bluuebunny/crossref_metadata_2025_split huggingface dataset:
Foam Diversion Modeling and Simulation
Authors: Robert J. A. , Mack M. G. 
Published: December 2007

SummaryThis paper presents a model of foam rheology in porous media, based on a set of experimental data gathered in linear cores at rates relevant to matrix-acidizing conditions. Foam was found to behave as two-phase flow, with a minimum yield stress required to displace the gas phase. At high foam rates, foam was highly shear-thinning, and the pressure gradient within the foam bank was observed to be independent of the foam rate. It was also found that nitrogen solubility in the aqueous phase can explain the long-term behavior of foam banks under brine flow.The modeling is applied to foam-flow simulation. In a two-phase finite-difference simulator, foam flow is represented by modifying the relative permeability to gas at each timestep, as a function of the injection conditions. Surfactant transport and adsorption and gas solubility have also been integrated into the simulator.Comparisons between simulation results and diversion experiments are presented, and the possibility of extension to field conditions is demonstrated by simulation of a hypothetical field case.Finally, the effects of surfactant adsorption and foam-injection conditions on diversion efficiency are briefly discussed.
Effectiveness of Chemically Enhanced Solubilization of Hydrocarbons
Authors: Kan A. T. , Hunter M. A. , Fu Gongmin , Tomson M. B. 
Published: December 2007

Summary
Hydrocarbon spills and leaks are a major source of groundwater pollution for urban and industrial regions of the United States. Cleanup is most often attempted using pump-and-treat methods with numerous wells and a central treatment facility. Such procedures are notoriously inefficient when hydrocarbons are trapped in oil ganglia or capillaries, or are irreversibly sorbed. The residual hydrocarbons cannot be displaced under reasonable hydraulic gradients. Therefore, it is important to develop a more efficient method of removing such a pollutant source. Miscible solvents and surfactants are often proposed as the chemical enhancer for pump and treat. Several researchers have applied the surfactant flush in both the laboratory soil columns and field-test plots. The efficiency of surfactants usually diminished within 20 pore volumes and a significant fraction of contaminant was not mobilized. Some thermodynamic or kinetic limitations may exist in surfactant flush. Research has shown that surfactant often adsorbed to soil and altered the adsorption/desorption properties of soil. These processes may be reversed by controlling the pH and ionic strength. Miscible solvent has been shown very effective in laboratory tests. There are strong reasons to believe that a combination of several enhancement regimes will have substantial performance advantages. Just as with bioremediation, different chemical-enhancement methods will probably be better suited to particular combinations of contaminant types and aquifer characteristics. This paper discusses the effectiveness of chemical-enhancement treatments and possible limitations.
Cost-Effective Design of Scale-Inhibitor Squeeze Treatments Using a Mathematical Model
Authors: Kokal S. L. , Raju K. U. , Bayona Hector 
Published: December 2007

SummaryScale formation and deposition in production facilities is a challenging problem faced by the oil industry. Their deposition leads to operational problems, safety hazards, and an overall decrease in production efficiency. Downhole scale-inhibitor squeeze treatments provide the most common and effective means of preventing the formation of oilfield scale deposits.This paper presents an analysis and design study of field-inhibitor squeeze treatments. A mathematical model was used to simulate inhibitor-squeeze return data from several Saudi Aramco wells. A wide range of sensitivities in squeeze treatments were investigated, including inhibitor concentration, inhibitor volume, overflush size, and shut-in time. An optimization of the squeeze injection parameters was carried out with the numerical simulator. This optimization was based on squeeze performance as well as on economic criteria. The results indicate that the optimized treatment strategy is very well-specific and depends on the water production rates and operational parameters, like the scale-inhibitor concentration and volume and the amount of overflush. Recommendations are made for optimizing (in terms of cost effectiveness) the squeeze-treatment design.
Development and Application of a Wellbore/Reservoir Simulator for Testing Oil Wells
Authors: Hasan A. R. , Kabir C. S. , Wang Xiaowei 
Published: December 2007

Summary
A comprehensive coupled wellbore/reservoir simulator was developed to study the behavior of single-phase oil flow in the wellbore. The wellbore is modeled numerically where mass, momentum, and energy of the fluid are conserved, while the reservoir fluid flow is treated analytically. Energy transport occurs through tubulars, cement sheaths, and the formation by conduction. However, both conductive and convective heat-transport mechanisms are operative for the annular fluid. Heat losses through seawater and air are also modeled for a well producing in an offshore environment.
A sensitivity study shows that heat loss through seawater becomes significant for long submerged tubulars (&gt; 2,000 ft), but is marginal for shorter pipes because of the fluid's short residence time. Further, a deviated well loses more heat to formation than its vertical counterpart for the same reason. Of the major variables, thermal conductivity of the annular fluid plays a key role in heat retention and, therefore, the wellhead temperature (WHT). We have identified the phenomenon of thermal storage. This storage behavior is associated with heat absorption or desorption by cement sheaths and tubulars and is reflected as the time taken to attain equilibrium WHT for a given flow rate. A longer storage period occurs at low flow rates because of lower associated fluid enthalpy.
Field data were used to demonstrate various applications of the simulator. We showed that both drawdown and buildup data of bottomhole pressure (BHP), wellhead pressure (WHP), and WHT can be modeled successfully given the tubular, completion, and reservoir data. Conversely, given the wellhead measurements (WHP and WHT), BHP values comparable to those measured can be computed.
Seismic Data Can Improve Stochastic Facies Modeling
Authors: Tjølsen C. B. , Johnsen Gyrid , Halvorsen Gunnar , Ryseth Alf , Damsleth Eivind 
Published: December 2007

SummaryHeterogeneous reservoir units comprised of fluvial channel sandstones that alternate vertically and laterally with finer grained, nonreservoir lithologies pose a serious problem to production drilling and field development planning. The interwell position of each reservoir sandstone body can be assessed, in most cases, only indirectly through conventional geological well-correlation and mapping, and the potential of drilling unsuccessful production wells is usually present.The scope of this paper is to present a new technique that ensures that information obtained from 3D seismic surveys is fully utilized in the discrete facies modeling of fluvial sandstone bodies in a heterogeneous reservoir unit.In our study area, we show that there is a useful, empirical relationship between seismic impedance and the facies (channel sandstones/nonreservoir). Notably, there is a high probability of obtaining channels in low impedance regions, whereas high impedance areas have a lower probability of channels. An opposite impedance behavior may occur in other reservoir environments.This relationship is utilized to guide the discrete modeling of channels. An example from a fluvial North Sea reservoir is presented. The use of seismic data as an additional source of conditioning data reduces the uncertainty in the stochastic reservoir model, because the uncertainty in the reservoir description in the interwell areas is reduced significantly.
Stressed Oil Permeability of Deepwater Gulf of Mexico Turbidite Sands: Measurements and Theory
Authors: Ostermeier R. M. 
Published: December 2007

Summary
Repeatable and reliable brine permeability measurements on sand and sandstone samples often have been suspect because of the possible occurrence of fines movement and migration. This is especially true for unconsolidated sands. To avoid the effects of fines movement and to isolate the effects of stress and compaction, oil permeability measurements were made by flowing refined oil through turbidite sand samples prepared at initial water saturation, Swi. In this state, any fines present are presumably water-wet and are thus immobilized in the water phase.
The methodology for doing these measurements is briefly reviewed, and data from several deepwater Gulf of Mexico (GOM) turbidite sands is presented. By eliminating fines migration as an issue, compaction effects on permeability are shown to be quite significant for these sands.
Based on simple scaling arguments as applied to tubular laminar flow, a permeability model has been developed and found to be in good agreement with the experimental data. This model provides a reliable means of estimating permeability given porosity, initial water saturation, and grain-size distribution. The model is not turbidite specific; it may be applicable to other sand depositional environments.
Deepwater Pipeline Intervention Work With an Acoustically Controlled Power Module
Authors: Confer Aurelio , Launaro Fabio , Bigoni Guiseppe 
Published: December 2007

Summary
The stabilization of submarine pipeline free spans along uneven sea bottoms is performed conventionally using technologies such as gravel dumping, post trenching, and mattress installation. A new technology has been developed to support free spans along the 26-in. Transmed Gas Pipelines crossing the Sicily Channel in water depths ranging from 50 m to 510 m. This technology is based on the pipeline mechanical support "Atlantis" and its installation module "Pegaso" and was developed keeping requirements such as short installation time, system redundancy, operational flexibility, and simple interface with the support vessel in mind.
The installation time reduction is achieved by automatic operational procedures that are controlled acoustically from the surface. Power is stored inside two dedicated battery packs placed on board Pegaso; no umbilical cable is necessary, so that a vessel equipped with a normal crane is enough to launch and operate the system.
Marine operations carried out in 1993 showed that a support can be installed in about 1 hour. In good weather conditions, three Atlantis were installed in 24 hours, including deck operations for recharging the battery packs. A total of 16 supports was installed along the 4th and 5th Transmed Gas Pipelines. The system has proved to be a cost-effective and flexible alternative to conventional technologies for free-span support, especially in deep waters. A cost/benefit analysis also shows the break-even point of the new technology vs. gravel dumping.
Gas Lifting a Major Oil Field in Argentina With High CO2 Content Associated Gas
Authors: Blann J. R. , Laville G. M. 
Published: December 2007

Summary
The El Trapial Field in the Neuquen Province of Central Argentina produces more than 55,000 BOPD after 4 years of operation. The associated gas produced at El Trapial contains as much as 75% CO2. Immediately after the discovery of the field, a study indicated that gas lift would meet environmental concerns and be an attractive economical alternative for producing the field. The study also concluded that the high CO2 fraction gas dissolved in the oil could be used satisfactorily for gas lift purposes. A plan was implemented at that time to design and construct the production facilities around gas lift as the primary artificial lift method. This paper addresses special precautions required for design of the production and gas lift facilities to gas lift successfully with high acid content associated gas. Also discussed is Petrolera Argentina San Jorge's experience with such a system at El Trapial during the first 2 years of operation.
Novel Techniques Show Links between Reservoir Flow Directionality, Earth Stress, Fault Structure and Geomechanical Changes in Mature Waterfloods.
Authors: Heffer Kes J. , Fox Richard J. , McGill Colin A. , Koutsabeloulis Nick C. 
Published: December 2007

Abstract
Recent studies have revealed a strong correlation between the directionality of reservoir flow in waterfloods and the local orientation of horizontal earth stresses. Field applications are described of a novel technique of determining interaction between wells as a potential indicator of flow directionality. This technique calculates the Spearman rank correlation coefficient between flow rates at pairs of wells. These applications have demonstrated that the reservoir dynamics associated with correlated rate fluctuations have at least some component coupled to geomechanics. Coupled geomechanical-fluid flow numerical modelling is able to explain some of the observations and offers an improved predictive tool for planning and managing waterfloods and determining optimal locations for infill wells.
Pattern Modification by Injection-Well Shut-ln: A Combined Cost-Reduction and Sweep-Improvement Effort
Authors: Collings R. C. , Hild G. P. , Abidi H. R. 
Published: December 2007

Summary
The Rangely Weber Sand Unit is a mature giant oil field that is currently under tertiary recovery with CO2. The Rangely oil field has been developed in stages, as have most large oil fields. This staged development over 50 years has had a significant impact on the distribution of remaining movable oil. Simulation studies indicated that oil cut could be improved if injection patterns were modified by shutting in injection wells to take advantage of relative well maturity. A field pilot project based on these studies has yielded results that indicate improved economic performance because of lower operating costs related to improved oil cut and reduced well maintenance.
Gravel Placement in Horizontal Wells
Authors: Penberthy W. L. , Bickham K. L. , Nguyen H. T. , Paulley T. A. 
Published: December 2007

Summary
Long, horizontal gravel packs are viable completions that have been placed successfully in more than 80 wells. Extensive field-scale testing has significantly aided the development of field procedures and operating guidelines. Software has also been developed to assist with horizontal gravel-pack design. To be performed properly, these completions require a systems approach for their implementation because drilling and displacing the completion interval, maintaining hole stability, selecting and running equipment, and maintaining returns during the gravel-packing operation must be integrated into the completion strategy. Field experience suggests that, in some cases, gravel packs maintain productivity better than prepacked screens or slotted liners.
Reduction in Fatigue Failures Through Crack Detection by Alternating Current Field Measurement
Authors: Gaynor T. M. , Roberts D. L. , Homan E. , Dover W. 
Published: December 2007

Summary
Once a crack is initiated by cyclic stress in a drillstring component, it will grow under further service loading and will fail when insufficient uncracked material remains to carry the applied load. Because the levels of cyclic and subsequent stress in drilling may be unknown (or unknowable), the drilling equipment supplier's main defense against component fatigue failure (after design) is detection of the initial crack, conventionally by magnetic-particle or dye-penetrant inspection (respectively, MPI or DPI).
A clean bill of health from MPI or DPI means only that no crack indications were found. The likely locations of cracks (e.g. thread roots in box connections) are often difficult to examine. Detection and interpretation are subjective and depend on the skill of the inspector. A crack and a surface defect may be indistinguishable from one another. No reviewable evidence of component inspection is left to allow an audit of inspection previously performed.
Alternating current field measurement (ACFM) induces a current in the surface of a component. If ACFM detects a perturbation in the magnetic field created in the free space above the surface, a surface defect is present. ACFM is able to determine the length and depth of a defect. It does not require a clear line of sight between operator and crack location. All data are recorded electronically and the evidence for the existence or nonexistence of a crack can be revisited.
The paper describes the theory of the technique, the equipment used, and practical results from the first application of ACFM to downhole motor components.
Newly Applied BHA Elements Contribute to Mainstreaming of Coiled-Tubing Drilling Applications
Authors: Gleitman D. D. , Hardin J. R. , Hightower C. M. , Gantt L. L. , Smith B. E. , Upchurch E. R. , Smith M. B. 
Published: December 2007

Summary
Coiled-tubing drilling (CTD) is coming into the mainstream in a number of locations and applications, and the availability of improved bottomhole assembly (BHA) elements is a significant contributor in this regard. This paper describes BHA elements, including a hydraulic orienter and measurement-while-drilling (MWD) system, recently used by Arco in CTD operations; examines their capabilities; and provides examples in which these tools were used successfully.
The BHA orienter is a newly engineered, simple, hydraulically actuated device. This paper examines its performance attributes affecting overall rate of penetration (ROP) and directional control of the BHA, including its actuation speed and its ability to change the BHA orientation while in a medium-radius curve. The MWD system represents a new application of an existing reliable system, with attributes that are especially important in the CTD environment. Modifications related to downsizing are examined, as well as relevant performance attributes including steering-data-update rate; real-time gamma log quality; mud-pulse-detection capability on coil in a range of drilling fluids; and reliability. The BHA is also looked at from an overall system perspective, including its integration with the coiled tubing (CT) and other equipment associated with the CTD operation.
As of the writing of Ref. 1, Arco Alaska Inc. and THUMS Long Beach Co. (a wholly owned subsidiary of Arco) had completed 16 CTD re-entry sidetrack jobs in Alaska and Long Beach, California, with these BHA elements. This paper summarizes overall performance and reliability from these jobs. Additionally, specific cases are examined in greater detail, with these BHA elements contributing to successful CTD window milling, medium-radius curves, and laterals. (As of this publication, Arco companies have performed 47 such jobs with these BHA elements; however, this paper focuses on the first 16 jobs.)
Acid-Sludge Characterization and Remediation Improve Well Productivity and Save Costs in the Permian Basin
Authors: Wong T. C. , Hwang R. J. , Beaty D. W. , Dolan J. D. , McCarty R. A. , Franzen A. L. 
Published: December 2007

Summary
Many oil wells in the Permian Basin have reported sludging problems associated with acid stimulations. The acid sludge is similar among wells and was identified as a viscous emulsion stabilized by asphaltene-rich organic solids. The sludging tendency of the oil increased with the concentrations of asphaltenes and resins, base number of the oil, and ferric ion content in the acid. Only three out of nine commercial acid systems tested were effective in preventing acid-sludge formation; they all use the same novel iron control technology, i.e., catalytic reduction of ferric ions. Several commercial and generic solvent systems were effective in dissolving acid sludge, including mixtures of an aromatic solvent (e.g., xylene) with either isopropyl alcohol (2:1 volume ratio), or ethylene glycolmonobutylether (EGMBE) (2:1 to 3:1 volume ratios). Selection of acid formulations and solvent systems was based on cost effectiveness and operation safety. Field implementation proved successful. If the results of this study had been implemented earlier in the lives of some of the Permian Basin properties, the recovery of 574 BOPD of lost or deferred production from 99 wells could have been realized. This would have resulted in an estimated increased revenue of over U.S. $3 million in 1 year.
Use of Preformed Gels for Conformance Control in Fractured Systems
Authors: Seright R. S. 
Published: December 2007

Summary
Using wide ranges of gel age, gel velocity, and fracture conductivity or tube diameter, Cr(III)-acetate-HPAM gels were studied as they extruded through fractures and tubes. Gels exhibited shear-thinning behavior in fractures and tubes that correlated with the gel superficial velocity and the fracture width or tube diameter. In fractures with sufficiently small widths, gels dehydrated during extrusion, thus reducing the rate of gel propagation. This effect was more pronounced as the fracture width decreased. Using the experimental results, a numerical study was conducted to compare placement of preformed gels and water-like gelants.
Alkaline/Surfactant/Polymer Pilot Performance of the West Central Saertu, Daqing Oil Field
Authors: Shutang Gao , Huabin Li , Zhenyu Yang , Pitts M. J. , Surkalo Harry , Wyatt Kon 
Published: December 2007

SummaryA tertiary pilot application of the alkaline/surfactant/polymer (ASP) process was initiated in Sept. 1994 in the west central area of Daqing oil field. The pilot pattern consists of four inverted five-spots, including four injectors, nine producers, and 2 observation wells, encompassing an area of 90 000 m2 and with a pore volume (PV) of 203 300 m3. The target layer is the Saertu II1.3 (SII1.3) sandstone, with an average porosity of 26% and permeability of 1.426 [m2. The crude-oil viscosity is 11.5 mPa • s at reservoir temperature and the connate-water salinity is 6800 mg/L. The pilot performance shows a pronounced response from ASP injection. The average pilot area oil production rate increased from 36.7 to 91.5 m3/d, while water cut decreased from 82.7% to 59.7%. For the central well Po5, which is surrounded by injection wells, the oil production rate increased from 3.7 to 27.1 m3/d, while water cut decreased from 84.0% to 45.8%. Numerical simulation results forecast that the oil recovery will be increased by 18.1% original oil in place (OOIP). Total pilot oil production as of March 1996 is 67 500 m3 of which 25 300 m3, or 18.3 % OOIP, is additional produced oil with the current oil cut of 29.7%.
Simulation of Cold Production in Heavy-Oil Reservoirs: Wormhole Dynamics
Authors: Tremblay Bernard , Sedgwick George , Forshner Ken 
Published: December 2007

SummaryThe laboratory investigation described arose from a need to observe more directly how sand production can lead to enhanced oil recovery during the cold-production process. The production of oil and sand into a perforation was simulated by use of a sandpack with an orifice at one end. The pack was imaged throughout the experiment with a computed-tomography (CT) X-ray scanner. The experiment showed that (1) stable wormholes can develop in unconsolidated oil sands, (2) they likely develop in the weaker sands (which normally contain the most oil) within a formation, (3) a critical flow rate is required for the wormholes to grow, (4) the high sand cuts observed in the field at the start of cold production indicate that the wormholes are growing, and (5) the decrease in sand production rate observed in the field indicates that the wormholes have stopped developing and are being emptied out by scouring.