bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multivariate Statistical Analysis of Stuck Drillpipe Situations
Authors: Hempkins W. B. , Kingsborough R. H. , Lohec W. E. , Nini C. J. 
Published: December 2007

SummaryStuck drillpipe accounts for losses of millions of dollars each year in the petroleum industry. Major efforts have been made to determine the causes of stuck pipe and to outline operating practices that will minimize the occurrence of the problem. No previously published efforts, however, have attempted to predict the chances of the pipe sticking on the basis of existing conditions. An analytic technique was therefore developed that evaluates 20 common drilling parameters to determine the probability of the pipe sticking in a particular well.
An Analytic Model for Electromagnetic Wireline Tools
Authors: Durgapal Prabha 
Published: December 2007

Summary
A mathematical model for electromagnetic tools is presented that accounts for the finite size of the transmitter and receiver coils, tool mandrel, a shielding conductor internal to the tool, and the concentrically stratified media surrounding the tool. The model is applied to various tools in the 20 × 103 to 1 × 109 -cycle/sec [20-kHz to 1-GHz] frequency range, and results indicate that this model will be useful in designing future tools.
Future Development of Water Control Methods in Air Drilling Operations
Authors: Roberts Alan P. 
Published: December 2007

In certain cases, the advantages of air drilling are very great. The economic incentives can be high, for we hear of operators who have saved more than $100,000 on one well through the use of air drilling. However, in the great majority of drilling situations, air cannot be used because of the water influx problem.
A number of techniques are available to fight water influx. Some have been successful under certain conditions. However, nearly all need considerable further testing and development before they can be considered as routine operations. In short, we are a long way from being over the hump with respect to water control. Now it often costs us considerable money before we even can determine the extent of our problem.

Water Control Methods Now Available
The best water control method now available is, of course, to drill our wells where we know water will not be encountered. Although this sounds facetious, we should certainly make a thorough study of a prospective air drilling location to determine the possibilities that water will be encountered and to make an estimate of the probable locations and number of water-bearing zones which must be penetrated. An idea of the quantity of water influx would be very helpful.
Unfortunately, unless previous air drilling has been done in the immediate area, we normally cannot predict with any high degree of certainty where water will be located. Logs from previous wells in the area are of some value, but apparently do not provide the entire answer. A study by a joint API-AAODC committee indicated that logs are effective in approximately 50 per cent of the cases in locating water-bearing zones.
In any case, it behooves us to obtain the best information available in order to intelligently make the decision as to whether or not air drilling should be contemplated. In some cases, planning the casing program with water zones in mind may make the difference between an economic air drilling operation or a series of expensive water shut-off operations.
Interpretation of Flowing Well Response in Gas-Condensate Wells
Authors: Jones J. R. , Raghavan R. 
Published: December 2007

SummaryA fully implicit compositional model is used to simulate the well response in a gas-condensate system. The objective of this work is to examine the flowing well response in a condensate reservoir and to examine the effect of liquid condensation on the well response as the pressure drops below the dewpoint.A theoretical foundation for the analysis of well test data in gas-condensate systems is presented. The concept of pseudopressure integrals is introduced and the utility of these integrals—the reservoir and the sandface integrals—to analyze well test data is presented. Short-time performance for both constant-(molar)-rate and constant-pressure production is examined. A pseudopressure transformation is used to incorporate the effects of multiphase flow and changes in fluid composition. We show that the pseudopressures may be used to determine formation flow capacity and skin factor. Estimates of skin factor, however, are approximate for production at a constant rate. Long-time performance is examined in detail for the constant-terminal-pressure case. These solutions should be useful in anticipating the problems involved in conducting production forecasts. An inflow equation for both modes of production is presented. The influence of important variables of interest, such as composition, relative permeability characteristics, mode of production, dewpoint pressure, and initial pressure level, is examined. Long-term performance appears to be particularly sensitive to the difference between the initial pressure and the flowing pressure, but the individual differences between initial and dewpoint pressures and between dewpoint and flowing pressures also have some influence on long-term rates. The consequences of neglecting the appearance of a second phase are documented.Steady flow in gas-condensate systems is also examined. These solutions are important in their own right and provide important insights into the performance of condensate systems (e.g., cycling). Of importance to this work, the steady-flow solution enables us to verify the accuracy of the numerical solutions and to evaluate the pseudopressure transformation used in this paper.
Effect of Turbulence on Transient Flow of Real Gas Through Porous Media
Authors: Lee R. L. , Logan R. W. , Tek M. R. 
Published: December 2007

SummaryThis paper represents the first effort in quantifying the "turbulence intensity" as related to deliverability front gas wells. A new dimensionless number called the Forchheimer number, NFo, has been proposed along with a generalized expression of turbulence coefficient. Applications include a new concept called "inverse productivity index, JI," proposed as an alternative to classical backpressure plots for characterizing gas well performance.
The Effect of an Immobile Liquid Saturation on the Non-Darcy Flow Coefficient in Porous Media
Authors: Evans R. D. , Hudson C. S. , Greenlee J. E. 
Published: December 2007

Summary
The results of an experimental research program to investigate the effects of immobile liquid saturations on the non-Darcy flow coefficient are presented. Sandstone cores of absolute permeabilities ranging from 50 to 800 md were used to investigate non-Darcy flow phenomena under multiphase conditions. Immobile liquid saturations were varied from 8 to 30% PV. The multiphase experiments were conducted with N2 gas as the flowing phase and glycerin as the immobile liquid phase. It was found that the non-Darcy flow coefficient for the multiphase case may be estimated with a dry-core non-Darcy-flow-coefficient/permeability relationship developed for the rock in question and the effective gas permeability at a given saturation.
For the immobile multiphase cases, the non-Darcy flow coefficient consistently increased with increased saturation. The experimental data obtained from this research were compared with the limited multiphase data in the literature. Where comparisons could be made, the data reported in this paper agreed favorably with the existing published data.
An analysis of the experimental data revealed that a unique relationship existed between the non-Darcy flow coefficient and the effective gas permeability, porosity, liquid saturation, and effective overburden pressure at a given temperature.
Correlations were developed from this analysis to predict the non-Darcy flow coefficient as a function of rock and fluid properties. Where possible, the correlations were used to predict the non-Darcy coefficient measured by other researchers and were compared with the dry-core correlations developed by Janicek and Katz and with a theoretical equation developed by Geertsma.
Prediction of Reservoir Compaction and Surface Subsidence: Field Application of a New Model
Authors: de Waal J. A. , Smits R. M. M. 
Published: December 2007

Summary
A new loading-rate-dependent compaction model for unconsolidated clastic reservoirs is presented that considerably improves the accuracy of predicting reservoir rock compaction and surface subsidence resulting from pressure depletion in oil and gas fields. The model has been developed on the basis of extensive laboratory studies and can be derived from a theory relating compaction to time-dependent intergranular friction.
The procedure for calculating reservoir compaction from laboratory measurements with the new model is outlined. Both field and laboratory compaction behaviors appear to be described by one single normalized, nonlinear compaction curve. With the new model, the large discrepancies usually observed between predictions based on linear compaction models and actual (nonlinear) field behavior can be explained.
An Analytic Model for Analyzing the Effects of Dissociation of Hydrates on the Thermal Recovery of Heavy Oils
Authors: Kamath Vidyadhar A. , Godbole Sanjay P. 
Published: December 2007

SummaryThis paper presents an analytic model that includes the effects of the presence of hydrates in a thermal recovery process. The model considers continuous injection of steam into a reservoir containing an oil zone overlain by a hydrate zone. The model results indicate that, although part of the steam is consumed in dissociation of hydrates to gas and water and the dissociated hydrate zone acts as a thief zone for steam, there is a reduction in heat losses to the overburden because of the "insulation" effect of overlying hydrates. Thus, the net reservoir heat efficiency is not significantly affected by the presence of hydrates. Although the model does not address the effect of gas generated from hydrate dissociation, it is speculated that the dissolution of the gas will cause oil swelling, oil-viscosity reduction, and improved steamflood performance.
Graded-Viscosity-Bank Design With Pseudoplastic Fluids
Authors: Stoneberger M. W. , Clarldge E. L. 
Published: December 2007

Summary
A method for the design of graded viscosity banks of pseudoplastic fluids in five-spot patterns of a single homogeneous layer is presented. This method is based on the extension of Koval’s work on unstable miscible displacements to multiple slugs in radial systems and then to five-spots, with corrections made for pseudoplastic viscous-fingering behavior. Experiments were performed in a Hele-Shaw model to determine the qualitative nature of the various displacements that occur and to determine the parameters used in the equations.
Experimental and Theoretical Study of Polymer Flow in Porous Media
Authors: Sorbie K. S. , Parker A. , Clifford P. J. 
Published: December 2007

Summary
In this paper, an extensive study is presented on the single-phase flow of xanthan/tracer slugs in a consolidated sandstone. The phenomena studied include polymer/tracer dispersion, excluded/inaccessible-volume effects, polymer adsorption, and viscous fingering. In some floods, there is also evidence of nonequilibrium effects. Macroscopic flow equations are derived that include terms to model all the behaviors listed above. A microscopic approach is also developed that describes certain features of polymer flow in porous media semiquantitatively.
Development and Evaluation of EOR Polymers Suitable for Hostile Environments—Part 1: Copolymers of Vinylpyrrolidone and Acrylamide
Authors: Doe Peter H. , Moradi-Araghi Ahmad , Shaw James E. , Stahl G. Allan 
Published: December 2007

Summary
This paper describes the properties of synthetic water-soluble polymers that are stable for extended periods of time in hard brines at very high temperatures. Several copolymers of vinylpyrrolidone (VP) and acrylamide (AM) were prepared and evaluated in our laboratories for EOR application in hostile environments. VP in the copolymer composition protects AM against extensive thermal hydrolysis, which otherwise will result in loss of viscosity and precipitation. A range of VP/AM copolymer compositions was found to tolerate the harsh conditions of 250°F [121 °C] in seawater for extended periods of time and to be suitable for EOR application under these conditions. The performance of these polymers in porous media was evaluated by extensive coreflood experiments in Berea sandstone at 250°F [121 °C] with synthetic seawater. The results indicate that these copolymers can easily be injected into porous media and that they can be effective polymers for EOR application in hostile environments.
Protective Colloid Muds Provide Cost-Effective Prevention of Wellbore Enlargement in the Gulf of Mexico
Authors: Chaney P. , Sargent T. L. 
Published: December 2007

Summary
Protective colloid muds prevented severe hole enlargement, even in "gumbo" shales and poorly consolidated sands. Improved hole size and excellent primary cement bond logs (CBL's) were achieved. Compared with five offset wells drilled with lignosulfonate muds, combined intangible drilling and cement costs were reduced by more than $35/ft [$115/m], a savings of more than 30%.
How To Improve Your Waterflood Brinkmanship
Authors: White Wilbur R. 
Published: December 2007

Abstract
This paper recognizes that most North Texas operators practice a certain amount of "brinkmanship" every time they start a new waterflood, even though good reservoir engineering is used. Eight possible methods of improving the brinkmanship are discussed and some examples are given. The eight methods are:
apply multi-zone floods, where possible; acquire larger holdings in the reservoir through favorable lease purchase arrangements; co-ordinate the proposed waterflood with development of water drive reservoirs; merge the proposed waterflood with any existing saltwater disposal problems; reduce investment by purchasing injection water; consolidate leases where possible; incorporate certain "poor boy" features based on judgment gained from local experience; and arrange joint expenditures with other operators in the area. The author concedes that these eight considerations will not insure success, but concludes that a reasonable economic venture may be created where none existed before.
Introduction
Our politicians and diplomats seem to think that they have a monopoly on "brinkmanship". This is not true. Waterflood operators in North Texas practice this dubious feat regularly. On almost every project, the operator must walk the brink between a reasonable profit and an unsatisfactory return on his investment. Too often the first economic projection on a proposed project shows the venture to be unfavorable or perhaps a borderline case. This paper deals with methods that might change the economic outlook from unfavorable to favorable. The obvious waterflood precautions, such as having cores checked and reservoir calculations made, will not be repeated here. Good engineering is even more important when second and third class reservoirs are being considered. Also, it is assumed that nobody would start a secondary project without some sort of economic analysis. This analysis may be a highly sophisticated projection, run on the latest million dollar computer and presented in great detail on rolls of perforated paper. Or, it may be a "cash register" estimate of future income and outgo carried only in the head of the intrepid operator. In either case, having made an accurate appraisal. the operator usually finds himself still on the brink. What then can he do to improve the economic outlook?
Apply Multi-Zone Waterfloods
Check the multi-zone prospects. Quite often a North Texas lease will have one blanket zone and perhaps two or three secondary stringers at various locations and depths. A paper by Moyer* estimated dual zone investment to be 32 per cent less than for separate facilities (Fig. 1).
JPT
P. 915ˆ
Pressure Drawdown and Buildup Analysis of Horizontal Wells in Anisotropic Media
Authors: Goode P. A. , Thambynayagam R. K. M. 
Published: December 2007

Summary
An analytic solution is presented for the pressure response during drawdown and buildup of a horizontal well. This method results from solving the three-dimensional diffusion equation with successive integral transforms. Simplified solutions for short, intermediate, and long times that exhibit straight-line sections when pressure is plotted vs. time are presented. The validity of the method is demonstrated by comparing with results generated numerically by a reservoir simulator and with an analogous analytic solution. Methods for analyzing pressure drawdown and buildup data are presented with examples. The method allows reservoir characteristics, including permeability, skin, and distance to boundaries to be determined. The early-time effects, where the well behaves as if it were in an infinite reservoir, are also discussed. Expressions to determine times to critical events, which are important for well test design, are presented.
A Statistical Study of Reservoir Permeability: Distributions, Correlations, and Averages
Authors: Jensen Jerry L. , Hinkley David V. , Lake Larry W. 
Published: December 2007

SummaryWe propose that reservoir permeability may be statistically distributed in a variety of ways. Two hypothetical cases of reservoir layering are statistically analyzed. This analysis suggests that a restricted family of functions—all related to the normal distribution—can be used to represent permeability distributions. The log-normal distribution is one member of the family.Several sets of field data are analyzed. The analyses show that (1) permeability data are not necessarily log-normally distributed, (2) all the permeability distributions considered are closely approximated by members of the proposed family of functions, and (3) improved porosity/permeability relationships result when the permeability distribution is known.
Reservoir Characterization of Tuscaloosa Sand by Mineralogical and Petrophysical Data
Authors: Hosseini Masood S. , Hayatdavoudi A. 
Published: December 2007

Summary
A laboratory investigation has been made of the relationship between mineralogical and petrophysical properties of Tuscaloosa sandstone with a combination of petrographic analyses, formation-resistivity-factor measurements, and rock failure analyses. Petrographic analyses revealed that on the basis of the mineralogy of pore-filling and pore-lining cements, Tuscaloosa sandstones can be divided into two distinct types: those with authigenic quartz-overgrowth cement blocking the pore throats and those with authigenic chlorite cement coating the sand grains and preserving the pore system. For each type of sandstone, a well-defined relationship exists between the cementation factor m and other physical properties of the rock, such as porosity, type of cement, compressive strength, cohesive strength, failure angle, angle of internal friction, Young's modulus, Poisson's ratio, and drilling strength. Furthermore, we found that the fracture mechanism is grain fracturing in a fairly brittle mode for silica-cemented sandstone, while the fracture mechanism is grain sliding and pore closure or expansion for chlorite-cemented sandstones.
Design, Installation, and Early Operation of the Timbalier Bay S-2B(RA)SU Gravity-Stable, Miscible CO2-Injection Project
Authors: Moore J. S. 
Published: December 2007

Summary
This paper reviews the design, installation, and early operation of a gravity-stable, miscible CO2-injection project initiated in April 1984. The purpose of the project is to determine process economics, recoverable reserves, and operational difficulties to evaluate better the potential for fieldwide large-scale CO2 flooding. The results will also help to justify the major investments required to provide pipeline CO2 to the gulf coast oil fields.
Measurement of CO2 Flow in its Supercritical and Gaseous Phases
Authors: Oakes F. G. , White J. T. 
Published: December 2007

Summary
Production of CO2 and its injection for tertiary recovery of hydrocarbons has produced a need for an accurate method, adaptable to microcomputer technology, for orifice measurement of CO2 fluid flow. A method meeting that need has been developed and successfully implemented. The accuracy of the method for orifice measurement of both gaseous and supercritical CO2 has been verified at the temperature and pressure conditions experienced in field operations. Details of the measurement method and its verification are presented.
The flow rate of any single-phase fluid through an orifice is proportional to the density (and related to the viscosity and ratio of specific heats) of the flawing fluid and the pressure differential across the orifice plate. Mathematical methods are available and applicable for calculation of all three of these physical properties as a function of pressure and temperature. While the work presented here is directed to the measurement of pure CO2, the method is applicable to measurement of any single-phase fluid, provided suitable models are available for calculation of the values of the three physical properties.
Study of Equilibrium Properties of Cr(III)/Polyacrylamide Gels by Swelling Measurement and Equilibrium Dialysis
Authors: Young T. S. , Hunt J. A. , Green D. W. , Willhite G. P. 
Published: December 2007

Summary
In observations of the long-term properties of a series of Cr(III)/polyacrylamide (PAAM) gels, the gels either underwent syneresis upon aging or swelled in contact with excess brine. Both syneresis and swelling can substantially change the volume and properties of a gel placed in a formation and therefore influence the effectiveness of a crosslinked-polymer treatment. Efforts were made to develop an understanding of these phenomena and to describe them in terms of the gel's physical and chemical states. A long-term gel's physical and chemical states are characterized by two parameters, effective crosslinking density and chromium density, determined by equilibrium swelling and equilibrium dialysis, respectively. Swelling and syneresis properties were correlated to the effective cross-linking density described in polymer network theory. A model based on Flory and Hermans' swelling equations was developed to calculate the effective crosslinking densities of gels prepared from solution. Attempts were made to relate the swelling and syneresis properties to the compositions of gel systems to allow prediction of long-term stability of a gel based on its composition.
An analysis of the amount of chromium that reacted with the PAAM was made by successive equilibrium dialyses of the gel followed by chromium analyses of dialysates by atomic and visible absorptions. The overall fractional conversion of chromium in the gelation was between 0.39 and 0.70. The equilibrium conversion of Cr(VI) to Cr(IH) ranged from 0.65 to 0.85. The effective crosslinking density obtained from the swelling experiment was &lt;5 % of the chromium density for all samples studied. A substantial fraction of reacted chromium is suspected to be present in the gel matrix either in the form of intramolecular crosslinks or attached to only one polymer segment.
Mechanical Performance of Fiberglass Sucker-Rod Strings
Authors: Tripp Harley A. 
Published: December 2007

Summary
The natural frequencies of fiberglass sucker-rod strings can be calculated by treating the rod strings as modified spring/mass vibration systems. The ratio of the pumping-unit operating speed to the rod-string natural frequency can then be used as a basis for understanding fiberglass-rod-string performance and for predicting downhole pump stroke lengths.