bluuebunny/crossref_metadata_2025_split huggingface dataset:
Well Configurations in Anisotropic Reservoirs
Authors: Economides M. J. , Brand C. W. , Frick T. P. 
Published: December 2007

SummaryHorizontal wells have emerged as a new means for well-productivity enhancement. Simultaneously, they have brought forward the need to recognize and account for permeability anisotropies, including vertical-to-horizontal and horizontal-to-horizontal directions. In addition, there is the possibility of multiple horizontal drainholes emanating from the same vertical well. Performance relationships for the most interesting well configurations are presented, including both early-time and late-time differences rather than only bounded flow regimes. Solutions for arbitrarily oriented single or multiple horizontal wells are introduced, along with a discussion of well-known existing relationships.
On the Mechanical Stability of lnclined Wellbores
Authors: Zhou Shaohua , Hillis R. R. , Sandiford Mike 
Published: December 2007

Summary
Consideration of the stress field around an arbitrarily oriented borehole shows that in an extensional stress regime (σv σH&gt;σh), wellbores parallel to the direction of minimum horizontal principal stress are the least prone to compressive shear failure (breakout). The most stable deviation angle (from the vertical) depends on the ratio of the horizontal principal stresses to the vertical stresses, and the higher the ratio σH/σV, the higher the deviation angle for minimizing breakout. In a strike-slip stress regime (σv &lt;σH&gt;σh), horizontal wells are the least prone to breakout, and the higher the ratio σH/σ v, the closer the drilling direction should be to the azimuth of σH.
A new compressive shear failure criterion, which is a combination of the effective strength concept and the Drucker-Prager criterion, is proposed for quantifying the stresses at which borehole breakout occurs. The lowest mud weight, at and below which breakout will occur, can be predicted by combining this criterion with the stress field around an arbitrarily oriented borehole. The highest mud weight at and above which a tensional or hydraulic fracture is induced can be predicted by combining the tensile strength of the rocks of the wellbore wall with the stress field around an arbitrarily oriented borehole. For the in-situ stress environments considered, the optimally oriented inclined wellbore is less prone to breakout (i.e., allows a lower mud weight) and tensional or hydraulic fracture (i.e., supports a higher mud weight) than a vertical well.
Zirconium Additives for High-Temperature Rheology Control of Dispersed Muds
Authors: Miano Fausto , Carminati Stefano , Lockhart Thomas P. , Burrafato Giovanni 
Published: December 2007

Summary
Environmental considerations have stimulated new interest in the use of aqueous drilling fluids in situations where oil-based muds have previously been preferred. The least expensive and most widely used aqueous drilling fluids are dispersed muds made up with bentonite clay. These bentonite muds, however, possess limited rheological stability at elevated temperature and are also often formulated with chromium-containing thinners that are increasingly subject to environmental regulation.
This paper describes a new zirconium-based rheology control additive of low toxicity that is extremely effective at extending the rheological stability of both chromium-containing and chromium-free bentonite muds at high temperature. The results of mud-aging experiments carried out between 150 and 200°C on both laboratory and field-conditioned bentonite muds illustrate the rheology-stabilizing characteristics of this additive. The low cost of drilling fluids formulated with the zirconium additive makes them attractive candidates for resolving the environmental issues and limited rheological stability of existing bentonite muds.
Transport in Shales and the Design of Improved Water-Based Shale Drilling Fluids
Authors: van Oort Eric , Hale A. H. , Mody F. K. , Roy Sanjit 
Published: December 2007

Summary
Transport of water and ions in shales and its impact on shale stability were studied to facilitate the improvement of water-based muds as shale drilling fluids. Transport parameters associated with flows driven by gradients in pressure and chemical potential were quantified in key laboratory and full-scale experiments. The experimental results show that the low-permeability matrices of intact, clay-rich shales can act as imperfect or "leaky" membranes that will sustain osmotic flow of water. Moreover, the ability of shales to act as osmotic membranes is shown to provide a powerful new means for stabilizing these rocks when exposed to water-based drilling fluids. Guidelines are presented for effective exploitation of shale membrane action and induced osmotic flows through optimized water-based drilling fluid formulation.
In addition, special attention is given to induced electro-osmotic water flow in shales driven by electric potential gradients, which may provide an exciting, new, environmentally benign means for stabilizing shale formations.
Tracer Flow and Pressure Performance of Reservoirs Containing Distributed Thin Bodies
Authors: Sato Kozo , Abbaszadeh Maghsood 
Published: December 2007

Summary
The effects of thin objects (fractures/barriers) on pressure distributions and displacement performances in staggered and direct linedrive patterns with uniformly and stochastically distributed objects at different density and length distributions are studied. Tracer breakthrough and well productivity are used to characterize the configuration of thin objects in the patterns. In most cases examined, tracer breakthrough time is more sensitive to the presence of thin objects than the well productivity. It is also found that representing fracture systems as equivalent anisotropic media may lead to erroneous pressure-distribution predictions around a well.
The study was carried out by using the complex variable boundary element method (CVBEM), which yields both the potential and stream functions simultaneously, and is suitable to track displacement fronts in the presence of thin objects. Singularities caused by such objects are expressed analytically through the conformal-mapping technique.
Use of Geology in the Interpretation of Core-Scale Relative Permeability Data
Authors: Ringrose P. S. , Jensen J. L. , Sorbie K. S. 
Published: December 2007

Summary
A number of factors, such as wettability, pore-size distribution, and core-scale heterogeneity, are known to affect the measured relative permeability in core plug samples. This paper focuses on the influence of geological structure at the laminaset scale on water-oil imbibition relative permeability curves. The endpoint positions and curve shapes vary as a function of the type of internal heterogeneity, the flow rate, and the assumptions on the pore-scale petrophysics (e.g. wettability). Interaction between the capillary forces and heterogeneity can occur at the cm-dm scale, which results in widely varying two-phase flow behavior for rocks with the same single-phase permeability. The geometry of heterogeneity as expressed in standard geological descriptions (e.g., cross-laminated, ripple-laminated, plane-laminated) can be translated into features of the expected relative permeability behavior for each rock type, thus aiding the interpretation of relative permeability data. We illustrate how our findings can help to interpret sets of relative permeability data from the field, using some examples from the Admire sand, El Dorado Field, Kansas.
Water-Droplet-Size Determination for Improved Oil-Treater Sizing
Authors: Thro M. E. , Arnold K. E. 
Published: December 2007

Abstract
The sizing of crude-oil treaters is still very much an art. While it is possible to perform laboratory studies on crude-oil samples, no one has published a proven field-test procedure that can be used to pick an appropriate treating temperature and treater dimensions for a specific field.
Dehydration and Desalting of Heavy and Viscous Crude Oil Produced by In-Situ Combustion
Authors: Popp V. V. , Dinulescu V. D. 
Published: December 2007

Summary
This paper presents the dehydration and desalting of heavy crude oil produced by in-situ combustion with thermochemical and gas stripping stages. Indirect heating of oil through cocurrent contact with recirculated water from the process, heated with metal heaters, will preclude temperature variations caused by flow fluctuations in the feeding of the plant during the thermochemical process. At the same time, the amount of mechanical impurities (carried out by the recirculated water) is diminished. The flue gas stripping stage increased the process efficiency using a double column and blown-in air heater.
Phase Splitting Of Wet Steam in Annular Flow Through a Horizontal Branching Tee
Authors: Chien Sze-Foo 
Published: December 2007

Summary
A phase-splitting equation for flow of a two-phase fluid through a tee junction was derived. It shows that the fluid quality at an outlet of the tee is determined by the relationship between the liquid and vapor extraction ratios of the fluid through that outlet. This equation applies to any tee junction regardless of its geometry, orientation, and inclination. This paper presents its application to the flow of wet steam through a horizontal branching tee.
Experimental data were for wet steam flowing through a standard branching tee of 2- and 4-in. sizes in a horizontal plane, inlet pressures from 400 to 800 psig, inlet qualities from 0.2 to 0.8, inlet vapor velocities from 40 to 120 ft/sec, and for vapor-extraction ratios in the 0.2 to 0.8 range. These data were analyzed focusing on the effect of the vapor-extraction ratio of the run stream on the liquid-extraction ratio of the same stream. A correlation between these two extraction ratios has been established with steam quality, superficial vapor velocity, and critical velocity at the inlet to the tee as controlling parameters. Using this correlation and the phase-split equation, we are able to predict steam qualities exiting from horizontal branching tees to within ± 15% of the experimental values, which is more accurate than other phase-splitting models.
Modeling and Scaleup of S†eamflood in a Heterogeneous Reservoir
Authors: Dehghani Kaveh , Basham W. M. , Durlofsky L. J. , Tucker K. E. 
Published: December 2007

Summary
A series of simulation runs was conducted for different geostatistically derived cross-sectional models to study the degree of heterogeneity required for proper modeling of steamfloods in a thick, heavy-oil reservoir with thin diatomite barriers. Different methods for coarsening the most detailed models were applied, and performance predictions for the coarsened and detailed models compared. Use of a general scaleup method provided the most accurate coarse grid models.
Performance and Expansion Plans for the Double-Displacement Process in the Hawkins Field Unit
Authors: Langenberg M. A. , Henry D. M. , Chlebana M. R. 
Published: December 2007

Summary
The double-displacement process (DDP) is a method for immiscible tertiary gas displacement of a watered-out oil reservoir. In the Hawkins field of east Texas, the effectiveness of the immiscible nitrogen injection process is strongly driven by favorable gravity-drainage characteristics that lead to improved sweep and displacement efficiencies for the gas/oil system relative to the water/oil system. This paper documents the initial 6 years of the double-displacement project in the East Fault Block (EFB) of the Hawkins Field Unit, confirming the viability of the double-displacement recovery mechanism. It describes how early project performance indicated that oil gravity drainage was occurring slower than expected, the studies initiated to investigate the slower oil gravity drainage, and the successful outcome of those studies. In addition, the paper describes how the project has responded favorably to optimization efforts and gives a brief description of how results from the EFB have been applied to a proposed expansion to the West Fault Block (WFB).
Reserves Determination Using Type-Curve Matching and EMB Methods in the Medicine Hat Shallow Gas Field
Authors: West S. L. , Cochrane P. J. R. 
Published: December 2007

Summary
Tight, shallow gas reservoirs in the Western Canada basin present a number of unique challenges in determining reserves accurately. Traditional methods such as decline analysis and material balance are inaccurate owing to the formation's low permeabilities and poor pressure data. The low permeabilities cause long transient periods that are not separated easily from production decline with conventional decline analysis, resulting in lower confidence in selecting the appropriate decline characteristics (exponential or harmonic), which effects recovery factors and remaining reserves significantly. Limited, poor-quality pressure data and commingled production from the three producing zones results in nonrepresentative pressure data and hence inaccurate material-balance analysis. This paper presents two new methods of reserve evaluation that address the problems described above for tight, shallow gas in the Medicine Hat field. The first method applies type-curve matching, which combines the analytical pressure solutions of the diffusivity equation (transient) with the empirical decline equation. The second method is an extended material balance (EMB), which incorporates the gas deliverability theory to allow selection of appropriate p/z derivatives without relying on pressure data. Excellent results were obtained when these two methods were applied to 10 properties that gather gas from 2300 wells. The two independent techniques resulted in similar production forecasts and reserves, confirming their validity. They proved to be valuable, practical tools in overcoming the various challenges of tight, shallow gas and in improving the accuracy in gas-reserves determination in the Medicine Hat field.
Tracer-Test Interpretation in Naturally Fractured Reservoirs
Authors: Ramírez-S. Jetzabeth , Samaniego-V. Fernando , Rodríguez Fernando , Rivera-R. Jesus 
Published: December 2007

Summary
This paper presents a solution for the inverse problem, or interpretation, of the radial flow of tracers in naturally fractured reservoirs. Our model considers cubic-matrix-block fracture geometry, and by using the Rosenbrock method for nonlinear regression, we can estimate up to six parameters for this cubic-block geometry. We carefully tested the nonlinear regression against synthetical tracer-concentration responses affected by random noise with the objective of simulating, as closely as possible, step-injection field data. Results were obtained within 95% confidence limits. We also investigate sensitivity of the inverse-tracer-problem solution on the main parameters that describe this flow problem. The main features of the nonlinear regression program used in this study are also discussed. The procedure can be applied to interpret tracer tests in naturally fractured reservoirs, allowing the estimation of fracture and matrix parameters of practical interest (longitudinal-fracture dispersivity, a, matrix porosity, ϕ2, fracture half-width, W, matrix block size, d, matrix-diffusion coefficient, D2, and the adsorption constant, kd). This work's method offers a practical alternative for tracer-flow-test interpretation.
Viscometric Principles of Onsets of Colloidal Asphaltene Flocculation in Paraffinic Oils and Asphaltene Micellization in Aromatics
Authors: Escobedo Joel , Mansoori G. A. 
Published: December 2007

Summary
Recently, we proposed a new technique for the determination of the onset of asphaltene flocculation.1 This new method is based on viscosity measurements of a crude oil upon titration with a precipitating solvent (e.g. n-pentane, n-heptane, etc.). The onset of asphaltene flocculation is detected by a sharp increase in the relative viscosity of the suspension in which asphaltene particle aggregation occurs. The key point in this development is the phenomenon of asphaltene flocculation induced by the addition of an n-paraffin hydrocarbon to a crude oil. The proposed method can also be applied to detect the onset of micellization of asphaltenes in aromatic solvents.
In this paper, we validate the proposed new technique from a theoretical standpoint.
Tailoring Hydrocarbon Streams for Asphaltene Removal
Authors: Del Bianco Alberto , Stroppa Fabrizio , Bertero Luigi 
Published: December 2007

Summary
Oilfield production is often hindered by asphaltene precipitation which tends to fill the pores of reservoir rocks and plug the wellbore tubing and other auxiliary equipment used during crude-oil recovery.
Several remedies to remove these deposits have been proposed and patented, but the injection of aromatic solvents such as toluene and light petroleum distillates is normally preferred. Previous studies with a number of pure aromatic hydrocarbons have shown that the solvent capacity of these molecules may be very different and that the degree of condensation plays an important role. In this regard, tetralins and naphthalenes are superior to alkylbenzenes. However, because the use of pure compounds is not economically feasible, we examined various industrial streams and correlated their chemical composition to the solvent capacity. This work allowed the identification of the pseudocomponents whose relative concentration is crucial for evaluating the solvent performances. On the basis of these data, we were able to find new products with ideal characteristics. The efficiency of one of these products was confirmed by the analysis of the data obtained when using this new solvent to remove asphaltene in damaged wells of an Italian field.
Evaluation of Rock/Fracture Interaction: During Steam Injection Through Vertical Hydraulic Fractures
Authors: Kovscek A. R. , Johnston R. M. , Patzek T. W. 
Published: December 2007

Summary
The design, results, and analysis of a steamdrive pilot in the South Belridge diatomite, Kern County, California, are reviewed. Pilot results demonstrate that steam can be injected across a 1,000-ft-tall diatomite column using hydraulically fractured wells and that significant oil is produced in response to steaming. A computationally simple numerical model is proposed and used to analyze reservoir heating and volumetric sweep by steam. Results from the analysis show that hydraulic fractures undergoing steam injection can be dynamic and asymmetrical.
Horizontal Well Testing of Isolated Segments
Authors: Frick T. P. , Brand C. W. , Schlager B. , Economides M. J. 
Published: December 2007

AbstractA horizontal well test in a large reservoir and with small wellbore storage should produce certain distinct flow regimes. These should lead to the estimation of three permeabilities (along, normal and vertical to the well trajectory) the total well skin effect and, perhaps, the effective (open) well length. The objective of this work is to optimize well test design to obtain the desired flow regimes. It is shown that the important early-time flow regimes can be masked by wellbore storage effects. Therefore, afterflow should be minimized by using downhole shut-in. The storage effects can be estimated with empirical equations. These relationships also mark the beginning of the first interprétable flow regime. It is shown that for very thin formations or in situations where the well is drilled close to the top or bottom boundaries the early radial flow regime may not be seen at all. The length of an almost fully laterally penetrating horizontal well may also distort the late-time radial flow. In both of these instances, calculation of the controlling permeabilities becomes difficult to impossible. It may thus be desirable to test smaller segments of the well. Placing an observation gauge in an isolated segment during the flow testing of another segment can provide further information. It is shown that the derivative of the pressure response in the observation gauge exhibits a characteristic hump. When the hump appears, the permeability along the well axis can be calculated. Testing of isolated segments would also deliver a detailed picture of the skin distribution along an extended horizontal well. From such a test valuable information for enhanced stimulation and selective well completion design can be drawn.
Why Our Reserves Definitions Don't Work Anymore
Authors: Caldwell R. H. , Heather D. I. 
Published: December 2007

Summary
Our current set of SPE reserves definitions, and their Security & Exchange Commission (SEC) counterparts, give a very misleading evaluation in a volatile pricing environment when dealing with mature, long life properties. Previous attempts to tighten the definitions through the use of "snapshot" price assumptions have had the opposite effect and have corrupted the technical uncertainty aspects of the definitions.
Probabilistic handling of pricing data allows evaluations to be performed that quantify economic uncertainty, thus removing the need for snapshot price assumptions or for a price forecast at all. The interaction between technical and economic uncertainties in reserves evaluation is discussed in the light of these results and the concept of a reference price for reserves evaluations is introduced.
Underbalance Criteria for Minimum Perforation Damage
Authors: Behrmann L. A. 
Published: December 2007

SummaryA simple viscous drag force equation has been applied to single-shot laboratory perforation/flow experimental data to obtain perforation damage skin vs. underbalance. The equations are applicable for oil wells in consolidated, nonsanding formations and are a function of reservoir porosity, permeability, and diameter of the perforation tunnel in the rock.The equations are independent of oil compressibility and viscosity. The dependency on perforation diameter suggests that larger charges are more damaging than small charges and that big hole charges are more damaging than equal-size deep penetrating charges. The equations can be used to calculate an optimum underbalance or a single-shot perforation skin for less than optimum underbalance. The single-shot skin can be used in well-flow analysis simulators to obtain a well perforation skin.
Multizone Subsea Completions in the Dai Hung Field, Vietnam
Authors: Lay K. R. 
Published: December 2007

Summary
The early production phase of the Dai Hung field development resulted in the drilling and completion of five subsea wells. Because of the complex nature of the reservoirs, selective multizone completions were installed for effective reservoir data acquisition and reservoir management. The downhole completion designs used equipment that was primarily of existing proven design and downhole equipment installation was successfully achieved in a single trip. Ongoing reservoir management will be aided by the use of a subsea wireline system to facilitate data acquisition.
Well Testing for Radially Heterogeneous Reservoirs Under Single and Multiphase Flow Conditions
Authors: Thompson L. G. , Reynolds A. C. 
Published: December 2007

SummaryIn this work, we examine the behavior of pressure-transient data for single and multiphase flow in radially heterogeneous reservoirs. To illustrate multiphase flow behavior in these systems, we focus on heterogeneous gas-condensate reservoirs; however, we also consider other multiphase flow problems. It is well known1 that in some instances, e.g., water injection/falloff in homogeneous reservoirs, pressure-transient data from buildup (or falloff) tests cannot be obtained by superposition of drawdown (injection) pressure responses. In fact, drawdown and buildup reflect properties in different regions of the reservoir. This behavior is common to most occurrences of multiphase reservoir flow and is exaggerated in the presence of radial heterogeneity. This theoretical work describes the information contained in transient pressure derivative data and explains the fundamental difference in behavior between multiphase drawdown and buildup pressure-transient data in radially heterogeneous reservoirs. We show that multiphase buildup data may be treated like single-phase buildup data, but drawdown data is most indicative of properties in that region of the reservoir where mobility is changing most rapidly with time.