bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Fractal Models To Describe Reservoir Heterogeneity and Performance
Authors: Pérez G. , Chopra A. K. 
Published: December 2007

Summary
Our work uses fractals to characterize the spatial correlation structures of porosity and permeability of vertical and horizontal logs in a braided-fluvial sandstone reservoir. The data comprise cores and logs of adjacent vertical wells and logs of horizontal wells. Small-scale realizations of interwell heterogeneity were generated with successive random additions (SRA) technique for new observed fractal models. A deterministic description is also developed. Effects of fractal and deterministic reservoir heterogeneity on reservoir performance were studied for waterflood and water-alternating-gas (WAG) injection processes. The effects of scale up on spatial correlation of porosity was investigated.
The fractal model of fractional Brownian motion (FBM) in the horizontal direction, having same intermittency exponent as for fractional Gaussian noise (FGN) in the vertical direction, is not supported by log observations in horizontal wells. Fractal character of core and log data of vertical wells is similar. The incremental WAG recovery response compared to waterflooding response is more sensitive to reservoir heterogeneity. Scale-up experiments indicate that spatial correlation structure of reservoir properties may be different at different scales.
Results of this paper will be useful for evaluation of infill drilling, and design, selection, and optimization of an EOR process. The proposed techniques also provide a framework to quantify uncertainty in reservoir performance.
Characterization of the Jet Perforation Crushed Zone by SEM and Image Analysis
Authors: Asadi Mahmoud , Preston Floyd W. 
Published: December 2007

Summary
This paper presents a method to measure porosity and permeability alteration of the crushed zone with scanning electron microscopy (SEM) and image analysis. A new phenomenon, shock metamorphism, was used to evaluate shock-wave penetration. Berea sandstone samples were prepared with a modification of the API recommended practice for test-sample preparation. Samples were perforated with low- and medium-penetration shaped charges. Analysis of the low-charge shot sample indicated an average porosity reduction of 25% and an average permeability reduction of 55% in the crushed zone. The sample shot with the medium-penetration shaped charge showed planar-element shock metamorphism.
Application of a General Material Balance for High-Pressure Gas Reservoirs
Authors: Fetkovich Michael J. , Reese Dave E. , Whitson C. H. 
Published: December 2007

Summary
This paper presents the derivation of a general gas material balance that has particular application to high-pressure gas reservoirs, [both normal pressured and overpressured (geopressured)]. Its main application is to calculate original gas in place and assist in calculating remaining recoverable reserves from pressure/production data.
The form of the material-balance equation is (p/z)[1−c¯e(p)(pi−p)]=(p/z)i(1−Gp/G),, which includes a pressure-dependent cumulative effective compressibility term c¯e(p) that is defined in terms of the following reservoir parameters: pore compressibility, water compressibility, gas solubility, and total water associated with the gas reservoir volume. "Associated" water includes connate water, water within interbedded shales and nonpay reservoir rock, and any limited aquifer volume. c¯e physically represents the cumulative change in hydrocarbon pore volume (PV) caused by compressibility effects and encroaching water.
High pressure gas reservoirs typically have concave downward p/z vs. Gp plots which may result in serious overestimation of original gas in place and remaining recoverable reserves. The proposed form of the gas material balance equation provides a method to linearize the p/z vs. Gp plot, and thereby predict the true original gas in place. A method is suggested to determine initial gas in place by analyzing the behavior of cumulative effective compressibility backcalculated from pressure/production data. The c¯e(p) function determined by this procedure, or estimated from logs and geological maps when sufficient production data is not available, is then used to forecast pressure/cumulative behavior. Two field examples are provided showing the application of the material balance equation to high pressure gas reservoirs.
Evaluation of Corrosion Inhibitor for Low-pH Ammonium Nitrate-Methanol Completion Fluid
Authors: Krilov Zoran , Soric Tomislav , Tomic Mihovil , Wojtanowicz A. K. 
Published: December 2007

Summary
A specially formulated completion fluid, low-pH ammonium nitrate-methanol-water mixture (ANM), compatible with argillaceous and calcareous Adriatic Sea sandstone formations, appears to be very corrosive for steel wellbore equipment. More than 12 commercially available, as well as some originally formulated, chemical additives were laboratory tested at room temperature using weight-loss and electrochemical methods to find an effective corrosion inhibitor for ANM.
Two inhibitors, a commercially available, organic, amine base (OA) and an originally formulated, inorganic, ammonium dihydrogen phosphate base (IB), showed effective protection of carbon steel in contact with ANM fluid (corrosion rate was less than 5 mil/yr). Both selected corrosion inhibitors did not exhibit any additional rock permeability impairment during fluid-rock compatibility flow tests if ANM fluid was filtered before injection into the core samples. For inorganic inhibitor IB, additional filtration of inhibited fluid is not required.
Strategies and Structures for Drilling and Service Contracts in the 1990's
Authors: de Wardt J. P. , van Gils J. M. I. 
Published: December 2007

Summary
Drilling in the nineties initiatives were introduced to the industry in early 1990. Contractual mechanisms for application of these initiatives have been developed. A strategy is developed for integrating services to provide a total service concept either directly through or parallel with a drilling contractor. Development of cooperative customer/supplier relationships are emerging as the way to sustain per-formance improvements.
Rheologically Stable, Nontoxic, High-Temperature, Water-Based Drilling Fluid
Authors: Elward-Berry Julianne , Darby J. B. 
Published: December 2007

Summary
An exceptionally stable, high-temperature, water-based drilling fluid has been developed based on a fundamental redesign of drilling fluid components and functions, while still using commercially available materials. Rheological stability was characterized by extensive Fann 50C low-shear-rate viscosity vs. temperature studies and supporting viscoelastic rheological data. The fluid has been used in both offshore and land applications, at temperatures as high as 420°F and densities as high as 15.5 lbm/gal.
Quantitative CO2-Flood Monitoring—Denver Unit, Wasson (San Andres) Field
Authors: Kittridge Mark G. 
Published: December 2007

Summary
This paper presents a technique for monitoring CO2-flood response and performance with wireline-derived petrophysical data. Gas saturation data derived with this method are in agreement with independent estimates available from a CO2 pilot project. Examples show the application of the method in the Denver unit (DU). Results obtained with this technique are useful for quantifying CO2 saturation, monitoring flood progress and vertical sweep, identifying potential out-of-zone injectant losses, and detecting non-responding layers.
Influence of Wellbore Hydraulics on Horizontal Well Pressure Transient Behavior
Authors: Suzuki Koichi 
Published: December 2007

Summary
In this paper, we discuss the influence of wellbore hydraulics in a horizontal wellbore on horizontal well pressure transient behavior. A finite-conductivity solution is obtained by a semianalytical method that incorporates three-dimensional (3D) flow in a reservoir and fluid flow inside a wellbore ranging from laminar to turbulent-flow regimes. On the basis of the finite-conductivity solution, finite-conductivity pressure transients are presented in terms of type curves, pressure derivatives, production distribution along a wellbore, and a pressure difference between the two ends of a wellbore. Furthermore, we provide a quantified criterion that allows us to approximate finite-conductivity solutions to an infinite-conductivity solution with respect to the following parameters: a formation flow capacity, a wellbore length, a wellbore radius, a relative pipe roughness, and the Reynolds number at the downstream end of a wellbore.
Estimates of Formation Sound Speed From Ultrasonic Reflections
Authors: Davidson J. A. , Morriss S. L. , Podio A. L. 
Published: December 2007

Summary
This paper presents preliminary results from experimental research concerning the ultrasonic reflectivity of rock samples. The goal is to determine whether meaningful petrophysical properties can be obtained through the analysis of reflected acoustic signals of the type produced with the new generation of ultrasonic borehole televiewers. Present emphasis is on analysis of the full-reflected waveform. Time-domain samples of the transmitted and reflected signals are transformed into the frequency domain by means of digital Fourier methods to determine the complex reflection coefficient of the rock. A simplified viscoelastic wave-propagation model converts the reflection coefficient estimates into wave velocity estimates. Sound speed estimates in reasonable agreement with those determined by use of standard experimental techniques have been obtained for a variety of sandstone samples. Signal-processing techniques for the analysis of waveforms recorded in an attenuating mud-filled borehole have been developed and tested in the laboratory.
Practical Application of Fractal Pressure-Transient Analysis in Naturally Fractured Reservoirs
Authors: Acuna J. A. , Ershaghi Iraj , Yortsos Y. C. 
Published: December 2007

Summary
Pressure-transient tests in naturally fractured reservoirs often exhibit nonuniform responses. Various models explain such nonuniformity; however, their relevance is often not justified on a geologic basis. Fractal geometry provides a method to account for a great variety of such transients under the assumption that the network of fractures is fractal. This paper presents an application to real well tests in various fractured reservoirs. The physical meaning of the fractal parameters is presented in the context of well testing. Examples showing a behavior similar to the finite-conductivity fracture model or to spherical flow are presented and explained by the alternative of fractal networks. A behavior that can be mistakenly interpreted as a double-porosity case is also analyzed.
Variable S-Matrix Method To Compensate for the Influence of Shaliness on Pulsed-Neutron-Capture Log Response
Authors: Neuman Charles H. 
Published: December 2007

Summary
An important limitation in applying pulsed-neutron-capture (PNC) logs to measure fluid saturation is the imperfect correction for the influence of rock-matrix shaliness. Most methods for calculating saturations when log data are influenced by shaliness use gamma ray response to divide the Σ measured into clean sand and shale components. The nonlinear relation between shale volume and fractional gamma ray response commonly assumed results in significantly smaller correction for intermediate shaliness than would a linear relationship. This paper presents core data that support the idea that Σma, varies almost linearly with gamma ray response. A simple method to compensate for shaliness is proposed that uses gamma ray response to predict composite Σma rather than dividing the rock matrix into sand and shale components.
Stochastic Reservoir Modeling Using Simulated Annealing and Genetic Algorithms
Authors: Sen Mrinal K. , Datta-Gupta Akhil , Stoffa P. L. , Lake L. W. , Pope G. A. 
Published: December 2007

Summary
This paper discusses and compares three different algorithms based on combinatorial optimization schemes for generating stochastic permeability fields. The algorithms are not restricted to generating Gaussian random fields and have the potential to accomplish geologic realism by combining data from many different sources. We have introduced a "heat-bath" algorithm for simulated annealing (SA) as an alternative to the commonly used "Metropolis" algorithm and a new stochastic modeling technique based on the "genetic" algorithm. We applied these algorithms to a set of outcrop and tracer flow data and examined the associated uncertainties in predictions.
All three algorithms reproduce the major features of permeability distribution and fluid flow data. For relatively small problems, the Metropolis algorithm is the fastest. For larger problems, the heat-bath algorithm is at least as fast and often faster than the Metropolis algorithm, with significant potential for parallelization. The performance of the genetic algorithm is highly dependent on the choice of population size and probabilities of crossover, update, and mutation.
The Use of Air-Bubble Spoilers To Suppress Vortex-Induced Vibrations of Risers
Authors: Abbassian Fereidoun , Moros Thanos 
Published: December 2007

Summary
For this paper, we considered the feasibility of a bubble spoiler as a vortex-suppression device. The introduction of bubbles in the flow reduced the dynamic forces on the riser by destroying the vortex-shedding structure. We constructed a semiempirical equation relating the reduction of the vibration amplitude to the amount of air required. Then we considered the effectiveness of bubble spoilers as a suppression device by investigating the dynamic response of a typical jack-up drilling riser for various suppression scenarios. We found that the volume of air required to effectively suppress the vortices was about 2.0 m3/s at 500 kPa.
Transient 2D Flow in Layered Reservoirs With Crossflow
Authors: Liu Ci-qun , Wang Xiao-Dong 
Published: December 2007

Summary
Analytical solutions of transient 2D flow through double-permeability media are presented. The pressure response of a vertically fractured well intercepting a layered reservoir with crossflow is described through the methods of integral transform and variable separation. The influences that parameters of a double-permeability model such as the permeability ratio, Fk interporosity flow parameter, λ, and storativity ratio, ω, have on the pressure response of a fractured well are calculated and analyzed by numerical inversion. Log-log diagnosis graphs of fractured well pressure are given and analyzed here.
How Fluid Loss Influences Primary Cementing: Literature Review and Methodology
Authors: Daccord Gérard , Baret J. F. 
Published: December 2007

Summary
Fluid loss during cementing has long been suspected to have detrimental consequences, including reduction of slurry volume; increased slurry density and viscosity; cement-cake deposition, which may cause additional decreases in friction pressure during placement; and near-wellbore reservoir filtrate invasion. This paper briefly reviews and quantifies these consequences. Given well geometry, job design, and cement slurry fluid-loss properties, we show how to predict the critical phenomena that are most likely to impair cementing and the most sensitive well or slurry parameters. By coupling these results and the degree of accuracy with which well parameters are known, one can calculate prediction uncertainty (the error bar) and deduce the key parameters that affect this error bar.
Effects of Crossflow and Layer Permeability Contrast on the Effectiveness of Gel Treatments in Polymer Floods and Waterfloods
Authors: Gao Hong W. , Burchfield Thomas E. 
Published: December 2007

Summary
Permeability-blocking treatments with gels were simulated for a reservoir composed of two independent, homogeneous layers, each with traverse isotropic permeability. Horizontal permeability contrast between the layers ranged from 0.0033 to 0.5. Vertical/horizontal permeability ratios for both layers were the same and set between 0.001 and 0.1. Gel treatments were pumped into the high-permeability lower layer. Polymer floods/waterfloods entered both layers; allocation of the pumped fluid depended on the mobilities for each layer. Near-wellbore gel treatments increased oil recovery in cases of low vertical/horizontal permeability ratios by improving the injection profile. Under the conditions examined (equal layer thickness and 3-cp oil and 0.8-cp water viscosities), results were most beneficial in reservoirs with a horizontal permeability contrast of ≈ 0.05. Gel treatments placed in the reservoir at the near-wellbore region or deep in the reservoir were ineffective in cases of high crossflow.
Water/Oil Relative Permeability Endpoints of Intermediate-Wet, Low-Permeability Rocks
Authors: Kamath Jairam , deZabala E. F. , Boyer R. E. 
Published: December 2007

Summary
The relative permeability endpoints of low-permeability, intermediate-wet mudstones increased with flow rate. This was because of both a decrease in capillary end effect and an increase in capillary number. Hence, conventional analysis will incorrectly describe field behavior. We recommend an improved methodology.
We imaged steady-state saturation profiles at the end of different rate floods on one sample. We analyzed these profiles, which were axially nonuniform, to obtain capillary-end-effect-corrected data for each flow rate. The saturation distributions were also radially nonuniform. We characterized core-scale heterogeneity using a miscible flow test and examined the influence of heterogeneity.
We conducted long-term tests on three short samples to study the higher-capillary-number regime. These tests displayed the existence of a critical capillary number, where the water relative permeability endpoint increased dramatically. The corresponding rate was over a magnitude smaller than flow rates traditionally recommended to eliminate capillary end effects.
New Results on Transient Well Tests Analysis Considering Nonlaminar Flow in the Reservoir
Authors: Rodolfo Camacho-V. , Mario Vásquez-C. , José Roldán-C. , Fernando Samaniego-V. , Luis Madas-C. 
Published: December 2007

SummaryThe aim of this work is to examine the wellbore pressure behavior in reservoirs with single-phase non-Darcy flow conditions produced at a constant sandface rate. The transient flow period is analyzed by means of results generated with a finite difference model. Analytical expressions of pressure drop and its semilogarithmic slope are presented for the first time. These equations contain the laminar flow solution as a particular case, and they provide means to evaluate the total skin factor. Another use of the analytical solution to the non-Darcy flow problem is to identify the presence of inertial effects by using a diagnostic plot, which consists of graphing the derivative of the pressure data vs. the inverse of the square root of time on a Cartesian paper. In this way, an analyst easily can predict the magnitude of the skin owing to nonlaminar flow under any condition of mechanical skin and rate. Furthermore, better stimulation jobs can be designed if non-Darcy flow conditions during a transient test are properly identified through the methodology presented in this study.The use of the methodology obtained in this work is illustrated with synthetic examples for homogeneous and naturally fractured reservoirs. Also, a field example of an undersaturated reservoir and a dry gas case (taken from the literature) shows the application of this technique. For the case of naturally fractured reservoirs, new insights are provided.
Pressure and Volume Evolution During Gas Phase Formation in Solution Gas Drive Process
Authors: Firoozabadi Abbas , Kashchiev Dimo 
Published: December 2007

Abstract
The pressure and volume evolution during gas phase formation in porous media is modelled by an instantaneous nucleation process. This model reveals that supersaturation (i.e., non-equilibrium state) for gas bubble formation is affected by the pressure decline rate. As a result, laboratory recovery measurements are influenced by rate effects, and material balance expressions may not be used to calculate the amount of oil and gas phases.
Coiled Tubing Sidetrack: Slaughter Field Case History
Authors: Hightower C. M. , Blount C. G. , Ward S. L. , Martin R. F. , Cantwell D. L. , Ackers M. J. 
Published: December 2007

Summary
The paper describes the successful sidetrack of an oil well in the Slaughter Field in West Texas using coiled tubing (CT). Several first-time CT operations performed during this workover include:
Setting a whipstock in casing on CT Cutting a window with CT Using mud pulse measurement-while-drilling (MWD) with CT in a "real" well Use of a fluid-operated orientation tool for in-hole toolface changes Successful use of an "autodriller" to maintain weight on bit while drilling
Directional control of the sidetracked hole proved to be ineffective due to a surface software problem. The resultant wellbore was not horizontal as planned, but instead closely paralleled the original well for much of its length. However, the previously non-productive well flowed 1000 barrels of fluid per day (BFPD) from the sidetrack following the workover.
Reservoir Description by Integrating Well-Test Data and Spatial Statistics
Authors: Sagar R. K. , Kelkar M. G. , Thompson L. G. 
Published: December 2007

Summary
We present a method to integrate log, core, and well-test pressure data to describe reservoir heterogeneities. The conditional simulation method of simulated annealing is used to incorporate diverse sources of data.
We use analytical solutions for radially heterogeneous reservoirs to define an equivalent radial permeability and a corresponding region of investigation. By numerical experimentation on drawdown well-test simulations in heterogeneous permeability fields, we determine that a weighted-area-based geometric average of the grid-block permeabilities within the region of investigation best defines the equivalent radial permeability. This information, along with the spatial statistics from core/log data, are coded into the overall objective function of the simulated annealing algorithm to yield a consistent reservoir description.
The Use of Broadband Microseisms for Hydraulic-Fracture Mapping
Authors: Sleefe G. E. , Warpinski N. R. , Engler B. P. 
Published: December 2007

Summary
We conducted a series of hydraulic-fracture experiments to examine improvements in seismic-fracture diagnostic technology that are available with the application of advanced receiver capabilities. We present characteristics of the microseisms, tool response behavior, and the results of the tests.
Laboratory Development and Field Testing of Succinoglycan as a Fluid-Loss-Control Fluid
Authors: Lau Hon Chung 
Published: December 2007

Summary
Research has shown that the biopolymer succinoglycan possesses a unique combination of desirable properties for fluid-loss control, including ease of mixing; cleanness; shear-thinning rheology; temperature-insensitive viscosity below its transition temperature, Tm; and adjustable Tm over a wide range of temperatures. Because succino-glycan is a viscous fluid, it relies solely on viscosity to reduce fluid loss. It does not form hard-to-remove filter cake that can cause considerable formation damage. On the basis of these findings, we used succinoglycan successfully as a fluid-loss pill before and/or after gravel packing in &gt; 100 offshore wells. Calculations based on laboratory-measured rheology and field experience have shown succino-glycan to be effective in situations where hydroxyethyl cellulose (HEC) is not. Even fluid loss &gt; 40 bbl/hr was reduced to several bbl/ hr after application of a properly designed succinoglycan pill. Most wells experienced no production problem after completion.