bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Pseudotime to Estimate Average Reservoir Pressure
Authors: Aanonsen S.
Published: December 2007

Several methods taking into account variations in compressibility and viscosity have recently been proposed to improve the estimate of average reservoir pressure from pressure buildup tests in gas reservoirs. This paper demonstrates how well-known methods developed for oil reservoirs can be applied directly if the pseudopressure transformation is combined with pseudotime. It is shown that the method is equally applicable both for gas reservoirs and oil reservoirs where substantial gas saturation has developed during production. The method may also improve the estimates of formation permeability and skin factor.

By introducing different flow regions where simplifying assumptions can be stated, it is shown that pseudotime is valid for buildup, but not for drawdown. In addition, it is shown that the use of the producing GOR at shut-in to calculate buildup pseudopressure in solution-gas-drive reservoirs also depends on these assumptions.

Numerical simulations demonstrating the validity of the method is presented for a circular as well as different rectangular geometries.
Concentration Effects on the Settling Velocities of Proppant Slurries
Authors: Dunand A. , Soucemarianadin A.
Published: December 2007

In this paper, we study the sedimentation of single particles and of suspensions in quiescent fracturing fluids.

In the first part of the paper, measurements of the terminal fall velocities of single spheres in hydroxypropyl guar solutions are reported. Classical viscometric measurements show that the viscosity function of these fluids is well represented by the Ellis model. After correction for boundary effects, the experimentally measured velocities compare well with theoretical predictions based on the Ellis model.

In the second part of the paper, we investigate the settling behaviour of concentrated proppant suspensions (5 to 41 % by volume of solids). The solid volume fraction is determined, as a function of vertical distance and time, using gammaray attenuation measurements. Settling velocities are compared with single sphere data.

Finally, the effects of the proppant concentration are discussed in relation with several existing models for hindered settling.
A New Approach to the Characterization of Reservoir Heterogeneity Based on the Geomathematical Model and Kriging Technique
Authors: Da Costa e Silva A. J.
Published: December 2007

One of the most significant problems of reservoir engineering is the construction of realistic mathematical models describing the nature and disposition of the heterogeneities that inevitably occur in petroliferous formations. This paper presents a new approach based on a geomathematical model resulting from the Theory of Regionalised Variables of G. Matheron and from the Kriging technique. The model is tested on a North Sea Oil Reservoir and results are remarkable.
A CO2 Injection Measurement and Control System
Authors: White J. T. , Benoit R. L.
Published: December 2007

Advances in microcomputer technology have heralded a new era in oil field automation. A novel measurement and control system has been implemented on the carbon dioxide injection wells in the Slaughter and Wasson Fields operated by Amoco Production Company. The heart of this system is a solar powered microprocessor based Remote Telemetry Unit which senses the necessary input parameters, performs the calculations necessary to measure the rate and pressure at which carbon dioxide is being injected, controls the position of a ball valve to maintain the desired flow rate and pressure, and sends selected information to a central automation computer for alarm and reporting purposes. The purpose of this paper is to describe the electronic hardware, the end devices, control element, and software that was used to implement this function.
Enhanced Recovery of a "J" Sand Crude Oil With a Combination of Surfactant and Alkaline Chemicals
Authors: Martin F. D. , Oxley J. C. , Lim H.
Published: December 2007

This paper presents laboratory results aimed at the enhanced recovery of a crude oil from a "J" Sand reservoir in Nebraska. The "J" Sand oil, typical of many midcontinent crudes, only contains small amounts of the organic acids that produce natural surfactants when alkali is added. As a result, the interfacial tensions between alkaline solutions and the crude oil are not low enough for efficient oil displacement. Although other mechanisms may be responsible for producing additional oil, the primary approach of this work was the addition of a surfactant to the alkaline solution in order to achieve ultralow interfacial tensions. The surfactant used was a synthetic petroleum sulfonate.

The alkaline chemicals that were considered include sodium carbonate, sodium hydroxide, sodium silicate, ammonium hydroxide, and potassium hydroxide. Using results on the effect of various alkaline chemicals on the phase behavior of the surfactant, the current paper outlines the rationale for selecting optimum formulations for this project.

For the optimum formulations of alkali and surfactant, interfacial tensions with the crude oil were measured. Alkali consumption and silica dissolution were monitored. Oil recovery tests in reservoir cores at 160°F were conducted with some of the more promising formulations.

Implications from the results of this work suggest that it is possible to select the appropriate alkaline chemical, as well as the molecular weight of the surfactant, to give optimum recovery for the conditions of water salinity and temperature in the reservoir. For example, a formulation can be chosen so that a preflush is not required for this project.
Optimum WAG Ratio vs. Rock Wettability in CO2 Flooding
Authors: Jackson D. D. , Andrews G. L. , Claridge E. L.
Published: December 2007

Enhanced oil recovery in carbon dioxide (CO2) miscible floods can be severely reduced by gravity segregation and/or viscous fingering of the CO2. Dimensionlessly scaled experiments have been conducted in a laboratory model of a quarter five spot to investigate the effects of rock wetting state, alternate injection of water and CO2 gas (WAG), and total CO2 slug size on secondary and tertiary extra oil recovery.

Laboratory model results in the water-wet beadpack show an optimum WAG ratio of 0:1 (continuous slug process) for tertiary floods, while the same floods in oil-wet packs have optimum recoveries at WAG ratios of about 1:1. Floods in both wetting states indicate that maximum recovery is a stronger function of slug size in secondary CO2 flooding than in tertiary flooding. The wetting state was found to be a major factor affecting flood performance, with the consequence that tertiary floods in the water-wet laboratory model were dominated by gravity forces, while oil-wet tertiary floods were controlled by viscous fingering.
High Differential Pressure, Radial Flow Characteristics of Gun Perforations
Authors: Regalbuto J. A. , Riggs R. S.
Published: December 2007

Tubing conveyed completion techniques are being utilized more frequently than in the past, because of the apparent advantages derived from underbalanced perforating. These advantages include cleaner perforations, reductions of additional stimulation treatments and reduced completion times. This paper presents the results of a laboratory study of gun perforations made under high differential pressure, radial flow conditions. In this study, Berea sandstone cores, modified to permit radial flow, are used to determine the relationship between perforation characteristics and the time-dependent pressure differential between pore pressure (i.e. formation pressure) and "well bore" pressure during the completion process.

The primary perforation characteristic investigated (Radial Flow Ratio) is defined as the ratio of the perforated flow rate to the flow rate of the unperforated core under identical conditions. The perforated flow rate is measured in radial flow after the perforation has been made under various time-dependent pressure differentials.

The results of three different series of perforation flow tests are presented. The tests are described as 1) No Surge: Pore pressure and "well bore" pressure are both equal to 1,200 psi at the instant of perforation, 2) Immediate Surge: Pore pressure is 1,200 psi and the "well bore" pressure is 200 psi at the instant of perforation, and 3) Delayed Surge: Pore pressure and "well bore" pressure are both equal to 1,200 psi at the instant of perforation after which a 1,000 psi underbalanced differential is applied to the core.

The Radial Flow Ratio (RFR) was affected by the application of a 1,000 psi surge pressure differential, both immediate and delayed. The immediate surge RFR was 58% greater and the delayed surge RFR was 50% greater than the no surge RFR.

Correspondingly, the hole volumes after surging increased 55% indicating that there was some elimination of the compacted zone material.

Underbalancing, either at the instant of perforation or subsequently, appears to improve the flow characteristics of shaped charge perforations.
Defining the Characteristics and Performance of Gas-Lift Plungers
Authors: Mower L. N. , Lea J. F. , Beauregard E. , Ferguson P. L.
Published: December 2007

A laboratory investigation was conducted to provide data necessary to better predict the behavior of gas lift plungers. A test well was instrumented to provide pressure, velocity, and volumetric information during the fall and rise cycle of a variety of commercially available plungers. A substantial data bank has been compiled and behavior of 13 different plunger configurations has been characterized by gas slippage, liquid fallback, and fall velocity. Performance characteristics of the individual plungers has been incorporated in a modified Foss and Gaul2 mathematical model which provides predicted minimum casing pressure in close agreement with actual laboratory tests.

As a second part of the evaluation program, actual field data was collected from four field locations with a variety of operating conditions. The correlations developed for the laboratory tests were then adjusted to fit field data. The final correlations and equations describing plunger lift operations have been included in a computer program that can be used for design and analysis of plunger lift operations.
Risk Weighting World Energy Price Stability
Authors: Omar A. E.
Published: December 2007

During the past fifteen years the world's economic system has suffered two shocks from massive increases in the price of oil. During this time there were conflicting forecasts of future energy developments, ranging from "no problem" to an ominous, more shocking third energy crunch. Although the former is probable in the near term, the latter view seems more likely tc prevail before the end of the next decade.

As a result of the two shocks which took place in 1973 and 1979, the world began to realize that the United States was no longer the marginal producer of the last barrel of crude oil needed to set market prices. Nor can OPEC alone, as recent events indicate, have the last word in setting market price.

The energy crisis is still with us even though the industrialized countries have succeeded in deferring it for a period of time. Therefore, a world model of the supply/demand relationships for crude oil using an econometric framework was developed. The model examines the potential for worldwide energy disruption that could result from the influence of one major area [consumer (s)/supplier(s)] or a combination of areas. The model has the potential to predict whether the potential for a third energy crunch is real or not. If that potential exists, the model will determine when that is likely to occur and will further help in projecting future relationships between supply/demand and the price of oil, thereby allowing better planning and development for producers and consumers alike.
A New Sealed Bearing Rock Bit for High-Speed Drilling
Authors: Carter M. W. , Daly J. E. , Van Nederveen H.
Published: December 2007

This report discusses the development and testing of a new sealed bearing rock bit for use with high speed drilling tools such as downhole turbines and positive displacement mud motors. The principal feature of this rock bit is a new low friction elas-tomeric seal. Characteristics of this new seal, specific design changes incorporated into the new design to increase its bearing capacity and the results of field testing of this new design are described.
The Drilling Command and Control System
Authors: Foreman R. D.
Published: December 2007

The best-Laid plans in drilling are often defeated by at least three major problems: (1) information scarcity – poor communication between rig and office hinders attempts to make good decisions; voluminous historical files yield little practical information, (2) data saturation – nobody can digest all of the real time data now available at the rig site, and (3) technology lag – the gap widens between what is technically feasible and what is routinely achieved. The Drilling Command and Control (DCC) system has been developed to mitigate these problems. Drilling Command and Control combines the best available computer, video, and satellite technologies to provide quality communications, reduce large volumes of data to practical use, and actively tracks all phases of the drilling operation. Its foremost feature is ease of use, as demonstrated by contract personnel who learn to perform at full capabilities within two weeks of DCC experience. This paper describes both the unique Drilling Command and Control system and its novel applications to drilling.
Fracture Evaluation Using Borehole Sonic Velocity Measurements
Authors: Liu O. Y.
Published: December 2007

Using waveforms acquired by multitransmitter and/or multireceiver borehole sonic tools, acoustic velocity (or slowness) was computed for compressional, shear, and Stoneley waves using direct phase determination (DPD),1 the slowness time coherence (STC) method,2 and multiple shot processing (MSP).3 It was found that values of Δt (or slowness) computed using the receiver locations, referred to as the receiver Δt, were different from those computed using the transmitter locations, referred to as the transmitter Δt, when the sonic tool was in the vicinity of fractures. The amount of differences in compressional, shear, and Stoneley Δt depends on the size and nature of the fractures. It is possible to determine the height, width, and dip angle of the fracture when these differences are used in conjunction with Dual Dipmeter* tool data.
Determination of Permeability Variation Factor V From Log Analysis
Authors: Kapadia S. P. , Menzie D. E.
Published: December 2007

The paper presents a technique for the determination of the coefficient of permeability variation, V, from quantitative well log analysis without the requirement of expensive coring programs or extensive laboratory effort. The method is an application of the improved empirical relationships proposed by Coats and Dumanoir (1973) in which the permeability index is derived as a function of porosity, resistivity at irreducible water saturation, hydrocarbon density and rock type.

Field examples illustrate the application of this new approach and the results obtained for a wide variety of lithologies.
Meren Field Offshore Treating Facilities for Seawater Injection
Authors: Adetoba A. L.
Published: December 2007

The need for pressure maintenance by water flooding of seven reservoirs in the Meren field to enhance oil recovery was established. Treating facilities have been designed to remove suspended solids and dissolved gases. Chemical treatment is used to control scale, corrosion and microorganisms. All these have solved the problems associated with sea water injection.
A Laboratory Evaluation of Barium Sulfate Scale Inhibitors at Low pH for Use in Carbon Dioxide EOR Floods
Authors: Ramsey J. E. , Cenegy L. M.
Published: December 2007

During a carbon dioxide flood, the floodwater pH can drop significantly causing scaling problems. An evaluation was therefore made of the efficacy of five barium sulfate scale inhibitors and of their cost-performance as the system pH was incrementally lowered from 7.0 to 4.0. A theory is presented linking a scale inhibitor's effectiveness at low pH to its dissociation constant.
East Painter Reservoir: An Example of a Compositional Gradient From a Gravitational Field
Authors: Creek J. L. , Schrader M. L.
Published: December 2007

The effects of gravity on composition in a static hydrocarbon fluid column has been studied since Sage and Lacey's (1) pioneering work in 1939. Recent investigators (2, 3, 4) have pointed out that the effects of gravity become more significant as a critical point is approached. Therefore, a reservoir with a large closure containing a rich condensate and volatile oil should have measurable contributions from gravity affecting the distribution of hydrocarbons in the reservoirs.

Several examples of reservoirs with large closures containing both a volatile oil and rich condensate exist in the Nugget Sandstone portion of the Wyoming Overthrust Belt. We show that the hydrocarbons present in these sandstone reservoirs have physical properties which may be correlated with depth. We further show that for one reservoir, East Painter Reservoir Field, that the variation in hydrocarbon composition with depth may be predicted with some accuracy by including the gravitational correction term to the equations governing equilibrium, i.e., migdh for each component. These results are important with regard to compositional simulation of the performance of these fields and in equity determination.
Role of Cement Fluid Loss in Wellbore Completion
Authors: Bannister C. E. , Lawson V. M.
Published: December 2007

The fluid-loss behavior of cement slurries against permeable formations and its relationship to interzonal fluid migration have been investigated. Static fluid-loss testing, designed to simulate cement placed in a wellbore, has shown that the cement fluid-loss rate through a deposited mud filter cake decreases with time. This decrease in fluid-loss rate is dependent upon the designed fluid-loss properties of the cement slurry, and significantly influences the loss of hydrostatic pressure required to control formation fluids. Once the pressure starts to decay, formation fluids can potentially enter the wellbore causing ineffective zonal isolation and, in some cases, gas migration to the surface.

The mechanism described indicates that hydrostatic pressure is initially transmitted after cement placement. During this period, fluid loss to the surrounding formation is compensated for by an equal decrease in slurry volume. The resulting changes in the solid-to-water ratio and gelation properties coupled with the growth of the cement filter cake cause the pressure against the formation to eventually decrease. The rate of pressure decrease is dependent upon the fluid-loss rate and the slurry's compressibility. Once the pressure approaches the formation pressure, interzonal fluid flow through the cement slurry occurs with its rate initially governed by the cement fluid-loss rate.

Several correlations have been made relating fluid loss to the pressure profile after wellbore completion. The results suggest that an API fluid-loss requirement of 100 mL/30 min, which may be sufficient during cement placement, is actually too high when consideration is given to the fluid loss that occurs after cement placement. Sufficient delays in the loss of pressure are obtained for an API fluid-loss requirement in the range of 10 to 30 mL/30 min with the actual value dependent upon wellbore geometry, overbalance pressure, mud fluid-loss properties and cement slurry design.
Practical Onsite Inspection and Testing Improves Fracture Treatment Quality
Authors: Robinson J. C.
Published: December 2007

A hydraulic fracture treatment quality control program was implemented in the Oregon Basin Field, Park County, Wyoming to ensure consistently high quality stimulation treatments on polymer augmented waterflood injection wells. The quality of the materials used was checked on location in addition to performing a comprehensive job review prior to each treatment. As a result of the quality control program, significant changes and improvements were made in the quality and performance of the fracture treatments.
Microcomputer Gas Reservoir Simulation Using Finite Element Methods
Authors: Logan R. W. , Lee R. L. , Tek M. R.
Published: December 2007

Two-dimensional finite element (FEM) gas reservoir simulators are developed for the IBM-XT microcomputer. A wide range of gas migration and deliverability problems are solved, in spite of the size and speed limitations of the microcomputer.

Using pseudopressure or p2 as the dependent variable, a radial cylindrical depth simulator was developed, verified and used to investigate several deliverability problems related to unsteady state, turbulence, and stratification. The quadratic finite element is shown to be a particularly attractive choice for problems involving skin and turbulence. The results, compared with previously published analytical work, indicate close agreement in characterizing gas deliverability performance. It is observed that for cylindrical reservoirs, the end-infinite-acting time and pseudosteadystate times are quite different. This phenomenon becomes more pronounced under turbulent conditions.

A relatively new concept of Inverse Productivity Index (IPI) has been used for the deliverability analyses, as an alternative to the classical back pressure plots. The analytical and numerical solutions presented reinforce the concept that solutions to gas deliverability problems are more naturally suited to the IPI-plot analysis.

An efficient single phase areal FEM reservoir simulator is also developed, with a pseudopressure formulation and boundary water-drive capabilities. This simulator is used to study gas migration, demonstrating good agreement with previously published work. In addition, it is shown that this areal FEM simulator is particularly effective in studies related to migration between adjacent communicating reservoirs with multiple wells, complex boundaries, and specified production/injection schedules.
Design and Analysis of a Nitrogen Step-Rate Test, Anschutz Ranch East Nitrogen Injection Project
Authors: Bennett C. O. , Clark T. J.
Published: December 2007

This paper presents the preparation, testing, and analysis of a nitrogen step rate test and the analysis of two falloff tests on a gas injection well in the Anschutz Ranch East Nitrogen Injection Project. Objectives of the tests were to determine the parting pressure, flow capacity, and relative influence of open fractures in the lower zone of the Nugget formation. The application of current technology in evaluating continuous gas injection wells is relatively undocumented. Gas pressure maintenance projects require many of the same operational considerations given to waterflood projects; i.e., good vertical sweep (wellbore conformance), and an injection pressure that is below formation parting pressure. Gas injection wells, however, in a retrograde condensate reservoir are inherently more difficult to analyze with conventional pressure transient methods because of changing gas compressibility factors and two-phase effects from condensing hydrocarbons. Therefore, extensive test planning and preparation must be completed for a gas injection well test to be successful.

Because of the complicating factors involved, several different methods of analyses were used with the step rate and falloff test data. The step rate test was analyzed with Odeh's superposition technique and a 1-D radial gas model to obtain the zone flow parameters and confirm that a break occurred. The falloff test data were analyzed with conventional and multirate techniques to determine the influence of natural fractures and confirm the zone flow parameters derived from other methods. Type curve analysis was also performed to aid the interpretation of the test results.

The step rate test results indicated that the test was successful. Conventional analysis indicated the parting of formation after the third step (of the seven performed) and the radial gas model also confirmed the change from radial to linear flow. A comparison of the reservoir properties derived from the various analysis methods (the radial model and multirate falloff analysis) and core data were in agreement. The test data analysis did not show the presence of an intense fracture network that would dominate the flow capacity of the zone.
Risk vs. Return Considerations for International Oil Exploration and Development Licenses
Authors: Rosenberg B. F.
Published: December 2007

Over the years, many forms of exploration and production agreements have been developed by governments throughout the world. The agreements can differ widely in terms of form, severity, and flexibility.

Although the different forms of agreements may provide similar results to each other under assumptions of a given level of success, the results can differ markedly with variance from that level of success, both in terms of tempering downside exposure and limiting the upside opportunity.

A company should evaluate a potential exploration/production opportunity and its related agreement over a range of possible outcomes in assessing the prospect's overall attractiveness.
Formation and Operation of Oil and Gas Unit Areas Subject to the Supervisory Authority of the U.S. Geological Survey
Authors: Rhodes Gerald D.
Published: December 2007

Introduction

Increasing numbers of petroleum engineers are becoming directly and indirectly involved in the formation and operation of unit areas subject to the supervisory authority of the U. S. Geological Survey. This paper is presented in the hope that it will aid those individuals whose work is directed toward the unitization of Federal and/or Indian trust lands.

EARLY EFFORTS TO HALT WASTE

As early as 1916 technologists of the Bureau of Mines and Geological Survey pointed out the waste that was resulting from close drilling patterns and the use of open earthen reservoirs for storage. At that time unitization was suggested as the solution to the problem of excess waste resulting from the operating practices of the day. Although many of the engineers and geologists in industry agreed with this suggestion, the oil industry as a whole paid it little heed because it considered the goal to be practically unattainable.

Henry L. Doherty condemned the wasteful practice of the industry and urged the initiation of better production practices and passage of uniform conservation laws before the Board of Directors of the American Petroleum Institute in Dec., 1916. He suggested unit operation of oil pools with each of the interest owners being paid according to the amount of oil that underlay the land in which the interest was owned. This proposal met with a considerable amount of opposition at first but when the price of oil dropped drastically following the discovery and development of the prolific Salt Creek field in Wyo., the Seminole and Oklahoma City fields in Okla. and the East Texas field, many producers started to consider Doherty's ideas more favorably.

Of course, the idea of unitization was not new. It had been the ambition of most oil men since the beginning of the industry to own an entire field so that drilling and production operations could be carried out in accordance with the individual operator's own ideas of efficiency and good economics free from harassment by his neighbors. Under the usual competitive situation one or two operators could set a drilling pace. and pattern which had to be followed by the other operators in the field to protect their lands from drainage of oil and gas.
Analysis of Factors Affecting Drillstem Tests in Low-Permeability Reservoirs
Authors: Peterson S. K. , Marietta C. , Holditch S. A.
Published: December 2007

A drillstem test (DST) can be run prior to completion of a well to determine if a formation is capable of producing oil or gas at commercial flow rates. In the eastern United States, drillstem tests are seldom used because a typical well will not produce at flow rates high enough to measure during a DST, especially in low permeability reservoirs where mud filtrate invasion prior to the drillstem test suppresses the gas flow rates. A closed chamber drillstem test can be used to measure these low flow rates but interpretation is often difficult. This paper examines the effects of mud filtrate invasion upon the results obtained from drillstem tests.

A two-phase, two-dimensional model was used to simulate a drillstem test following a period of mud filtrate invasion. Using the results of these drillstem test simulations, qualitative relationships between absolute permeability, gas relative permeability, filter cake permeability and thickness, and wellbore pressures during the filtrate imbibition period and flow period have been established.

All of the parameters investigated, except for the filter cake thickness, did influence the results from the drillstem test and the ability to forecast flow behavior based upon the drillstem test results. In particular, this study has shown that the parameters that affect the cleanup behavior of a formation can be ranked in order of importance as follows: absolute permeability, gas relative permeability, filter cake permeability, pressure drawdown and, finally, overbalance pressure during drilling.
Devonian Shale Production Data Analysis Southwestern West Virginia
Authors: Koziar Gregory
Published: December 2007

Evaluation of production data in Southwestern West Virginia had identified five Devonian shale well type categories and average reservoir properties associated with each category. Permeabilitythickness product can be uniquely identified from history matching regardless of the variability of other match parameters. Pressure buildup analyses conducted on three wells confirms this. A simple relationship exists between the permeabilitythickness product and ten-year cumulative production. History match data suggest that natural fracture property variations result in well quality variations.
Water-Wet Surfaces for Long-Term Paraffin Inhibition
Authors: Charles J. G. , Settineri W. J.
Published: December 2007

Water-wet surfaces are known to be an important factor in a mechanism of paraffin inhibition. Previous attempts to create these surfaces with chemical coatings or plastic-lined tubing have met with limited success. A patented process1 has been developed that overcomes the problems previously associated with obtaining long-lasting, strongly water-wet surfaces downhole. This process generates heat within the tubing, converts paraffin into a water-dispersible residue and super cleans the surface of the rods and tubing. The resulting effect is a hydrophilic surface on all wellbore production equipment. This environment reduces the adhesive force of the paraffin to the rod and/or tubing surface and allows the precipitated paraffin to be produced out of the well.
Analysis of Interference Pressure Tests in Naturally Fractured Reservoirs With Macroscopic Fracture and Pore System Permeabilities and Unsteady Interporosity Flow
Authors: Wijesinghe A. M. , Kececioglu I.
Published: December 2007

Existing pressure test solutions for naturally fractured reservoirs neglect the macroscopic pore system permeability, the wellbore storage and skin factors of the observation wells, and are limited either to single-swells in infinite domains or to concentric wells in circular reservoirs.

In this paper, two solutions for interpreting interference pressure tests in naturally fractured reservoirs are presented. The model on which these solutions are based incorporates both macroscopic fracture and pore system permeabilities, an improved unsteady interporosity flow model, and allows for wellbore storage and skin factors of the wells. In the first solution, the pressure response of a shut-in observation well to arbitrarily varying unsteady pressure fields is considered under the assumption that the observation well affects the flow field only locally. In the second solution, a general technique for exactly solving the governing equations for fluid flow in naturally fractured reservoirs with multiple non-concentric circular boundaries is first developed. The procedure is then specialized to two circular boundaries to determine the pressure changes induced in a circular reservoir by an eccentric flowing well with wellbore storage and skin. These two solutions, used together, will enable the development of pressure tests for determining the location of the center of a circular reservoir in addition to its radius and its hydraulic properties.
Process Variables of Enriched Air Combustion: An Experimental Study
Authors: Cady G. V. , Satchwell R. M.
Published: December 2007

Combustion studies for heavy crude oil in a porous matrix were made with nitrogen gas containing oxygen concentrations from 20.7 to 40.0 mole percent. The gas was injected into a linear combustion tube apparatus at a constant flux of 132 gas/hr ft2. Reactor pressure, produced gas analysis and temperatures were taken to provide basic and interpretive data for the comparison of combustion characteristics for each oxygen concentration.

Combustion theory indicates an increase in oxygen reaction rate as the partial pressure of the oxygen and fuel concentration increase. Other controlling variables include the combustion temperature, the activation energy and the Arrhenius constant or frequency factor. Our experiments indicated an increase in temperature, frontal advance rate, apparent hydrogen to carbon ratio and the amount of oxygen used to burn a pound of fuel. Fuel deposition studies using SEM micrographs indicated the fuel's association with clay materials present in the sand pack.
Systematic Basin Evaluation as Applied to the Philippine Petroleum Exploration Promotion Project
Authors: Reyes Raymundo A , Harrison John , Flower Louis G
Published: December 2007

An integrated multidisciplinary approach was effectively applied to a regional evaluation of the sedimentary basins of the Philippines. The approach resulted in the production of a comprehensive exploration package which appreciably enhanced the understanding of the petroleum geology and hydrocarbon potential of the studied areas. More significantly, new exploration concepts were formulated which offer a host of possibilities to explorationists who will venture into the marginally explored basins of the country.
Tidal Effect in Petroleum Well Testing
Authors: Hemala Milan L , Balnaves Charles
Published: December 2007

Earth, barometric and ocean tide effects have been observed for many years, principally in hydrogeological work. During testing of wells in the Timor Sea we have observed ocean tide effects in the reservoir with an amplitude of ~ 0.07 bar (1 psi) about 70 times larger than earth or barometric tide effects.

This paper has two aims: to provide an overview of analytical interpretation of tidal effects from a petroleum engineering viewpoint and second, based upon our simulations and observations, to propose that in addition to previous methods of interpretation the phase shift of ocean tide effects can be used to gain an insight into the presence of major reservoir heterogeneities, particularly fluid contacts.

There is a need for more field data and further investigations, however we believe we have demonstrated the existence of a useful and previously unused aspect of pressure measurement in offshore wells.
Horizontal Wells are Now used for Industrial Developments
Authors: Bosio Jacques
Published: December 2007

A vertical, or deviated, well, remains in a reservoir for a short distance only. Horizontal wells remain in the producing formation for several hundred meters, providing better productivity conditions.

ELF AQUITAINE and IFP (French Institute of Petroleum) have initiated, in 1978, a research project aimed at very progressively solving the drilling and completion problems encountered when drilling a horizontal well.

Several wells have been drilled and successfully completed, down to a 3000 m vertical depth. The offshore field of Rospo Mare, in Italy, is now being developed with horizontal wells drilled close to the top of the formation, to avoid water coning.

Numerous other applications are envisaged or have been realized by various international Companies in the USA, EUROPE and ASIA, through the services of HORWELL, a company created by ELF AQUITAINE and IFP to make their newly developed techniques available to the oil industry.
Development of the Cotton Valley Geopressure Zone in Panola County, Texas, Using Air/N2 Drilling and Openhole Completion Techniques
Authors: Smith J. E. , Neufeld M. H. , Sorrells D. C.
Published: December 2007

The Jurassic aged Cotton Valley Sands and overpressured Bossier Sands can be effectively drilled using air and/or nitrogen methods, logged, completed and open hole stimulated without ever exposing the wellbore to potentially harmful drilling fluids. This in turn increases well productivity and offers considerable cost savings to the standard mud and liner setting techniques.
Engineering Appraisal of Mathematical Models of Petroleum Reservoirs
Authors: Irby T.L. , Lamoreaux W.E.
Published: December 2007

The rapidly growing application of computer technology to reservoir problems demands a more thorough understanding, by reservoir engineers, of the basic precepts of mathematical models. This paper describes some of the various types of computer models and explains the equations in simplified reservoir engineering terminology. A discussion of the solution errors that occur, their causes and methods to minimize them, is followed by an appraisal of the practical economic limitations of applying the models to reservoir studies. The paper is concluded by presenting an example application of a computer model to a Gulf Coast Field unitization study. A summary of the basic data, calculated results and computing costs are given.

INTRODUCTION

The computer age has brought about several changes in the engineering methods and techniques employed by the reservoir engineer. Reservoir engineering has always References and illustrations at end of paper been an artistic application of scientific principles. This is particularly true with respect to the latest reservoir analyzer the mathematical model solved by a computer. The concepts involved are relatively simple and have a sound scientific basis, but to instruct the machine to perform the multitude of required operations takes more imagination and ingenuity than ever before required in applying reservoir engineering principles. Inability to program the machine, however, should not be a deterrent to the reservoir engineer's understanding of mathematical models and how he can best utilize them.

It is not the intention of this paper to give detailed explanations on the derivation of equations and methods of solution, or to compare the relative merits of various mathematical models now existing. It will endeavor to inform the practicing engineer of how he may utilize the models and what are the most important factors affecting their use. The importance of basic reservoir data and how it is used in the models cannot be over emphasized.
Focused Acceptance Testing: A Logical Approach for Qualifying Critical Service Connections
Authors: Bednarski J. A. , Klementich E. F.
Published: December 2007

Recently many new critical service, high performance, casing and tubing connections, all claiming superior performance have become available to the petroleum industry. To prevent failures due to misapplication, a system must be developed to expedite rational engineering judgement for selecting one connection over another. One such system can be realized in the form of a Focused Acceptance Test Program. In a Focused Acceptance Test Program (1) the intended applications of the connections are clearly defined, (2) a generic connection specification is developed, and (3) the suitability of a specific connection for those particular applications are demonstrated by way of a physical "focused" test program and/or mathematical analysis.

Focused Acceptance Testing is a cost effective physical test method designed to thoroughly demonstrate the connection capabilities at the loads and along the load paths expected in the intended application. Emphasis is placed on procedures and test load sequences with acceptance criteria based on realistic field service conditions.

This paper presents Focused Acceptance Testing as a logical and cost effective method for qualifying critical service connections for their intended applications. By following such a system, users will be able to select connections for a particular application on a rational engineering basis.
South Pass Block 60 Platform ‘G’ Conductor Preinstallation
Authors: Crane L. R.
Published: December 2007

A unique sequence of events in setting an offshore platform, allowed time to predrive well conductors and realize substantial cost savings over previously used methods. This method produced cost savings of about $1.4MM compared to previous installations.
Slimhole Exploration Drilling Program: Irian Jaya, Indonesia
Authors: Macfadyen M. E. , Johnston K. A. , Boyington W. H.
Published: December 2007

The following is a review of Continental Oil Company of Indonesia's slimhole drilling project in Irian Jaya, one of Indonesia's most remote provinces. The aim of this exploration program is to drill and evaluate twelve prospects, scattered over a large area, by drilling narrow bore wells using a purpose-built helicopter rig.
Mobile Bay: Drilling Fluid Problems and Solutions
Authors: Collins M. B. , Clancy L. W. , Monson R. F.
Published: December 2007

During the last three years, drilling in the southern-half of Mobile Bay, Alabama, and adjacent offshore tracts has drawn considerable interest. Gas finds have been numerous and of high volumes.

Bottomhole temperatures often exceed 400°F (204°C). Most wells encounter high-volume flows of calcium-magnesium chloride brines, and significant carbonate influxes. These combine to present unique problems for drilling fluids systems.

This paper reviews three wells in the area in which the problems above are encountered, and outlines the use and effectiveness of deflocculants and filtration control agents in these wells.
Well Control Simulator for IBM Personal Computer
Authors: Podio A. L. , Yang A.-P.
Published: December 2007

An advanced well control simulator has been developed for use on IBM-PC Microcomputers. One of the innovations introduced is the capability of interaction with the user through terminal input and output so as to easily follow the progress of the simulation and to easily modify the well parameters and configuration for repeated use in sensitivity analysis studies.

Innovation in the numerical model principally stems from realistically accounting for the gas distribution in the well and consideration of the effects of wellbore geometry, gas migration, frictional losses, sub-sea BOPs and the presence of drilled cuttings and drilled gas. The response of the model is thus more realistic than other simulators, a result which is evidenced by the absence of the "dunce-cap casing pressure profile" which is typical of simplified simulators.
Design and Development of a Unique Disc Brake System for Drawworks
Authors: Heilhecker J. K.
Published: December 2007

As drilling has gotten deeper and the corresponding hookloads have increased, band brakes historically used on drawworks have become marginal. In some instances they have provided insufficient braking force to prevent the blocks from falling to the floor.

The Galveston-Houston Company has developed a hydraulically-actuated, water cooled disc brake for drawworks which provides greater holding capability than conventional brakes, yet requires less mechanical input force. This paper describes the design and development of this unique disc brake system and presents the results of field operations to date. The paper will also discuss the safety aspects of the system when coupled with a device used to monitor the kinectic energy of the traveling block.

The system described in the paper has application on all drilling rigs but in particular, deep land rigs and offshore rigs which routinely handle heavy hookloads
Modular Marine BOP Stack
Authors: Taylor W. M. , Turlak R. J. , Schwegmann J. B.
Published: December 2007

The Modular Blowout Preventer (BOP) stack integrates, in a compact way, the main components of an underwater BOP assembly. In this approach the annular BOP, the ram BOP's and the wellhead connector are locked together using four hydraulically pretensioned stud bolts that extend the full height of the stack, outboard of the BOP bodies.

The development of modern, large bore, high pressure control equipment has brought with it greater efficiency for the marine drilling industry. But, these larger assemblies are also taller in their conventional form. Eliminating the individual connections between the stack components in the modular concept has resulted in a substantial savings in overall height. This compact BOP architecture is possible because of side ram exit allowing easy packer change in tight spaces. Also, by using four large bolts to preload the entire BOP and connector assembly, the ability of the modular stack structure to carry high bending and pressure induced loads has been greatly enhanced, (also confirmed in a finite element analysis of the complete assembly).

Four large stud bolts extended through two circular termination plates located on top around the annular BOP and the wellhead connector below. These plates or reaction rings, transmit the bolts loads that are developed during a bolt tensioning process, compressively preloading all stack components. Metal-to-metal sealing between the stack components is accomplished at this time as well. All four studs are simultaneously preloaded during initial assembly using detachable hydraulic tensioners. The net result is a rigid and compact stack assembly that will safely handle large bending moments and pressure applied loads.
Applications of a BHA Analysis Program in Directional Drilling
Authors: Rafie S. , Ho H.-S. , Chandra U.
Published: December 2007

The application of a three-dimensional directional drilling computer program, named DIDRIL*, is discussed. It is used to analyze building, dropping, and holding assemblies in straight, 2-D curved, and 3-D curved (spiral) boreholes. The effects of WOB, TOB, and borehole curvature on the build/drop and walk trends of the assemblies are studied. The results show that the curvature of the borehole has strong influence on the build/drop and walk tendencies of BHAs, whereas the TOB has little effect.
A Contractor's View of Drillpipe Life
Authors: Gensmer R. P.
Published: December 2007

The single highest unplanned expense on a drilling rig is the loss of drill pipe. Yet, virtually no published data are available on the life expectancy of a drill string. The majority of information on the type of failures discusses tool joint damage, a condition which accounts for only 3.67% of our losses. In response to this apparent void, we offer to share a unique data base of almost 1,300 pipe failures from 30 strings which were used in the Williston basin of North Dakota/Montana over the last 14 years. These strings were kept together as identifiable units for their useful life, were subjected to approximately the same drilling conditions, and thus, offer us field laboratory conditions.

Concentrating on the most numerous and costly pipe loss factors--tube holes/cracks--we will present an average pipe life curve with a 65% confidence envelope. This curve can be used in estimating the cost of running pipe and planning a replacement schedule. By implementing failure containment strategies, we showed a 50% increase in pipe life. However, as competitive pressures of the current market have resulted in increased operational stresses, we can see a regression in pipe life expectancy.

As the basis for working out solutions to this change, we will look at where the tube failures occur in relationship to location in the individual tube, location in the string, and depth in the well. The results give us symptoms of string failure which contradict some widely held beliefs such as: the tube losses occur chiefly in either the slip or weld areas.