bluuebunny/crossref_metadata_2025 huggingface dataset:
A Numerical Solution to the Unsteady-State Partial-Water-Drive Reservoir Performance Problem
Authors: Henson Walter L. , Wearden Paul L. , Rice John D.
Published: December 2007

Solutions to the unsteady-state partial water-drive reservoir performance problem can be obtained through the use of analogue computers or high-speed electronic digital computers. The solutions that have previously been resolved for use on digital computers, however, demand a knowledge of the aquifer parameters. Generally, the analogue computers now in use do not require this knowledge.

A solution is presented herein where the aquifer performance, expressed in terms of difference equations, is related to the reservoir performance as expressed by the modified Schilthuis material-balance equation. A numerical procedure for a medium-sized digital computer also is presented in which a solution to the set of equations defining the aquifer and reservoir performance is obtained and the aquifer parameters (permeability and sand thickness) are automatically optimized while simultaneously matching the known pressure behavior. Predicted pressure behavior can be calculated using rates from any assumed future production practice. The procedure provides an output format which presents the cumulative, incremental and average rate of natural water influx, the per cent gas-cap expansion, the calculated reservoir pressure, the measured reservoir pressure, and the difference between the measured and calculated pressures.

Results of a test problem are presented in comparison with results obtained by the Bruce Analyzer, Ohio Oil Co.'s Pace General Purpose Analogue Computer, and Sun Oil Co.'s Single-Pool Electronic Reservoir Analyzer. These results indicate that unsteady-state reservoir performance for a single-pool system can be adequately simulated by a numerical method employing a digital computer and that the special-purpose analogue computer can be supplanted by this method.
Development of Large, Nickel-Based Alloy 925 Composite-Block Trees for Extreme-Corrosion, Fire-Resistant Applications on Offshore Platforms
Authors: Haeberle Timothy , Kovach Paul J.
Published: December 2007

This case study presents the development of the first large components to be manufactured from nickel-based Alloy 925 for oilfield use: nine composite-block trees used on an offshore production platform producing gas/condensate containing H2S, CO2, and chlorides. Details are provided on the material selection process and the manufacture (forging, heat treating, and machining) of the composite blocks and smaller equipment. This report introduces Alloy 925 as a candidate for future oilfield applications, providing performance benefits for special design requirements.
Improving Wellhead Performance With Programmed Cement Shortfall
Authors: Britton J. S. , Henderson G.
Published: December 2007

Subsea wellheads can be subjected to extreme external loads when a drilling or production riser remains connected during storm or vessel drive-off conditions. In addition, vortex shedding from high currents and wave action on drilling and production risers can subject the wellhead to high-cycle fatigue loads. These extreme external and high-cycle fatigue loads can cause failure of the wellhead system when a fully cemented annulus between the 30-in. [76-cm] structural conductor pipe and 20-in. [51-cm] surface casing is not achieved. This effect of cement shortfall is most damaging when the cement level is just below the wellhead-body/conductor-housing region. Purposefully setting the cement level far below the mudline can be a cost-effective solution to the unintentional cement-shortfall problem.
Droplet-Settling vs. Retention-Time Theories for Sizing Oil/Water Separator
Authors: Arnold Kenneth E. , Koszela Paul J.
Published: December 2007

This paper discusses two techniques for sizing oil/water separators. Droplet-settling theory, based on Stokes' law governing water-droplet movement through a continuous oil phase, is used to develop sizing equations for both horizontal and vertical separators. Retention-time theory, which calculates theoretical fluid-retention time within the separator by relating liquid flow rates to vessel geometry, is also presented. Published separator data comparing vessel sizes to allowable capacities are analyzed using both sizing techniques.
Hydrocyclones: A Solution to Produced-Water Treatment
Authors: Meldrum N.
Published: December 2007

Progressing into deeper water and more hostile environments in the search for new oil and gas reserves has placed an increasing demand on the industry to develop lighter, more compact, and more efficient process equipment to replace their traditional counterparts. A recent application of cyclone technology for liquid/liquid separation of oil from produced water has shown considerable promise during extensive field testing. This paper outlines the basic construction and principle of operation of the deoiling hydrocyclone and discusses system design, early operational experiences, and test results from the first full-scale commercial application of the four-in-one hydrocyclone concept on the Murchison platform. In addition, and of perhaps more significance, early results from field tests of the larger 60-mm [2.4-in.] cyclones on the Hutton tension leg platform (TLP), where conventional equipment was adversely affected by platform motion, are discussed.
Development and Results of the Hale/Mable Leases Cooperative Polymer EOR Injection Project, Vacuum (Grayburg-San Andres) Field, Lea County, New Mexico
Authors: Hovendick M. D.
Published: December 2007

This paper presents a case history of the design, implementation, and results of a tertiary polymer EOR injection project conducted by Phillips Petroleum Co. in their Hale and Mable leases located in the Vacuum (Grayburg-San Andres) field, Lea County, NM. Polymer is being injected at a relatively low concentration, and the paper concludes that, given the reservoir rock and fluid properties prevalent in the Hale and Mable leases, a low-concentration polymer flood is just as effective as a higher-concentration flood as long as the total pounds of polymer injected is the same.
Type- and Decline-Curve Analysis With Composite Models
Authors: Olarewaju Joseph S. , Lee W. John , Lancaster David E.
Published: December 2007

This paper presents applications of new type curves generated with a composite model for the analysis of radially damaged and stimulated wells. These type curves can be used to estimate the depth and degree of damage or stimulation. Some of the type curves include phase redistribution, and the production type curves can be used to forecast incremental production from the stimulation of damaged wells.
The Value and Analysis of Core-Based Water-Quality Experiments as Related to Water Injection Schemes
Authors: Todd A. C. , Kumar Tarkeshwar , Mohammadl Shahrokh
Published: December 2007

This paper describes an experimental study of formation damage associated with low-concentration particle invasion in water injection schemes. Depth-of-invasion results are presented, the importance of core preparation is stressed, and the results from conventional cut-faced plugs are compared with those from the broken-faced plugs used in this study.
Innovative Devices for Testing Drilling Muds
Authors: Zamora Mario , Lai Damon T. , Dzialowskl Andrew K.
Published: December 2007

There are ample incentives and opportunities to improve current mud-testing equipment and to develop new instruments to measure mud properties not previously tested. This paper discusses three innovative devices for testing drilling muds: the automatic shearometer unit, the high-temperature/high-pressure (HTHP) dynamic filtration tester, and the filter-cake penetrometer. Each discussion includes a summary of previous technology, current API standards (if available), equipment description, and selected case studies.
Alternative Flow-Pattern Maps Can Improve Pressure-Drop Calculations of the Aziz et al. Multiphase-Flow Correlation
Authors: Al-Najjar Hazim S. H. , Al-Soof Nimat B. Abu
Published: December 2007

An improvement in pressure-drop calculations of the Aziz-Govier-Fogarasi multiphase-flow correlation is presented. This improvement was achieved after several combinations of different flow-pattern maps with the correlation were attempted.

Field data taken from 15 flowing oil wells of an Iraqi oil field and the published data of Poettmann and Carpenter and Chierici et al. are used for testing the performance of the various combinations. The introduction of ± 15% uncertainty in the values of bubblepoint pressures and solution GOR's predicted by the Vasquez fluid-property correlation appears to have insignificant effects on pressure-drop calculations. The effects of changing the direction of pressure-drop calculations confirms the findings of the work of Gregory et al.

Although all the attempted combinations show an improvement in pressure-drop calculations over the original correlation, the Duns-Ros flow-pattern-map combinations produce the best results. Its overall absolute average percent deviation for the Iraqi oilfield data set is 3.05%, compared with 7.23% for the original correlation. Also, the percent of calculated pressure-drop points deviating by more than ± 5% from the observed points is reduced from 52.5% for the original correlation to 17% for this combination.
Calculating Effective Absolute Permeability in Sandstone/Shale Sequences
Authors: Deutsch Clayton
Published: December 2007

Two averaging algorithms are proposed for determining block effective absolute permeability. The experimental relationship between the effective permeability, the volume fraction of shale, and the anisotropy of the shales is first observed through repeated flow simulations. A power-averaging model and a percolation model are proposed to fit the experimentally observed relationship. The power-averaging model provides a surprisingly easy and efficient way to calculate block effective absolute permeability. A simple graph is given to determine the averaging power from the geometric anisotropy (aspect ratio) of the shales for both vertical and horizontal steady-state flow. The effective absolute permeability can then be calculated with the averaging power, the volume fraction of shale, and the component sandstone and shale permeabilities. The effective permeability of a sandstone/shale sequence is affected when the shales are large with respect to the size of the gridblocks. A correction for large shales relative to small gridblocks is also proposed.
Experimental and Simulation Study of High-Temperature Foam Displacement in Porous Media
Authors: Friedmann François , Chen W. H. , Gauglitz P. A.
Published: December 2007

High-temperature surfactant foams are simulated by modifying gas-phase mobility in a conventional thermal simulator. Both surfactant-alternating-gas (SAG) and gas/liquid-coinjection processes are modeled. Foam generation by leave-behind and snap-off as well as foam coalescence and trapping mechanisms are incorporated in the model by an equation for the number density of foam bubbles; gas-phase relative permeability and apparent viscosity are modified according to the bubble density. Pressure and saturation data of laboratory corefloods are successfully history matched with simulation results. Field-scale sensitivity studies of the steam-foam-drive process demonstrate how the coalescence rate affects the extent of steam diversion.
An Experimental Investigation of the Fireflooding Combustion Zone
Authors: Kumar Mridul , Garon A. M.
Published: December 2007

In a laboratory study, an automated, linear-traversing, sampling probe enabled real-time gas analysis and temperature measurements within the combustion zone. Results showed that the combustion-zone thickness was on the order of 1 in. [25 mm] for a nominal injected air flux of 20 scf/hr-ft2 [1.7 × 10-3 std m3/s·m2]. The combustion-zone thickness was found to be kinetically controlled. The combustion reaction could not be represented by the commonly used first-order, Arrhenius kinetics; however, the actual kinetics of combustion is unimportant for performance prediction because the combustion-front velocity is oxygen-flow-rate-controlled.
Cold Lake Cyclic Steam Stimulation: A Multiwell Process
Authors: Vittoratos E. , Scott George R. , Beattie Craig I.
Published: December 2007

Cyclic steam stimulation (CSS) typically is thought of as a single-well process. At Cold Lake, however, where steam injectivity is achieved by fracturing the formation, considerable interwell communication is observed. The result is usually the watering out of a producer by condensed steam from a neighboring injector. These interwell interactions greatly complicate steam-injection scheduling for commercial projects involving hundreds of wells but do not seem to reduce bitumen production in early cycles. Field experience indicates that steaming rows of wells sequentially with 50% overlap in injection time between adjacent rows significantly reduces water transfer between wells, increases the conformance of the injected heat, and reduces the field's tendency to form communicating well couplets. Exploratory numerical simulations show that the impact of steaming strategy on bitumen production is not significant until later cycles.
High-Temperature Relative Permeabilities for Athabasca Oil Sands
Authors: Poilkar M. , Farouq All S. M. , Puttagunta V. R.
Published: December 2007

An experimental study of Athabasca bitumen/water relative permeabilities revealed little or no temperature effect on the relative permeabilities to water and bitumen over a range of 100 to 250°C [212 to 482°F]. Comparable results were obtained with both steady- and unsteady-state relative permeability measuring techniques. It was determined that the oil-phase relative permeability curve was convex. Measured curves were also compared with those obtained by history matching.
Production From Naturally Fissured Reservoirs Intercepted by a Vertical Hydraulic Fracture
Authors: Naceur K. Ben , Economides M. J.
Published: December 2007

A model is developed to simulate the behavior of naturally fissured and anisotropic reservoirs intercepted by a hydraulically induced vertical fracture of finite or infinite conductivity. The method is based on a numerical discretization of the formation, which is represented by a double-porosity model, for which transient interporosity solutions for pressure and cumulative production are presented. It is shown that matching the pressure behavior for those formations with homogeneous isotropic models leads invariably to a fracture length that is smaller than the actual fracture length.
Steamflood Material-Balance Applications
Authors: Peake W. T.
Published: December 2007

A simple steamflood material balance derived from a two-zone reservoir model is presented. Alternative forms of the material balance include the effects of an initial hydrocarbon gas saturation, PV compressibility, and a hot-water zone. In example applications, the material balance is used to calculate the amount of fluid migration from a 16-pattern steamflood pilot and the steam injection rate within a regular five-spot pattern.
Steamflooding in a Waterdrive Reservoirs Upper Tulare Sands, South Belridge Field
Authors: Dietrich James K.
Published: December 2007

A steamflood project in the strong edgewater-drive Upper Tulare reservoir at South Belridge recovered about 31% of the original oil in place (OOIP) at a cumulative steam/oil ratio (SOR) of 2.7 vol/vol. Seven years of downdip steam injection depressed water influx and created an oil bank updip from the injectors. Response continued under the influence of returning aquifer water and heat scavenging after the injectors were shut down.

Numerical reservoir simulation of the historical steamflood performance indicated that the high production/injection capacity (P/I) ratio induced early water encroachment and partial quenching of the growing steam zone. Restarting downdip steam injection at much higher rates after 6 years without injection was shown to recover more oil than continuing the steamflood with either a seven-spot or inverted nine-spot pattern.

An efficient steamflood operating policy in an edgewater-drive environment involves overproducing in the oil column to reduce reservoir pressure combined with high-rate downdip pumping of the aquifer to reduce water inflow during steam injection. Downdip steam injection rates greater than 100 B/D-acre and P/I ratios of about 1.4 STB/STB emerged as reasonable operating parameters in several projects.
The Optimization of Slant-Well Drilling in the Lindbergh Field
Authors: Vrielink H. J. , Hlppman A. M.
Published: December 2007

Since 1985, Dome Petroleum Ltd. has developed slant-well drilling in the Lindbergh heavy-oil field in east-central Alberta. The oil-bearing sands occur in the lower Mannville formations of the Cretaceous period. To date, four pads, each consisting of 15 or 16 wells, have been completed. The experience gained in completing these projects has allowed us to make optimum use of slant-well technology in multiwell pad applications.

The heavy-oil reservoirs in the Lindbergh field contain oil with a gravity of 0.98 g/cm3 [12.5° API]. The reservoir is at a vertical depth of 600 m [1,970 ft]. The wells are drilled on 4-ha [10-acre] spacing and placed on primary production for 2 years, after which steam stimulation is used for EOR. This primary production of cold oil has significant economic impact on the development of this field because capital recovery is achieved for drilling and completion before the massive investment into steam generation and distribution facilities. Maximizing this primary recovery requires that low-dogleg-severity (DLS), "straight" holes be drilled.

The Lindbergh area is characterized by high agricultural land use. With slant-well technology, the required spacing unit is achieved with minimum surface land usage, optimum hole quality, and minimum environmental impact. In this application, slant-well drilling provides an attractive alternative to conventional directional multiwell pad projects.

In the initial stages of slant-well development, drilling times of 5.5 days/well and costs** of $315/m [$81/ft] were experienced. Through an optimization process involving pad design, drilling equipment, casing design, bits and hydraulics, and directional/survey assemblies, significant savings in drilling time and cost were realized. To date, 71 slant wells have been drilled. In the latest project, drilling time averaged approximately 2 days/well and costs were reduced to $177/m [$45/ft]. These savings were achieved with an improvement in directional control and overall hole quality. This paper describes the optimization process and the techniques used to realize these savings.
Field Test Results With Alkaline Potassium Solutions To Stabilize Clays Permanently
Authors: Sloat Ben F.
Published: December 2007

The use of concentrated KOH to stabilize clays is becoming a common practice in Wyoming. Seventy-two injection wells, ranging from single pilots to fieldwide programs, have been treated and monitored since the technology was first introduced in Aug. 1984. This paper summarizes test results that fall into three broad categories: (1) those that increase recoverable reserves, (2) those that speed the rate of waterflood oil recovery, and (3) those that do more harm than good. Wells in the first two groups are examined starting with treatment design and wellsite preparation and moving on through the pumping stages to final evaluation of the results. The mixing and handling of highly alkaline solutions are covered from the service company and operator safety viewpoints, and with respect to the fluid-quality, chemical, and metallurgical requirements for proper placement of the solutions. Two wells are singled out for their special contribution to the learning-curve aspect of this new technology and for their value in helping to avoid making the same mistakes again.
Planning Directional Wells Through a High-Density Cluster of Existing Wells
Authors: Wang Zhihua , Inglis Tom A.
Published: December 2007

This paper describes a method for determining the optimum well path through a high-density cluster of existing wells by considering the close proximity of the other wells. A simple 2D or 3D path is proposed, checked for proximity to the other wells, and then modified if necessary according to dogleg severity and the proximity of neighboring wells. An example using North Sea data is presented.
Annulus Corrosion in High-Temperature Gas Wells
Authors: Sutanto Henry , Semerad V. A. W.
Published: December 2007

This paper details experience with corrosion in the annuli of wells in the Aran field, north Sumatra, Indonesia. Wells in this field characteristically have high production temperatures, rates, and pressures, and the produced fluids contain the potentially corrosive constituents CO2 and H2S. The field has been in production for about 10 years, and a number of wells have been worked over once or even twice. These workovers have detected corrosion problems that have led to changes in completion practices and have focused attention on methods to monitor and to detect ongoing annular corrosion.

It is normal practice to fill the annulus between the last cemented casing in a well and the production tubing with a noncorrosive "packer" fluid. Various types of packer fluid have been used in the Arun wells, and some of these fluids have caused unforeseen corrosion problems, which led to workovers to replace the problem fluid.
Use of Barometric Response to Obtain In-Situ Compressibility of a Coalbed Methane Reservoir
Authors: McKee Chester R. , Bumb Amar C. , Horner D'Arcy M.
Published: December 2007

A theory is presented for calculating the constrained (matrix) compressibility for aquifers from responses to tides and changes in surface pressure when both gas and water are present. With this theory, a new method to determine matrix compressibility without a pump test is developed. The method is then applied to a coalbed methane well in the Piceance basin.
Full-Field Compositional Modeling on Vector Processors
Authors: Young L. C.
Published: December 2007

Large full-field simulations have not previously been feasible with equation-of-state (EOS) compositional models. This paper describes an approach for efficient EOS calculations. The approach is based on a model formulation that minimizes the number of calculations together with vector processing to maximize the calculation rate. Tests of a simulator based on the approach show that large problems can now be solved. For example, a problem composed of nine components, 20, 000 gridpoints, and 1, 000 timesteps can be solved in as little as 15 minutes of CPU time.
Cleaning the Valhall Offshore Oil Pipeline
Authors: Marshall G. Robert
Published: December 2007

Severe wax deposits built up in the 20-in. [500-mm] Valhall subsea crude oil pipeline over a period of years. The successful program to remove these deposits gradually but completely with a series of foam and mechanical pigs is described, including details on equipment and procedures. The unique risks and difficulties associated with solids removal in offshore pipelines are discussed.
Resistance of Cemented Concentric Casing Strings Under Nonuniform Loading
Authors: El-Sayed A. A. H. , Khalaf Fouad
Published: December 2007

This paper discusses the case of two opposing unidirectional collapse loads uniformly distributed along the diameter of a single casing string and two cemented concentric casing strings. The stress distribution in the casing and cement and the deformation of the pipe are determined by adapting known solutions in the mathematical theory of elasticity to the problem of single- and dual-casing strings subjected to this type of loading. Results were obtained for the case of uniform hydrostatic radial collapse loads for the two casing sizes (9⅝ and 7 in.) and their cemented structures. The resistance of the single pipe to this type of nonuniform loading may drop to 11 % of its design resistance to uniform hydrostatic collapse pressure. The resistance of the cemented concentric strings under uniform and nonuniform loads is about the sum of the steel pipe resistances under the same conditions. The paper also includes the superposition of uniform and nonuniform collapse loads and the practical implications of these results. We conclude that nonuniform loading should be considered in casing design, especially opposite salt formations.
Downhole Casing Corrosion Monitoring and Interpretation Techniques To Evaluate Corrosion in Multiple Casing Strings
Authors: Watfa Mohamed
Published: December 2007

This paper reviews new developments in monitoring the corrosion of downhole casings. The results presented are based on corrosion-monitoring data from a large number of wells. The interpretation procedure outlines techniques for estimating metal losses, corrosion rates, and detection of holes in single and multiple casing strings.
Corrosion and Stress-Corrosion Cracking of Aluminum Alloy Drillpipe in a Water-Based, Low-Solids, Nondispersed Drilling Mud
Authors: Ciaraldi Stephen W. , Grimes David R. , Nichols Henry F. , Moore Steven O.
Published: December 2007

Corrosion and stress-corrosion cracking (SCC) tests were performed on aluminum drillpipe Alloy 2014-T6 in a water-based, low-solids, nondispersed (LSND) drilling mud. Variables examined included chloride concentration, temperature, state of aeration, and effects of galvanic coupling to tool-joint steel. Electrochemical corrosion test results suggested that the aluminum alloy has adequate corrosion resistance to at least 71°C [160°F], even when it is galvanically coupled to steel in aerated muds. However, SCC susceptibility of the alloy in aerated muds was clearly demonstrated by slow-strain-rate and rising-stress-intensity/SCC tests. SCC did not occur in deaerated muds. We concluded that oxygen scavenging and monitoring are important to the successful performance of aluminum alloy drillstrings in chloride-containing, water-based, LSND drilling muds. These conclusions were confirmed by excellent field performance.
Instrument Performance Models and Their Application to Directional Surveying Operations
Authors: Thorogood John L.
Published: December 2007

When planning, monitoring, or checking the results from a directional surveying program, one must be able to predict the probable errors associated with the different survey tools used. An "instrument performance model" is a mathematical algorithm that, when combined with a set of independently validated parameters describing the particular survey instrument in question and information about the well, enables the directional uncertainty to be computed at any point in a survey run. Randomization caused by axial rotation of the tool significantly affects the size of the predicted errors. The analysis accounts for rotation and incorporates a new depth-measurement-error treatment. Performance models have many practical uses in survey operations management and wellsite quality control. They enable research to be focused accurately and objective comparisons to be made between different instruments.
Effects of Wellbore Steam Segregation on Steamflood Performance
Authors: Kumar Mridul , Hong K. C.
Published: December 2007

The effect of steam segregation within the wellbore on the distribution of steam over the injection interval and on the resulting steamflood performance was numerically investigated. Results show that, because of gravity segregation, steam mass and heat distribution are nonuniform over the injection interval. The effect of steam segregation on predicted performance was important for heavy-oil reservoirs, especially when the vertical permeability was small compared with the horizontal permeability. In general, the segregation effect was more pronounced for reservoirs with high horizontal permeability (specific injectivity).
A Numerical Study of Viscous Instabilities: Effect of Controlling Parameters and Scaling Considerations
Authors: Kelkar Mohan , Gupta Surendra P.
Published: December 2007

An accurate finite-element simulator with a very fine 2D grid was used in this study of viscous instabilities. The simulator has negligible grid-orientation and numerical-dispersion effects and treats longitudinal and transverse dispersivities separately. The simulator was validated by comparing numerical results with the analytical solution for unit-mobility-ratio miscible displacements under varying longitudinal and transverse dispersivities and was further tested by simulating the results of published laboratory displacements under adverse-mobility-ratio conditions. A good match was obtained between the simulated and experimental results for recovery and effluent-concentration profiles for adverse-mobility-ratio displacements. A permeability variance of only 0.1 or an inlet concentration perturbation for a homogeneous system was enough to initiate the effects of viscous fingers seen in laboratory displacements.

Results showed that the parameters that control unstable displacements are the permeability variance (Dykstra-Parsons coefficient), the size of heterogeneity (scale length), the mobility ratio, and the dimensionless transverse Peclet number, NPet. It was concluded that the instabilities increase with increases in the permeability variance, the scale length, and the mobility ratio. With increased instability, the recovery decreases and the breakthrough time decreases. For NPer< 0.01, the displacement remains unstable. In addition, the effect of longitudinal dispersivity is negligible. As long as the parameters (mobility ratio, permeability variance, and size of heterogeneities, NPer<0.01) were the same, the effect of the size of the modeled medium on recovery and effluent profiles was insignificant. This implies that the effects of viscous instabilities can be scaled within the range of parameters investigated.
Well-Test Analysis for Solution-Gas-Drive Reservoirs: Part 3—A Unified Treatment of the Pressure-Squared Method
Authors: Serra Kelsen V. , Peres Alvaro M. M. , Reynolds Albert C.
Published: December 2007

This work considers the analysis of radial-flow, well-test pressure data under multiphase flow conditions. We show that drawdown- and buildup-pressure data can be analyzed to obtain estimates of effective permeability and the skin factor with a semilog plot of pressure squared vs. time. It is shown that the liquid Matthews-Brons-Hazebroek (MBH) functions can be used to obtain an approximate estimate of average reservoir pressure. A theoretical explanation for a semilog analysis method based on the pressure-squared method is presented.
Electromagnetic Propagation Logging While Drilling: Theory and Experiment
Authors: Clark Brian , Allen David F. , Best David L. , Bonner Stephen D. , Jundt Jacques , Lüling Martin G. , Ross Mike O.
Published: December 2007

The compensated dual resistivity (CDRSM) tool is an electromagnetic propagation tool for measurement while drilling. The CDR tool provides two resistivity measurements with several novel features that are verified with theoretical modeling, test-tank experiments, and log examples.
Pressure-Transient Analysis of Fractal Reservoirs
Authors: Chang Jincai , Yortsos Yanis C.
Published: December 2007

We present a formulation for a fractal fracture network embedded into a Euclidean matrix. Single-phase flow in the fractal object is described by an appropriate modification of the diffusivity equation. The system's pressure-transient response is then analyzed in the absence of matrix participation and when both the fracture network and the matrix participate.

The results obtained extend previous pressure-transient and well-testing methods to reservoirs of arbitrary (fractal) dimensions and provide a unified description for both single- and dual-porosity systems. Results may be used to identify and model naturally fractured reservoirs with multiple scales and fractal properties.
Quantitative Determination of Rod-Pump Leakage With Dynamometer Techniques
Authors: Nolen Kenneth B. , Gibbs Sam G.
Published: December 2007

This paper describes new methods for quantifying pump leakage that extend the effectiveness of dynamometer analysis and can lessen the dependence on well tests in determining the degree of pump leakage. Actual examples are included to illustrate the techniques. Traveling- and standing-valve leakage checks are also described.
An Improved Finite-Difference Calculation of Downhole Dynamometer Cards for Sucker-Rod Pumps
Authors: Everitt T. A. , Jennings J. W.
Published: December 2007

This paper presents a finite-difference representation of the wave equation developed for diagnostic analyses of sucker-rod pumping systems. A consistent method of computing the viscous damping term associated with the damped-wave equation is also presented.
Study of Gas Condensation in Transmission Pipelines With a Hydrodynamic Model
Authors: Mucharam Leksono , Adewuml Michael A. , Watson Robert W.
Published: December 2007

A nonisothermal, 1D, compositional, two-fluid, multiphase hydrodynamic model is used to describe the incipient formation and dynamic behavior of condensate in a natural-gas pipeline with undulating topology. The 26-in. [66-cm] -diameter case-study transmission pipeline traverses 180 elevation changes in its 30.72-mile [49.4-km] span. Results demonstrate the predictive and descriptive potential of the model in field applications and the significant effect of inclination and inclination changes on the hydrodynamics of gas/condensate flow in transmission pipelines. The model presented can serve both predictive and design purposes.
Laboratory Studies of Capillary Interaction in Fracture/Matrix Systems
Authors: Horie Tadashi , Firoozabadi Abbas , Ishimoto Koichiro
Published: December 2007

Current study of fractured petroleum reservoirs often is based on the assumption of capillary discontinuity between matrix blocks. Both theoretical analysis and examination of the field performance of some fractured reservoirs, however, indicate a degree of capillary interaction between matrix blocks. Experiments performed to gain an understanding of the capillary continuity across a stack of matrix blocks are described. Three matrix blocks with a total length of 3 ft [90 cm] were stacked and placed in a transparent core holder. Before the experiments with stacked blocks were conducted, rock properties, capillary pressure, relative permeabilities, and the aperture/overburden relationship were measured. Drainage capillary pressure data showed a threshold height of the same size as each of the individual matrix blocks.

Experimental results showed a strong capillary interaction (capillary continuity) between the neighboring blocks. Recovery from the top two matrix blocks far exceeds that from the same blocks when the assumption of capillary discontinuity is used. We believe that incorporation of the capillary-continuity concept in dual-porosity models will result in more realistic simulation of fractured reservoirs.
Studies Relating to the Predictiveness of Corrosion-Inhibitor Evaluations in Laboratory and Field Environments
Authors: Hausier Rudolf H. , Stegmann Donald W.
Published: December 2007

We attempted to understand the performance characteristics of various inhibitors under different conditions to determine realistic concentrations for field application. In all, 10 inhibitors drawn from five distinctly different chemistry classes were evaluated in four different test procedures of increasing severity of CO2 corrosion. From the performance/concentration curves established for each inhibitor in each test, effective concentrations were defined as the concentration necessary to achieve a certain target performance level—e.g., 0.1 mm/a [4 mils/yr]. Test procedures and inhibitors were then compared on the basis of effective concentration. It was found that the generally accepted wisdom regarding inhibitor testing is simply not valid—i.e., an inhibitor's ranking under one test condition is not predictive of its ranking under other conditions. As the severity of corrosion increases, effective inhibitor concentration also increases. Field data were available for two inhibitors. A comparison with laboratory data showed that laboratory tests were reasonably predictive for one inhibitor, but for the other inhibitor, laboratory tests seemed to overestimate the effective concentration for field use.
A Successful Treatment cf Formation Damage Caused by High-Density Brine
Authors: Cikeš Marin , Vranješevic Branka , Tomic Mihovil , Jamnicky Oljeg
Published: December 2007

This paper presents reservoir description, treatment design and execution, and pretreatment and posttreatment analyses of a well completed in Yugoslavia. Chemical aspects of calcium sulfate (CaSO4) scale dissolution by Na4EDTA are also given.
Scaling Up Heterogeneities With Pseudofunctions
Authors: Kossack Charles A. , Aasen Jan O. , Opdal Svein T.
Published: December 2007

This paper describes a multistep pseudofunction-generation process designed to incorporate several scales of heterogeneities into one set of final pseudofunctions to be used in large gridblocks for field simulations. A detailed description of the multistep scale-up process is provided. The calculational procedure and the results of an extensive numerical scaling-up experiment from Kyte and Berry pseudofunctions are described. Three geological descriptions involving random permeability variations are used. The effect of three scales (sizes) of heterogeneities on a standard oil/water relative permeability curve is determined from a three-step pseudofunction-generation process. Ranges of mobility ratios, viscosity/gravity ratios, and viscosity/capillary ratios are used in the displacements to provide a guide to the effect of various types and scales of heterogeneities on fluid flow in several regimes.
Extensions to Dietz Theory and Behavior of Gravity Tongues in Slightly Tilted Reservoirs
Authors: Fayers F. John , Muggeridge Ann H.
Published: December 2007

This paper investigates accuracy implications in the modeling of unstable gravity tongues in slightly tilted, anisotropic reservoirs. An extended form of Dietz's equation is examined and its range of validity established by reference to high-resolution simulation. The theory is also used to investigate the onset of viscous fingering with a new viscous-to-gravity number.
The Effect of Firing on Berea Sandstone
Authors: Shaw Jerry C. , Churcher Peter L. , Hawkins Blaine F.
Published: December 2007

The petroleum industry uses Berea sandstone as a standard testing material. It is often fired to desensitize indigenous clays. Here, we study the effect of firing by comparing unfired Berea to samples fired at 1000°C for 5 hours. The observed changes in the petrographic and petrophysical parameters are then related to single- and two-phase coreflood data.
New Solutions for Well-Test-Analysis Problems: Part 1—Analytical Considerations
Authors: Ozkan Erdal , Raghavan Rajagopal
Published: December 2007

Point-source solutions are derived in the Laplace-transform domain and an extensive library of solutions is documented to obtain pressure distributions and well responses for a wide variety of wellbore configurations: partially penetrating vertical wells, horizontal wells, and fractured wells (complete or limited entry). Wells may be located in infinite or bounded systems (rectangular or circular reservoirs). Several combinations of closed and/or constant-pressure boundary conditions are considered at the vertical and lateral reservoir boundaries. These solutions may be used to examine homogeneous or naturally fractured reservoirs.
Field Limitations of Liquid-Additive Cementing Systems
Authors: Grant W. Hal , Rutledge John M. , Christy Roger H.
Published: December 2007

The use of liquid additives has become prevalent in cementing operations, especially where logistics is a problem. Several precautions must be taken with these additives to ensure adequate performance in field operations. This paper compares the performances of several liquid-additive cementing systems with those of dry-blended-additive systems. Cement-slurry thickening time, fluid loss, free water, and compressive strength are examined; and sensitivity to changes in slurry density is illustrated. Laboratory data demonstrate the liabilities of the liquid-additive system, and three case histories are discussed. A cost analysis comparing dry- and liquid-additive systems with equivalent design criteria shows that liquid-additive systems are more expensive. A prejob quality-control checklist for use of liquid additives is presented, and a dry-blending procedure is recommended and illustrated. If followed, the procedure greatly increases the likelihood of uniform dry-blended additives in quantities as small as 0.2% by weight of cement (BWOC).
Cement Quality-Control Program Shows Substantial Savings
Authors: Bergeron Henry A. , Grant W. Hal
Published: December 2007

This paper shows improved results and savings from a quality-control program that emphasized controlled cement slurry properties and good field practices, including the use of spacers, controlled displacement rates, proper centralization, casing movement, and close monitoring of the cement blending. This study focuses on eight onshore and offshore fields in southern California. Roughly 135 wells with more than 180 casing strings were analyzed. These wells, drilled from 1980 to the present, range in depth from 2, 000 to 14, 000 ft [610 to 4270 m]. Two-thirds of the wells were drilled before the cement quality-control program was initiated in Aug. 1985.
Performance Comparison of Rolling-Cutter Bits With Alternative Nozzle Designs
Authors: Moffitt Stuart R. , McGehee David Y.
Published: December 2007

Controversy exists regarding the optimum nozzle design for rolling-cutter bits. This paper describes the use of controlled laboratory conditions to isolate the true benefit of various hydraulic designs. Tests were conducted in a pressurized drilling environment with 9⅞-in. [251-mm] tooth and insert bits in Mancos shale. Hydraulic designs include combinations of standard- and directed-nozzle bits with center jets and long and short extended-nozzle bits. Results indicate that directed nozzles provide substantially better bit cleaning and rate of penetration (ROP) than the standard- and short extended-nozzle designs and a slightly faster ROP than long extended-nozzle designs.
Reservoir Simulation of Cyclic Steam Stimulation in the Cold Lake Oil Sands
Authors: Beattle C. I. , Boberg T. C. , McNab G. S.
Published: December 2007

Steam injectivity during cyclic steam stimulation (CSS) at Cold Lake can be achieved only by injecting at pressures high enough to fail the formation mechanically. The reservoir also exhibits water/oil relative permeability hysteresis. This paper describes enhancements made to a thermal reservoir simulator to incorporate these Cold Lake physics. The geomechanical model allows both localized fracturing and global reservoir deformation (dilation and history-dependent recompaction). This representation allows the simulator to match injection and production pressures that are otherwise difficult to reproduce. The history-dependent relative permeability hysteresis model calculates gridblock relative permeabilities that always lie on or between input imbibition and drainage bounding curves. The model makes it possible to use laboratory-derived relative permeabilities in a simulation and still match field WOR's.
History Matching of High- and Low-Quality Steamfloods in Kern River Field, California
Authors: Johnson R. S. , Chu Chleh , Mims D. S. , Haney K. L.
Published: December 2007

History matches of high-and low-quality five-spot steamfloods were developed for the Kern River field. A uniform set of guidelines was then developed for predictive purposes. Oil and water production rates and cumulative productions were matched. Satisfactory predictions of steam breakthrough times, oil saturation profiles, and temperature profiles were also achieved. Increased vertical transmissibility at the injectors, relative permeability curve modifications, and accurate reservoir descriptions were required to achieve the matches.
An Experimental Study of Casing Performance Under Thermal Cycling Conditions
Authors: Maruyama Kazushi , Tsuru Eiji , Ogasawara Masao , Inoue Yasusuke , Peters Ekwere J.
Published: December 2007

We investigated the behavior of casing pipe body and connections under simulated thermal recovery conditions. The study, performed in a new computer-controlled thermal-well simulator, examined the thermal stress behavior and leak resistance of pipe and connections at temperatures up to 354°C [670°F] under severe loading conditions similar to those encountered in thermal wells. We also studied the biaxial collapse resistance of the casing under the large axial tension that would exist after the cooling period in a steam-stimulation process. Results indicate that in a steam-injection process in which the casing is maintained at its maximum temperature for a period of time, stress relaxation can occur in a constrained production casing, resulting in the development of excessive tensile stress during the cooling period. Premium connections with metal-to-metal seals maintained gas leak resistance at temperatures up to 354°C [670°F], whereas the connections without metal seals did not. The biaxial collapse resistance of casing under large axial tension depended on the stress/strain characteristics of the material. Hot-rolled Grade K55 casing with work-hardening characteristics showed a biaxial collapse resistance higher than that predicted by the von Mises yield criterion. From results of this study, we concluded that heavyweight Grade K55 casing with premium connections is a good candidate for thermal well completions.
Effect of Capillary Heterogeneity on Buckley-Leverett Displacement
Authors: Chang Jincal , Yortsos Yanis C.
Published: December 2007

The Buckley-Leverett (BL) equation has been routinely used for the description of immiscible displacement in laboratory Dperations and for parameter estimation and prediction. Recent advances, however, have led to a serious challenge of the validity of many of the traditional theories. For the case of BL displacement, most studies have examined heterogeneity effets as they relate to. viscous fingering. In this paper, we investigate the effects of capillary heterogeneity induced by variations in permeability in the direction of displacement. We study a variety of heterogeneity profiles, both uncorrelated and correlated spatially. We find that capillary heterogeneity significantly affects the saturation distributions, which closely follow the heterogeneity variation. The saturation response is stronger at lower rates, at more unfavorable mobility, under drainage conditions, and for smaller spatial correlations. The results are in agreement with available experimental data for primary drainage and secondary imbibition. They may be useful in the interpretation of saturation profiles and the identification of heterogeneity.
Evaluation of Dual-Injection Methods for Multiple-Zone Steamflooding
Authors: Hight M. A. , Redus C. L. , Lehrmann J. K.
Published: December 2007

For multiple-oil-zone reservoirs, steamflooding two zones at the same time is advantageous. Three methods for dual injection through a common wellbore were tested at Texaco's Kern River field in Bakersfield, CA. Because dual injection results in an excessive amount of heat transfer between injection streams, it was imperative to predict steam quality or water temperature at the sandface for each injection stream. To evaluate the merits of each method adequately, a computer model was developed to predict downhole temperatures, steam qualities, and pressures for each injection stream. Field tests of the three injection configurations provided measurements necessary for validation of the model. This paper describes the computer model, the field test, and the results from the three dual-injection scenarios.