bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Methods for Sampling Gas and Drill Cuttings
Authors: Williams Richard D. , Ewing Scott P.
Published: December 2007

Large variations exist in the sampling performance of conventional drilling-mud gas samplers, resulting from a combination of design and operational differences. These variations have been evaluated systematically, and modifications have been made that improve sampling performance and make samplers operate comparably. A new method of sampling for drill cuttings from drilling mud has been tested that overcomes deficiencies in sampling from shaker tailings. With this method, it is possible to obtain cuttings samples more representative of the drilled interval.
Effects of a Partially Communicating Fault in a Composite Reservoir on Transient Pressure Testing
Authors: Ambastha A. K. , McLeroy P. G. , Grader A. S.
Published: December 2007

Many reservoirs are faulted, and hydraulic characterization of these faults is essential for the design of field-scale developments. In addition to the effect that a fault has on fluid flow in the reservoir, it may separate two different reservoir regions with distinctly different properties. The detection of the properties on both sides of the fault and the distance to the fault are important in the reservoir-characterization process.

In this study, a linear fault is modeled as an infinitesimal-thickness skin boundary. Analytical solutions for pressure-transient behavior for a line-source, constant-rate well in a composite reservoir are obtained with one Fourier space transformation and time-space Laplace transformations. The solutions are presented for strip and infinite reservoirs. This study examines drawdown-pressure and pressure-derivative behavior and extends and generalizes many studies presented in the past. Correlating parameters for pressure-transient responses are presented. The possibilities of boundary detections are considered, and interference pressure responses in a composite, strip reservoir are briefly discussed.
Seismic Response for Reservoir-Fluid Evaluation
Authors: Rafipour B. J.
Published: December 2007

This paper describes a study of the relationships among lithology, pore-fluid content, stratigraphy, and the seismic response for clastic sedimentary rocks. We show how it is possible to generate seismic models from the petrophysical measurements. This procedure should provide a useful conceptual model for understanding the seismic response of a particular type of reservoir.
New Unified Method of Integrating Core Capillary Pressure Data With Well Logs
Authors: Alger R. P. , Luffel D. L. , Truman R. B.
Published: December 2007

A new unified method is presented for relating porosity, water saturation, capillary pressure (or height in the reservoir), and permeability through multilinear regression with core and log data. This method, an extension of Heseldin, is well-suited to computer processing. In addition to general use in reservoir description, this new method is also shown to be useful in several specific applications.
Severe Slugging in Pipeline/Riser Systems
Authors: Fabre Jean , Peresson Lucien L. , Corteville Jacques , Odello Robert , Bourgeois Thierry
Published: December 2007

Severe slugging in pipeline/riser systems was modeled by solving the local instantaneous equations for mass and momentum with a method of characteristics. The results are in good agreement with experimental data obtained in a 0.053-m-diameter flow loop for different pipeline slopes and various flow rates.
A Rule-Based System for Estimating Clay Distribution, Morphology, and Formation Damage in Reservoir Rocks
Authors: Vitthal Sanjay , Gupta Anuj , Sharma M. M.
Published: December 2007

A rule-based system has been developed that combines a knowledge base of known facts and heuristics with an inference engine to extract relevant information on clay composition, distribution, and morphology in a rock sample. The expert system uses the data to calculate a set of formation indices for the reservoir; i.e., it measures the reservoir's susceptibility to damage caused by clay swelling and migration.
Comparison of Multiphase-Flow Correlations With Measured Field Data of Vertical and Deviated Oil Wells in India
Authors: Ral R. , Singh I. , Srlni-vasan S.
Published: December 2007

The estimation of pressure drop for multiphase flow in deviated and inclined pipes is a very complex problem. Although many investigators have suggested solutions to this problem for vertical and horizontal pipes, only a few works are available for deviated and inclined upward flow in well tubing. Also, no two methods yield identical results for a given set of flow conditions.

Based on earlier studies, a composite model for pressure-drop calculation is proposed. A comparison is made between this composite model and methods proposed previously with 323 sets of field-measured data.

Onshore and offshore Indian oil and gas fields currently being exploited were selected. An extensive effort was made to acquire the large number of actual field-measured data required for this study, including some data sets collected from the literature. The 323 data sets cover a wide range of all parameters.

The accuracy of the pressure drop calculated by the proposed model shows good results. Study of its applicability in different ranges indicated that this model performs well in all the ranges of liquid flow rate, GOR, API gravity, and water cut. Several other methods performed well.
Fluid-Loss Control: The Key to Successful Acid Fracturing
Authors: Crowe C. W. , Hutchinson B. H. , Trittipo B. L.
Published: December 2007

Acid fluid loss is extremely difficult to control and is generally considered to be the major factor limiting the effectiveness of acid fracturing treatments. Chemical erosion of fracture faces and the development of wormholes are largely responsible for the reduced efficiency of acid fracturing fluids. The creation of acid wormholes increases the effective area from which leakoff occurs, thus reducing the acid hydraulic efficiency. Once wormholes form, most acid fluid loss originates from these wormholes rather than penetrating uniformly into the fracture face.

Methods of acid fluid-loss control are discussed and evaluated with an improved fluid-loss test procedure. This procedure uses limestone cores of sufficient length to contain wormhole growth. Studies demonstrate that if wormhole growth can be controlled, acid fluid loss approaches that of nonreactive fluids.

An improved acid fracturing fluid having unique Theological characteristics is described. This acid has a low initial viscosity but temporarily becomes extremely viscous during leakoff. This high leakoff viscosity blocks wormhole development and prevents acid entry into natural fractures. After the treatment, spent-acid viscosity declines rapidly to ensure easier cleanup.
Sandstone Acidizing Design With a Generalized Model
Authors: Taha R. , Hill A. D. , Sepehrnoorl K.
Published: December 2007

Acidizing of sandstones with HF/HC1 mixtures is most frequently applied to remove near-wellbore damage, often in reservoirs with considerable vertical heterogeneity. A previously presented model for such processes in which an organic resin diverting agent was used has been extended to account for any type of particulate diverting agent and to allow for injection of multiple sequences of acid and diverting agent at either constant rates or constant bottomhole pressures (BHP's). When used to design treatments for a typical U.S. gulf coast reservoir, the model has shown that the optimal treatment strategy depends on both diverting-agent efficiency and the desired depth of live acid penetration and that relatively high injection rates appear advantageous for the conditions imposed by the model.

A general model of diverting-agent behavior was developed from filtration theory. A single parameter, the specific cake resistance, is needed to model the diverting-agent behavior in the acidizing simulator. Calculation procedures to determine this parameter from laboratory tests of diverting agents were developed. These tests are either constant-rate, constant-pressure, or variable-rate and variable-pressure experiments; in each case, the specific cake resistance can be extracted from the experimental data. These procedures allow the efficiencies of various diverting agents to be compared on an equal basis.

The sandstone acidizing model was used to design a treatment for a typical gulf coast sandstone reservoir. On the basis of an overall skin factor for the well, various assumptions were made about the distribution of formation damage around this multilayered completion. Treatment results were found to be fairly sensitive to the details of the damage distribution, suggesting that the skin factor alone may not be an adequate design parameter.
Effects of Underbalance on Perforation Flow
Authors: Halleck P. M. , Deo M.
Published: December 2007

In a study of perforation flow in standard API test targets, underbalance between 500 and 1,000 psi [3.4 and 6.9 MPa] was needed to obtain optimum flow efficiency. Perforation cleanup due to transient pressure gradients was separated from that caused by postshot, steady-state flow. Perforations with low initial flow efficiencies could be improved by steady-state washing, but not to optimum levels. The amount of rock debris washed from the perforation during the washing phase correlated directly with the shooting underbalance applied. Tests performed in kerosene-saturated, brine-free targets resulted in generally lower flow efficiencies and required higher underbalances to obtain optimum levels.
A New Method of Matching Aquifer Performance and Determining Original Gas in Place
Authors: Gajdica Ronald J. , Wattenbarger R. A. , Startzman Richard A.
Published: December 2007

A new method is presented for determining the original gas in place (OGIP) from depletion performance data in gas reservoirs with water influx. A study of the performance of 32 gas reservoirs shows that the method gives generally better results than either the steady-state or the unsteady-state method currently used. The primary advantages of this method are that limiting assumptions about the aquifer geometry and properties are not necessary and the computation is automatic, quick, and relatively simple compared with reservoir simulation.

Monthly gas production and shut-in bottomhole pressures (SIBHP’s) are used as input data. A material balance is performed to determine aquifer influx. Linear programming (LP) is used to match the aquifer behavior automatically. Then the solution is repeated for various OGIP assumptions until the optimal value is determined.

With a gas-production and pressure-data history, the OGIP and an aquifer influence function (AIF) can be determined with this method and future performance can be predicted. (The AIF is a "type curve" for the aquifer.) Data from 32 offshore gas reservoirs were used to evaluate the method. Good results were obtained in most of these reservoirs. The method has useful application before, or instead of, a reservoir simulation study.
Geostatistics Applied to Gas Reservoirs
Authors: Meunler G. , Coulomb C. , Laille J. P.
Published: December 2007

The spatial distribution of many of the physical parameters connected with a gas reservoir is of primary interest to both engineers and geologists throughout the study, development, and operation of a field. It is therefore desirable for the distribution to be capable of statistical interpretation, to have a simple graphical representation, and to allow data to be entered from either two- or three-dimensional grids. To satisfy these needs while dealing with the geographical variables, new methods have been developed under the name "geostatistics." This paper describes briefly the theory of geostatistics and its most recent improvements for the specific problem of subsurface description. The external-drift technique has been emphasized in particular, and in addition, four case studies related to gas reservoirs are presented to show the wide range of geostatistics application.
Steady Adiabatic, Two-Phase Flow of Steam and Water Through Porous Media
Authors: Sanchez J. Michael , Schechter Robert S.
Published: December 2007

Reliable steam/water relative permeability curves that have not been previously reported were obtained under conditions of near-adiabatic, two-phase, steady flow in an unconsolidated Ottawa sandpack. Comparison of higher-temperature steam/water relative permeability curves to those for nitrogen/water at room temperature indicate that the two types of flows are essentially identical.
Flow of a Power-Law Fluid in an Eccentric Annulus
Authors: Uner Deniz , Ozgen Canan , Tosun Ismall
Published: December 2007

An eccentric annulus is modeled as a slit of variable height, and the volumetric flow rate of a power-law fluid in an eccentric annulus is compared with that in a concentric annulus for a given pressure drop. The results indicate an increase in the volumetric flow rate as the inner pipe is displaced from a concentric position. The effect of the eccentricity ratio on the volumetric flow rate becomes predominant, especially when the power-law index, n, is small.
A Method to Determine Semipermeabilities by Steady Rates
Authors: Gao Cheng-tal
Published: December 2007

The formation properties for individual layers of a multilayer reservoir are necessary for numerical simulation and tertiary process. Several multilayer well testing methods have been developed to estimate permeability-thickness product, kh, and skin factor, s, for individual layers. This paper gives an analytical method to calculate the vertical permeabilities of low-permeability intercalations between production layers in an n-layered reservoir with kh, s, and the steady flow rate of each layer when all layers produce together with a common wellbore pressure and a constant total rate.
Heat Transfer in Hydraulic Fracturing
Authors: Meyer Bruce R.
Published: December 2007

An analytical heat transfer model is presented for the combined convection along a vertical fracture with conduction and convection in the reservoir. The model couples the energy (heat transfer) and fracture propagation equations resulting in a closed-form, dimensionless-temperature integral solution.

Major model enhancements include incorporation of (1) a finite film coefficient, (2) time-dependent fracture temperature for calculating the instantaneous heat flux, (3) energy storage in the fracture, and (4) coupled energy and fracture propagation equations. The introduction of a power-law Nusselt number to determine the convection-film coefficient is also new and unique.

The influence of fluid leakoff and a finite convection-film coefficient as heat-reduction mechanisms is discussed. The effect of energy storage and a time-dependent fracture temperature on the heat transfer rate is also illustrated. Finally, simulation studies illustrating the effect of heat transfer on fracture propagation characteristics are presented.
New Laboratory Tests Evaluate the Effectiveness of Gilsonite Resin as a Borehole Stabilizer
Authors: Davis Neal , Tooman Clyde E.
Published: December 2007

Gilsonite® resin is a naturally occurring, mined carbonaceous material classified as an asphaltite. For many years, Gilsonite has been used in drilling fluids as an additive to assist in borehole stabilization. It has been well documented that this material works efficiently to minimize hole collapse in unstable shale sections. However, because Gilsonite is an asphaltite with a high-temperature softening point, duplication of its mending action in laboratory tests conducted at ambient temperatures and low pressures has been difficult.

New laboratory techniques have been developed only recently to evaluate Gilsonite under simulated downhole conditions. With innovative procedures and a newly built downhole simulation cell (DSC), we tested Gilsonite under temperatures and pressures similar to drilling conditions in which the product would normally be used. These tests indicate that borehole enlargement was minimized by use of Gilsonite while substantial enlargement was measured when the same drilling-fluid system was used without Gilsonite.

Another new test procedure was developed to discriminate between various types of Gilsonite products and to determine the most effective product under different temperature and pressure environments. This procedure made use of a high-temperature, high-pressure (HTHP) fluid-loss cell with Berea cores as a filtering medium. Scanning-electron-microscope (SEM) examination of the test cores from both testing procedures provided insight into the mechanisms of how Gilsonite provides stability under downhole conditions. Field data from wells drilled in widely different geological environments support the conclusions reached from laboratory tests.
Prediction of Layer Lengths From Layer Heights for Reservoir Simulations: A Statistical Analysis of Outcrop Data
Authors: Kossack Charles A.
Published: December 2007

This paper describes an attempt to determine the relationship between a geological layer's height and width from published data on outcrops. Data from 11 outcrops are included in the study. A statistical analysis is performed on the highly variable data. The results show some interesting trends, but the basic conclusion is that more data of higher quality are needed from the geological community before correlations such as those shown can be used.

Introduction

History matching reservoir performance or predicting future oil recovery with a numerical reservoir simulator requires a detailed description of the porous medium. The data available from the actual oil reservoir consist of the logs and cores taken from the sparsely drilled wells. In general, we know very little about the variations in the porous media between wells. To fill this information void, geologists have been studying outcrops of rock formations that have depositional environments similar to the oil reservoirs being studied. Because the outcrop data gathered are only a small sample of the total set of rock formation data, a statistical approach must be used when one applies the outcrop results to the oil-bearing formation.

Recently, researcher in the petroleum industry and in universities have been studying the effects of permeability variations and layering on oil recovery. The conclusions, at this point, are that an accurate reservoir description for use in reservoir simulators should contain the best estimate of the formation layer's thickness, length, and mean permeabilities, and the variation of permeability within the layer. One would ultimately like to be able to predict, in a statistical way, all the important formation properties between wells from core and log data, the geological analysis of the depositional environment, and the outcrop studies. This paper describes a small step toward achieving that goal. The results of published outcrop studies are analyzed statistically and compared.

JPT

P. 867^
Solutions of Heat-and Fluid-Flow Problems in Naturally Fractured Reservoirs: Part 2—Fluid-Flow Problems
Authors: Satman A.
Published: December 2007

This paper, the second of two concerning the solution of heat-and fluid-flow problems in naturally fractured reservoirs, covers solutions of fluid-flow problems in naturally fractured reservoirs.

The pressure transients occurring in a naturally fractured reservoir as a result of a constant production (or injection) rate are analyzed. The reservoir systems considered include an infinite and a finite system. Exact solutions and new approximate solutions for drawdown and interference tests are given. These approximate solutions are easy to use for designing and analyzing well test data. Type curves for analyzing pressure data are developed. The model is applied to drawdown and interference field data to illustrate the method of analysis and the applicability of the model.
Kepiting Field Production/Storage Barge - Design, Installation, and Operation
Authors: Carl Albert C. , Satar Sanussi , Liles Stephen P.
Published: December 2007

The Kepiting field is located in 295 ft [90 m] of water in the Natuna Sea, Indonesia. Development of this two-well field required innovative planning andinvolved unique designs of producing systems. The plan includes seafloor wellstied back to a spread-anchored, purpose-built, oil-process and -storage barge. The barge is designed to handle four producing wells and to process 10,000 B/D[1590 m3/d] well fluid and 10 million scf/D [283 × 100 std m3/d] gas. Excessgas beyond barge-fuel needs and artificial-lift requirements is flared on thebarge. Heated oil storage for 53,000 bbl [8430 m3] is available. Processedcrude is transported from the barge to a floating export terminal by a shuttletanker. Kepiting field was operated profitably from Oct. 27, 1986, to Aug. 8,1989, at which time the wells were plugged and the tieback risers disconnected. The production barge currently is operating at the Ikan Pari field, 50 nauticalmiles [80 km] northeast. This paper discusses the design and construction ofthe barge and the operating philosophy and experience.

Discussion

Project Implementation.

The Kepiting field development work-its oil wells, riser system, and the FPSO-was awarded on a basic concept. Bids includeddetailed engineering, from which the final design requirements would evolve. Front-end engineering showed that the proposed systems or their alternativeswould work. As the engineering work progressed and new information (oftenproprietary) became available, changes, alternatives, and details wereselectively included that improved cost-effectiveness or safety aspects(personnel, environmental, and use of resources). The project flow chart isshown in Fig. 3. Major work areas defined were (1) well completion, (2) trees, (3) flexible risers, (4) an FPSO with a shuttle tanker, and (5) a wirelinere-entry system.

This complex project required close coordination to bring thesystems together at the right time. This paper focuses on one aspect of theproject, the design and implementation of the FPSO.

Contracting and Construction.

When we decided to adopt a spread-moored FPSO, we knew that a new build would be required. We chose to lease the FPSO (on abare-boat type of charter) and its companion shuttle tanker (on a timecharter). Therefore, a request for tender was issued for a single-source leasecontract that included detailed design and supply of the FPSO, supply of asuitably equipped shuttle tanker, installing and anchoring the FPSO, startupand 45-day acceptance testing, and identification and procurement of a 2-yearsupply of spare parts. The bid package contained barge hull drawings, processflowsheets, process and instrument drawings (P and ID's), electrical one-linedrawings, specification sheets for equipment identified on the P and ID's, andan instrument index.

JPT

P. 480⁁
Development and Application of the Controlled-Freeze-Zone Process
Authors: Haut R. C. , Denton R. D. , Thomas E. R.
Published: December 2007

The controlled-freeze-zone (CFZ) process is a cryogenic distillation technique for separating CO2 and heavier compounds from methane (C1). This paper describes how the process controls the freezing and melting of CO2 in a specially designed section of an otherwise conventional distillation tower. In addition to describing the process, this paper compares the CFZ process to other gas-treating processes, discusses pilot-plant operational results, and gives examples of potential CFZ applications. The CFZ process is a simple, cost-effective method to process gas streams containing CO2 using proven facilities, equipment, and control philosophies and has been demonstrated through the operation of a large-scale pilot plant.
Simplified GERG Virial Equation for Field Use
Authors: Jaeschke Manfred , Audibert Serge , van Caneghem Patricia , Humphreys A. E. , Janssen-van Rosmalen Renée , Pellei Quinto , Schouten J. A. , Michels J. P. J.
Published: December 2007

A GERG (Groupe Européen de Recherches Gazières) equation of state (EOS) is presented to calculate the compressibility factor of natural gases. The equation, which does not require detailed gas analysis, can predict the compressibility factor when three of the four following gas properties are known: the gross calorific value, the relative density, and the mole fractions of N2 and CO2. The new equation, known as the SGERG-88 virial equation, is based on ideas presented in an earlier study. The new equation, however, applies to wider ranges of temperature and pressure and can be applied to gases containing hydrogen if the mole fraction of the hydrogen is known. The equation was tested on natural gases purchased, transported, and marketed by the European gas companies. Excellent agreement between computed and experimental compressibility factors was found. This difference is, in most cases (94% of the data points), less than 0.1% in the temperature range of 265 to 335 K and for pressures up to 12 MPa.
Analysis of Pressure-Falloff Tests Following Cold-Water Injection
Authors: Bratvold Reldar B. , Horne Roland N.
Published: December 2007

This paper presents generalized procedures to interpret pressure injection and falloff data following cold-water injection into a hot-oil reservoir. The relative permeability characteristics of the porous medium are accounted for, as is the temperature dependence of the fluid mobilities. It is shown that the saturation and temperature gradients have significant effects on the pressure data for both the injection and falloff periods. The matching of field data to type curves generated from analytical solutions provides estimates of the temperature-dependent mobilities of the flooded and uninvaded regions. The solutions also may be used to provide estimates of the size of the invaded region, the distance to the temperature discontinuity, heat capacities, and wellbore-storage and skin effects.
The Prediction of Volumes, Compressibilities and Thermal Expansion Coefficients of Hydrocarbon Mixtures
Authors: Avasthi Surjit M. , Kennedy Harvey T.
Published: December 2007

An equation developed for gaseous hydrocarbon mixtures predicts molal volumes with an average absolute deviation of 0.73 percent when applied to 264 natural gas and condensate systems including 2,043 PVT points. Another equation developed for liquid hydrocarbon mixtures predicts molal volumes with an average absolute deviation of 1.12 percent when applied to 346 crude oil systems including 1,759 PVT points. Both equations require composition of the mixture to be expressed as mole fraction of methane through heptanes-plus, hydrogen sulfide, nitrogen and carbon dioxide, together with the characteristics of the heptanes-plus fraction in addition to the temperature and pressure. The equations cover wide ranges of the variables involved, and their accuracy is considerably better Than that of other available methods.

The equations were differentiated to allow calculation of the coefficients of isothermal compressibility and isobaric thermal expansion. (In this paper the coefficient of isothermal compressibility and the coefficient of isobaric thermal expansion will be expressed as compressibility and thermal expansion coefficient, respectively.) Equations to calculate these quantities are presented.

Introduction

Calculations of reservoir performance for petroleum reservoirs require accurate knowledge of the volumetric behavior of hydrocarbon mixtures, both liquid and gaseous. Compressibilities are required in transient fluid flow problems, and thermal expansion coefficients are important in thermal methods of production.

An accurate laboratory investigation of the PVT behavior of each reservoir fluid encountered would be costly and time consuming. For this reason various correlations for predicting fluid properties have been developed and recorded and recent literature. Correlations have been presented in the form of graphs, tables and equations. Since an increasing number of studies are being conducted with the aid of electronic computers, recent efforts have been directed toward development of correlations suitable for computer programming. Application of computers permits the use of more complex correlations which otherwise are not feasible. Moreover, methods for predicting reservoir performance, particularly those based on the compositional material balance, depend upon the capability of accurately expressing the molal volumes and other fluid properties as functions of pressure, temperature and composition.

The coefficient of isothermal compressibility c is defined by(1)

and can be computed from the slope of isothermal specific volume curve for each pressure. The compressibility is a point function and has the dimension of reciprocal pressure.

The coefficient of isobaric thermal expansion beta is defined as(2)

It is a point function and has the dimension of reciprocal temperature. The thermal expansion coefficient can be obtained from the slope of an isobaric specific volume curve for any temperature.

SPEJ

P. 95ˆ
A Field Application of Pulse-Testing for Detailed Reservoir Description
Authors: McKinley R.M. , Vela Saul , Carlton L.A.
Published: December 2007

Johnson et al. have described a new well-testing technique that measures formation flow properties between wells. The technique, called pulse-testing, requires a sequence of rate changes in the flow at one well and measurement of the resulting pressure changes at an adjacent well with a very sensitive differential pressure gauge.

This paper describes an extensive application of the technique in a producing oil field. Pulse-tests on 28 of 45 possible well pairs in the field provided a picture of the areal distribution of reservoir hydraulic diffusivity, transmissibility and storage. The primary objective in presenting these data is to demonstrate the potential of the method for reservoir description. A second objective is to show in three ways the qualitative and quantitative accuracy of reservoir parameters determined from pulse-tests:pulse-test data show a nonuniformity in the field, closely correlating with the oil-water distribution as given by production data;pulse-test values for permeability are comparable with core values, andperhaps most important, the field responds to a conventional interference test in the manner in which pulse-test data predict it should.

Introduction

The pulse-testing technique by Johnson et al. is an ideal source of data for purposes of reservoir description, for it provides a measurement of formation storage S = phi ch, hydraulic diffusivity eta = k/phi c mu and transmissibility T kh/mu between wells.

This paper describes an application of this method in a producing oil field. Results were analyzed to give numerical values for the parameters eta, T and S. These values were compared with oil-water production data (for the effect of fluid saturation), with core data and with data from an interference test.

The reservoir in which the pulse-test survey was run is the result of a structural trap formed by a fault along the east side of a north-south trending anticline. A down-structure aquifer provides a natural flank water drive for the pool. The producing formation is a dolomitic limestone having mainly vugular permeability; the formation oil has a gravity of 29 degrees API with negligible dissolved gas. The field contains 19 wells, all on pump, arranged on 40-acre spacing along the top of the anticline.

Fig. 1 shows the location of all these wells except two at the south end of the field. The dashed line on the righthand side of the figure represents the approximate location of the fault with respect to well positions.

Pulse-Test Survey and Analysis of Data

A pulse-test requires a pulsing well and a responding well.

JPT

P. 313ˆ
Computation and Interpretation of Capillary Pressure From a Centrifuge
Authors: Skuse Brian , Flroozabadi Abbas , Ramey Henry J.
Published: December 2007

Centrifuge capillary pressure measurements usually are conducted at atmospheric air pressure. In such measurements, any capillary pressure exceeding atmospheric pressure requires a negative pressure in the wetting phase. Experiments were conducted to examine the effect of air pressure on air/brine capillary pressure. First, drainage capillary pressure curves were determined for six low-permeability core samples under atmospheric pressure. Then, drainage capillary pressure curves were determined at an elevated air pressure of 112 psia [0.77 MPa] for the same samples. The two capillary pressure curves for each core sample generally are in close agreement. Both measurements reported in this paper and data from the literature indicate stable behavior for the wetting phase under negative pressure conditions.
Prediction of Sulfate Scaling Tendency in Oilfield Operations
Authors: Yuan M. D. , Todd A. C.
Published: December 2007

This paper presents a model for predicting the scaling tendencies of barium, strontium, and calcium sulfates resulting from the mixing of injected and formation waters and from temperature and pressure effects. The model also predicts competitive simultaneous coprecipitation of BaSO4, CaSO4, and SrSO4, where sulfate is the common ion, reflecting the precipitation of more than one sulfate mineral. The supersaturations and amounts of precipitation of the sulfates are calculated from their solubilities, which in turn are calculated by the Pitzer equation for electrolyte ion activity coefficients.
In-Situ Stress Tests and Acoustic Logs Determine Mechanical Properties and Stress Profiles in the Devonian Shales
Authors: Gatens J. M. , Harrison C. W. , Lancaster D. E. , Guidry F. K.
Published: December 2007

The in-situ stress contrast between a reservoir rock and the surrounding formations is important to the design and analysis of hydraulic fracture treatments. The stress contrast between layers controls the fracture's vertical (height) growth, which in turn affects the fracture length and width. As part of the Gas Research Inst.'s (GRI's) Comprehensive Study Well (CSW) program in the Devonian shales of the Appalachian basin, we measured in-situ stresses directly and used these values to calibrate acoustic log measurements to develop stress profiles across the Devonian shales. This discusses the measurement and interpretation of in-situ stresses, the use of acoustic logs to determine mechanical properties and a more complete stress profile, and the practical use of the stress profile in fracture-treatment design and analysis.

In-situ stresses were measured directly throughout the Devonian shale interval with both openhole and cased-hole stress tests, conducted with nitrogen, a specially designed downhole shut-in tool, and a downhole quartz pressure gauge with surface readout. The paper describes the procedure used and presents interpreted stress-test results from two CSW's. Full-waveform acoustic tools were run to define elastic properties of the Devonian shales. These properties also were determined under both static and dynamic conditions from whole-core plugs taken in the shales. Logs were calibrated to core-measured values, and then elastic properties determined from the logs were used to compute an in-situ-stress profile, which was calibrated against field measurements of in-situ stresses. Finally, we discuss how these data are used to design and analyze hydraulic fracture treatments in CSW's.
Reservoir-Fluid Property Correlations—State of the Art
Authors: McCain W. D.
Published: December 2007

This paper presents correlations to determine reservoir-fluid properties from field data. The best available correlations were selected by comparison with a data base of hundreds of reservoir-fluid studies of samples representing all areas of the free world involved in active petroleum exploitation from 1980 to 1986. Also, correlations of formation-water properties are given.
Effect of Rotary Speed and Bit Weight on Penetration Rate of a Diamond Microbit
Authors: Dolph Jim R. , Brown Kermit E.
Published: December 2007

Presented are results of experiments on the penetration of a 1.25-in. OD diamond microbit into Georgia granite and Beekmantown dolomite. A study of the effect of bit weight and rotary speed on the penetration rate was carried out, at simulated borehole conditions, while following the effect of wear on the performance of the diamond bit.

A microbit drilling appartus was used, which enabled the control of rotary speed, weight on bit, circulation rate, hydrostatic pressure and overburden and formation fluid pressures. A 500 psi hydrostatic pressure and an atmospheric formation pressure were held constant since the only pressure that substantially affects drilling rate is the differential between the hydrostatic and formation pressures. Since it has been found that "confining pressure has no systematic influence on drilling rate" it was controlled at 500 psi in order to decrease equipment problems.

Quarried samples of Georgia granite and Beekmantown dolomite with respective grain densities of 2.64 and 2.72 gm/cc and compressive strengths of 17,000 and 24,200 Ib/ sq in. were drilled. The very low permeabilities of the samples enabled the use of water as a drilling fluid. A circulation rate of 7.3 gal/min was maintained throughout the tests.

A 1.25-in., surface-set, spiral-type diamond drill bit was used. The bit consists of 14.75 carats of 219 diamonds, giving an average diamond size of 15 diamonds per carat.
Application of Higher-Order Methods in Compositional Simulation
Authors: Saad Naji , Pope Gary A. , Sepehrnoori Kamy
Published: December 2007

A third-order differencing scheme is described and compared with several alternative methods commonly used to discretize the convection term of the component conservation equations of compositional simulators. This new method can be used at higher cell Peclet numbers than those used with other common convective differencing schemes, resulting in a substantial saving in computation time for the same accuracy. Comparisons are made with analytical solutions and with 2D and 3D simulation results for single-point upstream weighting, two-point upstream weighting, and Chaudhari's method.
An Analysis of Gravity-Segregated Piston-Like Displacement in Stratified Reservoirs
Authors: Ekrann Steinar
Published: December 2007

This paper develops the conditions for gravity-stable displacement in stratified reservoirs. Results are given for the shape of a gravity-stabilized displacement front and for the asymptotic behavior of nonstable segregated fronts. Partial stability may prevail in the latter case. The analysis assumes piston-like displacement and incompressible fluids and is based on the vertical-equilibrium (VE) approximation.
Estimation of Solution GOR of Black Oils
Authors: Rollins John B. , McCain William D. , Creeger Todd J.
Published: December 2007

An empirical equation was developed to estimate stock-tank GOR from field data for black oils. Solution GOR at or above bubblepoint pressure can be obtained as the sum of the estimated stock-tank GOR and the measured separator GOR. The equation was derived with data from two-stage separations of 301 black-oil samples.

Introduction

Volumetric and material-balance calculations of oil in place require estimates of oil FVF and bubblepoint pressure. Several correlations, the most applicable of which was proposed by Standing, I are available for determining bubblepoint pressure and oil FVF when an estimate of solution GOR is available. Frequently solution GOR, Rsb, is estimated for pressures at or above the bubblepoint by setting its value equal to the initial producing GOR.

However, the initial producing GOR often does not include gas vented from the stock tank. This omission can cause the estimate of Rsb to be low by 20 % or more. 2 The inaccurate estimate of Rsb then introduces error into estimates of bubblepoint pressure and FVF, and hence into oil-in-place calculations. This paper presents a method of using readily available field data to obtain an accurate estimate of Rsb. Total producing GOR, R, is equal to the sum of stocktank GOR, Rst, and separator GOR, Rsp.
The Changing Scene in Labor Relations
Authors: Sartain A.Q.
Published: December 2007

A fundamental labor relations problem is understanding and motivating the "new model" of American worker with his increased information and insistence upon equality and dignity. Unionization shows little promise of meeting this problem, but unfortunately neither do management thinking and actions. Apparently, best prospects for unionization are professional workers.

Introduction

It would seem that, in an age of many and tremendous changes, almost everyone would be aware of those changes and of their nature and extent. Such however is far from the actual situation.

For one thing, many changes, while very large in the aggregate, may be the result of small daily or weekly variations and hence difficult to see, especially for the nearby viewer. For another, we have prejudices and preconceptions that block our appraisal. This is true in the technological field, but even more so in human relationships.

A single illustration will have to suffice. There are a host of beliefs about human beings, widely accepted and seldom questioned, that have no evidence to support them but that at the same time provide the explicit or implicit basis for much decision and action. Examples are "Human nature never changes," "Everyone is out for himself to get as much as he can for as little as he can put out," "People (and especially people in the lower classes) have an inherent resistance to change," "The only way to a worker's heart is through his pocketbook," and literally dozens more (including much of what passes for "principles of management"). All of these statements are false if not positively and seriously misleading; and they greatly distort and guarantee the inaccuracy of our conclusions.
Adaptive-Implicit Method in Thermal Simulation
Authors: Oballa Viera , Coombe Dennis A. , Buchanan W. Lloyd
Published: December 2007

An adaptive-implicit method (AIM) for thermal simulation that provides different degrees of implicitness in various gridblocks is discussed. A special treatment of flow terms during appearance or disappearance of any particular phase is critical. This treatment creates a more stable Jacobian matrix, especially in cases where an implicit block is downstream of an explicit neighbor. The maximum eigenvalue of a local amplification matrix, which is related to a dimensionless front velocity, determines the switching between implicit and explicit treatment. The switching, which is automatic and problem-independent, is superior to classical threshold switching based on the magnitude of changes of key reservoir variables. Results from the simulation of several thermal recovery processes are presented. The saving in computer time over a fully implicit method ranges from 34 to 62%. The maximum savings can be achieved in the simulation of large field-scale problems in which the fronts are moving fairly slowly.
Compositional Reservoir Simulation on Microcomputers
Authors: Young L. C. , Hemanth-Kumar K.
Published: December 2007

The practicality of solving compositional reservoir simulation problems with microcomputers is investigated. The results show that, when coupled with efficient simulation software, microcomputers are effective in the solution of moderate-sized problems. For example, a problem with 4,000 gridpoints, 7 components, and 200 timesteps can be solved in less than 2½ hours.
Utilization of Mainframe Network To Distribute PC Software
Authors: Glynn G. J. , Ottinger M. B.
Published: December 2007

The corporate network of mainframe computers is being used to distribute PC software to engineering staffs company-wide. This method provides a single, easy-to-use source for PC software and requires significantly less manpower both to distribute and to receive software vs. the traditional means of using diskettes.
Radio Alarm Monitoring System
Authors: Meek J.W.
Published: December 2007

A radio alarm monitoring system, serving eight widely separated leases, has been operated since Jan., 1966, by Pan American Petroleum Corp. in the vicinity of Hobbs, N. M. Twelve oil wells and four gas wells are being served by single-channel transmitters at each lease, with receivers located at the pumper's base station and in his truck. The pumper's work area includes the alarmed leaves and four non-alarm leases. These leases encompass approximately 580 sq mile, with the nearest lease located some 30 miles from the pumper's base station.

As a result of satisfactory operation of this system, labor requirements to pump the leases have been reduced by 40 percent with no loss in production. A radio alarm monitoring system of this type is considered to be a reliable method of reducing operating costs where conditions warrant. This paper discusses the radio equipment in use and the type of alarms installed at different leases to make remote monitoring possible. Also discussed is the field fabrication of a minimum production alarm that has proved reliable.

Introduction

In early 1964, Pan American Petroleum Corp. considered using alarms on some isolated properties to develop more economic operation. From knowledge of these properties and information on alarm functions and capabilities, it was decided that an alarm system would be designed around the basic idea of the pumper's concentrating his time at the Greenwood unit battery. Alarms would be transmitted from outlying marginal leases to notify him that some operating problem required his attention. By transmitting alarms to a base station, 24-hour surveillance could be maintained, permitting the pumper to schedule his time to visit alarmed points during his regular work day.

One significant location was the northern Delaware Basin area where scattered properties ranged in productivity from high capacity to marginal and where there was a greater potential for reducing labor costs by eliminating contract pumping jobs. Since the properties under study involved various types of production over a large area, careful consideration was given to the number of wells that with proper monitoring, could be handled by one man. Because of the distance from existing telephone lines, radio transmission was considered the best available means of furnishing alarms. This paper discusses the system that was installed.
Integral Equations for the Problem of a 3D Crack in an Infinite, Fluid-Filled, Poroelastic Solid
Authors: Kurashige Michlo , Clifton R. J.
Published: December 2007

Two integral equations are derived for the 3D problem of a pressurized plane crack in an infinite, fluid-saturated, poroelastic solid. These equations relate normal tractions and fluid pressures on the crack faces to crack openings and fluid injection rate per unit fracture area. An important application of these equations is the prediction of hydraulic fractures induced during waterflooding of reservoirs to enhance gas and oil recovery.
Rock/Fluid Interactions of Carbonated Brines in a Sandstone Reservoir: Pembina Cardium, Alberta, Canada
Authors: Sayegh S. G. , Krause F. F. , Girard Marcel , DeBree Cornelius
Published: December 2007

When CO2 is injected into petroleum reservoirs it forms carbonic acid in the brine phase and interacts with reservoir rock. Row tests were performed by continuously circulating CO2-saturated brines through Cardium formation cores. All the cores initially showed a large drop in permeability, after which permeability rose steadily but did not regain its initial value. Microscopic examination of the cores indicated that fines had been released and had migrated toward pore throats, reducing permeability. In addition, mineral alterations occurred, including the dissolution of calcite and siderite, which may account for the gradual rise in permeabilities noted in the experiments.