bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Heavy Oil Reserves in South Oman
Authors: Nandyal Madhava , Thurber S. S. , Al-Hinai K. M. , Jaffer N. A.
Published: December 2007

Significant discoveries of heavy oil accumulations (7+ billion barrels STOIIP) in South Oman have led to a greater emphasis on their development in the last 3-4 years. These fields are now being developed in a systematic manner keeping in mind the potential production problems and the practical use of enhanced oil recovery (EOR) techniques.

Most of the reserves occur in glacial to periglacial sandstones of Permo-carboniferous age which exhibit rapid facies variations. Geologic models developed from core data, drilling, seismic and petrophysical reviews, require continuous revision. Extensive appraisal drilling campaigns are in progress in the larger fields to define the reservoir limits and to delineate the observed rapid lateral variations in reservoir thickness, petrophysical characteristics and accumulation of oil. An integrated approach is followed in production planning and development. The high viscosity of the crude and unconsolidated nature of the formations create a typical sand production-problem environment. The occurrence of H2S in some fields and anticipation of early water production from both edge and bottom aquifers has necessitated cautious planning of facilities. Low solution-GOR and high crude viscosity preclude flowing production. Consequently, beam pumping is being installed in all fields. Most fields are planned for development on a square-grid pattern with varied well spacing which considers crude characteristics, reservoir properties and future EOR possibilities.

Since primary recoveries are expected to be low (5 to 15 percent), steps are being taken to initiate a pilot polymer flood and, at least, one pilot steam flood. Steam soak is also considered possible for the more viscous (>1000 cP) reservoirs. Necessary basic reservoir data are being gathered for these projects and reservoir simulation process design studies are in progress. Facilities design and installation is also underway.

Considering the huge investments required for large-volume heavy oil production, phased development is planned in order to avoid a high production spike followed by a long period of declining production. Phased development will also allow a plateau production level as Oman's presently known lighter oil fields slowly decline.
Wellsite Gas Detection Helps in Controlling Abnormal Pressure and Picking Perforations on Development Wells
Authors: Struckel J. C. , Mercer R. F.
Published: December 2007

Data obtainable with a low cost wellsite total gas detector can provide valuable assistance in production drilling. Gas liberated by the drill bit into the drilling mud is an effective tool for accurate perforation selection even if wireline log interpretation proves inconclusive. Gas produced into the mud system by the formation provides valuable assistance in detecting and monitoring abnormal pressure. Optimum mud weight can also be determined from produced gas data.
A Simplified Approach to Design of Fracturing Treatments Using High Viscosity Cross-Linked Fluids
Authors: McLeod H. O.
Published: December 2007

Simple models are presented to evaluate or design hydraulic fracturing treatments using perfect transport fluids. The fracture geometry program calculates dimensions of a vertically contained fracture and the expected productivity ratio for the fractured well. A sand concentration program helps schedule sand to prevent sandouts and to ensure sufficient proppant at the wellbore.
High Efficiency Fracturing Fluids for High-Temperature, Low-Permeability Reservoirs
Authors: Baumgartner S. A. , Parker C. D. , Williams D. A. , Woodroof R. A.
Published: December 2007

Reservoirs with permeabilities of less than 1 md and bottomhole temperatures in excess of 250°F are commonly encountered in the continuing search for hydrocarbons. Successful completion of these wells often requires the use of Massive Hydraulic Fracturing (MHF) treatments.

The fracturing fluids used in MHF treatments are frequently subjected to excessive shear and prolonged exposure at high bottomhole temperatures. Early fracturing fluids proved unsuitable for these MHF treatments due to a rapid loss of viscosity at high temperatures. As a result, narrow fracture widths, excessive fluid loss and poor proppant transport occurred. Cool-down pads, increased polymer concentrations and delayed polymer hydration systems were employed in an attempt to improve the MHF treatment success ratio.

A laboratory study was undertaken to develop a more efficient high temperature fracturing fluid. Rotational and pipe viscometers were used to evaluate thermal and shear stabilities under reservoir conditions. Fluid loss testing measured the effectiveness of fluid leakoff control. Fluid breakout testing ensured a controlled loss of viscosity and minimal proppant pack gel residue. As a result of this study, a more efficient high temperature fracturing fluid was developed.

This paper presents laboratory data comparing the thermal stability, shear stability and fluid loss control of the High Temperature Gel (HTG) with those of a conventional titanate crosslinked gel. Field case histories axe presented to demonstrate the efficiency with which the HTG system has been used to successfully stimulate low permeability gas wells with bottomhole temperatures in excess of 250°F.
Laboratory Simulations of Hydraulic Fracturing
Authors: Papadopoulos J. M. , Narendran V. M. , Cleary M. P.
Published: December 2007

Two novel distinctly different laboratory apparatus have been developed to allow controlled, precise, repeatable and observable experimental simulations of hydraulic fracturing over a broad range of well-determined dominant parameters and practical geometries. One system avoids specimen preparation (by using predetermined interface separation), while the other most efficiently employs castable blocks with proper scaling of fracture toughness to correctly capture crack turning. These are based on a rigorous analysis of the physics and equations governing the hydrafrac process, which allow the extraction of the role played by each physical variable - so that these can be incorporated correctly in the scaling, e.g. from field operations to lab conditions. The experiments have already verified most of the primary features and results of the analysis: principal achievements include vindication of a characteristic time for the process, containing excess crack-opening pressure, material modulus and fluid rheology; general agreement with numerical results for actual growth rates of various fracture geometries; and verification of even more detailed predictions for evolution of cracks with mutual/tectonic interaction in various structural geometries and stress fields. Being perhaps the first stable, quasi-static and observable simulators, these apparatus promise to have a very broad range of applications in geophysics, resource extraction, structural analysis and geotechnical engineering.
Effect Of Stress Distribution On Hydraulic Fracture Geometry: A Laboratory Simulation Study In One Meter Cubic Blocks
Authors: Ahmed Usman , Strawn Jon , Wilson Michael , Schatz John
Published: December 2007

The success of a hydraulic fracture treatment is greatly enhanced by control of the created fracture geometry. Of particular importance is the migration of the fracture into the boundary lithologies, which is largely determined by in- situ stress. Most of the presently used hydraulic fracturing models assume a constant fracture height confined to the pay zone, which predicts unrealistically large fracture lengths. Currently, a joint research program (involving The Gas Research Institute of Chicago, Chandler and Associates of Denver, and Terra Tek, Inc. of Salt Lake City) is underway that is evaluating, in the laboratory and in the field, several techniques to place (in conjunction with hydraulic fracturing) deeply penetrating fractures into pay formations not boundedby high stress barriers. Field work is taking place in the Douglas Creek Arch area of Colorado.

This paper presents a part of that program, the laboratory model study of hydraulic fracture propagation in one meter cubic blocks. The test block is loaded in a large frame which allows the independent application of minimum and maximum horizontal stressesto the simulated pay zone and two boundary lithologies, anda vertical stress to the entire block. The test block is internally strain gaged to allow the inference of the actual stress distribution both prior to, during, and after the fracture.Following hydraulic fracturing with a dyed fluid, the block is broken andthe created fracture surface area is examined. Through the use of this test set-up, the effect of in-situ stress on fracture geometry has been demonstrated, and a method of fracture geometry control basedon perforation placement has been established.
Use of Foaming Agents To Alleviate Liquid Loading in Greater Green River TFG Wells
Authors: Vosika J. L.
Published: December 2007

Downtime and decreased production due to liquid accumulation in the wellbore are common problems among low volume tight formation gas wells. Recently, foaming agent injection was initiated in several Greater Green River Basin area wells as a low cost method to combat liquid loading problems.

This paper illustrates that the use of foaming agents has proven to be an inexpensive yet effective solution to liquid loading problems in area gas wells.
A Sensitivity Analysis of the NPC Study of Tight Gas
Authors: Rosenberg J. I. , O'Shea Patrick , Mercer James , Morra Frank , Brashear J. P.
Published: December 2007

In 1980, the National Petroleum Council (NPC) published the results of a two-year, multi-company study of unconventional natural gas1 It concluded that low permeability, "tight" gas reservoirs have significant potential for the U.S. domestic energy production. The size of this potential depends on the geological assessment, extraction technology performance, and production economics. The NPC assessment remains the most exhaustive and credible estimate of tight gas potential since its publication.

The Tight Gas Analysis System (TGAS) is a joint project of the Gas Research Institute and the U.S. Department of Energy. It is designed to "automate" the NPC analytical approach to tight gas assessment by creating a comprehensive model that will permit sensitivity analysis of key assumptions, updating as new data become available, and timely reinterpretation of results in light of changing technology and economics.

The TGAS model also introduces the concept of economic rent which was not explicitly reported in the NPC assessment. Economic rentis defined as the difference between the minimum required selling price for producing an incremental unit of gas (i.e., marginal cost) and current sales price. This approach assumes that all costs remain constant in real terms throughout the development of the project. This minimum required selling price is defined as that gas price (per Mcf) which equates the present value of the after-tax net cash flows from a project to zero; that is, the minimum price that fully reimburses all costs, including the risk adjusted cost of capital and taxes. Net cash flow is evaluated at the full cost of exploration and development; all transfer payments to government and royalty holders are included in this price. The reader should note that portions of this economic rent may be distributed among other participants in gas development including drillers, suppliers, royalty holders, and taxing agencies. However, if the NPC assumption that costs remain constant is retained, then economic rent is a useful index of economic attractiveness.
Determination of In-Situ Stress From Anelastic Strain Recovery Measurements of Oriented Core
Authors: Teufel L. W.
Published: December 2007

A reliable method for determining the in situ stress state in deep formations is of great importance to the gas industry in designing massive hydraulic fracture treatments of low permeability reservoirs. Knowledge of the horizontal in situ stress directions and magnitudes would allow prediction of fracture azimuth and height. In this paper a method using anelastic strain recovery measurements of oriented core will be presented as a reliable and practical tool for determining both the directions and magnitudes of the principal horizontal in situ stresses in deep formations. The principal horizontal stress directions are determined directly from the principal horizontal strain recovery directions. The principal horizontal stress magnitudes are calculated from the principal strain recovery magnitudes, overburden stress, and Poisson's ratio of the rock using a viscoelastic model by Blanton. In addition, petrophysical measurements of the core parallel to the principal directions of strain recovery, at atmospheric pressure and at elevated confining pressure, suggest that the strain recovery process is a consequence of microcrack formation and expansion.
A New Approach for Optimizing Bit Hydraulics
Authors: Doiron H. H. , Deane J. D.
Published: December 2007

A method is presented for optimizing roller cone bit hydraulics programs to provide minimum cost per foot drilled. The method differs from traditional optimization techniques in that optimum pump operating conditions are determined rather than being arbitrarily imposed as a constraint on the optimization process. The method considers rate of penetration (ROP) response to increased bit hydraulic horsepower (BHHP) as well as increased fuel and pump maintenance costs to provide increased BHHP. Optimum conditions may be determined through a parametric analysis or by imposing simple relationships between pump fuel and maintenance costs and ROP response to increased BHHP.

Full scale laboratory drilling data under various overbalance pressure conditions are presented to demonstrate the relationship between ROP and BHHP. Laboratory and field results with blanked nozzles and asymmetric three nozzle configurations are also presented.
Correlations for the Reservoir Fluid Properties of Alaskan Crudes
Authors: Ostermann R. D. , Ehlig-Economides C. A. , Owolabi O. O.
Published: December 2007

Reservoir fluid properties such as bubble point pressure, formation volume factor, solution gas/oil ratio, and viscosity are required for the analysis of reservoir performance. Ideally, these properties would be determined experimentally, from laboratory PVT analyses. Frequently, these properties must be predicted in advance of PVT studies. Since the crudes from different regions have different propeties, it is prudent to assess the accuracy of the available correlations and make an informed selection for each region or type of crude.

PVT reports have been assembled from several Alaskan oil fields in the Cook Inlet Basin (CIB). The experimentally determined values for bubble point pressure, oil formation volume factor and live and dead oil viscosity have been compared to the values calculated from several popular correlations.

CIB crudes are characterized as low sulfur crudes with a high nitrogen content. Crudes from the Alaskan North Slope have high nitrogen and carbon dioxide contents. The presence of non-hydrocarbon gases has a marked influence on bubble point pressure. Correction factors must be applied.

The available correlations and corrections have been compared for application to CIB crudes, and specific recommendations for their use are included in the conclusions. The appendices to the paper also include a convenient compilation of the equations for the correlations.
The Rheological Properties of Prudhoe Bay Oil and the Effects of a Prolonged Flow Interruption on Its Flow Behavior
Authors: Economides M. J. , Chaney G. T.
Published: December 2007

The rheological properties of Prudhoe Bay oil, as with any other mixture of hydrocarbons, are markedly affected by the lowering of temperature. The Transalaska pipeline traversing the state in a North-South direction is subjected to severe ambient temperatures during the winter months. A prolonged flow interruption would result in inevitable heat losses from the trapped crude oil. The temperature decline would cause a significant alteration of the flow behavior. A fundamental heat transfer study and laboratory measurements were combined in order to forecast the rheological response and subsequent start-up requirements of Prudhoe Bay oil in gathering lines and in the Transalaska pipeline.
Stress-Sensitive Permeability in a High-Permeability Sandstone Reservoir—The Kuparuk Field
Authors: Adams B. H.
Published: December 2007

Buildup test analyses for wells in the Kuparuk field, Alaska, give permeability values that are two to seven times higher than values from drawdown test analyses. Often buildup skins indicate extreme formation damage, while drawdown skins indicate minimal damage. This sandstone reservoir exhibits the characteristics of stress-sensitive permeability. Stress-sensitive permeability usually is associated with low-permeability gas reservoirs where permeability decreases as the reservoir is depleted. Although Kuparuk is a high-permeability oil reservoir, its effective permeability may drop to one-sixth of original permeability during production. Clearly, stress-sensitive permeability is not limited to low-permeability reservoirs.

The existence of stress-sensitive permeability was demonstrated using welltest analyses, simulation studies, core analyses, and laboratory flow experiments. Comparisons of buildup and drawdown test analyses first suggested this mechanism. Comparisons were made for most wells in the field, with significant differences between buildups and drawdowns evident in a majority of the analyses. Simulation of welltests required stress-sensitive permeability to match both buildup and drawdown tests. Core analyses and laboratory flowtests were done to determine the cause and magnitude of the stress-sensitive permeability.

Evidence points to open vertical fractures as the cause of this stress-sensitive permeability. These fractures are small-scale, with characteristic heights on the order of inches, and apparently randomly distributed in the reservoir. Because of the fractures' size and distribution, the reservoir behaves as a homogeneous porous medium with stress-sensitive permeability rather than as a classical naturally fractured reservoir. Welltests show no typical fractured reservoir behavior (i.e., linear flow).

The extreme effects of stress-sensitive permeability, as seen in this reservoir, can seriously impact field operations. Productivity and injectivity estimates will be incorrect if variable permeability is not recognized and incorporated in these estimates. Also, use of buildup skins calculated from constant permeability equations, such as the Horner method, to determine wellbore condition (damaged or undamaged) can lead to unnecessary and useless stimulation treatments.
Motion Compensation Equipment Fluid, Compenol
Authors: Schlater D. R. , Globe Tony
Published: December 2007

Development in motion compensation equipment for floating drilling has up to now centered in the area of cylinders and hydro-mechanical techniques. With this system well developed an improvement in the operating fluid is presented. This fluid improves on both the fire resistance and environmental acceptability of existing fluids.
Effect of Bottom Water and Gas Cap on Thermal Recovery
Authors: Ali S. M. Farouq
Published: December 2007

Many heavy oil formations are characterized by a bottom water sand, or a high gas saturation zone near the top. Either can have an undesirable effect on steam injection and in situ combustion response. The purpose of this paper is to present: (i) field test, (ii) laboratory model, and (iii) mathematical simulation results pertaining to bottom water or gas cap in thermal recovery processes. Some guidelines are offered for judging the suitability of a formation for one of the thermal methods.

Selected steam injection and in situ combustion projects, where a bottom water or high gas saturation zone was present, are discussed. It is shown that in a number of situations, it was possible to conduct a successful steamflood in spite of bottom water or gas zone. This was not so in some of in situ combustion projects under such conditions, where the water zone led to severe air channeling.

The laboratory model results mainly pertain to bottom water type situations in steamflooding. Results obtained by the author for tar sands, as well as those of other investigators, are discussed. A high conductivity zone near the base of the formation can serve as a means of initial heating. Subsequent steam displacement behavior would depend largely on oil viscosity and formation characteristics. One instance of a gas zone in in situ combustion is also considered.

The simulation results are those of the author, as well as other published data, concerning the effect of bottom water on cyclic steam stimulation, steamflooding, and in situ combustion response. Bottom water sand thickness is an important variable in cyclic steam stimulation, and in particular, steamflood response. In situ combustion seems to be relatively insensitive to the bottom water sand thickness, however, even small thicknesses can lead to severe air bypassing. A gas zone seems to be undesirable in the case of cyclic steaming and in situ combustion, but may be used to advantage in steam-flooding.
Persistent Action of Thin-Film Spreading Agents Used in Cyclic Steam Stimulation
Authors: Blair C. M. , Scribner R. E. , Stout C. A.
Published: December 2007

The production histories of eight of 15 wells that received injections of a special class of interfacially active chemicals during an earlier field study have been followed during a subsequent cycle in which no chemical was used. When compared to production in the original steam-only cycle, the results show that the positive effect of the original chemical application persists into the next cycle. However, two wells, in which interfacially active agent was injected during the next cycle, gave even greater oil production.
A Rod Pumping System for California Lift Requirements
Authors: Tait H. C.
Published: December 2007

Artificial lift requirements in California oilfields cover a full range of demanding operating and environmental conditions. These extend from typical demands of lifting depth and volume, to atypical requirements of heavy crude, thermal enhancement and the unique environmental restrictions of our urban sites and offshore fields.

A new rod pumping system has been developed which deals with these requirements. Performance results to date confirm reduced power consumption and improved pumping performance. Combined with the compact equipment size, these characteristics appear to offer benefits to California operators.
Interaction of a Buoyant Tower with A Dynamically Positioned Drillship
Authors: Cowan Roes , Horton Edward E. , Alinaghian Yousef
Published: December 2007

The Buoyant Tower concept provides the means to drill for and produce oil and gas in water depths from 1,200 feet to depths in excess of 20,000 feet. The tower is freestanding and consists of a series of buoyant cylinders extending from the seafloor to within several hundred feet of the ocean surface. This concept provides a continuous buoyant column that acts as a support mechanism for extending concentric well casing and production tubing from the seafloor to well heads located at the tower top.

A unique problem associated with this long slender compliant tower is the interaction of the tower with a dynamically positioned (DP) drillship. The drillship performs several functions consisting of:

Installing the piles at the base of the tower. Drilling and completing the wells. Workover operations.

This paper addresses the feasibility of connecting a standard marine riser to the tower top from a floating DP drillship. This discussion outlines the approach to making rational predictions of the coupled ship/tower behavior and details some of the requirements necessary for conducting such an investigation.

The baseline case addressed in the discussion considers a 2,000 foot long Buoyant Tower in a water depth of 2,300 feet. The tower has a 6-well capacity with a tapered base section. The DP drilling vessel has characteristics typifying current conventional equipment. Solution methods consist of coupled rigid body and finite element models in the frequency domain.
Small Angle X-Ray Diffraction by Microemulsions
Authors: Chen Lidian , Marsden S. S.
Published: December 2007

Microemulsion systems have been prepared by using a wide range of concentrations of either of two surfactants (TRS-10-80 or ethanolamine salt of dodecyl-o-xylene sulfonic acid (EADXS), toluene as the oleic phase and either water or dilute brines (1% or 2% NaCl) as the aqueous phase. Some were isotropic liquids but others displayed the birefringence characteristic of liquid crystals. X-ray diffraction at small Bragg angles by samples of these systems encapsulated in thin-walled, glass capillary tubes was sought and found in most systems. This usually consisted of a single ring similar to the Debye-Scherrer photographs obtained with microcrystalline powders at higher Bragg angles and had Bragg spacings corresponding to from 60 to 200 Angstrom units. For those systems having high surfactant concentration, there were generally maxima of intensity at positions perpendicular to the axis of the capillary tube suggesting orientation of larger particles or units such as those in liquid crystals.

The calculated Bragg spacings increased with a decrease in concentration of surfactant and with an increase in concentration of the toluene and/or the aqueous phase. For the systems of TRS-10-80, the presence of the NaCl at the lower concentrations had an unmeasurable effect on the x-ray diffraction but at the higher concentrations the Bragg spacings did not increase as fast. For the systems of EADXS, the presence of NaCl had no effect at either concentration on x-ray diffraction.

To a first approximation, the results can be interpreted in terms of an expanding, lamellar, hydrous liquid crystalline system in which the aqueous phase forms layers between the polar faces of bimolecular sheets of surfactant molecules and the toluene forms similar layers between the non-polar faces. The mechanism for this as well as its application to EOR is discussed in the paper.
A Synergistic Chelation System for Acidizing in the Presence of High Iron Concentrations
Authors: Ewing B. C. , Pabley A. S. , Callaway R. E.
Published: December 2007

A series of screening tests have been performed to determine the chemical types needed for chelating iron (Fe+++) at concentrations as high as 50,000 ppm in spent acid. The chemicals tested were liquid citric acid (LCA), nitrilotriacetate (NTA) and acetic acid (AA). A blend of liquid citric acid and nitrilotriacetate was found to be practical in a 50-50 volume blend with acetic acid added in some cases as an intensifier and pH buffer. The testing was done at room temperature (80°F, 27.7°C) and verified at 170°F (77°C). Compatibility tests and freeze-thaw tests were also run on the blend. From the data, a practical loading schedule for use in the field has been proposed.
Miscible Displacement: The Liquid - Liquid Case
Authors: Warren J.E. , Price H.S. , Skiba F.F. , Varga R.S.
Published: December 2007

PUBLICATION RIGHTS RESERVED

This paper is to be presented at the 36th Annual Fall Meeting of the Society of Petroleum Engineers of AIME in Dallas, October 8–11, 1961, and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper.

The process by which one miscible liquid displaces another liquid in a two-dimensional porous medium has been investigated by means of experimental digital computation. The effects of viscous and gravitational forces, molecular diffusion, microscopic dispersion and heterogeneous permeability have been explicitly included in the behavior equation's. A general numerical method for solving the difference analogues of the behavior equations has been developed and the occurrence of oscillatory numerical solutions has been explained.

Based on the computed results, it has been concluded that, for the viscosity function chosen, gravity segregation does not materially affect the recovery at breakthrough in a homogeneous system. It has been observed that randomly heterogeneous permeabilities cause macroscopic dispersion which tends to damp out viscous fingers; it has been suggested that viscous fingering may be a laboratory phenomenon and not a reservoir problem.

Introduction

During the last ten years, almost one hundred papers on the subject of oil recovery by miscible displacement have appeared in the literature. These papers which have covered a wide range of interests—physical principles, mathematical theory, laboratory experiments, field tests and economics—have indicated the potential importance that has been assigned to this process by the petroleum industry. Despite the concerted efforts that have been reported, the future of miscible displacement as a practical method for improving the recovery of oil remains uncertain.
Adsorption of Asphaltenes and Water on Reservoir Rock Minerals
Authors: Collins S. H. , Melrose J. C.
Published: December 2007

New data relating to the adsorption of asphaltenes on reservoir rock minerals are reported. The data were obtained by contacting samples of several different clay mineral types, as well as of Berea sandstone, with toluene solutions of a petroleum asphaltene fraction. This material was recovered from a deposit on the tubing string of a producing well. It was characterized with respect to molecular weight and elemental composition. Adsorption isotherms were determined and found to be of the Langmuir type, indicating monolayer adsorption. For each of the samples an independent surface area measurement was made. This permitted the probable size of the adsorbed asphaltene particles to be estimated. The effect of water on the adsorption of asphaltenes on kaolinite was also determined. It was found that adsorption was reduced but not eliminated by the presence of water. In these experiments the water was either pre-adsorbed on the clay or simply dissolved in the solvent. The amount of co-adsorbed water corresponded to 30-50 monolayers, indicating the probable formation of liquid bridges of water between clay particles. Estimates were obtained for the magnitude of the microscopic toluene/water contact angles which characterize these liquid bridges.
Noise and Vibration Control Offshore Towards an Improved Design Procedure for Topside Facilities
Authors: Venables R K , Manning C J
Published: December 2007

Noise and vibration control can affect the health and safety of persons employed on offshore installations in a number of ways.

Noise can be directly injurious to health; prolonged exposure to high levels of noise, or short duration exposure to very high levels, will permanently impair hearing. High levels of vibration can cause sickness and loss of balance. Both noise and vibration induce stress which is cumulative with other stresses such that, in a hazardous and demanding work environment, errors of judgement can be made and working efficiency reduced. High noise levels can also mask public address and alarm systems, and interfere with speech, telephone and radio communication. Finally, much lower levels of noise and vibration may prevent or disturb sleep and relaxation.

For these reasons, serious consideration must be given to the control of noise and vibration on offshore installations. There are now the knowledge, expertise and hardware to control satisfactorily noise and vibration in the majority of situations, but there are a number of limiting factors, including cost and engineering feasibility, and the interaction with other safety measures. The cost of noise and vibration control features, if included at the design stage, has been estimated to be from 1 to 10% of the total topside cost of an offshore installation, depending on its size and complexity. If they are initially omitted and noise and vibration have to be treated retrospectively, then this cost can easily be doubled, and engineering feasibility will limit what can be achieved.
Development Of New-Generation, High-Pressure Marine Wellheads
Authors: Kempston R , Hart B
Published: December 2007

DESIGN CRITERIA, DEVELOPMENT & FIELD HISTORY

Design Criteria of the 21.1/4"-5000 × 13.5/8"-15000 Two-Stack Wellhead

Development of the 21.1/4"-5000 × 13.5/8"-15000 Two-Stack Wellhead

The initial step in the design of this system was to develop the new 21.1/4"-5000 and 13.5/8"-15000 subsea wellhead hub configurations. The 21.1/4"-5000 hub was obtained by boring out the 18.3/4"-10000 hub to 21.1/4" and designing a new AX gasket. This was feasible as the pressure end load of the 21.1/4"-5000 was much less than that of the 18.3/4"-10000 hub. Also, with the lower working pressure, there was sufficient wall thickness to permit boring out the ID of the 18.3/4"-10000 hub.

For the 13.5/8"-15000 housing a double hub profile was proposed. This hub profile would give the needed bearing area required for the pressure end load plus bending moment and still allow the housing to be run through the 21.1/4"-5000 BOP stack. A finite-element analysis was then done to determine if the stresses were in an acceptable range. In order to reduce the high radial loads which are caused by casing load plus test pressure acting on the 45° landing shoulder in the 13.5/8"-15000 housing, hardened teeth were included on the casing hangers.

Prototype parts were then made and assembled as shown in Fig. 4. The highly-stressed areas were then analysed using strain gauges whilst an internal pressure of 22500-psi was applied to the 13.5/8"-15000 housing. (Note: The load due to 22500-psi test pressure is approximately equivalent to 16400 ft. of 7"-381b/ft and 15900 ft of 9.5/8"-53.5 lb/ft of casing in 121b/gal. mud plus 15000 psi-test pressure).
On The Fatigue Analysis of a Differential Thread Connector
Authors: Chen L Y , Williams M R
Published: December 2007

This paper presents a fatigue analysis of a differential thread connector for a special high strength 9 5/8", 471b/ft offshore production riser. The connector was designed to be manufactured from a commercially available upset casing thereby eliminating the need for welding and enhancing the riser's fatigue life expectancy. The method of finite element analysis was used to determine the peak static and alternating stresses in the connector. Conditions considered in the analysis include assembly pre-load, dead weight and static/dynamic bending movements due to waves. Typical North Sea wave data were selected for this analysis. Miner's rule was employed to estimate the fatigue life of the connector in conjunction with the ASME section VII, Division 2 S-N curve.
Evaluation of Splashzone Maintenance Coating Systems by Accelerated Laboratory Testing and Field Trials
Authors: Tischuk J L , Brebner G
Published: December 2007

Maintenance painting of platform splashzones is one of the most difficult offshore coating problems. There is a limited and frequently interrupted weather window for working, the temperature is generally low, the relative humidity is usually high and surfaces may be subjected to salt spray or complete immersion within a few hours of coating application.

Once a coating is on the steel, it is continually wet and must resist abrasion and impact from the sea and from debris which is in the sea. In order to stand up to these conditions, splashzone coatings must adhere tightly to the steel, they must be tough and resilient and they must be resistant to the spread of local damage.

Occidental's Piper and Claymore Platforms were installed in the North Sea in 1976 and 1977 respectively. The original splashzone coatings applied during fabrication were high-build vinyl systems over zinc silicate primers. The same coating systems were used on the platform topsides. By 1978 there was a need for coating repairs because the vinyls had poor abrasion resistance. It has proved impossible to use the original coating system for the repairs because it is intolerant of ambient conditions.
The Demand for Petroleum Engineers
Authors: Calhoun John C.
Published: December 2007

Since 1978 the Society of Petroleum Engineers has conducted an annual survey of companies and universities in order to obtain data on the supply and demand for petroleum engineers. The purpose of this presentation is to report on the results of trie 1983 survey with respect to demand and to compare these results with indications of demand from other sources.

The SPE survey information includes a five-year history of the numoers of engineers employed at year end, a five-year history of hirings, and a five-year projection of expected hirings. In 1982 the author presented a summary of the general conclusions that could be drawn from the series of surveys up to and including the 1982 survey1. Reference will be made to those results throughout this presentation. It is not possible to compare absolute results of these surveys from year-to-year because the companies that report are not the same ones each year.

In 1983 only 16 organizations responded to the questionnaire in a sufficiently uniform manner to construct the sample. This is the smallest number of respondents since the surveys were initiated (1979-62; 1980-35; 1981-35; 1982-27). The total population of engineers represented by the respondents also is the smallest of any of the surveys. Table 1 gives the 1983 survey data for engineers and petroleum engineers; employed at years end and the expected total work force of engineers for the future five years. The latter shows both a high and low estimate. The data are also shown in Figures 1 and 2, with earlier survey data for comparison. The future work force of petroleum engineers is not a pari: of the survey.
A Graphical Method for Estimation of Production Response From Cyclic Steam Stimulation Using Past Performance Data
Authors: Ershaghi Iraj , Al-Adawiya M. S. , Kagawan V. D.
Published: December 2007

A graphical solution method is presented whereby the production and injection data from a number of steam stimulation cycles for a given well are used to estimate recoveries from future cycles.

The proposed method was established based on the experimentation with the analytical model originally proposed by Boberg and Lantz1. It requires a log-log plot of cumulative oil production vs. cumulative steam injection. The technique allows the computation of a response factor for individual wells undergoing cyclic stimulation in a given reservoir.
Comparison and Analysis of Reservoir Rocks and Related Clays
Authors: Crocker M. E. , Donaldson E. C. , Marchin L. M.
Published: December 2007

A series of instrumental and chemical analyses was made to determine the surface chemical properties of sedimentary rocks and the physical characteristics of the pores. A scanning electron microscope (SEM) with energy dispersive X-ray analytic capability was used to study the morphology of the samples, surface mineral composition and type and location of clays. A centrifuge was used to determine the pore size distributions which are correlated with the SEM observations. An inductively coupled plasma (ICP) was used to obtain complete analyses of the rocks and effluents from ion exchange tests. The ion-exchange capacity and surface area in the Berea and Cottage Grove sandstones were found to be related to the distribution of the clays in the rock matrix. Upon comparison to conventinal methods the SEM was found to give quick positive results with regards to pore size, pore geometry and pore size distribution.
Conservative and Nonconservative Buckling of Drillpipe
Authors: Dunayevsky V. A. , Judzis Amis
Published: December 2007

This paper considers three-dimensional and planar buckling of drill pipe under different boundary conditions. 3-D forms of instability and threshold criteria are presented. Post-buckling behavior of suspended drill pipe is studied for one special case of free-end boundary conditions.
Formation Blocking Agents: Applicability in Water - and Steamflood i ng
Authors: Navratil Martin , Sovak Mojmir , Mitchell M. S.
Published: December 2007

New types of high temperature resistant formation blocking agents were studied. Laboratory techniques are described and results shown which should provide a basis for selection of blocking agents for field applications.

Permeability reductions in tar sands as a function of solution concentration and slug size are shown together with the effects of temperature. Blocking capability of these products in brine and steam floods was demonstrated in simulated heterogeneous models with various permeability contrasts.

Prior to their in-situ gelation, these products were shown to have viscosity close to that of water, have controlled rate of gelation and appear to be capable of permanently reducing the water and steam permeability of highly permeable zones in a controlled manner.
Elevated Temperature Testing of Mobility Control Reagents
Authors: Ryles R. G.
Published: December 2007

The viscosity stability behavior of dilute aqueous polymer solutions was studied at temperatures up to 150°C. It was shown that performance was test-method dependent if necessary precautions were not taken. Suitable procedures are described. In the absence of significant quantities of oxygen (ca. 1 ppb residual) polyacrylamides were found to be stable for many months, with or without addition of chemical scavenging agents, and they gave an incremental viscosity response in low to medium salinity waters. The performance of biopolymers was found to be dependent upon source. All polymers studied exhibited degradation in the presence of air. The use of stabilizers greatly retarded viscosity loss under these conditions.
Computer Modeling of Katy Cockfield Sands
Authors: Dalton B. A. , Kane T. V. , Ramsower S. E.
Published: December 2007

The Katy field is a major Gulf Coast gas accumulation with over 6 trillion cubic feet (170 Gm3) originally in place in the Cockfield (Yegua) formation. After more than 40 years of cycling and production operations, induction logs from recently drilled wells indicated uneven water advance within several sands which had, in the past, been treated as single reservoirs. A comprehensive geologic/engineering re-evaluation resulted in defining 48 sand members within an interval which had been described as 14 producing zones. Extensive computer modeling applications aided the geologists and engineers in describing the many vertical and areal reservoir heterogeneities which must be understood in order to maximize ultimate recovery.
Computer-Controlled Measurement of Laboratory Areal Flood Saturation Distributions
Authors: Davis L. A.
Published: December 2007

A microcomputer controlled microwave absorption instrument has been developed for automated measurement of laboratory linear and areal flood oil/water saturation distributions. The instrument design and performance characteristics are given in detail, and the roles of micro, mini and mainframe computers in data collection and analysis are described. Much of the design criteria and features are applicable to other oil recovery laboratory experimentation. An applications study is presented in a companion paper, SPE 12038.

An error analysis study of experimental saturation distribution data is used to identify localized structured water present in a linear core at residual oil saturation to chemical flood. Comparison is made to the residual microemulsion phase predicted by a simulator study of the experiment.
Numerical Simulation of the Litho-Density Tool Lithology Response
Authors: Watson C. C.
Published: December 2007

The numerical simulation of gamma ray logging in the context of the measurement of a formation's average photoelectric absorption properties by the LITHO-DENSITY Tool (LDT) is discussed. The accuracy of a model of the LDT's response, which has been developed using the MCNP transport code, is exhibited through comparison to experimental data. This model is then used to examine in detail the connection between the tool's response and formation properties by means of spectral studies of the spatial, angular and energy distribution of the photons which contribute to this response. Further model calculations of the collision density distributions of detected gamma rays are used to explore bow the LDT's measurements spatially sample the formation.
Monte Carlo Computational Model for the Gamma-Ray Spectroscopy Tool (GST)
Authors: Tsang James S. K. , Evans Michael L.
Published: December 2007

The GST tool is a gamma-ray spectrometer designed to measure the elemental constituents of a rock formation. The carbon to oxygen ratio measured by the tool is a valuable quantity for locating oil- and/or gas-bearing formations. A Monte Carlo model has been developed that simulates the response of the GST tool. Comparisons of calculated and experimental results are shown for a variety of borehole sizes and formation lithologies, porosities, and salinities. The GST model can corroborate and extend experimentally determined responses and, hence, provide a better understanding of tool function.
Fracture Height Containment by Creating an Artificial Barrier with a New Additive
Authors: Nguyen H. X. , Larson D. B.
Published: December 2007

This paper discusses the development of a novel fracture treatment technique which uses a nonreactive, buoyant diverter to control upward propagation of vertical fracture during the treatment. It is necessary to control such growth to prevent fracture penetration into undesirable zones, such as gas cap, water-bearing or nonproductive zones, and to promote maximum fracture extension within the producing interval.

Results of field evaluations indicate that the new treatment technique is successful. It offers a unique solution to preventing upward fracture growth that is independent of the formation properties and geologic stress environment.
An Engineering Simulator for Drilling: Part I
Authors: Millheim K. K. , Huggins R. L.
Published: December 2007

This paper (Part 1) reports on the development of an Engineering Simulator for Drilling (ESD), an analytical system's approach to planning and analyzing drilling systems in real or faster than real time.

It is shown that a complex drilling system can be subdivided into component parts of geology, the drilling rig, wellbore, fluid system, and the drill string. Representing each subsystem with the appropriate set of algorithms that best depict the physics of the system, and interacting the various algorithms with other systems an accurate representation of the complete drilling process is achieved.

Each subsystem is described, showing the causality of some of the major algorithms. The use of previous analytical and laboratory drilling research in the development of some of the algorithms is cited.

The Engineering Simulator system is described, including the overall top down design of the operating system, the use of interactive color graphics, and the special use of the simulator computer hardware.

How the simulator is used to initialize and operate a drilling system is explained. The Engineering Simulator for Drilling (Part 2)1 goes into the operating levels of the ESD and how a drilling person would use it. Part 2 also gives an example of how a drilling system could be evolved and operated using the interactive graphics menus and pictures.