bluuebunny/crossref_metadata_2025 huggingface dataset:
Salinity Dependence of the Shaly Sand Formation Resistivity Factor, F*
Authors: Yuan H. H.
Published: December 2007

The Yuan-Diederix equation relates the conductivity of a brine-saturated rock to the brine conductivity and membrane and Nernst potentials for the sample for a given salinity contrast. The equation has only one parameter, namely, the shaly sand formation resistivity factor, F*. Because the equation is essentially local in salinity, data from Waxman-Smits Group 2 samples for which conductivity and membrane potential data have been simultaneously measured allow the determination of F* as a function of salinity.

For situations where the clay conductivity is smaller than the brine conductivity, the Waxman-Smits assumption of constant F* is valid. However, where the clay conductivity exceeds the brine conductivity, F* may no longer be constant, implying that the Waxman-Smits assumption of constant F* is not always valid. An implication of salinity-dependent F* is that membrane potential measurements may be necessary for cases where the clay conductivity exceeds the brine conductivity. This can be critical for shaly sand evaluation.

New simultaneous conductivity and membrane potential data are reported for a set of very shaly sandstones which confirm the salinity dependence of F* when the clay conductivity exceeds the brine conductivity. The effect is greatest for montmori1lonite-bearing samples. Procedures for applying membrane potential measurements are described.
Outcrop Characterization of Flow Unit and Seal Properties and Geometries, Ferron Sandstone, Utah
Authors: Tyler N. , Barton M. D. , Finley R. J.
Published: December 2007

Outcrop studies provide high-resolution information about facies architectural controls on the spatial distribution of petrophysical attributes in reservoir analogs. One of the sandstones in the Ferron delta system in central Utah has been selected for detailed analysis as an analog of Gulf Coast deltaic reservoirs. Unit 5 of the Ferron, a wave-modified deltaic sandstone, consists of a meandering distributary system that fed stratified delta-front deposits. Lateral migration, coupled with rising base level, resulted in horizontally and vertically heterogeneous distributary sandstones, in contrast to the delta front where vertical heterogeneity is dominant and lateral complexity minimal.

Permeability distribution and structure are strongly related to facies composition, stratal type, and grain size. Thus, distributary-channel sandstones have the highest mean permeability, delta-front sandstones the lowest. Within the distributary system the trough-crossbedded stratal type has the highest mean permeability. Variogram analysis indicates correlation at several scales—largest correlation lengths are 182 m in the distributary-channel sandstones. At the stratal level horizontal correlation lengths are less than 6 m and relate to erosional discontinuities and bed size. Quantification of permeability characteristics suggests a hierarchy of bounding-surface types that have attendant geometric and permeability characteristics. Such characteristics can be critical input to reservoir simulation studies of analogous reservoirs in the Gulf Coast Basin, many of which are major natural gas producers.
Correlation of Capillary Pressure Relationships and Calculations of Permeability
Authors: Ma Shouxiang , Jiang Ming-Xuan , Morrow N. R.
Published: December 2007

Correlation of capillary pressure data and the development of the widely used J(S) correlating function are reviewed. The pore structures of core samples, which give the same (in practice closely similar) J(S) curves, are described as operationally similar. Similarity of J(S) curves can be recognized by parallelism of semi-log plots of capillary pressure vs. saturation. Curves so identified were grouped to obtain a pore structure factor based on J(S) curve shapes rather than determining Purcell lithology factors for individual formations. The modified Purcell method gave improved correlation between measured and predicted permeabilities.

A general solution of the Thomeer model in terms of the tangent angle for the Pc(S) curve is presented which facilitates tests of correlations between permeability and selected features of capillary pressure curves. Single point correlation methods based upon the tangent α as introduced by Swan son for α=45°, are shown to hold for a wide range of saturation. Curve methods which consider all of the curve such as suggested by Purcell or any selected parts can be tested at will. The method is designed for semi-empirical investigation of a very large database of core analysis results which include porosity, permeability, and capillary pressure by mercury injection.
Centrifuge Capillary Pressure: Method of the Center of Forces
Authors: Jaimes O.
Published: December 2007

Shown that the commonly used methods of reduction of centrifuge capillary pressure data, based on the Hassler and Brunner theory, lead to double valued capillary pressure functions. To avoid this problem, an alternate equation with two methods of solution has been developed. This equation uses the concept of the center of forces to convert centrifuge data into capillary pressure curves. The proposed methods do not make assumptions about the form of the solution, nor do they use numerical differentiation of experimental data, and, lastly, they do not result in double valued capillary pressure curves. Several examples, including laboratory and analytical data with the computed capillary pressure curves, are presented along with a comparison of the results obtained using the new and several previously developed methods.
Borehole Caliper while Drilling from a 2-MHz Propagation Tool and Borehole Effects Correction
Authors: Rosthal R. A. , Best D. L. , Clark B.
Published: December 2007

The Compensated Dual Resistivity (CDR*) tool computes two apparent resistivities, Rad and Rp8, from the attenuation and phase shift of a 2-MHz electromagnetic wave measured between two receivers. While these measurements are insensitive to the borehole in most situations, the relative phase between a receiver and a transmitter is quite sensitive to the borehole diameter and the mud conductivity. Since the mud conductivity is known, this sensitivity can be used to estimate the borehole diameter during drilling, tripping or washing down. This phase caliper can be obtained in real time using data transmitted to the surface, or it can be calculated after bit runs using data stored in the tool. The borehole diameter can then be used to apply borehole corrections to Rad and Rp8. The borehole correction algorithm can also use any other caliper or bit size as input. Graphs showing the borehole effects for a range of borehole sizes, mud resistivities and formation resistivities are presented. Log examples of the phase caliper and borehole-corrected resistivities are presented.
A Modified Scaling Law and Parachor Method Approach for Improved Prediction of Interfacial Tension of Gas-Condensate Systems
Authors: Danesh A. S. , Dandekar A. Y. , Todd A. C. , Sarkar R.
Published: December 2007

The interfacial tension (I.F.T.) of petroleum reservoir fluids are commonly predicted by either the parachor method or the scaling law. Both methods have been evaluated against literature data of binary systems. The predictive capability of the methods have been improved by a simple modification of the original correlations. The superiority of modified methods have been demonstrated by comparing predicted results with experimental I.F.T. values for two gas condensate fluids at wide ranges of pressure and temperature.
Phase Behavior Modeling of Gas-Condensate Fluids Using an Equation of State
Authors: Sarkar R. , Danesh A. S. , Todd A. C.
Published: December 2007

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

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

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

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

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

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

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 (< 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

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

Pertamina/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

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

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

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

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

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

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

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=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

Time-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

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.
Imaging of Wet Specimens in Their Natural State Using Environmental Scanning Electron Microscope (ESEM): Some Examples of Importance to Petroleum Technology
Authors: Mehta S.
Published: December 2007

The barrier to imaging wet or oily specimens in their "native" states in a scanning electron microscope (SEM) at high resolution and large depth of focus has been broken by the development of a new microscope known as the environmental scanning electron microscope (ESEM). With the new features built into the ESEM, the need for preparing samples with various specimen-destroying preparation techniques has been eliminated. For example, wet reservoir rocks can be imaged and analyzed in their "native" state, without drying, freezing, or coating with a conductive layer, by saturating the ESEM specimen chamber with water vapor {PH2O = ~0.46 psi [3.2 kPa] at 25°C [77°F]} during examination. The ESEM also allows dynamic experiments to be performed in a variety of gases at pressures up to 0.6 psi [4kPa] and temperatures up to 1000°C.

This paper presents the key features of the ESEM which distinguish it from the conventional SEM, and results of some ESEM feasibility studies important in petroleum technology such as matrix acidization, water-flooding, and clay and cement hydration. The results indicate that the ESEM combined with the energy-dispersive x-ray spectroscopy is a powerful new technique capable of providing a new understanding of many exploration and production related studies not previously possible with conventional "high-vacuum" SEM microscopy.
Intelligent Utilization of a Unified Flow Pattern Prediction Model in Production System Optimization
Authors: Arirachakaran S. , Papadimitriou D. A. , Jefferson L. L. , Brill J. P. , Shoham O.
Published: December 2007

Accurate predictions of flow patterns for multiphase flow in pipes remain unresolved problems in petroleum engineering. Many efforts have been directed towards improved understanding of the phenomena and the development of physical models that allow more accurate analytical predictions of the flow pattern transition boundaries in steady-state multiphase flow. The primary goal of such models is to provide a truly general method that predicts existing flow patterns, once the flow rates, pipe geometry, and the fluid properties are specified. A unified approach, in which the same transition mechanisms can be applied over the whole range of inclination angle, has also been proposed.

The most essential part of solving engineering problems that depend on flow pattern predictions is the interpretation of results. The ability to explore and manipulate the results using a computerized flow pattern simulator would greatly enhance an engineer’s capability to optimize the design of multiphase transportation systems. This would also permit eliminating undesirable operating conditions; e.g. severe slugging at the riser in offshore operations. Progress in the area of Artificial Intelligence (AI) has made possible the partial realization of human decision making ability in a computer program. An intelligent program, supported by a knowledge data base, an inference engine, and human interaction, is an effective and economical solution for the present needs of advanced production optimization.

A computer simulator is undergoing development, using a Knowledge Based System approach. The system attempts to imitate, and eventually replace, a multiphase flow engineering expert. The Expert System utilizes an inference engine which is based on analytical mechanistic models and the expertise of many multiphase flow engineering experts and consultants. It is capable of predicting the existing flow pattern based on the current design, and will offer advice on alternatives and the direction to proceed if the existing flow pattern is unacceptable, or potentially problematic.
The Management of Occupational and Environmental Exposure to Naturally Occurring Radioactive Materials (NORM)
Authors: Miller H. T. , Bruce E. D. , Cook L. M.
Published: December 2007

The recognition of NORM as a potential occupational, environmental, and regulatory concern in U.S. production operations has prompted the identification of management tools and the preparation of radiation protection programs for field use. This paper outlines the steps followed by one company to identify the extent of NORM contamination, estimate the level of risk to its employees and the general public, communicate that risk to its employees, examine management alternatives for dose and risk reduction, prepare operational guidance for its U.S. and overseas operations, and to assure that the recommended operating procedures are understood and followed.

The identification of NORM containing Radium in production operations in April 1986 was followed by an extensive survey of all suspect facilities. The results and the subsequent exposure assessment of internal and external occupational radiation exposure are reported. Also reported are data on scale in pipes, equipment contamination, soil contamination and the presence of 226 and 228 Radium in produced water.

Methods used to communicate the results of the exposure assessment to employees will be included.

The next step taken was to identify and establish the environmental acceptability of operating procedures, possible disposal options and site remediation methods. The options studied will be described, the method of study will be explained, and recommendations of scientifically reasonable procedures will be made.

Knowledge gained from the exposure assessment was combined with the studies of waste management options to develop a radiation protection program for production operations. The contents of this program will be briefly outlined.

Finally, the paper will discuss the training of the operations staff. Short training outlines for senior environmental safety and health managers and radioactive materials technicians will be presented.

* CURRENT ADDRESS: Martin Marietta Energy Systems P.O. Box 1410 Padacuh, KY 42001
The Use of a Managed Reserve Pit System To Minimize Environmental Costs in the Pearsall Field
Authors: Hall C. R. , Ramos A. B. , Oliver R. D. , Favor J.
Published: December 2007

Due to the great amount of horizontal drilling activity in the Pearsall Field, a tremendous volume of drilling waste is generated. Because of the quantity and cost of this waste, Oryx Energy Company has established a Pit Management System(PMS). The purpose of the Pit Management System is to facilitate improved handling of drilling waste associated with horizontal wells in the Pearsall Field. The program utilizes designated drilling foremen in strictly location, maintenance and cleanup roles. The field application of the pit management system has provided drilling personnel the ability to minimize drilling wastes without compromising drilling operations in the Pearsall Field. The effectiveness of the system has been evaluated by comparing disposal volumes and costs for wells without a PMS to wells drilled using such a system.

The PMS has resulted in a significant reduction in waste volumes and waste disposal costs. It’s use has minimized the effects of the various drilling conditions experienced in the Pearsall Field. It can be seen that the PMS is a viable consideration for dealing with drilling wastes. It has reduced waste volumes, lowered handling and disposal costs, while not compromising drilling operations. It has encouraged and produced innovative ideas from field and office personnel resulting in improved methods of handling waste.

A PMS can be used wherever a reserve pit can be built. It is a relatively simple, but flexible, method to minimize waste generation and reduce costs.
Waste Management Modeling Using Reservoir Characterization Techniques
Authors: Knutson C. F. , White L. J. , McCormick K. A. , Barber D. G.
Published: December 2007

Reservoir characterization techniques were used to develop a hybrid (two scale) 3D model of the 180 m thick interbedded basalt flow and sediment system that constitutes the vadose zone underlying the Radioactive Waste Management Complex (RWMC) at the Idaho National Engineering Laboratory, Idaho. Geostatistical data was captured from a study of well logs, cores, and cuttings from the subsurface at the RWMC and from nearby outcrops. In general the data was cast in the form of stochastic distribution equations, allowing easy assignment of parameter values.

The geometry of the units comprising the vadose zone was developed with a backstripping technique and stochastic interpolation between the wells using a geostatistical model for flow geometry and kriging for sediment geometry.

Porosity, permeability, and saturation values were stochastically assigned to locations in the existing wells in 0.33 m steps from the surface to the aquifer where no measured data was available and to an array of virtual wells on a 60 m x-y grid covering the RWMC area. Thus, a data matrix was developed utilizing the geometric model and stochastic distribution equations, that provided flow and storage capacity data in 0.33 m steps in the z axis with an x-y spacing of 60 m or less.
Evaluation and Completion Procedure for Low-Permeability Sandstones for Waste Water Disposal
Authors: Hunt J. L. , Frazier K. , Pendergraft B. P. , Soliman M. Y.
Published: December 2007

Waste water disposal is one of the many environmental issues becoming increasingly difficult to deal with. A single disposal well may not be sufficient to handle the large volume of waste water generated by many industrial plants. Increasing the injectivity of a well by hydraulic fracturing is a viable solution to this problem.

This paper discusses the application of a numerical water injection simulator to evaluate a low permeability sandstone reservoir for waste water disposal. The injection model is used to study the effects and feasibility of hydraulically fracturing the reservoir to improve injectivity.

Also discussed are the field implementation of the hydraulic fracturing treatment, testing of the well to evaluate the treatment, and a comparison of observed and simulated injectivity.

A description of the model and results from the actual case history are presented.
Coordinated Laboratory Studies in Support of Hydraulic Fracturing of Coalbed Methane
Authors: Penny G. S. , Conway M. W. , McBane R.
Published: December 2007

A series of laboratory experiments have been conducted with specially designed equipment to aid in measuring leakoff and pressure drop of proppant-laden slurries while flowing between coal, and quantifying regained permeability and conductivity of various fluids and proppants once placed in a coal fracture.

The rheology and proppant transport of borate-crosslinked fluids with and without proppant have been evaluated in a slot with walls cast from the surfaces of fractured coal in an effort to quantify the impact of tortuous coal fractures on the pressure drop down the fracture.

The long-term conductivity and permeability of various sands have been measured between fractured Fruitland Coal. Predictive equations have been developed to predict permeability between coal vs sand sieve size, and predict loss of permeability due to embedment and gel damage. Non-Darcy flow factors and constants are presented for calculating non-Darcy flow vs sand type and size between coal.
A Systems Response Model for Simultaneous Determination of Capillary Pressure and Relative Permeability Characteristics of Coalbed Methane
Authors: Ohen H. A. , Amaefule J. O. , Hyman L. A. , Daneshjou D. , Schraufnagel R. A.
Published: December 2007

This paper presents a predictive technique for simultaneous determination of capillary pressure and relative permeability characteristics of coalbed methane reservoir specimens. The technique utilizes a systems-response model of transient fluid production data from a modified porous-plate experiment. The model consists of(1) a modified Langmuir-type equation for the extrapolation of transient laboratory production data to capillary equilibrium, (2) a one-dimensional, two-phase, dual porosity simulator, and (3) an automatic parameter estimation routine based on the Levenberg-Marquardt non-linear optimization scheme. Different modules of the model are integrated to determine capillary pressure and relative permeability characteristics as well as cleat pore volume of coal specimens.
An Analysis of Fruitland Coalbed Methane Production, Cedar Hill Field, Northern San Juan Basin
Authors: Young G. B. C. , McElhiney J. E. , Paul G. W. , McBane R. A.
Published: December 2007

A three-dimensional, multi-well reservoir simulation study was completed on the Cedar Hill field. The history match provides new insight into the reservoir parameters of the basal Fruitland coals in the northern San Juan Basin and presents evidence for the beneficial effects of well interference in coalbed methane production.
Gas Reserve Growth Analysis of Fluvial-Deltaic Reservoirs in the Frio and Vicksburg Formations Located in the Stratton Field, Onshore Texas Gulf Coast
Authors: Sippel M. A. , Levey R. A.
Published: December 2007

The reserve growth in a mature gas field is analyzed using a historical review over the past 20 years. The Stratton field is presented as an example of the significant additional gas reserves which are available through conventional drilling and completion methods using existing technology. The reserve growth is quantified and categorized by reservoir architecture, well density and depth.
Effect of External Boundary Conditions on Steady and Semi-Steady Radial Flow Equations Based on Darcy, Forchheimer, Brinkman, and Capillary-Orifice Models
Authors: Civan F. , Tiab D.
Published: December 2007

The solutions for steady and semi-steady state radial flow using four fundamental momentum equations for description of flow in porous media are obtained and compared. Specifically, Darcy, Forchheimer, Brinkman, and Capillary-Orifice equations are considered for bounded and partial water drive reservoirs. A general solution which reflects all four flow models is presented.

It is shown that the solutions presented in this paper provide accurate results in oil and gas reservoir analysis. Analysis of partial water drive reservoirs is considerably improved when using these solutions. An important application of these solutions is the determination of flowing well pressure of grid blocks in areal reservoir simulator for bounded and partial water-drive systems.

The method for characterization of the water drive strength factor f introduced by Kumar is extended to include the non-Darcy flow and fluid compressibility effects in bounded and partial water-drive reservoirs.
A New Recovery Technique for Gas Production From Alaskan Gas Hydrates
Authors: Islam M. R.
Published: December 2007

An enormous amount of natural gas is trapped in hydrate form in the North Slope of Alaska. Recently, these gas hydrates have been identified as an alternative natural gas resource. However, this resource is extremely difficult to exploit. Recent studies have mainly focused on steam and/or hot-brine stimulation of gas hydrate reservoirs. Unfortunately, the presence of permafrost (leading to excessive heat loss to the surrounding) and high reservoir pressure make conventional thermal recovery techniques inadequate. This paper studies the feasibility of electromagnetic heating for dissociating solid gas hydrates. A series of numerical simulation runs is conducted to demonstrate the feasibility of the proposed gas recovery technique.

For a wide range of reservoir parameters, gas recovery and the energy efficiency ratio (i.e. the ratio of energy of produced gas to heat injected) are computed. The effects of reservoir rock properties, hydrate-zone thickness, magnitude of the electric power, and the production/heating strategy were studied. Results were compared with those with steam and hot brine stimulation. Significantly higher energy efficiency is observed with electromagnetic heating. It is shown that the radius of heating did not have to be very large in order to develop a continuous stream of gas production. However, the maximum flow rate was a function of electrical power and the well configuration.