bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Simulation of Gravel Packing
Authors: Winterfeld P. H. , Schroeder D. E. 
Published: December 2007

SummaryTo obtain maximum productivity from unconsolidated formations where sand control is required, it is important to understand the mechanics of gravel packing. This paper describes a finite-element, numerical simulator that can predict gravel placement in the perforations and annulus of a wellbore. The equations for the simulator include mass and momentum conservation. Wellbore geometry, physical properties, and fluid and gravel-pack properties are simulator input. Experiments in a 100-ft full-scale wellbore model for three gravel-packing configurations have been successfully simulated. These configurations are a circulating pack with a washpipe, a squeeze pack, and a circulating/squeeze pack with a washpipe and a lower telltale screen. The low cost, speed, and extrapolation capabilities of the numerical simulator will greatly enhance our ability to predict gravel placement in a wellbore.
Barium and Calcium Sulfate Precipitation and Migration Inside Sandpacks
Authors: Allaga D. A. , Wu Gang , Sharma Mukul M. , Lake Larry W. 
Published: December 2007

Summary
This paper is an experimental and theoretical study of permeability reduction of sandpacks caused by solids generation and migration. Two solids, calcium and barium sulfate crystals, were injected into and generated within the sandpacks by chemical reaction. We found that we could simulate the effluent concentrations, including the produced solids, with a fractional flow model for solids migration.
A New Method for Predicting Friction Pressures and Rheology of Proppant-Laden Fracturing Fluids
Authors: Keck Richard G. , Nehmer Warren L. , Strumolo Gary S. 
Published: December 2007

SummaryThe prediction of friction pressures for proppant-laden fracturing fluids requires estimations of both the base-gel friction factor and the effect of proppant on fluid rheology. This paper introduces two new expressions, each theoretically based with constants determined from data, that address these two issues for hydroxypropyl guar (HPG)-based fracturing fluids in laminar and turbulent flow.The paper first introduces a new expression for the turbulent friction factor of HPG base gels. This implicit expression for the friction factor is more theoretically correct and requires one less empirical constant than explicit forms currently used. The effect of proppant on the effective viscosity of non-Newtonian fluids is then discussed and a new expression, which includes shear rate, temperature, gel concentration, and proppant volume fraction as parameters, is derived. Developed from laboratory data and existing slurry rheology theories, this expression is shown to provide excellent predictions of laboratory and field data for both tubing and annulus injection.
Implementation of the Ekofisk Field Waterflood
Authors: Hallenbeck L. D. , Sylte J. E. , Ebbs D. J. , Thomas L. K. 
Published: December 2007

Summary
This paper describes the design, implementation, and initial results of the full-field water-injection program in the Ekofisk field of the North Sea. Two pilot waterfloods, injection-well-pattern design, vertical confinement considerations, optimization of production-well sidetracks, core fracture analysis and orientation, regional permeability variations, reservoir geology and faulting, and overall anisotropy are discussed. Results of a comprehensive waterflood surveillance program are presented as well as 3D-model predictions for ultimate recoveries.
Field Study of Offshore Cement-Spacer Mixing
Authors: Benge Glen 
Published: December 2007

Summary
Rheological data from cementing-spacer fluids are usually based on laboratory-prepared samples of the spacer and used to determine the flow rate required to provide the flow regime necessary for maximum efficiency of the spacer and to estimate the annular friction pressures associated with the spacer. Actual rheological properties are rarely measured on location, and the problems experienced with settling, foaming, and mixing are difficult to simulate in the laboratory. This paper reviews the field data from three commercial spacers mixed at offshore locations and compares them with laboratory data for base spacer materials and weighted spacer mixes. The flow rates required to obtain turbulent and plug flow for each spacer are compared, and settling, foaming, and mixing problems are discussed. Because of solids settling in either the slugging pits or surface samples, the spacer formula is sometimes modified on location to improve solids suspension. The rheological effects of increasing concentrations of base spacer material, bentonite, and polyanionic cellulose (PAC) are discussed with a comparison of the rheological data from these spacers.
Effects of Strain Rate and Confining Pressure on the Deformation and Failure of Shale
Authors: Cook J. M. , Sheppard M. C. , Houwen O. H. 
Published: December 2007

Summary
Previous work on shale mechanical properties has focused on the slow deformation rates appropriate to wellbore deformation. Deformation of shale under a drill bit occurs at a very high rate, and the failure properties of the rock under these conditions are crucial in determining bit performance and in extracting lithology and pore-pressure information from drilling parameters. Triaxial tests were performed on two nonswelling shales under a wide range of strain rates and confining and pore pressures. At low strain rates, when fluid is relatively free to move within the shale, shale deformation and failure are governed by effective stress or pressure (i.e., total confining pressure minus pore pressure), as is the case for ordinary rock. If the pore pressure in the shale is high, increasing the strain rate beyond about 0.1 %/sec causes large increases in the strength and ductility of the shale. Total pressure begins to influence the strength. At high strain rates, the influence of effective pressure decreases, except when it is very low (i.e., when pore pressure is very high); ductility then rises rapidly. This behavior is opposite that expected in ordinary rocks. This paper briefly discusses the reasons for these phenomena and their impact on wellbore and drilling problems.
Slim-Hole Drilling in Harsh Environments
Authors: Fultz J. D. , Plttard F. J. , Sawyer F. D. , Farmer W. R. 
Published: December 2007

Summary
Wells with small liners occasionally require unique methods of drilling, completion, and reworking, especially deep-hole wells and wells with severe doglegs. Innovative drilling procedures were used successfully on two wells with those downhole conditions. On the first well, cement was drilled in a 3½-in. liner with a small mud motor and heavyweight mud. On the second well, a large mud motor was used as a downhole power swivel to drill in a 3½-in. liner. Both jobs were completed at depths of 13, 000 to 20, 000 ft with mud weights &gt; 18 lbm/gal and bottomhole temperatures (BHT's) &gt;300°F.
Understanding Kick Tolerance and Its Significance in Drilling Planning and Execution
Authors: Redmann K. P. 
Published: December 2007

Summary
Kick tolerance is a drilling parameter that has prompted both confusion and misunderstanding in the drilling industry, yet its importance to drilling engineers may be increasing exponentially. The increasing number of worldwide drilling catastrophes may spur government agencies to tighten controls on casing-setting-depth criteria, requiring pipe to be set once minimal kick tolerance values are reached. A thorough understanding of kick tolerance is necessary in both drilling operations and casing program design. Confusion involving kick tolerance may be attributed to the concept of zero gain, which is commonly referred to in many accepted definitions of kick tolerance. This paper presents an innovative approach to determining true kick tolerance that not only incorporates the conditions of an influx within the wellbore but also considers the possible reductions in kick tolerance caused by the circulation of that influx from the wellbore. New techniques are available for hand-held calculators, which are now more accurate in determining influx pressure and volume anywhere within the wellbore. A typical well example with illustrations describes kick tolerance and empha sizes the influence of other drilling parameters. Integration of kick-tolerance considerations into the well planning process also is dem onstrated.
Light-Oil Steamdrive Pilot Test at NPR-1, Elk Hills, California
Authors: Gangle F. J. , Weyland H. V. , Lassiter J. P. , Veith E. J. , Garner T. A. 
Published: December 2007

Summary
A steamdrive pilot was run on a light-oil reservoir at the Naval PetroleumReserve No. 1 (NPR–1) in the Elk Hills oil field, Kern County, CA. From areservoir perspective, the steamdrive process behaved much as expected. Thefirst event to occur was the appearance of freshened water productionaccompanied by CO2 gas 3 months from startup of steam injection. The secondevent, an increase in crude gravity, appeared 3 months later, or 6 months intothe project. Finally, the third event was the arrival of the heat front at theproducing wells 13 months after startup. From a production perspective, CO2 in the freshened produced water caused wellbore scale damage and loss of well productivity. The steamdrive, however, mobilized residual oil, which mostly wascaptured outside the pilot pattern area. Acid stimulations to restore well productivity were done by injecting inhibitor in the steam feedwater and by designing acid cleanup treatments on the basis of results from laboratory tests.
CO2 Foam With Surfactants Used Below Their Critical Micelle Concentrations
Authors: Kuhlman M. I. , Falls A. H. , Hara S. K. , Monger-McClure T. G. , Borchardt J. K. 
Published: December 2007

Summary
Using surfactants below their critical micelle concentrations, CCMC, to reduce gas mobility throughout a reservoir can be advantageous. When used in reservoir brines below their CMCMC inexpensive anionic surfactants propagate through rock with little delay owing to adsorption. Yet gas mobility is reduced below that of a watertlood in either surfactant-water-altemating-gas (SWAG) or coinjection experiments. Moreover, oil recovery is higher than in processes without surfactant. In contrast, at concentrations above the CCMC, surfactant adsorption is much higher and the injected surfactant concentration can be greatly delayed. In addition, CO2 mobility can be reduced so far below that of a watertlood that injectivity suffers. Moreover, oil recovery can be reduced because oil is emulsified and its mobility is lowered. This type of foam should be considered only for near-wellbore fluid diversions.
Change in Apparent Viscosity off CO2 Foam With Rock Permeability
Authors: Lee H. O. , Heller J. P. , Hoefer A. M. W. 
Published: December 2007

Summary
This paper summarizes new and previous high-pressure experiments measuring the mobility of CO2 foam in porous rock, including both sandstones and carbonates, with permeabilities ranging from &lt; 1 md to hundreds of millidarcies. Foam mobility is defined here as the ratio of the combined flow rate per unit superficial area to the pressure drop required for simultaneous flow of dense CO2 and brine/surfactant through the sample and can be expressed in units of millidarcies per centipoise. The measured results, which can also be expressed in terms of the apparent viscosity of the CO2 foam, give a quantitative basis for the belief that this displacing fluid should be particularly effective in heterogeneous formations. From a macroscopic viewpoint, the CO2 foam acts like a single fluid with a viscosity equal to the ratio of the rock's brine permeability to the measured mobility. According to our results, the apparent viscosity depends on rock permeability in a nonlinear fashion, increasing from a minimum of about 2 cp for the tightest rocks to an apparent maximum of about 1, 000 cp for Berea. Individual mobility measurements were made at steady-state conditions; this is justified by consideration of oilfield operational constraints. Results of auxiliary experiments are given and the methods described. These include measurements of essential surfactant characteristics, such as durability against coalescence of the dense CO2 bubbles in brine/surfactant solution. Results given also show the influence of other factors, such as surfactant concentration and type, flowing fraction of the dense gas, and overall rate, on foam mobility.
Microvisual and Coreflood Studies of Foam Interactions With a Light Crude Oil
Authors: Schramm Laurier L. , Turta Alexandru T. , Novosad Jerry J. 
Published: December 2007

SummaryFoam stability in the presence of crude oil is important to foamflood performance. Microvisual observations were made to assess the degree of foam-lamella/oil interactions occurring between a light crude oil and foams being considered for foam flooding applications in Alta., Canada. Foam behaviors ranged from quite stable, with almost no foam/oil interactions, to quite unstable, where oil was extensively emulsified and imbibed into the foam. These behaviors matched phenomenological model predictions and also were consistent with coreflood mobility reduction factors and incremental oil recoveries obtained in foam flow experiments in Berea sandstone cores at ambient temperature, low pressure, and residual oil saturation (ROS).
Design, Operation, and Evaluation of a Surfactant/Polymer Field Pilot Test
Authors: Holley S. M. , Cayias J. L. 
Published: December 2007

Summary
Oryx Energy Co. evaluated the design and operation of a low-tension surfactant/polymer pilot in the McCleskey sandstone of the Ranger field in Eastland County, TX. The test was performed in a watered-out area developed on 40-acre spacing that was chosen because good reservoir permeability, the availability of fresh water, and high residual oil saturations (ROS's) made it suitable for a surfactant/polymer process. Major disadvantages of the area were a potential lack of pattern confinement and a salinity contrast caused by the injection of fresh water. The purpose of the test was to determine the applicability of the technology and its implementation. The pilot was successful on the basis of both monitored results and produced oil but did not achieve its design objectives because of reservoir heterogeneity and reduced sweep efficiency. The successful propagation of chemical fronts and oil recovery within the pilot area demonstrated that in this and similar reservoirs, surfactant flooding can recover tertiary oil in significant quantities on large areal spacing. This paper discusses the design, operation, and evaluation of the field project and includes considerations for the successful implementation of the technology.
Formation Damage From Polymer Solutions: Factors Governing Injectivity
Authors: Fletcher A. J. P. , Lamb S. P. , Clifford P. J. 
Published: December 2007

Summary
This paper addresses polymer-solution injectivity and what physico-chemical environments result in formation damage. The roles of Fe(III) and filtration are shown to be particularly important. The effects in the field are predicted, with special reference to wellbores likely to suffer from thermal fracturing. It is shown that fractured wellbores are unlikely to suffer from injectivity problems.
Physical Model Steamflood Studies Using Horizontal Wells
Authors: Ahner P. F. , Sufi A. H. 
Published: December 2007

Summary
A small, scaled physical vacuum model was built to study a steamflood process that uses a horizontal well to form a communication between vertical injector/producer well pairs in a heavy-oil reservoir. Linedrive steamflood operation was simulated over 1.37- and 2.75-acre patterns at 427- and 650-bbl/D injection rates. These studies yielded 60% to 80% recoveries at steam/oil ratios between 4 and 6.
Improvement of Gravity Drainage by Steam Injection Into a Fractured Reservoir: An Analytical Evaluation
Authors: van Wunnik John N. M. , Wit Krijn 
Published: December 2007

Summary
Analytical techniques were used to study improvement of gas/oil gravity drainage by steam injection in a densely fractured dome-shaped low-permeability reservoir containing viscous oil. Aspects of the process studied include mixing of the steam and hydrocarbon gas, the temperature distribution in the caprock and reservoir, and oil production by thermal expansion and gravity drainage. The models developed are applied to the Qarn Alam reservoir of Oman, which may be a candidate reservoir. The steam-injection process appears very attractive for this reservoir; an oil/steam ratio of 0.5 m3/Mg may be achieved.
A New Recovery Technique for Heavy-Oil Reservoirs With Bottomwater
Authors: Islam M. R. , Chakma Amit 
Published: December 2007

SummaryThis paper proposes a new recovery mechanism for heavy-oil reservoirs containing bottomwater zones. Many heavy-oil reservoirs are considered unproductive because of the presence of a bottomwater zone. No known mechanism now exists for producing oil from these reservoirs. Recently, horizontal wells have been proposed as a unique solution for producing reservoirs that are thin, fractured, or contain a bottomwater zone. For heavy-oil reservoirs, however, horizontal wells alone may not be sufficient. The electro magnetic heating process has proved to be effective in in-situ heating of oil-bearing formations. Such heating, which is limited to small radii, in combination with a horizontal well offers an attractive process for recovering billions of barrels of oil unrecoverable by other means. The process of electromagnetic heating proposed here is coupled with gas or water injection to create a favorable pressure gradient in the presence of a bottomwater zone. Scaled model experiments were performed to study the feasibility of the process of inert-gas injection along with electromagnetic heating. The variables studied were oil/water-zone thickness ratio, oil viscosity, horizontal-well placement, inert-gas injection rate, and production-well temperature. A recovery as high as 77 % oil in place (OIP) was obtained even in the presence of a bottomwater zone as thick as the oil zone. This technique offers heavy-oil production at a cost lower than that of any other thermal recovery scheme.
Development of a Method for Partially Uninvaded Coring in High-Permeability Sandstone
Authors: Rathmell J. J. , Tibbitts G. A. , Gremley R. B. , Warner H. R. , White E. K. 
Published: December 2007

Summary
A newly designed polycrystalline-diamond-compact (PDC) core bit and water-based muds with bridging solids are shown to provide 4-in. diameter cores with a 2.5-in. uninvaded center. High-permeability sandstones were cored at rates exceeding 90 ft/hr in laboratory and field tests. The mechanisms controlling filtrate invasion are quantified.
Foamed Cement for Squeeze Cementing Low-Pressure, Highly Permeable Reservoirs: Design and Evaluation
Authors: Chmilowski Walter , Kondratoff L. B. 
Published: December 2007

SummaryFour different cement squeezing techniques have been used on wells producing from the Keg River formation in the Rainbow Lake area of Alberta, Canada. This paper evaluates 151 cement squeeze treatments performed at 96 wellsites and compares the use of foam cement vs. conventional squeeze treatments and techniques. Discussion includes key aspects, such as candidate selection, slurry design, treatment design, economic evaluation, and operational considerations.
Electrical Stability, Emulsion Stability, and Wettability of Invert Oil-Based Muds
Authors: Growcock F. B. , Ellis C. F. , Schmidt D. D. 
Published: December 2007

Summary
Until now, drilling-fluid specialists measured trends in the electrical stability (ES) test to decide the appropriate emulsifier treatment for invert-emulsion oil-based muds without knowing what the ES test was measuring. This paper describes what happens in a mud during an ES test, how mud composition affects trends in the ES measurements, and how observed trends can be used to deduce mud-emulsion stability and oil wettability. During an ES test, electrical breakdown is induced in the mud between the electrodes. This process was observed, with an optical microscope, to involve formation of a conductive bridge composed of aqueous fluid and particulate matter. Experiments showed that water forms the conductive pathway in the bridge, whereas the solids appear to be involved only as carriers of the water. Eo, the voltage at which the conductive bridge is formed and the current rises abruptly, was found to be a function of the viscosity and the types and concentrations of solids, aqueous fluid, and emulsifiers (surfactants). These trends are consistent with a theoretical expression for breakdown of paniculate-contaminated dielectric fluids, which suggests that the Eo of a mud is an absolute measure of its emulsion stability but only a relative measure of its oil-wetting tendency. Trends in Eo are also consistent in most cases with other field indicators of emulsion stability, such as high-temperature, high-pressure (HTHP) fluid loss. Anomalies in E0 trends are explained in terms of a physicochemical model for electrical breakdown.
Use of New Ranging Tool To Position a Vertical Well Adjacent to a Horizontal Well
Authors: Tarr B. A. , Kuckes A. F. , Ac M. V. 
Published: December 2007

Summary
As part of a heavy-oil pilot project, three vertical wells had to be drilled in close proximity to the horizontal section of a horizontal well. Because the separation distances specified were smaller than the position uncertainty associated with conventional directional surveying, a special electromagnetic ranging technique had to be developed. The technique proved reliable and was used to complete the project successfully.
Interrelationship Between Critical Cement Properties and Volume Changes During Cement Setting
Authors: Sabins F. L. , Sutton D. L. 
Published: December 2007

Summary
This paper surveys cementing terminology for clarifying cement setting and its capability to control interzonal fluid flow. It also demonstrates the results of several test procedures designed to measure two or more cement properties simultaneously under conditions that simulate job applications. These procedures test the validity of theories and procedures for controlling annular gas flow, cement bonding, interzonal channeling, and intrazone isolation. From these results, guidelines may be developed for using laboratory data to determine times for temperature logs, perforating, and stimulation treatments. Existing laboratory equipment was modified and new equipment was designed to measure the interrelationships between static-gel-strength development, volume reductions, hydration temperatures, permeability changes, net plastic-state shrinkage, and compressive strength.
Test results indicated that (1) hydration volume reduction (HVR) during the transition period is relatively small and shows a general correlation to unit volume cement content; (2) temperature increases from hydration show a rough correlation to static-gel-strength development; (3) permeability during static-gel-strength development decreases rapidly and shows a definite correlation to fluid-loss test values; (4) plastic-state shrinkage is only a very small part of the total HVR; (5) a general correlation exists between compressive strength, HVR, and heat of hydration; (6) the HVR for an expansive cement was greater than that of a nonexpansive cement, but its plastic-state shrinkage was less.