bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of Oil-Water Flow Patterns in Vertical and Deviated Wells
Authors: Flores Jose G. , Chen X. Tom , Sarica Cem , Brill James P. 
Published: December 2007

SummaryAn oil-water flow pattern classification and characterization for wellbores is proposed based on the integrated analysis of experimental data, including frictional pressure drop, holdup, and spatial phase distribution, acquired in a transparent test section (2-in. i.d., 51-ft long) using a refined mineral oil and water (ρo / ρw = 0.85,μ o /μw 20.0, and σo-w = 33.5dyn/cm at 90°F). The tests covered inclination angles of 90°, 75°, 60°, and 45° from horizontal.The oil-water flow patterns have been classified into two major categories given by the status of the continuous phase, including water-dominated flow patterns and oil-dominated flow patterns. It was found that most water-dominated flow patterns show signifi- cant slippage but relatively low frictional pressure gradients. In contrast, all the oil-dominated flow patterns exhibit negligible slippage but significantly larger frictional pressure gradients. Six flow patterns have been characterized in upward vertical flow; three were water dominated and three were oil dominated. In upward inclined flow there were four water-dominated flow patterns, two oil-dominated flow patterns and a transitional flow pattern. Flow-pattern maps for each of the tested inclination angles are presented. A mechanistic model to predict flow-pattern transitions in vertical wells is proposed. The transitions to the very-fine- dispersed flow patterns were evaluated by combining the concepts of turbulent kinetic energy with the surface free energy of the droplets, while the transitions to the churn flow pattern and the phase inversion were predicted based on the concept of agglomeration. The model compares favorably with the measured data.
Polymer Gel Dehydration During Extrusion Through Fractures
Authors: Seright R. S. 
Published: December 2007

Summary
Some of the most successful water shutoff treatments in fractured reservoirs used relatively large volumes of Cr(III)-acetate-HPAM gel that extruded through fractures during the gel placement process. The gel can dehydrate during extrusion, and consequently, propagate at an unexpectedly low rate if the fracture conductivity or width is sufficiently small. This paper characterizes the dehydration phenomenon and its relation to gel extrusion. The findings are relevant to gel placement during field applications.
Impact of Perforations on Hydraulic Fracture Tortuosity
Authors: van Ketterij R. B. , de Pater C. J. 
Published: December 2007

Summary
We performed scaled model tests to study the relation between completion and treatment parameters and the near wellbore geometry for highly deviated, cased perforated wellbores. We have instrumented our casings to observe the moment fluid flow around the casing causes a signi®cant increase in the amount of pressure acting on the wall of the borehole. When fluid flow around the casing occurs extensively before fracture initiation, this leads effectively to an open hole situation at the moment of initiation. Otherwise the perforations will be the only possible initiation sites. In our experiments with a perforation phasing of 90° the perforations on top of the borehole acted in most cases as initiation sites. We performed stress calculations with a simple analytical model to understand the influence of the perforation angle on initiation pressure and fracture propagation.
Physical Properties of Carbonated Oils
Authors: Welker J.R. 
Published: December 2007

Abstract
The growing interest in the use of CO2 in crude oil recovery increases the need for data on the effect of CO2 on hydrocarbon physical properties. Data are presented on the solubility of CO2 in various dead oils, the swelling changes in CO2 -oil solutions and the effect of CO2 on dead oil viscosity. This later property shows the most pronounced effect, with viscosity reductions up to 98 per cent of the uncarbonated viscosities. An empirical method of estimating the viscosity of carbonated oils is presented. The apparatus and procedures used are described in sufficient detail to allow others to make similar studies.

Introduction
The effect of dissolved carbon dioxide on the swelling and viscosity reduction of specific hydrocarbon oils has been observed and recorded by a number of investigators. The object of this paper is to offer a means of predicting these effects for crude oils free from natural gas, using the dead state viscosity and gravity of the crude oils. The CO. solubility and swelling of numerous crude oils were determined in a visual cell at various pressure levels. The viscosity of the oils carbonated to various pressure levels was then determined by measuring the pressure drop across a capillary tube. From these data, the physical properties were correlated empirically. The resulting correlations allow the prediction of CO solubility, swelling and viscosity reduction if the dead state gravity and viscosity of the oils are known.
Adaptive Compensation of the Mud Pump Noise in a Measurement-While-Drilling System
Authors: Brandon T. L. , Mintchev M. P. , Tabler Herb 
Published: December 2007

Summary
Mud pulse telemetry is one of the promising methods for transmission of valuable downhole information in measurement-while-drilling (MWD) processes. Quality, speed, and reliability of mud pulse telemetry are, however, drastically jeopardized by various powerful noise contributors. Among these the mud pump noise could be the most damaging artifact for the mud pulse information signal. The real-time monitoring requirement and the variable dynamic frequency characteristics of the mud pulse signals make the utilization of traditional noise filtering techniques very difficult if not impossible. In this study, two new methods for real-time adaptive compensation in the specific noise environment of MWD are suggested. The methods are designed and tested assuming the worst case scenario of about 50% of the information signal present in the reference channel. Successful real-time compensation in such harsh noise environments is reported.
Water Injection in Water-Wet Fractured Porous Media: Experiments and a New Model with Modified Buckley–Leverett Theory
Authors: Terez Ivan E. , Firoozabadi Abbas 
Published: December 2007

Summary
This study examines water injection in water-wet fractured porous media and its modeling using the Buckley–Leverett theory. New experimental data on water injection in Berea and Austin chalk matrix block(s) are presented. Water injection in Austin chalk with a permeability of 0.01–0.04 md and porosity of 5% results in about 20% recovery from the rock matrix.
In the second part of the paper, we use the Buckley–Leverett displacement in a dual-porosity model to simulate the literature data as well as experimental data from this work. A new model is devised for the simulation of water injection in fractured porous media. A major element of the new model is the multiplication of the transfer flux by the fracture saturation with a power of 1/2. This simple model can account for both cocurrent and countercurrent imbibition and computationally it is very efficient. The results of the proposed model and the fine-grid simulation are in good agreement with the experimental data.
Conditioning Geostatistical Models to Two-Phase Production Data
Authors: Wu Zhan , Reynolds A. C. , Oliver D. S. 
Published: December 2007

Summary
A discrete adjoint method for generating sensitivity coefficients related to two-phase flow production data is derived. The procedure is applied to calculate the sensitivity of wellbore pressure and water-oil ratio to reservoir simulator gridblock permeabilities and porosities. Using these sensitivity coefficients, an efficient form of the Gauss-Newton algorithm is applied to generate maximum a posteriori estimates and realizations of the rock property fields conditioned to a prior geostatistical model and pressure and/or water-oil ratio data obtained under two-phase (oil and water) flow conditions.
Designing Under- and Near-Balanced Coiled-Tubing Drilling by Use of Computer Simulations
Authors: Gu Hongren , Walton I. C. , Stein D. A. 
Published: December 2007

Summary
This paper describes the use of two computer simulation utilities to design underbalanced or near-balanced coiled tubing drilling: one is a steady-state design module and the other is a transient wellbore simulator developed for coiled-tubing operations. The steady-state design module provides various design parameters for a drilling operation, and the transient wellbore simulator predicts the outcome from a particular design for the entire operation. Simulation results show the desired under or near balance can only be achieved by certain combinations of liquid and gas rates when using foam as the drilling fluid or using gas injection through gas-lift mandrel or parasite string. The effects of cuttings loading, depth of injection point and reservoir inflow on the downhole pressure or underbalance are presented and discussed. A procedure for designing under- or near-balanced drilling is described and demonstrated with an example using the computer utilities. A field example is used to show the accuracy of the simulator by comparing the measured and simulated downhole pressures.
An Overview of Air/Gas/Foam Drilling in Brazil
Authors: Negrão A. F. , Lage A. C. V. M. , Cunha J. C. 
Published: December 2007

Summary
Air, gas, and foam drilling has been used in specific areas in Brazil as an alternative to the traditional drilling process. This work focuses on the benefits and operational improvements obtained with those two-phase flow drilling operations. The comparison between the performance of conventional and two-phase flow drilling has been showing that this technique, when appropriately used, presents some advantages: (1) minimum or no damage to sensitive pay zones, (2) immediate and continuous evaluation of cuttings for hydrocarbon shows, (3) avoidance of lost circulation, and (4) higher penetration rates in hard formations. This work shows recent on-shore two-phase flow drilling field cases in Brazil using both, jointed pipe and coiled tubing techniques. The results obtained in those wells are analyzed and also the surface equipment design, the appropriate technique for connections, as well as the comparison between field data and predictions from simulators are discussed. Future plans for two-phase flow drilling operations in Brazil are also commented. Additionally, potential areas and concrete actions for improving operational feasibility of this technology are identified. The target is a safer and more economical air, gas, or foam drilling operation.
Optimum Conditions for Wormhole Formation in Carbonate Porous Media: Influence of Transport and Reaction
Authors: Fredd C. N. , Fogler H. S. 
Published: December 2007

Summary
The effects of transport and reaction on the phenomenon of worm-hole formation were investigated for a wide range of fluid systems including strong acids, weak acids, and chelating agents. These fluid systems are influenced by a variety of transport and reaction processes such as the transport of reactants to the surface, the reversible surface reactions, and the transport of products away from the surface. When these transport and reaction processes are taken into account, a common dependence of the dissolution phenomenon on the Damköhler number is observed. There exists an optimum Damkohler number at which a minimum number of pore volumes are required for channel breakthrough. This optimum Damkohler number occurs at approximately 0.29 for all the fluid/ mineral systems investigated in this study. In addition, an optimum kinetic parameter exists at which wormhole formation is most efficient. This optimum kinetic parameter occurs at a value of about 130. Together, the Damkohler number and the kinetic parameter provide a complete description of the dissolution phenomenon.
Effect of Perforation Density on Single-Phase Liquid Flow Behavior in Horizontal Wells
Authors: Yuan H. J. , Sarica Cem , Brill J. P. 
Published: December 2007

Summary
A general horizontal well friction factor expression was developed using the principles of conservation of mass and momentum. Horizontal well friction factor correlations were developed based on theoretical analysis and a large amount of experimental data. It was observed that the friction factor for a perforated pipe with fluid injection can be either smaller or greater than that for a smooth pipe, depending on influx to main flow rate ratios. The proposed friction factor correlation can be used in any horizontal well model that considers pressure variation along the wellbore.
From Seismic to Reservoir Properties With Geostatistical Inversion
Authors: Lamy Philippe , Swaby P. A. , Rowbotham P. S. , Dubrule Olivier , Haas A. 
Published: December 2007

Summary
The methodology presented in this paper incorporates seismic data, geological knowledge and well logs to produce models of reservoir parameters and uncertainties associated with them. A three-dimensional (3D) seismic dataset is inverted within a geological and stratigraphic model using the geostatistical inversion technique. Several reservoir-scale acoustic impedance blocks are obtained and quantification of uncertainty is determined by computing statistics on these 3D blocks. Combining these statistics with the kriging of the reservoir parameter well logs allows the transformation of impedances into reservoir parameters. This combination is similar to performing a collocated cokriging of the acoustic impedances.
How Much Core-Sample Variance Should a Well-Log Model Reproduce?
Authors: Jennings J. W. 
Published: December 2007

SummaryA new log-calibration technique presented in this paper determines how much core-sample variance should be reproduced by a calibrated log. The linear calibration parameters are then calculated from this variance and the log and core-sample means. The method relies on the idea that the correlation structure of core data and a calibrated log should be the same for distances longer than the log resolution, after the variance reduction due to log averaging is accounted for. The procedure is illustrated by using synthetic data, followed by example applications that use real data.
Translating Outcrop Data to Flow Models, With Applications to the Ferron Sandstone
Authors: White C. D. , Barton M. D. 
Published: December 2007

Summary
Quantitative models are needed to predict interactions between rock properties and drive mechanisms in geologically complex reservoirs. Analog studies using outcrop data provide insights for modeling, understanding, and predicting the behavior of oil and gas reservoirs. Stratigraphic cornerpoint grids preserve the geometries and facies distributions of outcrop data sets. Flow simulations of two outcrop exposures of sandstone-rich fluvial-deltaic tongues within the Cretaceous Age Ferron sandstone (Utah) revealed differences in fractional flow, recovery efficiency, and deliverability that can be related to stratigraphic setting. Compared with homogeneous models, models based on the landward-stepping tongue exposed at the Picture Flats locality had more tortuous flow paths and lower gas recovery efficiency. In the seaward-stepping tongue exposed at the Interstate 70 location, the displacement was layer like. Gas deliverability at the Interstate 70 locality varied with the well location; it was highest when the well penetrated high-permeability shallow-marine sediments and lowest when flow was restricted by a shale-lined valley-fill succession.
Microseismic Monitoring of the B-Sand Hydraulic-Fracture Experiment at the DOE/GRI Multisite Project
Authors: Warpinski N. R. , Wright T. B. , Uhl J. E. , Engler B. P. , Drozda P. M. , Peterson R. E. , Branagan P. T. 
Published: December 2007

SummarySix hydraulic-fracture injections into a fluvial sandstone at a depth of 4,500 ft were monitored with multilevel, triaxial, seismic receivers in two wells, resulting in maps of the growth and final geometry of each fracture based upon microseismic activity. These diagnostic images show that the hydraulic fractures are highly contained for smaller-volume KCl-water injections, but height growth is significant for the larger-volume, higher-rate, higher-viscosity treatments. Fracture lengths for most injections are similar regardless of volume and fluid type.
Effect of Wettability on Adverse-Mobility Immiscible Floods
Authors: Vives M. T. , Chang Y.-C. , Mohanty K. K. 
Published: December 2007

Summary
Many immiscible displacements in reservoirs occur at adverse mobility. The 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 five-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 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 or a small saturation shock is expected from one-dimensional fractional flow theory. Bypassing attributed 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.
Use of Pore-Network Models to Simulate Laboratory Corefloods in a Heterogeneous Carbonate Sample
Authors: Xu Baomin , Kamath Jairam , Yortsos Y. C. , Lee S. H. 
Published: December 2007

SummaryMany carbonate rocks have pore features that are large at the core plug scale. Conventional laboratory assessment of recovery behavior in these carbonates can be unreliable. Pore-network modeling offers an approach to improve our analysis of flow and displacement in such heterogeneous rocks. This paper reports on a systematic approach to link pore model inputs and laboratory data to a calibration methodology, and the subsequent use of a porenetwork model to match laboratory corefloods in a heterogeneous dolomite. It is found that spatial correlation effects, determined from core samples using thin section and computed tomography (CT) data, are important for a satisfactory match.
New Environmentally Safe High-Temperature Water-Based Drilling-Fluid System
Authors: Thaemlitz C. J. , Patel A. D. , Coffin George , Conn Lee 
Published: December 2007

Summary
A new, environmentally safe water-based polymer system has been developed for drilling applications with temperatures up to 232°C (450°F) and high pressures. The system components are newly developed synthetic polymers that do not contain chromium or other environmentally harmful materials. These new synthetic polymers are designed to perform specific functions at high temperatures and the innovative designs of these thermally stable polymers allow for the use of a minimum number of products in the formulation of high-temperature fluids.
The new system consists of two basic polymeric components for rheology and filtration control at high temperatures. High- temperature fluid formulations are greatly simplified utilizing this new system, with only the two polymeric components being required, along with a pH control additive, weight material, and small amounts of clay for filler cake quality. This simplicity is a significant advantage over "traditional" high-temperature systems, which normally require the use of a large number of additives to control or limit the effects of thermal degradation.
The new system may be formulated with fresh water or sea water, providing flexibility for a variety of drilling environments. Excellent resistance to common contaminants, such as calcium and magnesium hardness and solids accumulation, is another important characteristic of this new system.
This paper will review the previous state of the art with respect to high-temperature, water-based muds and will generically discuss the unique chemistry of the newly developed polymer system components. System formulation and application will be discussed.
State-of-the-Art Cuttings Transport in Horizontal Wellbores
Authors: Pilehvari A. A. , Azar J. J. , Shirazi S. A. 
Published: December 2007

SummaryIn the ever-growing use of, directional and horizontal drilling, hole cleaning is a common and costly problem. It can become particularly critical in the case of extended reach drilling where larger and longer wellbores are drilled. During the past two decades, especially in recent years, many laboratory studies as well as field observations have been directed towards addressing the cuttings transport problem. This has resulted in better understanding of the subject and some remedies to the problems. Several correlation/models have also been developed that give the field engineer a tool to better specify the hydraulic requirements in cleaning the hole. However, because of the complexity of the subject, a comprehensive and proven model, which does not exist at this time, requires much more laboratory research and field studies.
Proactive Approach to Well Construction Safety in Alaska's Kuparuk River Field
Authors: Petrash D. K. , Graff A. O. , Trantham J. A. 
Published: December 2007

SummaryIn 1995, the Kuparuk Drilling Group (KDG) recognized that safety performance had continually improved since well construction commenced in the Kuparuk River Field in 1981. However, it was also recognized that performance improvement appeared to be losing momentum. Upon analysis of the trend, it was noted that most efforts to reduce workplace risk were focused on: engineering controls; administrative controls and operating practices; and personal protective equipment.In order to return to improving safety performance, attain world class status, and help employees return safely from the workplace to their families, the KDG solicited input from the drilling contractor to develop and implement a proactive behavior-based safety program. Part of the development included a goal-driven incentive, the Safety Performance Goals Program, which deem-phasizes safety statistics and fully complements the overall safety objectives.
Uncertainties in Reservoir Fluid Description for Reservoir Modeling
Authors: Meisingset K. K. 
Published: December 2007

Summary
The objective of the present paper is to communicate the basic knowledge needed for estimating the uncertainty in reservoir fluid parameters for prospects, discoveries, and producing oil and gas/condensate fields. Uncertainties associated with laboratory analysis, fluid sampling, process description, and variations over the reservoirs are discussed, based on experience from the North Sea.