bluuebunny/crossref_metadata_2025_split huggingface dataset:
Equilibrium Ratios of Water in the Water-Triethylene Glycol-Natural Gas System
Authors: Scauzillo Frank R. 
Published: June 2014

Abstract
Equilibrium data which should be useful in the design and/or evaluation of glycol dehydration units were prepared from an analysis of various published data and the correlation of these data by the use of the thermodynamic equilibrium ratio. The equilibrium ratios of water are used to solve the glycol absorber problem; such solutions are necessary to define the number of trays and the glycol circulation rate needed to meet drying requirements.
Activity coefficients were obtained which relate directly to the equilibrium ratios of water in the water-TEG-natural gas system. These activity coefficients have been used to calculate the equilibrium dew points for aqueous TEG concentrations of 60 to 99.9 weight per cent for the temperature range of 40 to 120F. They also provide a means of calculating equilibrium ratios for water in the water-TEG-natural gas system; this applies to any desired TEG concentration and to the temperature range from 40 to 120F.

Introduction
During the last several years, the drying of natural gas with aqueous triethylene-glycol (TEG) solutions has become very prominent. Most users of TEG as a drying agent have been satisfied with the performance of TEG solutions at the conditions used; however, there always has been some discussion of the drying ability of TEG solutions at conditions not commonly encountered such as temperatures below 50 or 60F, but more particularly temperatures above 100F, and pressures above 1,000 psia. Today, when higher wellhead temperatures such as 120F are more commonly encountered many are skeptical of TEG's ability to dry sufficiently well to provide dew points around 32F, which is generally the maximum tolerable when attempting to dry a gas to contract specifications of 7 lb/MMscf.
These views probably have evolved to some extent from the days when suppliers would not guarantee dewpoint depressions in excess of 65 to 75F. Also, the feelings about TEG drying may have arisen from the lack of information about the equilibrium relation of water in the drying operations.
Investigation of the Mitigation of Lost Circulation in Oil-Based Drilling Fluids by Use of Gilsonite
Authors: Guo H.. , Voncken J.. , Opstal T.. , Dams R.. , Zitha P.L.J.. L.J. 
Published: June 2014

Summary
Fluid-loss control is an essential property of oil-based mud (OBM) that can affect the success of drilling operations. This paper presents an investigation of the mitigation of lost circulation in OBM by use of leakoff-control-additive gilsonite. A simple physical model was developed to describe the static-filtration process considering the formation and properties of the filter cake. Both high-pressure/high-temperature (HP/HT) American Petroleum Institute (API) press and core-flow-filtration experiments were performed to evaluate the leakoff behavior of OBM. Core-filtration experiments were carried with the aid of a computerized-tomography (CT) scanner to monitor the invasion of the filtrate into the sandstone core at time intervals. In the long time limit, the model predicts that the fluid loss follows the classical Carter equation; that is, the volume of leakoff increases as the square root of time for the static filtration through a filter paper and through the sandstone core. Dual-mode filtration diminishes the rate of fluid loss considering the effect of emulsion. The model also provides a relation between pressure drop and filtrate rate, which can be used to estimate the permeability of filter cake in the experiment. The leakoff behavior with additive observed in the experiment is well-explained by the microstructure of rapid-buildup filter cake, which is mainly responsible for the control of fluid loss. The role of different components of OBM, such as solid particles, emulsion droplets, and additives, is discussed in light of our observations.
An Economically Successful Miscible-Phase Displacement Project
Authors: Block W.E. , Donovan R.W. 
Published: June 2014

Abstract
A slug-type miscible-phase displacement project has been in operation in the 29D pool of the Midway-Sunset field, Kern County, Calif., since March, 1958. This project has resulted to date in the production of 230,000 bbl of additional oil which can be attributed to propane injection. The project is profitable, and the investment was returned in two years. The pool production rate during April, 1960, was 900 B/D, which was 540 B/D more than the previous gas-injection operation.
Reservoir pressure is currently about 1,300 psia. The pool now has four injection wells and 12 producing wells, all drilled on 10-acre spacing. To date, a slug of 18 million gal of propane has been injected.
Impressive oil stimulation, accompanied by gas-oil ratio reduction, has been observed in most of the first-line wells and several of the second-line wells. Breakthrough of propane occurred in the first-line wells early in the life of the project but has occurred in only one second-line well. Continued production of stimulated wells has shown that additional oil can be recovered after propane breakthrough.
The original plan of operations called for injection of a propane slug followed by gas. However, the well's demonstrated ability to produce large quantities of oil after propane breakthrough, and the attendant depletion of the slug, caused the plan of operations to be modified to include recycling of produced propane in a miscible state.

Introduction
A slug-type miscible-phase displacement project was started in the 29D pool in March, 1958. The pool is located in the Midway-Sunset field about three-miles southeast of Taft, Kern County, Calif.
This reservoir was chosen for a miscible-phase displacement secondary recovery program because of the following factors.The quantity of 31°API oil remaining in the reservoir was great enough to make secondary recovery attractive.The pool pressure of 1,500 psia and temperature of 1800° F insured direct miscibility of a propane-injection stream with the reservoir oil.Well configuration and condition and the type of completion were such that good control could be maintained.The production mechanisms were known and understood.The pool size, and the reservoir rock and fluid characteristics were known.
Under these circumstances, it was believed the process could work if properly engineered. As of April 1, 1960, the project had paid out and now is operating on a profitable basis.
Use of Oxygen Scavengers To Control External Corrosion of Oil-String Casing
Authors: Schremp F.W. , Chittum J.F. , Arczynski T.S. 
Published: June 2014

Abstract
This paper describes a laboratory study of causes of external casing corrosion and the test work that led to the use of oxygen scavengers to prevent this attack. External casing failures are classified as water-line, casing-casing, collar and body failures. A corrosion mechanism based on principles of differential oxygen availability is developed that is consistent with facts known about each kind of failure. The field use of oxygen scavengers is depicted as a direct result of the laboratory study.
A part of the paper is devoted to reporting on the field use of hydrazine to control external casing corrosion. Results of field measurements made over a period of several years are presented as evidence of the effectiveness of the hydrazine treatment. The first conclusion reached is that the use of hydrazine materially reduces the cathodic protection requirements for treated wells. This result is interpreted to mean that a reduction is taking place in the amount of corrosion on the casing. Results indicate also that hydrazine shows its greatest usefulness within the first 12 to 18 months after a well is completed when pitting corrosion is likely to be most active.

Introduction
According to surveys sponsored by the National Association of Corrosion Engineers, the cost of repairing casing leaks caused by external corrosion may exceed $4 million per year. In addition, well damage and lost production resulting from casing leaks probably costs the petroleum industry an additional $5 to $6 million per year.
Concern about the cost of external casing corrosion led to an extensive laboratory study of factors causing this external corrosion and to the development of a new approach to its prevention. This paper presents a discussion of various causes of external casing corrosion, details of laboratory studies and the results of the field use of an oxygen scavenger in well cementing fluids to prevent the external corrosion of oil-string casing.
A Procedure for Measuring Contact Angles When Surfactants Reduce the Interfacial Tension and Cause Oil Droplets to Spread
Authors: Adejare O.O.. O. , Nasralla R.A.. A. , Nasr-El-Din H.A.. A. 
Published: June 2014

Summary
Viscoelastic surfactants (VESs) are used as diverting agents in carbonate matrix acidizing. However, these surfactants can adversely affect the wettability around the wellbore.
Receding contact angles were measured with the conventional method to study the effect of spent-acid solutions with an amphoteric amine-oxide VES and the mutual solvent ethylene glycol monobutyl ether (EGMBE) on the wettability of Austin cream chalk rocks. The conventional method involves the injection of oil droplets into the surfactant solution. However, contact angles could not be measured when oil droplets were injected into spent-acid solutions with VES and EGMBE, because low oil/acid interfacial tensions (IFTs) cause them to spread on the rock surface.
A new procedure was used for these contact-angle measurements. Rocks were centrifuged in spent-acid solutions with VES and EGMBE, so that the surfactant changed the interfacial properties of the rock. Then, contact angles were measured in spent acid with hydrochloric acid (HCl) only, to prevent VES and EGMBE from reducing the oil/acid IFT. The effect of the surfactants in the spent acid on the acid/rock and acid/oil IFT, which is the wettability, is shown by the difference in contact angles before and after centrifuging.
With the new procedure, a spent-acid solution with HCl, 1 vol% of VES, and 10 vol% of EGMBE made an oil-wet rock water-wet and a water-wet rock strongly water-wet at 25°C. This suggests that an EGMBE post-flush enhances the relative permeability to oil, under the parameters investigated.
Contact angles are a function of the oil/rock, acid/rock, and oil/acid IFTs. However, the wettability of the rock is a function of the oil/rock and acid/rock IFT only. The new procedure measures contact angles in such a way that the surface-active agents change the oil/rock and acid/rock IFT only so that “spreading,” an artifact caused by oil/acid IFT reduction, may not occur.
A Simple Method for Correcting Spot Pressure Readings
Authors: Brons F. , Miller W.C. 
Published: June 2014

Abstract
Pressure information for use in material-balance calculations is obtained, where possible, from pressure build-up surveys in shut-in wells. Using proper extrapolation methods, static pressures are obtained which, by averaging, give the field static pressure.
Often, particularly in fields with a large number of wells, only spot pressure readings are available. A graphical method is presented here which enables the determination of the corrections which must be applied to the spot readings to give an estimate of the static pressure. Although the static pressures thus obtained are not so reliable as those from build-up surveys, they are more nearly correct than the spot readings themselves for use in material-balance calculations.

Introduction
The average static pressure in a bounded reservoir is determined from a number of individual-well pressure measurements. Where pressure build-up curves are available, extrapolation methods such as described in Ref. 3 may be used to determine the static pressure in the drainage area of each individual well.
The possibility of using pressure build-up curves presupposes that each well being surveyed is closed in during a certain period and that, during this time, a pressure recorder is left suspended in the hole. For surveys in fields with a large number of wells, this is usually not feasible for economic and other reasons. Either a large number of pressure recorders would have to be used simultaneously or, using a limited number of recorders, the time interval needed to complete a field-wide survey would be too long. The data obtained for this incomplete coverage are insufficient to permit reliable averaging of the few calculated static pressures over the entire reservoir.
In many such cases another type of pressure information is available, i.e., spot pressure readings. During this type of pressure survey all wells are closed-in simultaneously and, after a reasonable shut-in time (e.g., three days), pressure readings are taken by running the recorder in and out of each successive well. These surveys, which are less expensive, are often taken at regular intervals, say once or twice a year.
Impact of Uncertainty in Estimation of Shale-Gas-Reservoir and Completion Properties on EUR Forecast and Optimal Development Planning: A Marcellus Case Study
Authors: Jayakumar R.. , Rai R.. 
Published: June 2014

Summary
The use of multistage-fractured horizontal wells has made production from shale-gas plays feasible. The production history from these wells is characterized by long linear transient flow. The key reservoir (nature) and completion (nurture) properties that affect flow behavior of the well are permeability, original hydrocarbon in place (OHIP), number of hydraulic fractures, fracture area, and fracture spacing. Understanding the interrelationship between these parameters is critical for optimal development of shale-gas-resource plays. The proposed shale-gas workflow uses a hybrid analytical model. An analytics-based diagnostic process analyzes well performance history, and a numerical model validates the feasible history-match models for representative forecasts. The model results allow the user to capture the range of uncertainty in estimating individual reservoir or completion properties, such as permeability, fracture area, and fracture spacing. The diagnostic process provides the relationship between key factors dictating well performance, such as OHIP, effective fracture area, effective reservoir permeability, effective fracture spacing, and well spacing. In this paper, wells from the Marcellus play in Pennsylvania, USA, are evaluated by use of the proposed shale-gas workflow. Surveillance is an integral part of this workflow. The paper shows how surveillance can be used for resource management and exception management. Along with data mining, the workflow accelerates the learning curve to evaluate the effectiveness of current field practices. The results help with understanding the effectiveness of proppant pumped, the potential number of contributing clusters, and production issues. Continued surveillance reduces the uncertainty surrounding all parameters. This knowledge base can then be used to optimize the asset-development strategy, maximizing the return on investment.
The Stability of a Pipe Stand Racked in a Derrick, Part 1—Foundation
Authors: Sawaryn S.J.. J. 
Published: June 2014

Summary
The paper presents an exact analytical solution using higher-order functions for the deflection and buckling of a simple pipe stand in a derrick, modeled as an inclined slender column, with self-weight and pinned at both ends. The results are consistent with industry practice where an intermediate finger board is used to support 93-ft stands of both 2⅜- and 2⅞-in. steel pipe but is not required for 3½-in. pipe. These observations suggest a suitable safety factor for application in other cases. The results are an important limiting case for the general pipe-stand model presented in Part 2.
Buckling lengths are presented for a range of pipe sizes and types. Sensitivities, such as the presence of tool joints, differences in material, wear, and the effect of pipe stick-up above the top racking board, are also introduced. Although there is good agreement between the theory and operational practice for triples, further investigation is needed for quads.
Construction columns are normally designed to support significant loads, and in most cases, self-weight plays only a minor role. This is not the case for a simple pipe stand in a derrick, for which stability is solely dependent on self-weight. More-formal analysis of these conditions is warranted because of the trend of increased mechanization and the need to preserve safety and improve operational efficiency.
To the author's knowledge, there is no existing industry guidance for the flexing and stability of pipe stands in a derrick.
Fast Simulation of Polymer Injection in Heavy-Oil Reservoirs on the Basis of Topological Sorting and Sequential Splitting
Authors: Lie Knut-Andreas , Nilsen Halvor Møll , Rasmussen Atgeirr Flø , Raynaud Xavier 
Published: June 2014

SummaryWe present a set of algorithms for sequential solution of flow and transport that can be used for efficient simulation of polymer injection modeled as a compressible two-phase system. Our formulation gives a set of nonlinear transport equations that can be discretized with standard implicit upwind methods to conserve mass and volume independent of the timestep. In the absence of gravity and capillary forces, the resulting nonlinear system of discrete transport equations can be permuted to lower triangular form with a simple topological-sorting method from graph theory. This gives an optimal nonlinear solver that computes the solution cell by cell with local iteration control. The single-cell systems can be reduced to a nested set of nonlinear scalar equations that can be bracketed and solved with standard gradient or root-bracketing methods. The resulting method gives orders-of-magnitude reduction in run times and increases the feasible timestep sizes. In fact, one can prove that the solver is unconditionally stable and will produce a solution for arbitrarily large timesteps. For cases with gravity, the same method can be applied as part of a nonlinear Gauss-Seidel method. Altogether, our results demonstrate that sequential splitting combined with single-point upwind discretizations can become a viable alternative to streamline methods for speeding up simulation of advection-dominated systems.
Preconditioning for Efficiently Applying Algebraic Multigrid in Fully Implicit Reservoir Simulations
Authors: Gries Sebastian , Stüben Klaus , Brown Geoffrey L. , Chen Dingjun , Collins David A. 
Published: June 2014

Summary
Fully implicit black-oil simulations result in huge, often very-ill-conditioned, linear systems of equations for different unknowns (e.g., pressure and saturations). It is well-known that the underlying Jacobian matrices contain both hyperbolic and nearly elliptic subsystems (corresponding to saturations and pressure, respectively). Because a reservoir simulation is typically driven by the behavior of the pressure, constrained-pressure-residual (CPR)-type two-stage preconditioning methods to solve the coupled linear systems are a natural choice and still belong to the most popular approaches. After a suitable extraction and decoupling, the computationally most costly step in such two-stage methods consists in solving the elliptic subsystems accurately enough. Algebraic multigrid (AMG) provides a technique to solve elliptic linear equations very efficiently. Hence, in recent years, corresponding CPR-AMG approaches have been extensively used in practice.
Unfortunately, if applied in a straightforward manner, CPR-AMG does not always work as expected. In this paper, we discuss the reasons for the lack of robustness observed in practice, and present remedies. More precisely, we will propose a preconditioning strategy (based on a suitable combination of left and right preconditioning of the Jacobian matrix) that aims at a compromise between the solvability of the pressure subproblem by AMG and the needs of the outer CPR process. The robustness of this new preconditioning strategy will be demonstrated for several industrial test cases, some of which are very ill-conditioned. Furthermore, we will demonstrate that CPR-AMG can be interpreted in a natural way as a special AMG process applied directly to the coupled Jacobian systems.
An Adaptive Hierarchical Multiscale Algorithm for Estimation of Optimal Well Controls
Authors: Oliveira D.F.. F. , Reynolds A.. 
Published: June 2014

Summary
In determining the optimal well controls by maximizing net present value (NPV) for the remaining life of a reservoir, one typically defines the length of the control steps a priori. Moreover, these control steps are often the same for all wells. We provide a scale-splitting/merging method for adaptively selecting the number and the lengths of control steps as the overall optimization proceeds. We start with a reasonably small number of control steps and find the associated optimal controls by maximizing NPV. Both the adjoint-gradient-based steepest-ascent method and ensemble-based optimization (EnOpt) are considered as optimization algorithms. Because the correlation length used to generate the ad hoc covariance matrix indigenous to EnOpt affects the results, we implement a simple method to reduce the correlation length as the optimization proceeds. This enables EnOpt to generate a good approximation for well-control problems in which the optimal solution is bang-bang. The adaptive approach is applied to two example problems, and the results are compared with those obtained with a predetermined number of control steps.
A Review of the Literature: Motor Vehicle Safety Initiatives in the Oil and Gas Extraction Industry
Authors: Retzer Kyla , Hill Ryan , Burton Jason 
Published: June 2014

Abstract

BACKGROUND
Motor vehicle crashes are the leading cause of death in the U.S. oil and gas extraction industry, resulting in approximately thirty worker fatalities every year. Many oil and gas extraction companies have developed comprehensive motor vehicle safety programs; some have described the impact of those programs at industry conferences, in industry magazines, or in trade journals. The purpose of this paper was to conduct a systematic review of the motor vehicle safety initiatives that have been published in this industry. This paper will summarize the reported effectiveness of these initiatives, identify the research gaps in the literature, and describe recommendations to enhance future motor vehicle safety research in the oil and gas extraction industry.

METHODS
To be included in this review, articles had to meet the following criteria: 1) available in an online database; 2) published during 1990-2012; 3) describe a motor vehicle safety initiative within an oil and gas extraction company; and 4) objectively measure the effectiveness of at least one component of a motor vehicle safety initiative.

RESULTS
The authors identified 38 articles that met the criteria above. Oil and gas extraction companies have employed a variety of interventions to improve motor vehicle safety among their workforce; the most common found in this review were in-vehicle monitoring, journey management, driver training and qualification, and driver fitness and alertness.

CONCLUSIONS
There is a need to improve the quality of research articles examining motor vehicle safety in the oil and gas extraction industry. The authors’ systematic review found a limited number of published articles describing motor vehicle safety initiatives in the oil and gas extraction industry, particularly in the U.S. In addition, the articles often suffered from a weak study design and did not evaluate the long-term impact of their initiatives over time. There is a continued need for oil and gas extraction companies to evaluate the impact of their motor vehicle safety initiatives and publish their findings in peer-reviewed journals to enhance the dissemination of effective strategies.