentences constructible with a dictionary over a finite alphabet, from the viewpoint of descriptive set theory. Among others, this gives some true co-analytic sets. The case where the dictionary is finite is studied and gives a natural example of a set at level ω of the Wadge hierarchy.
Converse dual cardinals
Authors: Brendle Jörg , Zhang Shuguo
Published: December 2007

We investigate the set (ω) of partitions of the natural numbers ordered by ≤* where A ≤* B if by gluing finitely many blocks of A we can get a partition coarser than B. In particular, we determine the values of a number of cardinals which are naturally associated with the structure ((ω), ≥*), in terms of classical cardinal invariants of the continuum.
The generalised type-theoretic interpretation of constructive set theory
Authors: Gambino Nicola , Aczel Peter
Published: December 2007

We present a generalisation of the type-theoretic interpretation of constructive set theory into Martin-Löf type theory. The original interpretation treated logic in Martin-Löf type theory via the propositions-as-types interpretation. The generalisation involves replacing Martin-Löf type theory with a new type theory in which logic is treated as primitive. The primitive treatment of logic in type theories allows us to study reinterpretations of logic, such as the double-negation translation.
Computable trees of Scott rank ω1CK, and computable approximation
Authors: Calvert Wesley , Knight Julia F. , Millar Jessica
Published: December 2007

Makkai [10] produced an arithmetical structure of Scott rank ω1CK. In [9], Makkai's example is made computable. Here we show that there are computable trees of Scott rank ω1CK. We introduce a notion of “rank homogeneity”. In rank homogeneous trees, orbits of tuples can be understood relatively easily. By using these trees, we avoid the need to pass to the more complicated “group trees” of [10] and [9], Using the same kind of trees, we obtain one of rank ω1CK that is “strongly computably approximable”. We also develop some technology that may yield further results of this kind.
Fusion over sublanguages
Authors: Hasson Assaf , Hils Martin
Published: December 2007

Generalising Hrushovski's fusion technique we construct the free fusion of two strongly minimal theoriesT1.T2intersecting in a totally categorical sub-theoryT0. We show that if. e.g.,T0is the theory of infinite vector spaces over a finite field then the fusion theoryTω, exists, is complete and ω-stable of rank ω. We give a detailed geometrical analysis ofTω, proving that if bothT1,T2are 1-based then.Tω can be collapsed into a strongly minimal theory, if some additional technical conditions hold—all trivially satisfied ifT0is the theory of infinite vector spaces over a finite field.
A constructive view on ergodic theorems
Authors: Spitters Bas
Published: December 2007

Let T be a positive L1-L∞ contraction. We prove that the following statements are equivalent in constructive mathematics.

(1) The projection in L2, on the space of invariant functions exists:

(2) The sequence (Tn)n∈N Cesáro-converges in the L2 norm:

(3) The sequence (Tn)n∈N Cesáro-converges almost everywhere.

Thus, we find necessary and sufficient conditions for the Mean Ergodic Theorem and the Dunford-Schwartz Pointwise Ergodic Theorem.

As a corollary we obtain a constructive ergodic theorem for ergodic measure-preserving transformations.

This answers a question posed by Bishop.
Axiomatizing Kripke's theory of truth
Authors: Halbach Volker , Horsten Leon
Published: December 2007

We investigate axiomatizations of Kripke's theory of truth based on the Strong Kleene evaluation scheme for treating sentences lacking a truth value. Feferman's axiomatization KF formulated in classical logic is an indirect approach, because it is not sound with respect to Kripke's semantics in the straightforward sense: only the sentences that can be proved to be true in KF are valid in Kripke's partial models. Reinhardt proposed to focus just on the sentences that can be proved to be true in KF and conjectured that the detour through classical logic in KF is dispensable. We refute Reinhardt's Conjecture, and provide a direct axiomatization PKF of Kripke's theory in partial logic. We argue that any natural axiomatization of Kripke's theory in Strong Kleene logic has the same proof-theoretic strength as PKF. namely the strength of the systemramified analysis or a system of Tarskian ramified truth up to ωω. Thus any such axiomatization is much weaker than Feferman's axiomatization KF in classical logic, which is equivalent to the systemof ramified analysis up to ε0.
T-height in weakly o-minimal structures
Authors: Tyne James
Published: December 2007

Given a weakly o-minimal theoryT, theT-height of an element of a model ofTis defined as a means of classifying the order of magnitude of the element. IfTsatisfies some easily met technical conditions, then this classification is coarse enough for a Wilkie-type inequality: given a set of elements of a model ofT, each of which has a differentT-height, the cardinality of this set is at most 1 plus the minimum cardinality of a set that generates the structure.
Stable embeddedness in algebraically closed valued fields
Authors: Hrushovski E. , Tatarsky A.
Published: December 2007

We give some general criteria for the stable embeddedness of a definable set. We use these criteria to establish the stable embeddedness in algebraically closed valued fields of two definable sets: The set of balls of a given radius r < 1 contained in the valuation ring and the set of balls of a given multiplicative radius r < 1. We also show that in an algebraically closed valued field a 0-definable set is stably embedded if and only if its algebraic closure is stably embedded.