bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of heavy metals on microbial growth kinetics including lag time: Mathematical modeling and experimental verification
Authors: Şengör S. Sevinç , Barua Sutapa , Gikas Petros , Ginn Timothy R. , Peyton Brent , Sani Rajesh K. , Spycher Nicolas F.
Published: June 2009

Heavy metals can significantly affect the kinetics of substrate biodegradation and microbial growth, including lag times and specific growth rates. A model to describe microbial metabolic lag as a function of the history of substrate concentration has been previously described by Wood et al. (Water Resour Res 31:553–563) and Ginn (Water Resour Res 35:1395–1408). In the present study, this model is extended by including the effect of heavy metals on metabolic lag by developing an inhibitor-dependent functional to account for the metabolic state of the microorganisms. The concentration of the inhibiting metal is explicitly incorporated into the functional. The validity of the model is tested against experimental data on the effects of zinc on Pseudomonas species isolated from Lake Coeur d'Alene sediments, Idaho, USA, as well as the effects of nickel or cobalt on a mixed microbial culture collected from the aeration tank of a wastewater treatment plant in Athens, Greece. The simulations demonstrate the ability to incorporate the effect of metals on metabolism through lag, yield coefficient, and specific growth rates. The model includes growth limitation due to insufficient transfer of oxygen into the growth medium.
A Study of the Madison ‘B' Reservoir East Poplar Field, Roosevelt County, Montana
Authors: Harrelson H.E.
Published: June 2009

A portion of a study of the B Reservoir of the East Poplar Field made by the East Poplar Unit Engineering Committee is summarized. The study was undertaken to review the performance of the reservoir after five years of operation.

The B Reservoir consisted of two limestone zones and one dolomite zone in good pressure communication. The usual problems of analyzing reservoirs of this type were made more complex by a 200-ft tilt in the original oil-water contact. A thick interval of transition from oil to water also existed which it was necessary to quantitatively define in order to study recovery efficiency.

The B Reservoir contained 213,200,000 bbl of tank oil originally in place[588 bbl/acre-ft]. Calculations have indicated that 39.7 per cent of the tank oil originally in place may be recoverable. Cumulative production as of Jan. 1,1958, was 16.3 per cent of the ultimate recoverable oil.

A pilot pressure maintenance project was initiated in Sept., 1956, testing the feasibility of augmenting a limited natural water drive. Produced saltwater was injected below the original oil-water contact through two wells. Increases in productivity were noted on four wells after the injection of only400,000 bbl of water. The project has been encouraging enough to anticipate future expansion.

Introduction

The East Poplar Field was discovered in March, 1952, with the completion of the East Poplar Unit No. 1. The field lies in Northeast Montana on the Fort Peck Indian Reservation in Roosevelt County. It is approximately 55 miles south of the International Boundary and 8 miles northeast of the town of Poplar.

There are three oil reservoirs of importance in the field, the Madison A, Band C Zones. In addition, oil production has been established in the Kibby Sandbut has not thus far proved commercial. Minor gas production has also been obtained from the Judith River Sand.

This paper is confined to a discussion of the B Reservoir, occurring at a depth of approximately 5650 ft, and containing most of the reserves of the field.
Gamma Ray Permeability Relationship in the Denver-Julesburg Basin
Authors: Smith Clarence E.
Published: June 2009

This paper is the result of an investigation made to determine an empirical relationship between Gamma Ray curves and core analysis permeability values for wells in the Denver-Julesburg Basin. It is proposed to show that an empirical relationship does exist and to present information and curves to substantiate the belief that we can derive permeabilities from Gamma Ray data. This type of information can be a valuable aid in application to Basin workovers and completion activities.

Introduction

The majority of Gamma Ray surveys are being taken for correlative information for use in conjunction with perforating of oil and gas pay intervals. All the service companies are now using the Scintillation type instrument. However, a number of currently producing wells have been surveyed with the Ionization type instrument; and in order to make this study comprehensive, both types of equipment are included in this investigation. This work is based on the theory that the permeability of the "D" and"J" sands of the Denver-Julesburg Basin is a function of the clay cementing material found in the pay zone pore space. The idea is not a new one as C.L. Rabe did the preliminary work, and he came to the conclusion that permeabilities could be related to Gamma Ray data. Using Rabe's recommended method for correcting Gamma Ray logs for drag, sensitivity changes, thin bed effects, and converting to a common scale was found to be entirely laborious. For practical reasons, it was decided to check and see if an empirical relationship could be established without going through all the corrections mentioned.

Development of Permeability Curves

Ionization Instrument

All the core analyses of wells that have been surveyed with the Ionization type instrument were compared for similarities in deflection changes and changes of permeabilities. In order to expedite this comparison, the core analyses were plotted on transparent paper using the same footage scale as the Gamma Ray log. It soon became apparent that plotting of these permeabilities would not correlate too well with the Gamma Ray curves. Therefore, it was decided to calculate the average weighted permeability of each foot of the core analysis.
Coupling Equation-of-State Compositional and Surfactant Models in a Fully Implicit Parallel Reservoir Simulator Using the Equivalent-Alkane-Carbon-Number Concept
Authors: Han C. , Delshad M. , Pope G. A. , Sepehrnoori K.
Published: June 2009

Equation-of-state (EOS) compositional and surfactant models are coupled in a fully implicit parallel reservoir simulator using the equivalent alkane carbon number (EACN) of the oleic phase. The EACN of the oleic phase is computed using a mole-fraction-weighted carbon number for each component present in the oleic phase. Important microemulsion properties such as optimum salinity and optimum solubilization parameter as a function of the EACN of the oleic phase are implemented on the basis of known correlations. Type II(-) surfactant phase behavior is considered in this study. The simulator developed is validated using our implicit-pressure/explicit-concentration (IMPEC) chemical-flooding simulator. Case studies, including a large-scale simulation, emphasize that surfactant floods should be modeled carefully, taking the EACN of crude oil into consideration for more realistic and accurate oil-recovery predictions.
Numerical Modeling of Diffusion in Fractured Media for Gas-Injection and -Recycling Schemes
Authors: Hoteit Hussein , Firoozabadi Abbas
Published: June 2009

Diffusion in fractured reservoirs, unlike in unfractured reservoirs, can affect significantly the efficiency of gas injection in oil reservoirs and recycling in gas/condensate reservoirs. The physical diffusion, similar to gravity, results in the change of the path of the injected gas species from the fractures to the matrix, giving rise to late breakthrough. In this work, we present, for the first time, a consistent model to incorporate physical diffusion of multicomponent mixtures for gas-injection schemes in fractured reservoirs. The multicomponent diffusion flux is related to multicomponent diffusion coefficients, which are dependent on temperature, pressure, and composition. These coefficients are calculated from a model based on irreversible thermodynamics. Current simulation models of fractured reservoirs that include diffusion are based on inconsistent models of gas-to-liquid diffusion at the fracture/matrix interface. We avoid this deficiency by assuming that the gas and liquid phases are in equilibrium at the interface. The concept of crossflow equilibrium (i.e., vertical equilibrium) is invoked in our model to avoid the use of transfer functions. In this work, we use the combined discontinuous Galerkin and mixed methods on 2D structured grids to calculate fluxes accurately and to have low numerical dispersion to study physical diffusion. Four examples are presented. In one of the examples, a field-scale study is performed to investigate gas injection in a fractured reservoir away from miscibility pressure and close to miscibility pressure. Results show a significant effect of diffusion on recovery performance away from miscibility pressure. In another example, recycling in a fractured gas/condensate reservoir is presented to demonstrate that diffusion has a significant effect on condensate recovery.
Transient Flow in Discretely Fractured Porous Media
Authors: Izadi Mehdi , Yildiz Turhan
Published: June 2009

This paper presents a semianalytical model for transient flow into multiple vertical wells producing from a porous medium containing randomly distributed discrete fractures. Both vertical openhole wells and hydraulically fractured vertical wells are considered. The semianalytical model simulates pressure and pressure-derivative characteristics of wells and flow distribution along and through both the natural and the hydraulic fractures.

The study shows that single or multiple isolated natural fractures yield negative pseudoskin factors in vertical wells near isolated fractures. The negative pseudoskin factor is a function of fracture conductivity, density, length, distance from the wellbore, and azimuth.

Using the model, we demonstrate that the shape of the pressure derivative is related to fracture distribution. The results of this study indicate that the conventional double-porosity analysis to predict the storativity ratio of a naturally fractured system is not reliable. Also, the displacement between two semilog straight lines is not necessarily a good indicator of the storativity ratio.
Mechanisms, Parameters, and Modeling of Naphthenate-Soap-Induced Formation Damage
Authors: Sarac S. , Civan F.
Published: June 2009

Naphthenate-soap deposition and the related formation damage in petroleum reservoirs are investigated by means of laboratory-scale experimental and theoretical studies. Experiments were carried out in three directions to understand and quantify the naphthenate-soap-deposition problem. Static bottle tests were conducted to determine the precipitation rate for various pH and temperature conditions. Microscopy investigations were carried out to verify the growth of naphthenate-soap particles under different pH conditions. Core-flow tests were conducted to generate naphthenate-soap particles and to determine the permeability impairment caused by subsequent deposition of these particles in porous media under flowing conditions and different pH values. A power-law expression was proposed and verified for the precipitation rate of the naphthenate-soap particles. The parameters of the rate equation were correlated with respect to pH and temperature. This also allowed the determination of the critical pH value for the onset of naphthenate-soap precipitation. The results of the particle-size experiments were described by a particle-growth equation, and the parameters of the equation were correlated with respect to pH. The core-flow experiments proved the occurrence of formation damage caused by naphthenate-soap precipitation and subsequent deposition. The permeability impairment in core-flow experiments was described by a new differential model. The applications presented in this study provide insights for understanding the mechanism and magnitude of naphthenate-soap-induced formation damage and help in taking proper measures to avoid the formation damage caused by naphthenate-soap deposition.
Lease Automation: The Present and the Future
Authors: Morgen Ralph A. , Young Edwin C.
Published: June 2009

Production Automation Practical

Workable and economical equipment is available today to give automation from the wellhead to the pipeline. This automation can be most readily divided into three groups of equipment: Group 1, "Flowing and Production Controls";Group 2, "Well Testing"; and Group 5, "Custody Transfer". Let us examine each of these groups separately to determine the requirements of each.

Group 1, Flowing and Production Controls

These controls are required to regulate flow from the wellhead to the flowline, pressure control in the flow line and production equipment, level control in the production equipment, and temperature control where required. Access from wellhead to pipeline is provided through valving on flowing wells and through the pumping unit for wells on pump. The automation controls require dare used to shut-in the well when required by a preset program or in response to an alarm condition. The normal pressure, level, and temperature controls used on the production equipment are included in the alarm system.

An automated lease usually consists of several wells being produced into a central production facility. For ease of handling it is usually expedient to locate several flow diverter valves connected together into a manifold for the purpose of routing the fluids from the wellhead to either production or test facilities. Where flowing wells are manifolded together, it is often practical to use three-way, three-position valves for the purpose of shutting in the well.

It is an exception for this three-position valve to be the only shutoff between the wellhead and the production equipment. It is more common to close both of the outlets of the three-position valve to cause pressure to build up in the flow line. A two-way valve, installed at the wellhead and controlled by a hi-lo pressure pilot, senses this rising pressure and shuts in the well. For leases with relatively short-distance flow lines, a low pressure signal to the hi-lo pressure pilot may be used to indicate a ruptured line, and will cause the pilot to shut-in the well. Thus, the pilot acts as a high and low safety device as well as the means of shutting in the well in accordance with programming or in response to an alarm shut-in condition.
Wire Line Formation Testing in Open and Cased Holes in Southern Louisiana
Authors: Fischer J.S. , Havard E.H. , Van Ness A.E.
Published: June 2009

The Formation Tester is a tool which is run in either open or cased holes on a conventional logging cable. Tests may be made rapidly and safely at various depths in the hole. The Formation Tester provides: a sample of the formation fluids, GORs, a means to determine accurate gas-oil, or oil-water contacts, bottom hole pressure data, an index to the permeability of the small zone adjacent to the tool.

There are many formation testing problems peculiar to soft formations. Development of solutions has been very successful. The problems encountered and their solutions were:The percentage of successful tests was less than expected because unconsolidated sands would not support the packer. This problem was almost completely solved by the introduction of the shaped charge and snorkel testers.The number of fishing jobs needed to be reduced. This problem was overcome by keeping the cable in constant motion so that hydrostatic pressure could not seal the cable to the wall of the hole.Interpretation was confusing. It was found after many tests that the amount of oil or gas recovered was the factor which determined what the ultimate production would be. The water produced should not be used as an indicator of final production.

The Wire Line Formation Tester has recently been used in cased holes with very good success. The operation and application are similar to those in open holes with the following additional applications: old wells may be tested, cement jobs can be evaluated for channeling, directional holes may be tested without wire line hazards.

Introduction

The Wire Line Formation Tester has, in the past year, become widely used and is now becoming a standard tool for formation evaluation in Southern Louisiana. During the first two years of testing the soft formations of these coastal regions, results were not as satisfactory as had been anticipated. Many problems were present. Many solutions were attempted. The purpose of this paper is to describe the equipment and techniques which have contributed to the recent success of the tester. In addition, the newly developed method of testing in cased holes will be discussed.
Study of Enhanced-Oil-Recovery Mechanism of Alkali/Surfactant/Polymer Flooding in Porous Media From Experiments
Authors: Shen Pingping , Wang Jialu , Yuan Shiyi , Zhong Taixian , Jia Xu
Published: June 2009

The fluid-flow mechanism of enhanced oil recovery (EOR) in porous media by alkali/surfactant/polymer (ASP) flooding is investigated by measuring the production performance, pressure, and saturation distributions through the installed differential-pressure transducers and saturation-measurement probes in a physical model of a vertical heterogeneous reservoir. The fluid-flow variation in the reservoir is one of the main mechanisms of EOR of ASP flooding, and the nonlinear coupling and interaction between pressure and saturation fields results in the fluid-flow variation in the reservoir. In the vertical heterogeneous reservoir, the ASP agents flow initially in the high-permeability layer. Later, the flow direction changes toward the low- and middle-permeability layers because the resistance in the high-permeability layer increases on physical and chemical reactions such as adsorption, retention, and emulsion. ASP flooding displaces not only the residual oil in the high-permeability layer but also the remaining oil in the low- and middle-permeability layers by increasing both swept volume and displacement efficiency.
Analytical Determination of Optimum Bit Weight and Rotary Speed Combinations
Authors: Graham J.W. , Muench N.L.
Published: June 2009

This paper presents an analytical method for the selection of optimum combinations of rotary speed and bit weight to minimize total drilling cost. A mathematical analysis of the cost to drill any depth interval is the basis of the method. In the analysis, it is assumed that the total drilling cost can be expressed as the sum of rig cost for making round trips, rig cost for drilling, and bit cost. It is further assumed that bit life is limited by bearing failure, that bit weight is not limited by considerations such as hole deviation, and that drilling hydraulics are adequate. Based on these assumptions, the following important question is proposed: Do optimum combinations of bit weight and rotary speed exist which will minimize the cost to drill specified depth intervals? This question is understood more specifically through a consideration of the following facts. When either bit weight or rotary speed is increased, the rig cost for drilling becomes less because penetration rate is increased. However, when greater bit weight and/or faster rotary speed is used, both rig cost for making round trips and bit cost become greater because bit life is decreased. Whether or not a change in bit weight (or rotary speed) will increase or decrease drilling cost is determined by a mathematical analysis.

To perform the analysis, the results of past field experience are used to derive empirical mathematical expressions for bit life expectancy and for drilling rate as a function of depth, rotary speed, and bit weight.
The Future Course of United States Exploration
Authors: Gardner Frank J.
Published: June 2009

Oil exploration in future will depend more and more upon proper thought and perspective on the part of those engaged in it. Success will demand flexibility and imagination in order to picture the possible occurrences of oil which are not readily evident at the surface.

There will be an increasing emphasis on world-wide exploration, and Americans will be the leaders in this world-wide search. We need not fear the apparent flood of oil which might result, for in the long run the world is going to need every drop of oil energy that it can muster. The supply of oil is a finite thing, and within a hundred years or so a new kind of energy must takeover the world.

There are numerous unexplored habitats of oil in the United States. The most important ones lie in the Rocky Mountain states, on the continental shelves, and in Alaska. But other less important ones are scattered from coast to coast.

In addition, a great deal of oil is yet to be discovered in unexploited habitats of oil. These include the deeper measures in older provinces and the ample flanks of sparsely-explored basins of the west and Midwest.

For the past few years, the oil finding profession has been undergoing some sweeping changes. These fall into several fields, but all are involved with THOUGHT and PERSPECTIVE. Webster defines perspective as "the capacity to view things in their relation or relative importance; i.e., some folks can'tsee the wood for the trees, while others have perspective." In terms of logic, all perspective is thought, but not all thought is perspective.

It is this last phrase with which we're concerned here. A successful oil finder now and in the future is the man who can form images in his mind and relate them one to the other in proper perspective. More important, his mind is flexible enough to narrow this perspective to focus on the problem immediately at hand, or broaden it to encompass the world.
Research on Methods for Improving Oil Recovery in Pennsylvania Oil Fields
Authors: Slobod R.L.
Published: June 2009

Introduction

It is now common knowledge in the industry that only about one third of the oil in known reservoirs will be recovered by present methods of production. Since 240 billion barrels of oil have been discovered and only 90 billion barrels are expected to be produced, the unrecovered oil in fields already discovered amounts to approximately 150 billion barrels. This tremendous quantity of oil is of great economic value and is the prize for those who devise new or improved methods for increasing recovery.

One approach being used by many to obtain some of these reserves is the use of heat and "in-situ" combustion as a recovery scheme. Such methods are particularly adaptable to viscous crudes which apparently cannot be recovered by any other known scheme.

A second and different approach is based on the fact that oil can be displaced completely by fluids miscible with it. Consequently, we are presently seeing great activity ill the-industry in the development and testing of a variety of miscible displacement schemes for increasing recovery. The most common of these which are now being field tested include high pressure gas displacement, condensing gas drive, and the LEG slug process. All of these methods require the use of pressure of the order of 1500 psi or higher. Unfortunately, most of the old Pennsylvania fields are shallow. The material in this paper describes some of the efforts of our laboratory to develop a type of miscible displacement which works at low pressures and so would be applicable to Pennsylvania oil fields. In particular, we have been working on the development of a relatively new modification of the miscible flood called the"Alcohol Slug Process." The work reported here describes this process, and discusses supporting studies which were performed to test or prove the validity of the laboratory work.
Present Status of Nuclear Magnetism Logging
Authors: Coolidge J.E. , Gamson B.W.
Published: June 2009

The Nuclear Magnetism Log (NML), which responds only to formation fluids, is described. Basic principles on which this new development rests are reviewed. Field examples are given for a broad spectrum of operating conditions. These include large variations in mud composition, different geological provinces, various reservoir rock conditions, a wide range of formations fluid contents and composition, and well depth, temperature and pressure. Two distinct NML measurements are made. The Free Fluid Index (FFI) is a formation permeability and productivity, and is an excellent correlation index. Thermal relaxation data (T1) distinguish oil or gas and water zones with good reliability and provide information about reservoir permeability.

Introduction

The purpose of well logging is to obtain quantitative information about the presence and amount of reservoir fluids and the characterization and percentage of their chemical species namely, hydrocarbon or water. Other useful information desired is formation fluid for production. In addition, it is useful to have a logging technique which is a good correlation between well sand is universal in application irrespective of hole geometry, mud composition, reservoir rock composition, and physical properties, etc.

Interpretation of existing commercial logging techniques is predicated upon empirical correlations derived from the measurement of gross reservoir properties. They are in the main properties such as resistivity, transmission of sound, natural radioactivity, induced radio-activity, and spontaneous potential which are not simple functions of the diverse reservoir rocks and fluid compositions encountered in oil exploration. The use of other than a primary property of the reservoir fluid frequently gives rise to ambiguous interpretation of well logging data. For a long time a direct means has been sought of measuring some physical or chemical property of solely the reservoir fluids and not the rock matrix to yield a relatively unambiguous result.

Measurement of the nuclear magnetic properties of protons offers a unique means of meeting the objectives of well logging. Under operating conditions in the borehole, nuclear magnetism logging is responsive only to hydrogenous fluids in the reservoir. The magnitude of the signal is quantitatively related to the geometrical configurations of the tool and borehole and the thermodynamic and nuclear magnetic properties of the formation fluids.
Determination of Gas Trapping With Foam Using X-Ray Computed Tomography and Effluent Analysis
Authors: Nguyen Q. P. , Rossen W. R. , Zitha P. L. J. , Currie P. K.
Published: June 2009

Foam is used worldwide to improve acid placement in matrix acid treatments and to redirect gas flow in improved oil recovery. Gas trapping is a major factor in foam processes; it affects foam mobility and controls diversion of liquids such as acid injected after foam. Most previous studies of gas trapping have relied on fitting effluent-gas tracer profiles to a 1D model for transport of tracer in the presence of trapped gas, including mass transfer between flowing and trapped gas. We present new experiments where X-ray computed tomography (CT) directly determines the gas-tracer distribution in situ. The key is using a gas-phase tracer [xenon (Xe)] visible in CT. The CT images show clearly that the standard 1D model used to interpret tracer effluent profiles is incorrect in its assumptions. For the first time, here we compare the in-situ tracer distribution from CT images to the trapped-gas saturation estimated from fitting the effluent tracer profile to the 1D model, augmented here for the effect of pressure variation along the core. The effluent profile is determined indirectly from the CT images in two ways: (1) by imaging the tracer concentration in the flowline downstream of the core and (2) by using a mass balance on the tracer in the core. Estimates of trapped-gas fraction using the 1D model vary by as much as a factor of 0.2 among reasonable fits to the effluent data, and flowing-gas fraction varies by as much as a factor of 1.5 or 2. The experiments span a range of foam qualities and injection rates in Bentheim sandstone. Estimates of trapped-gas fraction derived from the 1D model decrease with increasing gas-injection rate and increase weakly with increasing liquid-injection rate in our experiments. The CT images show a shift to a wider variety of fluctuating flow paths as liquid- or gas-injection rate increases.
The Legal Status of California's Offshore Oil
Authors: Kline Mortimer A.
Published: June 2009

Introduction

This discussion will be neither technical nor legal, but principally a factual exposition of the manner in which the state of California leases its tide and submerged lands for oil and gas development.

You may consider this paper an addition to the masterful presentation by Thomas C. Moroney of the Honolulu Oil Corp. before the 1955 Fall Meeting of the AIME. Mr. Moroney's expertly developed thesis reviewed the state of California's legislative trials and tribulations incident to its offshore resources commencing in 1921 and concluding with the epochal Cunningham-Shell Tidelands Act of 1955.

As you know, for many years prior to 1955, the tide and submerged lands under the jurisdiction of the state of California could be leased for oil and gas operations only if they were known or believed to contain oil or gas and were then subject to drainage by a well or wells located on or in adjacent properties. Also, there was a period of leasing inactivity resulting from the decision of the Supreme Court decreeing that California did not own the belt extending three miles off her coast line, but that the United States, because it had to protect the country and conduct its foreign relations, had paramount rights" in and power over the area, an incident to which was full dominion over its resources, including oil, gas and other hydrocarbon substances.

The title situation was rectified by the passage of the "Submerged lands Act" in 1953, which finally established state ownership of the submerged lands in controversy.

The passage by the legislature of the Cunningham-Shell Tidelands Act created a major change in former state policy relating to these resources.

Incidentally, Cunningham and Shell are the names of two legislators and have no connection, direct or remote, with any oil company or oil operator of similar name.

The Cunningham-Shell Tidelands Act is now embodied in the Public Resources Code of California. As you know California is known as one of the"Code" states. By this we mean that the principal body of the law which governs our state is set forth in great detail in a series of publications which we call "CODES".
Correlation of Factors Affecting the Gravity Separation of Crude Oil-Water Mixtures
Authors: Johnston Jerry L. , Campbell John M.
Published: June 2009

Introduction

This basic investigation was prompted by the lack of a scientific method for determining the amount of settling surface needed to permit the gravity separation of oil and water for a particular set of conditions, i.e., oil gravity, per cent water cut, and oil viscosity. Consequently, both static and dynamic separation tests were performed, in order to determine the relative importance of the variables involved. As a result of this work, a correlation is presented that enables one to predict the length and diameter of settling vessel needed.

Theory

Inasmuch as the settling of water particles in oil is similar to the gravity separation of solid particles in a fluid, it was felt that a modified application of Stokes' law would establish the general relationship of the variables. In order to employ this simple approach, it is convenient to assume that:The water droplet is spherical, incompressible, and nonporous.Gravity is the only accelerating force present.The particle is free moving and is not hindered in any manner.The oil is incompressible and of such volume that no "wall effect"is encountered.
Drilling With Surfactant Muds
Authors: Hyde R.B. , McCaskill James N.
Published: June 2009

The need for and the development of surfactant muds is briefly discussed. The components, preparation and application of four types of surfactant muds are given. Case histories of both calcium and sodium surfactant muds are traced. Incidental to the problems occurring, the calcium surfactant mud was successfully converted to a low sodium system. In another well, a low sodium system was successfully converted to saturated salt surfactant mud and desired total depth was reached. Because of their flexibility and stability under severe conditions, these muds should find wide application in future deep drilling operations. They have proved to be a practical solution of many of the shale problems; stable at high temperature; and an excellent completion fluid.

Introduction

Drilling operations to greater depths and in areas of complex drilling problems have often been handicapped or halted because of the inability of conventional drilling fluids to remain stable under the severe conditions encountered. Elevated bore-hole temperatures, solids build-up, and contamination greatly unbalance conventional drilling fluids, causing excessive viscosities, gel strengths, and fluid losses. These abnormal physical properties in turn contribute to more severe problems, such as lost circulation, blow outs, salt-water flows, and stuck pipe or casing strings. The result of these problems may be either a loss of time, expensive fishing jobs, or a complete failure of the drilling operation to reach the desired objective. Surfactant muds are a new concept in drilling fluids designed to eliminate some of the problems associated with deep drilling. These muds were originally developed for high temperature stability. However, field experience with surfactant muds has demonstrated their capacity to resist solids build-up, severe contamination from salt or anhydrite, and maintain excellent viscosity, gel strength and fluid loss properties under very difficult drilling conditions.
The Long-Range Crude Oil Productive Capacity of the United States
Authors: Davis Warren B.
Published: June 2009

Both physical and economic factors should be considered in long-range predictions of U. S. productive capacity. A mathematical model of the U. S. producing industry which considers both types of factors has been developed. This model has been used to predict the future crude oil producing rates of the U. S. under several possible conditions. The predictions indicate even with an increase of 33 per cent in the real price of crude oil, production probably will reach a peak about 1967 and decline thereafter. Even with a substantial volume of shale oil production, steadily increasing crude imports probably will be needed. The two principal factors affecting ultimate volume of crude to be found in the U. S. are drilling return [barrels of reserves developed per foot drilled], and crude oil price.

Introduction

Several estimates of the future crude oil producing rates of the U. S. petroleum industry have been made. The published versions of these estimates have made assumptions that have a critical effect on the answers obtained. The most significant assumption, one made in all cases known, is that there will be found and produced in the U. S. some finite volume of crude oil. A second universal characteristic of these estimates is that they apparently take no explicit account of many of the economic factors which should affect the answers. Probably some account of these factors has been taken, but the published data do not show it. In particular, no published study considers the effect of variations in the price of crude oil.

It is a well known fact that crude oil deposits vary enormously in size. There is no obvious reason why there should be a lower limit to the size of these deposits. There is some evidence that occasionally operators have drilled into a deposit so small that it is depleted in the process of carrying out a drill stem test. There is a lower limit to the size of a commercial deposit at the present time, but if the economic factors involved in crude oil production were changed radically, this lower commercial limit could change. This might make many deposits, not now commercial, producible. Therefore, the economic factors should affect not only the rate of recovery but also the ultimate volume of oil to be recovered in the U.S.
Does Skip‐Row Planting Configuration Improve Cotton Net Return?
Authors: Larson James A. , Gwathmey C. Owen , Mooney Daniel F. , Steckel Lawrence E. , Roberts Roland K.
Published: June 2009

Cotton (Gossypium hirsutum L.) growers want information about alternative planting configurations to reduce seed, technology, and other production costs. We evaluated the impact of solid and 2 × 1 skip‐row configurations on net returns for cotton grown in 25‐, 76‐, and 102‐cm rows based on yield and fiber quality data from an experiment in adjacent nonirrigated and irrigated fields at Milan, TN. Price differences for fiber quality were calculated using USDA‐Agricultural Marketing Service spot prices. Effects of planting configuration on fiber quality were not significant or small relative to row spacing effects. Price discounts for fiber quality were larger in stripper‐harvested 25‐cm rows than in spindle‐picked 76‐ and 102‐cm rows under irrigation. Skip‐row cotton provided similar or larger net returns relative to solid‐planted cotton for 25‐ and 76‐cm spacings for base lint prices from 84 to 136¢ kg−1. For 76‐cm rows, equivalent yields for solid and skip‐rows and seed, technology, and harvest cost savings were enough to justify skip‐rows. Technology and harvest costs did not vary with planting configuration for 25‐cm rows, but seed cost savings and equivalent yields were enough to justify skip‐rows. Skip‐row cotton had a lower net return than solid‐row cotton in 102‐cm rows because savings in seed, technology, and harvest costs were not enough to offset lower yields. Producers interested in skip‐row cotton should consider rows spaced 76‐cm or less to maximize net returns.
Herbage, Phosphorus, and Nitrogen Yields of Winter‐Season Forages on High‐Phosphorus Soil
Authors: Muir James P. , Bow John R.
Published: June 2009

In climates where cool seasons can produce a forage crop, annual grasses and forbs can be used on dairies to recycle nutrients back to the animals and to phytoremediate soils high in P or N. In north‐central Texas, on a Windthorst fine sandy loam (fine, mixed, thermic, Udic Paleustalf) with 250 mg P kg−1, an on‐dairy trial measured yields of dry matter (DM), N, and P, as well as fiber fractions of five cool season legumes, six grasses, and two brassicas. Some grasses yielded >8 Mg herbage DM during high rainfall years, whereas the most productive legumes and brassicas could only match half that production. Because the soils were high in nitrate‐N and plant‐available P, concentrations of these were high in herbage, resulting in >150 kg N ha−1 yield in seven of the entries and >20 kg P in eight entries during a high‐rainfall year. Potential for extracting, fixing, and sequestering N and P, combined with generally low fiber concentrations, indicated that some of these forages hold promise for nutrient recycling or phytoremediation of high‐N or ‐P dairy soils with the added benefit of producing nutritious forage for the dairies.
Volunteer Corn Presents New Challenges for Insect Resistance Management
Authors: Krupke Christian , Marquardt Paul , Johnson William , Weller Stephen , Conley Shawn P.
Published: June 2009

Genetically‐modified (GM) corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] dominate the North American agricultural landscape and are becoming increasingly important as biofuels. However, as herbicide‐tolerance and insecticidal traits are often simultaneously expressed by individual plants, glyphosate [N‐(phosphonomethyl) glycine]‐resistant (GR) volunteer corn is becoming a widespread problem as a weed in corn‐soybean rotational systems. We show that these volunteer corn plants not only have herbicide‐tolerance genes but also express insecticidal “Bt” protein. We also report high levels of damage to these plants from larvae of the target pest, the western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte). This suggests that volunteer herbicide‐tolerant Bt corn has the potential to present problems both for weed management and insect resistance management, as it may facilitate more rapid evolution of Bt resistance in corn rootworm populations.
Root‐Knot Nematode‐Resistant Alfalfa Suppresses Subsequent Crop Damage from the Nutsedge‐Nematode Pest Complex
Authors: Fiore Cheryl , Schroeder Jill , Thomas Stephen , Murray Leigh , Ray Ian
Published: June 2009

Southern root‐knot nematode [RKN, Meloidogyne incognita (Kofoid & White) Chitwood], yellow nutsedge (YNS, Cyperus esculentus L.), and purple nutsedge (PNS, C. rotundus L.) occur together as a mutually beneficial pest complex in sandy soils. All crops grown in infested soils are affected due to the wide host range of the nematode, the perennial life cycle of the nutsedges, their interactions, and few control options. Therefore, studies were established in fall 1997 and 1998 to determine the influence of growing a nematode‐resistant or susceptible alfalfa (Medicago sativa L.) crop compared with cotton (Gossypium hirsutum L.) on these pests over 3 yr and during a subsequent rotation to a chile pepper (Capsicum annuum L.) crop. Nutsedge and nematode populations were reduced to nearly zero in plots planted with alfalfa, but remained at damaging levels in plots planted with cotton. Before planting pepper, plots rotated from cotton were fumigated with 1,3‐dichloropropene (1,3‐D) for nematode suppression according to standard practice. Pepper yields were over two times higher after the alfalfa compared with cotton. Nutsedge populations following alfalfa, regardless of cultivar, were initially very low but resurged to levels comparable to the cotton by the end of the chile growing season. Nematode populations following the resistant alfalfa were comparable to populations after fumigation of cotton plots and lower at the end of the chile growing season than populations following the susceptible alfalfa. The benefit of the alfalfa crop lasted for 1 yr; therefore, growers must consider long‐term strategies for extending suppression of this pest complex.
Grazing Effects on Yield and Quality of Hard Red and Hard White Winter Wheat
Authors: Holman Johnathon D. , Thompson Curtis R. , Hale Ronald L. , Schlegel Alan J.
Published: June 2009

Six hard red (2137, Jagalene, Jagger, OK101, Stanton, and Thunderbolt) and six hard white (Burchett, Lakin, NuFrontier, NuHills, NuHorizon, and Trego) winter wheat (Triticum aestivum L.) varieties were evaluated for grain yield and quality in southwestern Kansas in 2004 and 2005. Cattle commonly graze wheat in this region from late November to mid March in a dual‐purpose system. The experimental design was a randomized complete block with split‐plot treatment arrangement. Main plots were grazed or ungrazed, and subplot treatments were wheat varieties. Yield was not affected by color. Yield was reduced 23% when grazed beyond wheat jointing. NuHorizon yielded less when grazed. Test weight was 4 kg m−3 greater among red varieties in 2004 and 4 kg m−3 greater among white varieties in 2005. Grazing did not affect test weight. Color and grazing did not affect protein concentration. White varieties sprouted more than red varieties, but Burchett sprouted less than Stanton. Grazing did not affect sprouting. Kernel diameter was 0.1 mm greater among red than white varieties. Grazing reduced kernel diameter 0.1 mm in 2004. Kernel hardness was 4% greater among white than red varieties. Grazing increased kernel hardness 3% in 2005. Seed weight was 5% greater among red than white varieties. Grazing reduced seed weight 4%. Both red and white wheat can be used in a dual‐purpose system with no substantial affects on yield or quality. Producers should select varieties on the basis of their system and environment because certain varieties responded better to grazing and environmental conditions than others.
Biplot Analysis of Rainfed Barley Multienvironment Trials in Iran
Authors: Mohammadi Reza , Amri Ahmed , Ansari Yousef
Published: June 2009

The main objective of this work was the analysis of barley (Hordeum vulgare L.) multienvironment trials (MET) first to identify superior genotypes for the barley crop area in Iran, and second to investigate if different megaenvironments exist. The analyses were performed via GGE (genotype + genotype × environment) biplot methodology on the grain yield of 13 barley genotypes, selected from the joint project of Iran/ICARDA, grown for three consecutive seasons (2003–2005) at six locations, representative of major barley growing areas in Iran. The by‐year and combined analyses showed that the variation between locations was always the most important source of yield variability. Collective analyses of yearly and combined GGE biplots were able to identify high‐yielding genotypes and their areas of adaptation, and suggested the existence of four barley megaenvironments. The first megaenvironment consisted of the location of Ardabil (ARDA), where genotype G11 was the highest yielder; another megaenvironment is represented by the location of Kermanshah (KERM), with G2 as the best genotype. The megaenvironment was comprised of the locations Maragheh (MARA) and Zanjan (ZANJ), with G13 as the highest yielder, whereas the Ghamlo (GHAM) and Shirvan (SHIR) locations made up the fourth megaenvironment, with G4 and G10 as the recommended genotypes. The SHIR, ZANJ, and GHAM were more representative and are considered desirable for selecting genotypes adapted to the whole target region. In contrast, ARDA was best at discriminating high‐ and low‐yielding genotypes. The highest‐yielding genotypes (G4, G3, and G13) were more unstable over locations and years, while high‐yielding genotypes (G5 and G8) were more stable.
Empirical Research on Efficiency of the Electricity Futures Market
Authors: Yang Hongming , Liu Sidong , Zhang Yongxi , Luo Xiao
Published: June 2009

By means of econometrics, the calculating models and methods of efficiency analysis of the electricity futures market are proposed from three aspects: the market validity, the price discovery function and the hedge function. In this paper, considering the heteroskedasticity and nonstationarity of the electricity price, the validity test method of the electricity futures market is proposed by using the variance ratio. Based on the co-integration theory, the price discovery function analysis method of the electricity futures market is proposed. In addition, based on the generalized autoregressive conditional heteroskedasticity, the hedging ratio and performance evaluation method of the electricity futures market is proposed. By the empirical research on the Nordic electricity futures market, it can be found that its operation is efficient. It satisfies the weak-form efficiency hypothesis; the futures and spot prices are co-integrated; the futures market plays a dominant role in the price discovery; the hedge reduces the risk of transaction to a certain extent; and the operation efficiency during 2000-2003 is higher than that during 1996-1999. Although there are some inefficient factors, the Nordic electricity futures market is gradually tending towards maturity.
Electrical Treeing in Polymer Nanocomposites
Authors: Alapati Sridhar , Thomas M. Joy
Published: June 2009

This paper presents a study of electrical treeing phenomena in polymer nanocomposites. The polymer nanocomposite studied consists of epoxy resin as base polymer and silica as nano filler. Treeing experiments were performed at a constant ac voltage of 20kV, 50Hz on epoxy samples without any fillers as well as epoxy silica nano composites with 1% by weight of nano silica. Times for tree inception as well as tree growth patterns were studied. The results show that addition of small amount (1% by weight) of nano silica particles in epoxy resin can improve the treeing resistance by delaying the tree inception time as well as the time required by the tree to reach the opposite electrode. Treeing phenomena has been analyzed and interpreted by a physical model to explain the behavior in nanocomposites. The nature of bonding at the interface between epoxy and nano filler is characterized by using FTIR spectrometry. It has been shown that the type of bonding at the interface has an influence on the electrical tree growth pattern.