bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Semianalytical Approach to Pseudopressure Calculations
Authors: Klins M.A. , Biterge M.B. 
Published: December 2007

Summary.
Real-gas pseudopressures allow rigorous analytical solutions to the nonlinear mass/momentum equations for gas flow in porous media. These solutions, however, are in terms of pseudopressure rather than reservoir pressure. To convert pseudopressures to their complementary reservoir pressures, one of three techniques is traditionally applied: numerical integration, table look-up, or curve-fit analysis. All three interject some numerical error into the m(p) calculations. This paper introduces a new, "exact" procedure for making the pseudopressure/pressure conversion. It is applicable to a wide range of reservoir properties including, sour gases, temperatures up to 460 degrees F [238 degrees C], and pressures to 10,000 psia [70 MPa]. Sample calculations are shown and comparison with a number of other pseudopressure estimates is made.

Semianalytical Approach to Pseudopressures
Al-Hussainy et al. introduced the notion of pseudopressure, m(p), to analyze real-gas flow phenomena in porous media. Since that time, at least three approaches have been presented that convert reservoir pressures to their complementary pseudopressures: numerical integration, table look-up and interpolation, and curve-fit approximation.
Of these three, the most commonly applied approach is numerical integration by use of known gas correlations for viscosity and supercompressibility. Its major advantage is that it allows the user to select the and z correlations of his/her choice before numerical integration. The drawbacks are that it requires a large number of and z calculations to create a table of p/ z vs. pressure, that a numerical integration procedure and accompanying and z programs must be developed, and that the magnitude of error inherent in numerical integration is unknown and depends on the number of data points used in the integration.
The semianalytical approach, then, involves the actual solution of the m(p) integral defined in Eq. 1. If the viscosity and compressibility terms in Eq. 1 are replaced with selected correlations. the real-gas pseudopressure equation can be solved analytically and an exact solution (for the correlations chosen) of m(p) obtained.

Model Development.
Real gas pseudopressure with a zero base pressure of integration is defined as
= ...................(1)
Substitutions for p/z, dp, and p with Eqs. 5, 9, and 10 can be made with a change in the variable of integration from p to pr introduced.
By using the imperfect-gas law, we can calculate gas densities:
= ..............................(2)
and
= ..............................(3)
where Dranchuk et al. assume that the critical gas con pressibility factor is 0.27 and
= ..............................(4)
Then it follows that
= ....................(5)
and
= .........(6)
With the Dranchuk et al. correlation for z factors,
= ....................(7)
P. 468^
Discussion of Application of Oil Muds
Authors: Bloemendal J. W. 
Published: December 2007

Abstract
I would like to comment on three oil-mud papers: "Behavior of Oil Muds During Drilling Operations," "Low-Toxicity Oil Muds: A Knowledge of Downhole Rheological Behavior Assists Successful Field Application," and "Magnesium Oil Mud Provides Gauge Hole in Bischofite/Carnallite Formations" (April 1986 SPEDE, Pages 97–106, 107–14, and 115–21, respectively).
I fully agree that an oil mud is superior in drilling unstable, deviated, or water-sensitive formations. I have serious doubts, however, about the practical and economical application because of the disadvantages mentioned by most authors but not discussed enough to convince me to give up my opposition to oil-based muds (OBM's).
I question the higher rate of penetration claimed for relaxed API-WL OBM's compared with water-based fluids, because the improved performance of OBM's might be largely or entirely a result of the beneficial effects of polycrystalline-diamond-compact bits, higher API-FL, lower effective bottomhole density, better lubricity (which results in higher weight on bit), higher revolutions per minute, more favorable rheological properties, and probably many more effects that cannot be recognized easily in practice. Maybe we still have our equipment for laboratory drill tests rigged up to investigate the isolated effect of OBM's while the other factors are changed one at a time.
Analysis of Productivity of Inclined Wells and Its Implication for Finite-Difference Reservoir Simulation
Authors: Lee S. H. 
Published: December 2007

Summary
A boundary-integral method was used to study the productivity of inclined wells. The previous analytical equations for productivity indices were derived mainly for two-dimensional (2D) or three-dimensional (3D) radial flow and a line source or sink in an unbounded domain. Even when a simple impermeable plane boundary exists near a well, the analytical solution becomes a complicated infinite series of functions. Hence, it is desirable to develop a simple, general method to analyze accurately the Darcy flow around inclined wells in an arbitrary reservoir geometry. Use of Green's function allows a general solution of the Darcy equation to be expressed in the form of a Fredholm integral equation of the second kind. This integral equation has been solved numerically by a collocation technique.
This boundary-integral method was used to analyze the effects of reservoir boundaries, anisotropic permeability, well location, and inclination angle on well productivity. Finally, the commonly used well-productivity equation for a finite-difference method was carefully examined by comparison with accurate numerical solutions from the boundary-integral method. This study indicated that the equation can yield erroneous results for an inclined well. The well productivity calculated here can easily be incorporated in finite-difference simulation for inclined wells.
Analysis of Radial Transport of Reactive Tracer in Porous Media
Authors: Falade G. K. , Brigham W. E. 
Published: December 2007

Summary
This paper presents some new close-form analytical solutions to equations describing radial transport of reactive tracers in porous media under conditions of tracer adsorption, nonuniform convection, and variable dispersion coefficient. Three different types of variable dispersion coefficients were considered and exact solutions presented in Laplace space. The special case where shear mixing or convection dominates dispersion, which is important for tracer test studies, was programmed on a computer to obtain concentration profiles for the continuous- and slug-injection test models.
The Importance of Correct Running and Handling Procedures for Premium Tubular Goods
Authors: Walstad D. E. , Crawford D. W. 
Published: December 2007

Summary
The demand and requirements for tubular goods to handle deeper wells with more hostile environments have resulted in increased popularity and widespread use of proprietary sour-service steel grades and corrosion-resistant alloys (CRA's) with premium connections.
Because of the great potential economic disasters that could result if damaged tubulars are run in hostile environments, obtaining maximum performance from the tubulars is imperative. Improper handling and running damage can cause (1) unnecessary and excessive damage to the threaded areas, requiring field repair or rethreading; (2) failure of the tube—i.e., collapse, burst, small leaks, or fatigue; (3) leaks or connection parting (failure); and (4) catastrophic failure—such as blowouts, loss of well, loss of equipment, or loss of life.
For adequate tubing and casing performance, equal emphasis should be focused on running and handling procedures, tubing, casing design, and materials selection.
This paper discusses all phases of running and handling for premium tubular goods and presents supportive field data from three geographic areas.
An Overview of Free-Point Tools
Authors: Weido V. C. 
Published: December 2007

Summary
Service companies traditionally have used similar types of downhole tools to locate the lowest free point in a string of pipe. Advancing technology has encouraged new concepts and innovative tool designs that are changing this specialized service.
Traditional tools make static measurements of incremental tension or torsional deviation on either side of the forecasted point at which the pipe is stuck. The speed with which the free point is located depends on the initial forecast and procedural requirements necessary for the measurement. In a sense, the operator approaches the free point by successive approximations.
This paper introduces two new tool designs to minimize interpretation error and to accelerate the location of the lowest free point. Each design provides a log record of the free-point service. One of these tools extends the concept of static measurements of incremental tensile and torsional deviation, while the other relies on the measurement of magnetic permeability and produces a continuous log. Example logs from each tool design are presented.
Evaluation of Gas-Extraction Efficiency During Mud-Logging Operations
Authors: Elder Suzanne S. 
Published: December 2007

Summary
Field and laboratory tests described in this paper were designed to develop a better understanding of conditions that affect gas analysis during mud logging. The test objectives were to quantify gas losses, if any, from the mud at the bell nipple or in the flowline during drilling and to study the effects of changing mud properties on gas-trap extraction efficiency.
Interactive Computer Graphics System Improves Planning of Directionally Drilled Wells in the East Wilmington Field
Authors: Lutz T. S. , Kendle D. W. 
Published: December 2007

Summary
The Long Beach Unit of the East Wilmington field contains more than 1,200 wells directionally drilled from four manmade islands and five land-based drilling sites. Planning new wells that avoid interference with existing wells becomes more difficult and time-consuming as the density of wells in the Unit increases. Improvements and modifications in design procedures have culminated in the interactive computer graphics system now in use.
The interactive computer graphics system (ICGS) permits the viewing of a proposed new well or redrill well course, together with all existing well surveys and other proposed well courses in the area of interest. Plan, section, and traveling cylinder views can be displayed to allow the identification of design problems. The significance of the problems is then minimized by use of the interactive features of the system to refine the design parameters. The system's interactive features are also used to create, edit, and plot the finalized design.
Reductions in design and drilling costs and many other less-direct benefits have been realized as a result of the system's use. The step-by-step use of the system from the user's point of view is described and examples of its graphic output are presented. To the best of our knowledge, this is the most advanced system of its kind in use today.
A Mathematical Model for the Scale-Inhibitor Squeeze Process
Authors: Hong S. A. , Shuler P. J. 
Published: December 2007

Summary
A mathematical model was developed to describe the scale-inhibitor-adsorption squeeze process. The objective of this study was to create a tool that will predict the duration of a squeeze treatment, given the operating parameters and the rock and inhibitor properties.
Assuming that there is local equilibrium between the inhibitor in solution and on the rock, the mathematical model was solved analytically by the method of characteristics. Algebraic equations were derived to calculate the scale-inhibitor concentration in the produced water and the squeeze lifetime. The validity of the model is demonstrated by a comparison of its predictions with field and laboratory data. Sensitivity of the squeeze lifetime to variables associated with the process is presented. One important conclusion is that scale inhibitors should be screened on the basis of their adsorption characteristics and their effectiveness at low concentrations in preventing scale formation.
Finally, the complete mathematical model, which allows for time-dependent adsorption/desorption of the inhibitor, is solved numerically. Accurate predictions of the squeeze process require incorporation of these kinetic effects when the residence time is short compared with the time required to reach equilibrium. As demonstrated here, this can be significant, especially in laboratory tests performed to measure squeeze lifetime. Scaling up laboratory results for the field should be done with caution because these kinetic effects tend to increase squeeze lifetime. The equilibrium model gives the most conservative prediction of squeeze lifetime.
An Experimental Investigation Into the Effects of Chemical type on CO2/Heavy-Hydrocarbon Phase Behavior
Authors: Wilburn D. L. , Bankston B. A. , Monger T. G. 
Published: December 2007

Summary
This paper provides PVT and compositional data for seven CO2/synthetic-oil systems. The oils were composed of light paraffins plus heavy hydrocarbons selected from three chemical types: paraffins, naphthenes, and aromatics. Results for the different oils are contrasted with a comparison basis of equivalent molar-averaged normal boiling point. This parameter is easy to calculate and provides a means by which chemical effects can be quantified in the presence of oil volatility effects.
The results demonstrate that two oil compositional effects control the extent of hydrocarbon extraction by CO2. The major effect is usually the oil volatility, but effects of hydrocarbon chemical type can be dominant. The data suggest a trend for the influence of chemical type on oil miscibility with CO2: paraffins are beneficial, aromatics are less beneficial than paraffins, and naphthenes are detrimental. The effect of chemical type on oil swelling is also significant.
A New Chrome-Free Lignosulfonate Thinner: Performance Without Environmental Concerns
Authors: Park L. S. 
Published: December 2007

Summary
Chrome-free lignosulfonates are increasingly used in aqueous drilling fluids because of potential environmental concerns associated with the chromium counterparts. A basic design study of a chrome-free lignosulfonate showed three major reaction parameters affecting its performance: type and concentration of complexed metal ion, oxidation level under optimal pH, and lignosulfonate raw liquor. A new chrome-free lignosulfonate formulation based on titanium metal ion was developed and its plant scale-up was conducted. Testing of the new titanium-complexed lignosulfonate was found to give improved rheological control vs. other available chrome-free lignosulfonates in various water-based drilling fluid applications.
Optimization of Offshore Field Development to Minimize Investment
Authors: Grimmett T. T. , Startzman R. A. 
Published: December 2007

Summary
Offshore oil and gas development is identified with high investment. Considerable incentive therefore exists to reduce investment and to improve field profitability. A computational method has been developed to optimize field development and to minimize investment.
Investment can be reduced through an optimal choice and arrangement of production facilities. The selection, size, and location of major facilities—such as platforms, templates, or subsea manifolds—heavily affect capital investment. The allocation of field wells to these facilities affects drilling and completion costs. An extremely large number of feasible development options exist that may result in a wide range of economic outcomes. Choosing the option that minimizes investment can be a major computational problem.
The solution of extremely large economic problems of this nature has not been reported previously. An integer mathematical programming computational tool, using a method called "zero-one implicit enumeration," was developed for modeling and solving this problem. This technique allows for efficient probletn solution on a computer.
A model of an example field development was formulated. This model contains a mathematical function representing the investment to be minimized and includes design restrictions inherent to the development project. The model contained nearly 10190 combinations of development options. The application of a branch-and-bound algorithm allowed selection of an optimum development in a relatively short time on a computer.
A Generalized Compositional Model for Naturally Fractured Reservoirs
Authors: Peng Chungshlang P. , Yanosik John L. , Stephenson Robert E. 
Published: December 2007

SummaryThis paper presents the formulation of a generalized dual-porosity compositional reservoir model. The model uses the implicit-pressure, explicit-saturation (IMPES) method, with semi-implicit treatment of wells, and the Newton-Raphson iteration method to solve the dual-porosity flow equations. The model was used to study the depletion performance of dual-porosity volatile-oil and gas-condensate reservoirs.
Use of Tracers To investigate Drilling-Fluid invasion and Oil Flushing During Coring
Authors: Brown A. , Marriott F. T. 
Published: December 2007

Summary
This work develops a method in which chemical tracers in the drilling fluid help determine mud filtrate invasion and the degree of oil flushing during coring of steamed and unsteamed heavy-oil formations. Salts of iodide and bromide were added to the drilling fluid while Well T03 was cored through the Lombardi and Aurignac zones at San Ardo field in California. Vertical core plugs, taken from the periphery to the center of the retrieved whole core, were analyzed for tracer concentration.
Tracer analyses indicated minimal filtrate invasion in the not-yet-steamflooded Lombardi zone and complete filtrate invasion in the steamflooded Aurignac zone. Tracer and oil saturation analyses showed the Lombardi zone to be uniform from top to bottom with an average oil saturation of 42.5% and an average porosity of 31.1%. interpretation of tracer and oil saturation data permitted the construction of a layered model for the Aurignac zone. The layers ranged from an average oil saturation of 8% in the steamflooded layer to 37% in the bottom layer. The data showed that significant oil flushing (6%) occurred only in cores taken from the hot-waterflooded layer just below the steam zone.
Vertical core-plug porosities and saturations, as determined by a unique calculating scheme, were compared with conventional and Elkins-corrected values. The comparison indicated that misapplication of the Elkins method in high-temperature formations may result in significant errors.
Electrical Savings in Oil Production
Authors: Johnson J. E. 
Published: December 2007

Summary
Many oil-production operations do not use electricity efficiently. Recommended models for improving electrical efficiency and reducing electric bills are (1) to install pumpoff controllers and timers, (2) to modify pumping-unit stroke length and speed, (3) to use multimode motors in low mode, (4) to use cog-type belts, (5) to improve power factor with capacitors, and (6) to use electric-rate options.
Horizontal-Well Pressure Analysis
Authors: Ozkan Erdal , Raghavan Rajagopal , Joshl Sadanand D. 
Published: December 2007

SummaryThis paper presents an analysis of the pressure-transient behavior of a horizontal well or a drainhole. The performances of horizontal wells and fully penetrating vertical fractures are compared. Dimensionless wellbore pressures are computed for two classic boundary conditions: infinite conductivity and uniform flux. Results are presented as pseudoskin factors and as type curves. In addition to conventional pressure-vs.-time type curves, derivative type curves from pressure/time predictions are presented. The derivative approach we discuss is applicable to a broader range of problems than that considered here.Computations suggest that horizontal-well productivity is governed by two parameters: (1) the dimensionless well length, LD[LD=L/(2h)k2/k], and (2) the dimensionless well radius, rwD (the ratio of well radius to well half-length if the formation is assumed to be isotropic). Results indicate that horizontal-well productivity (infinite-conductivity idealization) is almost identical to that of a fully penetrating vertical fracture of infinite conductivity if LD &gt;4.0. This result shows that horizontal wells may perform better than vertically fractured wells if nonideal aspects associated with vertically fractured wells, such as limited conductivity or height, are taken into account.Results have been obtained for the range 0.1≤LD≤100 and for the range 10−4≤rwD ≤10−2; these ranges should encompass expected values of horizontal-well length, reservoir height, and the ratio of vertical and horizontal permeability. Pressure responses and pseudoskin factors are calculated for four different well locations within the productive interval. The pseudoskin factors are insensitive to well location.
The Performance of Perforated Completions in Gas Reservoirs
Authors: Ichara Mark J. 
Published: December 2007

SummaryA finite-element program was used to study the influence of shot density, perforation length, phasing angle, formation permeability, formation anisotropy, and turbulence factor on the performance of perforated completions in gas reservoirs. The results indicate that when permeability is low (&lt; 10 md), turbulence effects are negligible, and perforation length and phasing angle affect productivity ratio. In anisotropic formations, high shot density (≥ 12 shots/ft [39 shots/m]) with deep penetration (≤ 15 in. [38 cm]) is required for the well to perform better than an openhole completion. Turbulence effects can cause up to 75% loss in production in high-permeability formations. The nomograph presented can be used to predict productivity ratios and skin factors in gas reservoirs.