bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Real-Time Anticollision Alarm Improves Drilling Safety
Authors: Leder Pearl Chu , McCann D. P. , Hatch A. 
Published: December 2007

Abstract
A critical concern in directional drilling is ensuring the avoidance of collisions while drilling on multi-well locations. Collision avoidance planning is ordinarily carried out prior to well spud and is therefore valid only to the planned trajectory. Once drilling commences, deviation from the plan invariably occurs which may not only increase subsurface collision risk, but also compromise the ability to maintain adequate quality control of rigsite anticollision computations in an often stressful and demanding drilling situation.
New high performance, multi-user computer systems at the rigsite provide the capability for clear anticollision analysis in real time without the need for hand computations. In this paper we describe a unique computer application which performs traveling cylinder calculations automatically in real time. The present bit location, computed from survey and depth measurements, is shown on a rigfloor color display along with the trajectories of the offset wells. Position uncertainties for both the current hole location and all the offset wells are computed and plotted as error ellipses on the screen. In addition, the application has a "look-ahead" feature which projects the trajectory beyond the current bit depth, and a "Smart Alarm" is triggered if any of the offset wells come within a user specified alarm proximity.
Field data are shown which illustrate the effectiveness of the technique. The alarm has been designed to give early warning of potential collision situations. As a result, it improves safety and quality control at the rig and helps avoid the environmental damage that can result from well collisions.
Horizontal Drills and Their Cost Effective Use for Characterizing and Remediating Under Obstructions
Authors: Wilson David D. , Layne Roger 
Published: December 2007

Abstract
A survey completed in during the summer of 1995 indicates that there have been more than 400 horizontal environmental wells installed for subsurface remediation. This paper investigates the costs of installing a horizontal well and for obtaining subsurface samples using a directional drilling rig. Two case studies are presented that illustrate the diversity of horizontal well installations and their associated costs. Furthermore, it was found that the costs of obtaining soil samples using a directional drilling rig is based on a daily drilling rate. The daily drilling rates of two distinct systems are discussed.
Optimizing Reservoir Performance Under Uncertainty with Application to Well Location
Authors: Aanonsen S. I. , Eide A. L. , Holden L. , Aasen J. O. 
Published: December 2007

Abstract
Stochastic parameters representing geological uncertainties in reservoir modeling may be classified in 2 types: 1) Continuous stochastic variables (e.g., degree of communication through a fault); and 2) Discrete stochastic variables representing different geological interpretations (e.g., same/different channel observed in different wells) each with a given probability.
A method for optimizing reservoir performance is presented, which may take into account both these types of uncertainties in a consistent and simple way by finding values of reservoir management variables that optimize the expected performance over the population of possible reservoirs. The method is based on response surfaces and experimental design and is implemented in a user-friendly computer program which may be used together with any reservoir simulator or analytical flow model.
In this paper, the method is illustrated through 3 examples of optimizing well locations under uncertainty.
Accurate predictions for the production of vaporized water
Authors: Morin E. , Montel F. 
Published: December 2007

Abstract
The production of water vaporized in the gas phase is controlled by the local conditions around the wellbore. The pressure gradient applied to the formation creates a sharp increase of the molar water content in the hydrocarbon phase approaching the well; this leads to a drop in the pore water saturation around the well bore. The extent of the dehydrated zone which is formed is the key controlling the bottom-hole content of vaporized water.
The maximum water content in the hydrocarbon phase at a given pressure, temperature and salinity is corrected by capillarity or adsorption phenomena depending on the actual water saturation.
Describing the mass transfer of the water between the hydrocarbon phases and the aqueous phase into the tubing gives a clear idea of vaporization effects on the formation of scales. Field example are presented for gas fields with temperatures ranging between 140°C and 180°C, where water vaporization effects are significant. Conditions for salt plugging in the tubing arc predicted.
A Mechanistic Foam Model for Simulation of Steamfoam Field Applications
Authors: Hatziavramidis D. T. , Alameddine B. R. , Weinstein H. G. , Djabbarah N. F. , Revay J. M. 
Published: December 2007

Abstract
Starting in 1985, Mobil conducted a series of pilots and commercial-size steamfoam operations in South Belridge, California, which demonstrated significantly higher recoveries of heavy oil in combination with attractive process economics. To evaluate these succeses and guide future steamfoam field applications, a steamfoam model was incorporated into an in-house developed thermal simulator and was used in simulations to (1) match field performance, (2) confirm the extent and nature (i.e., accelerated vs. incremental) of additional oil recovered by steamfoam, and (3) determine optimum time for steamfoam injection termination.
The model is shown to be robust, with affordable complexity in the description of the relevant physics of the steamfoam process, and faithful in reproducing field performance.
An Overview of the North Ward Estes CO2 Flood
Authors: Ring J. N. , Smith D. J. 
Published: December 2007

Abstract
A CO2 pattern flood was initiated in a west Texas (Permian Basin), sandstone reservoir as a tertiary recovery process in 1989. This paper is an overview of the development and management of the North Ward Estes CO2 Flood. The primary objective of managing the CO2 flood has been to maximize oil recovery for maximum profitability. This has been accomplished by maintaining a consistent water-alternating-gas (WAG) process, optimizing CO2 utilization, and maintaining a proper balance between patterns. Reservoir modeling, which is emphasized in this paper, has also been critical in the development and management of this flood.
Pressure Falloff Testing of Enhanced Coalbed Methane Pilot Injection Wells
Authors: Seidle J. P. , McAnear J. F. 
Published: December 2007

Abstract
As part of the effort to interpret Amoco’s enhanced coalbed methane recovery pilot, each of the four nitrogen injectors was tested with a pressure falloff test (PFOT) after approximately five months of injection. An additional test was done on the final injector at the termination of the pilot. The tests were analyzed to obtain flow capacity, wellbore condition, and average reservoir pressure for use in subsequent simulation studies. Stress effects on reservoir permeability and wellbore skin were investigated. Results from the PFOTs yielded an injectivity index which can be used to estimate compression requirements for enhanced coalbed methane recovery projects.
The Effects of Stress on Coalbed Reservoir Performance, Black Warrior Basin, U.S.A.
Authors: Sparks D. P. , McLendon T. H. , Saulsberry J. L. , Lambert S. W. 
Published: December 2007

Abstract
This paper presents the first field scale measurements of in-situ stress effects on permeability of coal seams. The importance of these effects on a highly compressible reservoir such as coal is demonstrated by relating permeability and production to stress. Well testing complications and the implications of stress toward exploitation of existing reserves and exploration for new reserves are also discussed. Additionally, comparisons of this paper’s findings to prior theoretical work, core testing, and limited field data are presented.
The Relation of Diagenetic Clays and Sulfates to the Treatment of Coalbed Methane Reservoirs
Authors: Nick Kevin E. , Conway Michael W. , Fowler Kathleen S. 
Published: December 2007

Abstract
Field procedures and laboratory experiments to stimulate production from coalbed methane reservoirs have largely been designed from experience with fractured reservoirs and coal geochemistry. This paper descibes experiments to investigate the occurrence of cements in the permeability pathways in coal samples from mines and cores and how these diagenetic materials interact with completion and stimulation fluids based on core flow tests. Core flow testing of coals generally suggests damage by polymers and stimulation by several acids. Examination of cleat surfaces from the Mary Lee and Black Creek coal seams in the Black Warrior Basin and Fruitland coal from the San Juan Basin by light microscopy, SEM, and XRD analyses show the presence of carbonate, quartz and iron sulfide cements in impermeable cleats and quartz, illite, kaolinite, barite, gypsum, and iron sulfates in permeable fractures. Fracture morphology is also complex with many branching shapes and surface textures. Illite is typically the most abundant clay and is also interlaminated with or interspersed in the coal. Kaolinite is most likely to migrate and its occurrence in meniscus forms and packed against steps in the cleats document mobility. Coal fines are also present in the cleats, concentrated with clays at steps and bends in the cleats. Injection of fluorescin tagged guar through coal plugs demonstrated the polymer’s affinity for clay and identified permeability pathways in coal.
Application of Fuzzy Expert Systems for EOR Project Risk Analysis
Authors: Chung Ting-Horng , Carroll Herbert B. , Lindsey Rhonda 
Published: December 2007

Abstract
This work describes a new method for enhanced oil recovery (EOR) project preassessment. Instead of using the conventional costly simulation approach, a fuzzy expert system was developed. A database of EOR project costs and oil prices of the past decades was incorporated into the expert system. The EOR project risk-analysis includes three stages: (1) preliminary screening of EOR methods, (2) field performance estimation, and (3) economic analysis. Since this fuzzy expert system has incorporated both implemented EOR technology and experts’ experience, it thus reduces the requirements of massive laboratory and field data for input. Estimates of displacement efficiency (Ed) and sweep efficiency (Ev) were formulated for each EOR process. Ed and Ev were treated as fuzzy variables. The overall recovery efficiency is evaluated from the product of Ed and Ev using fuzzy set arithmetic. Economic analysis is based on the estimated recovery efficiency, residual oil inplace, oil price, and operating costs. Examples of the application of the developed method for a CO2-flooding project analysis is presented.
Modeling of Horizontal Well and Lifting Mechanisms to Improve Ultimate Recovery in a Depleted Field in Lake Maracaibo, Venezuela
Authors: Saputelli L. , Mata T. , Jimenez Z. , Banerjee S. , Lozada T. 
Published: December 2007

Abstract
Recovery of the remaining reserve of millions of oil barrels is inhibited by depleted reservoir pressures and existing exploitation policies in Lower Lagunillas Reservoir in Lake Maracaibo, Venezuela.
Numerical simulation results indicated that proper production and reservoir management policies such as, controlled drawdown, producing wells at rates below the critical rates, low gas-oil-ratio production will promote efficient gravity segregation process, and subsequent optimum final recovery. Combination of infill horizontal wells and adequate lifting mechanisms yielded the recovery of additional reserves.
Horizontal Injection Well Experience in the Valhalla Boundary Lake "M" Pool
Authors: Doerksen Timothy C. , Nicoud Richard A. , Lueers Kenneth H. , Yeung Wunbing S. , Ford W. Randy 
Published: December 2007

Abstract
Horizontal water injection wells were used to initiate a waterflood in the Valhalla Boundary Lake "M" pool. A simulation model of the pool indicated that vertical injection wells would not provide adequate injectivity to match withdrawals. Horizontal wells were proposed, drilled and used to repressure the reservoir to bubble point, achieve target injection rates and maximize production from the reservoir. The targets for the horizontal injectors and the associated waterflood have been surpassed to date.
Improved Reservoir Characterization and Management of a Mature Oil Field via Integrated Team Approach
Authors: Norris S. O. , Reinhardt B. K. 
Published: December 2007

Abstract
An iterative approach to reservor characterization, conducted by an integrated work team, proved to be essential to adequately understand and manage the late life production of the Trinity Shoal "N" Sand Reservoir. This paper describes the approach taken by the team in obtaining a superior simulation history match, which resulted in a more complete understanding of the reservoir, lead to the identification of successful infill well locations, and improved long term reservoir management plans.
Effect of Wettability on Adverse Mobility Immiscible Floods
Authors: Vives M. T. , Chang Y. C. , Mohanty K. K. 
Published: December 2007

Abstract
Many immiscible displacements in reservoirs occur at adverse mobility. Effect of wettability on these displacements is not well understood and often ignored in reservoir simulation. Recent macroscopic theories of viscous fingering treat adverse immiscible flows similar to miscible flows, the mixing in the fingered region being controlled by a Todd-Longstaff-type functional form. The wettability of the medium is taken into account only through the use of appropriate relative permeabilities. The goal of this paper is to understand the macroscopic bypassing in adverse mobility immiscible floods. Immiscible displacements are conducted in a quarter 5-spot model in both drainage and imbibition modes at similar effective mobility ratios and viscous-to-gravity numbers. The level of bypassing and gravity override is visualized and measured. Tertiary water-alternating-gas (WAG) displacements are also conducted at various WAG ratios and viscosity ratios. Fractional flow analysis and numerical simulation are used to understand these displacements.
Experiments show that macroscopic viscous fingering is present in adverse viscosity immiscible displacements where no saturation shock is expected from 1-D fractional flow theory. Bypassing due to both fingering and gravity override is higher in the drainage mode than in the imbibition mode, with other key parameters being the same. Optimum WAG ratio in water-wet rock is a function of oil/solvent viscosity ratio. The macroscopic flow theory needs to include capillarity and viscous fingering to match these experimental findings.
Steady-State and Unsteady-State Two-Phase Relative Permeability Hysteresis and Measurements of Three-Phase Relative Permeabilities Using Imaging Techniques
Authors: Eleri O. O. , Graue A. , Skauge A. 
Published: December 2007

Abstract
The objective of this work is to improve determination of two-phase and three-phase relative permeabilities by the use of saturation imaging techniques. The first part of the paper reports on steady-state and unsteady-state relative permeability experiments performed on restored-state carbonate reservoir cores. The aim was to study how relative pemeability test methodology impacts relative permeability curves, hysteresis and residual oil saturations in these intermediate-wet cores. Refined oil was used.
Significant hysteresis was observed in both the unsteady-state water and oil relative permeabilities. The characteristics of the unsteady-state water relative permeabilities imply that viscous instabilities were present during the waterflood. Centrifuge capillary pressure-wettability tests performed on companion core plugs both before and after the relative permeability tests showed good agreement with the unsteady-state results, but indicated change towards less oil-wetness during the steady-state tests. The main conclusion of this work is that extensive flushing of a restored-state core with refined oil may lead to a non representative relative permeability data and should therefore be avoided.
The second part of the paper presents a summary of results obtained from three-phase unsteady-state flow in water-wet sandstone (Berea and Clashach) cores. In-situ saturation measurements show that the water relative permeability is dependent on water saturation alone, and that there is no change in water relative permeability due to three-phase flow. The waterflood residual oil saturation was found reduced in the presence of a gas phase, and may depend on the phase (oil or gas) injected prior to waterflooding.
Determination of Relative Permeability and Recovery for North Sea Gas Condensate Reservoirs
Authors: Chen H. L. , Wilson S. D. , Monger-McClure T. G. 
Published: December 2007

Abstract
Laboratory experiments on gas condensate flow behavior were conducted under reservoir conditions. Two North Sea gas condensate reservoirs that have distinct rock and fluid properties were studied. The objectives of the corefloods were to investigate the effects of rock and fluid characteristics on critical condensate saturation (CCS), gas and condensate relative permeabilities during in-situ condensation, hydrocarbon recovery and trapping by water injection, and incremental hydrocarbon recovery by subsequent blowdown.
It was found that both CCS and relative permeability were sensitive to flow rate and interfacial tension. The results on gas relative permeability rate sensitivity suggest that gas productivity curtailed by condensate drop out can be somewhat restored by increasing production rate. Phase behavior and interfacial tension influence the extents of gas relative permeability reduction and condensate mobility. High interfacial tension ultimately caused condensate relative permeability to decrease with increasing condensate saturation. Condensate immobile under gas injection could be recovered by water injection, but more immediate and efficient condensate recovery was observed when the condensate saturation prior to water injection exceeded the CCS. Approximately 27 %PV gas was trapped by water injection. Subsequent blowdown recovered additional gas, but incremental condensate recovery was insignificant.
Thirty (30) Years of Steamflooding: Reservoir Management and Operational Experiences
Authors: Ramkhalawan C. D. , Khan J. , Bainey K. R. 
Published: December 2007

Abstract
The Petroleum Company of Trinidad and Tobago Limited (Petrotrin) has a heavy oil reserves base of 300 million barrels of heavy oil in the southern part of the island of Trinidad. The Company, and its predecessors, first embarked on a thermal recovery program in its acreage from 1963 with cyclic/steamflooding operations. At the present time, the Company is operating eleven (11) steamfloods and is currently implementing another major project. This paper presents a case history of the Company's thirty-two years experience in steamflooding, inclusive of reservoir management and monitoring methods, innovations and operating practices. To date (1995 June), the Company has recovered a total of 77 million barrels of heavy oil from its acreage, with a current production level of 9000 BOPD. During this period, new diagnostic methods were initiated, as well as new innovations. These include cluster drilling, slim-hole injectors, insulated tubing and packers, non-gravel packed injectors, high volume pumps, limited entry perforating, insulated casing completions, diverting agents, dual injectors, iso-fluid mapping and other reservoir management techniques. In summary, the Company has had extensive success in steamflooding operations and continues to utilise this method for exploitation of its heavy oil reserves. With its proven success and existing infrastructure for this type of operation, the Company still has major opportunities in heavy oil recovery. Additionally, new methods of operation, financing and project management are being pursued to exploit these reserves. Based on Trinidad's complex geology and heterogeneous reservoirs, heavy oil recovery has been a major success through the Company's scope of operations. Several innovations in reservoir management and operating strategies can be implemented in other similarly adverse environments for heavy oil recovery.
Effects of Capillary Heterogeneities on Spontaneous Imbibition
Authors: Zeybek M. , Gurakin G. , Donmez A. , Onur M. 
Published: December 2007

Abstract
This paper presents numerical studies of spontaneous imbibition phenomenon in a heterogeneous matrix block of porous medium in one and two dimensional systems. Heterogeneous distributions of permeability as well as wettability that could affect spontaneous imbibition are considered. Deterministic and stochastic heterogeneity profiles with correlated and uncorrelated fields for permeability and wettability distributions are considered. Both countercurrent with gravity forces and simultaneous cocurrent and countercurrent flows are studied.
Numerical model is tested with an experimental study with input measured parameters. Deterministic profiles for permeability have strong effects on saturation and recovery curves for countercurrent imbibition in one and two dimensional systems. Uncorrelated permeability fields with log-normal and fBm statistics yield strong responses in saturation with high amplitudes. Correlated fields give smooth responses in saturation. However, recovery curves are affected considerably by correlated fields depending on realizations. Heterogeneous forms of wettability have strong influence on responses in saturation and weak influence on responses in recovery curves compared to responses in heterogeneous permeability fields. Interaction of gravity with heterogeneity is also considered for countercurrent flow in one dimensional systems. Some examples of heterogeneous forms of permeability and wettability are also considered in two dimensional systems.
Parachors in Terms of Critical Temperature, Critical Pressure and Acentric Factor
Authors: Broseta Daniel , Ragil Karine 
Published: December 2007

Abstract
The method of parachors is widely used in conventional thermodynamic codes and reservoir simulators to calculate oil/gas interfacial tensions of complex hydrocarbon mixtures. In the low-to-moderate interfacial tension regime, a value p≈11/3 has previously been shown to be the "best" parachor exponent. This exponent is a critical exponent and its value is consistent with the values of critical exponents characterizing the liquid/vapor critical behavior. Therefore parachors may be viewed as critical amplitudes.
By using critical scaling theory, parachors are related to other critical amplitudes and critical parameters that describe the bulk thermodynamic behavior of fluids. A simple expression relating the parachor of a pure compound to its critical temperature Tc, critical pressure Pc and acentric factor ω is proposed: P= (0.85-0.19ω)Tc12/11 /Pc9/11 where the parachor P is in units of (dyn/cm)3/11cm3/mol, Tc in K and Pc in MPa. This equation matches (within experimental error) the known parachor values of normal fluids (e.g. alkanes, aromatics, CO2, N2, H2S, etc…).