bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase Behavior Modeling of Gas-Condensate Fluids Using an Equation of State
Authors: Sarkar R. , Danesh A. S. , Todd A. C. 
Published: December 2007

Abstract
A modified Zudkevitch and Joffe method of determining parameters of an equation of state (EOS) is described and applied to the Patel and Teja (PT) equation. All the parameters of the PT equation are considered temperature dependent and evaluated from the vapour pressure, liquid molar volume and critical compressibility factor of pure compounds. The attraction term in the PT equation is modified by a temperature dependent parameter for super critical components. Conventional random mixing rules are applied to obtain the EOS parameters for mixtures, with no binary interaction coefficients for hydrocarbon mixtures.
The modified equation was validated against experimental data of gas condensate systems and compared with other leading EOS. A large number of data, including the dew point pressure, condensate drop-out, and the density of gas and condensate phases at equilibrium conditions over a wide temperature range was generated and used in this validation. The proposed method predicted the experimental data, particularly the retrograde condensate volume, more accurately than others. The method can be applied to any equation of state.
Transient Pressure Analysis of Three Wells in a Three-Composite Reservoir
Authors: Chu L. , Grader A. S. 
Published: December 2007

ABSTRACT
An analytical solution to a three-composite concentric reservoir with three active wells, as shown in Fig. 1, is presented. Reservoir properties are different for each region, representing a true composite system, and the wells are arbitrarily located.
The solution presented in the paper describes the pressure response at the active wells and at other characteristic points in the reservoir. This general well/reservoir configuration allows us to assemble dozens of specific configurations that are currently not possible. For example, this new solution can describe the pressure response of a storage-and-skin well near a linear boundary. At the same time, the solution can be applied to two-well systems in a true two-composite reservoir separated by a conductive discontinuity. The new solution can be applied to interference testing between oil and gas wells across the gas/oil contact. The new model also describes the pressure response of an active well with different inner boundary conditions in various reservoir shapes, such as a square, a rectangle, a curved stringer and a wedge.
The solution is obtained by application of the Laplace transformation theory coupled with the addition theorem for Bessel functions. It is shown, both analytically and numerically, that the new model contains several well-known solutions as subsets of the general solution.
The Magnetic Resonance Imaging Log Characterized by Comparison with Petrophysical Properties and Laboratory Core Data
Authors: Coates G. R. , Peveraro R. C. A. , Hardwick A. , Roberts D. 
Published: December 2007

ABSTRACT
Core samples are examined using a 10 MHz NMR spectrometer and results are compared with those from the Magnetic Resonance Imaging Log*(MRIL) (operating frequency 1 MHz) in the same rock formations. The frequency dependence of this technology and its link to petrophysics is investigated, thus offering the first link between core and log NMR data for this new tool.
Comparisons of MWD, Wireline, and Core Data From a Borehole Test Facility
Authors: Hutchinson M. W. 
Published: December 2007

ABSTRACT
Six service companies demonstrated commercial and prototype Measurement While Drilling (MWD) formation evaluation tools in two research wells at a borehole test facility in northern Oklahoma during the summer of 1990 as part of a joint industry project. This paper compares both wireline and MWD resistivity, neutron porosity, bulk density, photoelectric and caliper data, as well as MWD, wireline, and core spectral gamma data. The comparisons are made between tools run through the same geological formations and under the same borehole conditions. The data in this report show that MWD tools can provide good quality data suitable for geological and reservoir characterization. The data also demonstrate some of the differences between various designs of MWD sensors and wireline devices.
The Benefit and Reliability of Using Cross-Well Tomography for Reservoir Characterization
Authors: Lo T-W. , Inderwiesen P. L. , Melton D. R. , Howlett D. L. , Lewis A. V. , Ponek M. F. , Livingston N. D. , Hatcher W. B. 
Published: December 2007

ABSTRACT
Benefit and reliability of using cross-well seismic tomography for reservoir geology interpretation and EOR monitoring are illustrated by a case study from a tar sand reservoir. Emphasis is placed on how to use the tomograms and how to check their reliabilities.
Evaluation of Interfacial Friction Factor Prediction Methods for Gas/Liquid Stratified Flow
Authors: Xiao J. J. , Shoham O. 
Published: December 2007

ABSTRACT
Many methods exist in the literature for the determination of the interfacial friction factor in gas-liquid stratified flow. The purpose of this study is to compare and evaluate these methods against a large number of published experimental data.
Data analysis has revealed that currently available methods for calculating the interfacial friction factor are unsatisfactory. Until better methods become available, however, it is recommended to use the correlation developed by Andritsos & Hanratty (1987) for small diameter pipes (D ≤ 0.127 m or 5 in.) and to use a modified Duns & Ros correlation proposed by Baker et al. (1988) for large diameter pipes (D ≥ 0.127 m or 5 in.). Also, the method proposed by Shoham & Taitel (1984) can be used for the entire range of pipeline diameters.
Low-Rate Pipe Movement During Cement Gelation to Control Gas Migration and Improve Cement Bond
Authors: Sutton D. L. , Ravi K. M. 
Published: December 2007

Abstract
The traditional use of pipe movement was to enhance mud displacement, and there was little reason to continue movement after the cement slurry was in place. New technology has shown the rate and magnitude of the pressure loss during the cement gelation period has a major influence on cement job quality. A recently completed investigation using specialized laboratory equipment and large-scale models conclusively illustrates that low-rate rotation or reciprocation during the cement gelation period effectively delays the loss of pressure in the cement column. As movement was stopped during the test, resistance to fluid or gas migration in the annulus developed rapidly. Using gas migration terminology, this equates to a short transition time (&lt; 10 minutes). When compared to static conditions, pipe rotation continued to ≥ 500 lb/100 ft2 resulted in higher shear level and hydraulic bond. Torque needed for rotation was always lower than values calculated from static gel strength and was in the range for safe rotation without pipe thread failure.
A Study of Formation Damage Potential During Cementing Operations
Authors: Jones R. R. , Carpenter R. B. , Conway M. W. 
Published: December 2007

Abstract
A reduction in near wellbore permeability can dramatically decrease hydrocarbon production. This study examines the extent of formation damage caused by 1) incompatibility between the formation and injected fluids, 2) exposure times and 3) leakoff volumes. Dynamic fluid loss studies are presented to illustrate the effects of some drilling muds, spacer fluids and cement slurries on typical Berea sandstone. The studies were conducted using 2×5" inch long, pre-saturated, 500 millidarcy core specimens to evaluate the damage potential from fines and filtrates. These tests simulated applications at typical bottom hole circulating temperatures and differential pressures. Permeability was measured at depths of 0.5, 3.0, 5.5 and 8.0 inches from the exposed formation faces.
Prior industry studies have concentrated on using filtrates and small core specimens to measure changes in permeability. Although beneficial, these tests do not simulate filter cake deposition or exposure time for different fluid phases during a cementing application. Drilling muds may be exposed to a formation for many days, while most spacer fluids only contact the formation for 5 to 15 minutes, and cement slurries for a few hours.
Test results indicated that lignin or PHPA muds cause minimal formation damage to Berea sandstone. They also built very dense, low permeability filter cakes which restricted invasion of fines and filtrate from spacers and cement slurries. Most formation damage was confined to within 1–2 inches of the exposed core face.
The studies also showed that fresh water spacers were much more damaging than those containing small concentrations of potassium chloride (KCl). Tests incorporating API cement slurries demonstrated their excellent bridging and cake building characteristics. The addition of fluid loss additives such as hydroxyethylcellulose (HEC) polymer or polyvinyl alcohol (PVA) latex decreased filtrate loss and formation damage. These tests also revealed that the selection of the polymer for fluid loss control is important. Duplicate tests using styrene butadiene resin (SBR) latex resulted in excessive formation damage at penetration depths up to eight (8) inches. Scanning electron microscopic (SEM) analysis was conducted to further illustrate the results obtained from the dynamic fluid loss studies.
While these results are not considered quantitative, the apparatus and procedure permitted dynamic fluid loss testing under simulated downhole conditions using whole treating fluids. The extent of formation damage caused by some drilling muds, spacer fluids and various cement slurry formulations were evaluated. These test methods can be used to improve critical job designs for problematic reservoirs and to screen for damaging additives.
Analysis of and Solutions to the CaCO3 and CaSO4 Scaling Problems Encountered in Wells Offshore Indonesia
Authors: Oddo J. E. , Smith J. P. , Tomson M. B. 
Published: December 2007

ABSTRACTPertamina/MAXUS Southeast Sumatra Petroleum, Inc. is the largest offshore oil producer in Indonesia. CaCO3 and CaSO4 scaling in and around the submersible pumps of Pertamina/MAXUS' Farida/Zelda reservoir wells led to premature pump failures and costly workovers to bring the wells back into production. Twenty-four well brines were analyzed on-site to accurately determine brine chemistries and scale samples were analyzed to determine exact composition. Well histories were studied to find correlations of procedures which led to scaling problems. Saturation Indices, developed at Rice University and presented in the paper, were applied to the problems to give insight into the causes of the intermittent, but costly scale formation. Discussions were held with a submersible pump consultant and pumps were examined to provide additional data for the analysis. Thirteen scale inhibitors were evaluated at 225 F (107 C) and 300 psia (2.07 MPa) in a 1.1% CO2 atmosphere using a flow simulator developed at Rice University to find the most effective scale inhibitor to use in the wells to mitigate scale formation.The CaSO4 scaling problem was determined to be a result of HF/HC1 acid treatments performed on the wells to increase productions rates. These acid treatments were followed by KCl seawater overflush solutions. The problem can be eliminated through the limited use of strong acid stimulation treatments and by putting a fresh water plug between the formation and the seawater or using scale inhibitor in the seawater overflush and kill fluids. Calcium from the dissolved CaCO3 in the formation due to the acid environment precipitated with sulfate ions from seawater to form the CaSO4 scale. CaCO3 scale formed due to the increased temperature, the use of rotary gas separators and the decreased pressure in and around the submersible pumps. Since production rates need to be maximized and increased temperatures and decreased pressures are necessitated by the production scheme, it has been decided to use chemical scale inhibitors in the wells. The wells are being squeezed to protect them from CaCO3 scale formation.Wells that had phosphonate residuals from previous inhibitor squeezes had longer pump runs than wells without inhibitor protection. One specialty proprietary chemical and generic aminotrimethylene phosphonic acid (ATMP) were found to be the most effective scale inhibitors in flow through testing and wert effective at 1.5 ppm. Since the specialty chemical had precipitated in the container, ATMP was recommended.
Transient Aspects of Unloading Oil Wells Through Gas-Lift Valves
Authors: Capucci E. G. , Serra K. V. 
Published: December 2007

ABSTRACT
The analysis and design of gas lift strings in oil wells have been done without considering the transient effect of multiphase flow in pipes. The reason for this fact relies on the complexities aspects of unloading gas lift wells since the initial static condition(dead well) until the condition of stabilized flow. At the begining, the annulus space may contain liquid at any level which is pushed downward in a piston like manner by the injected gas. The reservoir is represented by the inflow performance curve (IPR). The problem is solved by a computer model based on the liquid and gas mass conservation laws and the momentum conservation law of the mixture. The model couples the annulus and the upward vertical multiphase flow through gas lift valves. Mass transfer between phases is not considered. Operational variables (pressure, superficial liquid and gas velocities, slippage liquid hold up) are displayed as functions of time and depth. Gas injection rate at surface, liquid and gas flow rates through gas lift valves, as well as pressure profiles in the annulus space are also monitored with time. Proposals for new transient analysis and design of gas lift installations are suggested.
Low-Surface Safety Valve Control System Pressures Improve Economy and Safety in Offshore Operations
Authors: Golden T. A. 
Published: December 2007

Abstract
Low pressure pneumatic surface safety control systems are desirable due to their less complex circuits. Low control pressures, however, are unable to open surface safety valves against high pressure unless large actuator cylinders are employed. Large pneumatic cylinders are often impractical due to wellhead space constraints. New compact actuators that provide the greatest amount of force at the point in the valve stroke where the resistant forces are greatest can be utilized to take advantage of low control pressures. The double-piston action of compact pneumatic actuators can also reduce the potentially damaging forces acting on the bonnet and gate during the opening cycle.
Releasable Fusible Lockopen Device Enhances Emergency Shutdown Capabilities
Authors: Gilbert D. L. , Maxwell J. D. 
Published: December 2007

Abstract
This paper describes the need for and subsequent development of a firesafe device which locks open wellhead surface safety valves while conducting through-wellhead operations, and which is manually releasable to allow closure of the valve in an emergency.
The device incorporates a eutectic material which will provide for closure of the valve in a fire and meets the requirements of API Specification 14D for fusible lockopen devices. Existing fusible lockopen equipment used by offshore operators is not manually releasable once the hold-open pressure applied to the actuator is released (by activation of the platform emergency shutdown system) due to the large forces involved.
This new assembly is a significant improvement over existing equipment because: (1) it is manually releasable, (2) it can be released remotely by utilizing a cable/pulley system (3) all component parts are retained upon release, (4) it is adaptable to most valves and actuators currently in use, and (5) it greatly enhances well shut-in capabilities while conducting through-wellhead operations.
Design, Testing, and Field Use of a New Selective Reeled Tubing Well Stimulation System
Authors: Pleasants C. W. , Head D. W. , de Ruiter J. 
Published: December 2007

ABSTRACT
Reeled tubing equipment and services are commonly used for the live well injection of acid and other types of well stimulation fluids. Until the introduction of inflatable packer systems, there was no acceptable method of isolating the injection of such fluids; this resulted in the pressurizing of the entire tubing string, or "bullheading" into the zone as commonly referred to in oil field operations. Though current inflatable packer technology allows for zonal isolation by utilizing single and straddle pack systems1, such systems are complex and injection pressure limited due to the differential rating of the packer elements.
In order to meet the demands of high pressure stimulation, a new line of downhole tools has been developed for use with reeled tubing which create a ’ mechanical, positive, selective, sealing and isolation system. These new tools isolate and protect well components from stimulation fluids and pressure by employing conventional sealing technology and existing downhole selective landing nipples. When the features of these new tools are combined with the advantages of reeled tubing, i.e., speed, continuous circulation, live well servicing, etc., the result is an efficient system for well stimulation operations.
The Use of Interruptible Power in West Texas Waterflood Operations
Authors: Scott G. T. , Petter M. K. , Bulls F. B. 
Published: December 2007

ABSTRACT
Interruptible power purchased from electric utilities has been used by chemical and process industries for many years, but is not generally used in oil producing operations. Interruptible power represents an established option to reduce electric power costs, which are often the oil producer’s single largest operating expense. The recent use of interruptible power in Amoco Production Company’s West Texas waterflood operations has significantly reduced operating expenses.
Interruptible power rates are offered by many electric utility companies; however, the impact on producing operations is generally not known. This paper addresses the initial areas of concern and offers over two years of case history data showing how interruptible power affects operating costs, production equipment, producing rates and safety/environmental operations. The information presented will enable the producing operator to make an informed decision on the use of interruptible power. Although this paper deals with TU Electric Company’s interruptible power rate, the information presented will be applicable to interruptible rates offered by other utilities.
A Case Study of Hydraulically Refractured Wells in the Devonian Formation, Crane County, Texas
Authors: Olson K. E. 
Published: December 2007

ABSTRACT
Case histories of three hydraulically refractured wells are presented including selection criteria, fracture design and field execution.
The field was developed on 40-acre spacing in the 1960’s. The original completions in the Devonian formation at an average depth of 9000 feet included a fracture stimulation. The stimulation consisted primarily of gelled brine water carrying a maximum of two pounds per gallon of 20/40 sand. Recent pressure buildup analysis confirmed that sustained fracture lengths were not created during these original completions.
Three wells were selected as refrac candidates using the following criteria: future field development plans, "high" bottom hole pressure, positive to slightly negative skin, and original completion design (stimulation size, type, success, and initial well potential).
The objective of refracturing designs was to create longer, more conductive fracture wings, with the ultimate goal of optimum drainage.
Problems encountered during refracturing included: 1) the presence of proppant still in place from the original stimulation, 2) casing integrity, 3) inadequate wellbore to formation communications, 4) rate and pressure limitations, 5) open zones above the zone of interest, and 6) poor hydraulic isolation between zones.
This paper will conclude with guidelines for well selection, design techniques, and suggestions for addressing "old wellbore" problems.
Experimental Tests of a Simple Permeability Composition Formula
Authors: Noetinger B. , Jacquin C. 
Published: December 2007

Abstract
This paper proposes a general and rigorous theoretical framework for averaging the single-phase permeability, which has been validated by laboratory experiments. This approach uses powerful tools of statistical mechanics (field-theory), and provides exact results for log-normally distributed permeabilities, without any restriction about the width of this distribution.
On the other hand, laboratory experiments were performed on both a 3-D heterogeneous sandstone and a limestone blocks. Their overall (effective) permeabilities were measured first. Then they were both cut into 300 plugs, whose permeabilities were measured in turn, and later plotted on a histogram.
A very simple 3-D algebraic permeability composition formula is given, Keff=&lt;k1/3 &gt;3, in which the brackets correspond to an arithmetic mean. Its form differs significantly from the widely-used geometric mean, a well-known 2-D result.
In both cases, excellent agreement is observed between experimental results obtained for the overall permeability and the algebraic prediction given by our local permeability-composition formula.
An Investigation of the Effect of Cyclic Loading on Fracture Conductivity
Authors: Ouabdesselam M. , Hudson P. J. 
Published: December 2007

ABSTRACTTime-dependent reductions infracture conductivity have been implied in instances where post-treatment well test data have been available and analyzed. This study evaluates the importance of fatigue failure in a cyclically stressed proppant pack as a contributing factor to fracture conductivity impairment. Permeabilities and pack widths for common mesh sizes of a sand and a ceramic proppant, using formation core plates of varying hardness, were measured after repeated closure stress cycles. Interactions between proppant and formation materials were examined in the SEM in an attempt to correlate fatigue-induced damage with known lithological classifications, and with proppant particle microstructures.Under the action of repeated stresses, such as in the production/shut-in cycles of some hydraulically fractured wells, fatigue failure in the propped fracture occurs within the proppant particle as well as on the fracture face. The data obtained in these experiments show that both proppant permeability and fracture width gradually decrease with increasing number of cycles, as the proppant and adjacent formation break down, and the supporting structure of the propped fracture progressively weakens. The ceramic proppant exhibited better overall resistance to fatigue failure than the natural sand did. Experiments run with low hardness core plates showed increased sensitivity to repeated stresses, reflected by a greater degree of fracture width reduction and flow channel obstruction. The effect of fatigue-induced fracture width reduction is expected to increase with decreasing proppant concentration.
Controlling Paraffin-Deposition-Related Problems by the Use of Bacteria Treatments
Authors: Santamaria M. M. , George R. E. 
Published: December 2007

ABSTRACT
Five wells with a history of paraffin related problems were selected for treatment with a commercially available bacteria product∙
Wax deposition was so severe in these wells that production was often halted due to stuck rods. Wax deposition was controlled by hot oiling. Some wells required hot oiling as often as twice a week.
The produced oil from each of the wells was characterized for paraffin content. Produced water from each well was also characterized and closely monitored for potential adverse affects from the paraffin treating bacteria.
Paraffin related treating costs for the wells was reduced by the use of bacteria. Production down time due to hot oiling was also reduced. The application of the bacteria to control paraffin related problems can be beneficial; however, there are some potential limitations to bacteria applications.