bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of Uranium Leach Mining
Authors: Schechter R. S. , Bommer Paul M. 
Published: December 2007

Abstract
In-situ leach mining for uranium is an emerging technology. Currently, the selection of a well pattern designed to recover mineral values is governed primarily by arguments based on hydrological considerations.
The effects of well pattern and well spacing on uranium recovery and oxidant utilization are considered in this paper. As expected, formation permeability heterogeneities and anisotropics are found to be important issues requiring careful consideration; however, it also is shown that chemical factors cannot be ignored. In particular, it is shown that the oxidant efficiency and the produced uranium solution concentrations are sensitive to the presence of other minerals competing with uranium for oxidant.
If the Damkohler number for competing minerals, which measures the speed of the reaction, exceeds that for uranium, the competing mineral will have to be oxidized completely to recover a large proportion of the uranium. If the Damkohler number is smaller, it may be possible to achieve considerable selectivity for uranium by adjusting the well spacing.
It also is shown that the oxidant efficiency is generally highest for well patterns that give streamlines of roughly equal length and that there is a minimum distance between injection and production wells to utilize oxidant most advantageously.
Chemistry, Physical Nature, and Rheology of Aqueous Stimulation Foams
Authors: Holcomb David L. , Callaway Ed , Curry Lynn L. 
Published: December 2007

Abstract
Laboratory equipment has been designed specifically to study effectively the microscopic structure of flowing foams at high pressures. In addition, application of foaming-agent optimization techniques to design stable foams at varying foam qualities is demonstrated at high pressures – i.e., 500 to 2,000 psig (3448 to 13 792 kPa). Capillary viscosity data for these foams is established and correlated with a video-photomicroscopic study of the flowing foam and their designated bubble qualities. Foaming-agent screening information from the tests is provided indicating the foaming-agent generic chemistry that allows optimal foam stability under high-pressure conditions.
Professional Engineering Liabilities Under U.S. Common Law and Securities Laws
Authors: Sheehan Thomas F. 
Published: December 2007

Summary
The reporting requirements of oil companies to the Securities and Exchange Commission (SEC) in their 10-k filings on Reserve Recognition Accounting (RRA) provide petroleum engineers with both an opportunity and a problem. The opportunity is additional professional service income generated by the performance of reserve auditing and reserve estimating. The problem is generated by U.S. securities laws and their enforcement by the SEC on the accuracy of the petroleum engineer reports on reserve estimates and reserve audits. What the oil and gas industry accepts as accurate within the allowances of the industry will be rejected by the SEC.

Introduction
To put the liability of an engineer for his negligent acts, errors, or omissions in its proper perspective requires a review of the theory of U.S. tort and contract laws.In the U.S., for a plaintiff in a lawsuit to prevail in a tort action requires that he show there was a duty owed him by the defendant and that the defendant breached that duty by his negligent conduct (which was the actual cause of the plaintiff's injury), which is measurable in money damages for which the plaintiff prays for relief and judgment of the court. plaintiff prays for relief and judgment of the court. The defendant may respond to the plaintiff's charges that the plaintiff was guilty of contributory negligence or that the plaintiff's action should be barred by the statute of limitations.Engineers are subject to lawsuits not only from their clients but also from third parties who are not in privity with the engineer.The leading case abolishing the architect's protection of privity of contract was Inman v. protection of privity of contract was Inman v. Binghamton Housing Authority, decided in 1957.Courts have not recognized the distinction of the role of the architect as contrasted with that of the engineer in the design-construction process. While states license architects and engineers separately, each profession and the agencies regulating them tend to differ as to where one profession begins and the other ends.The best working definition I have found in explaining the difference between architecture and engineering is that the entire structure and all of its component parts is architecture, if such structure is to be used by human beings as a place to work or assemble. Therefore, if one wants to erect a courthouse, one would employ an architect, but if one proposes to construct a power plant, one should proposes to construct a power plant, one should employ an engineer.U.S. case law on the liabilities of engineers, thus, is wedded to that of architecture. Writers on the subject of their liabilities use the terms interchangeably, justifying their actions on the basis that architects usually have some engineering training and frequently perform engineering services.There is no body of case law for petroleum engineers because there have been so few cases where petroleum engineers have been sued. petroleum engineers have been sued. JPT
P. 1869
Bubble Point Pressure Correlation
Authors: Lasater J.A. 
Published: December 2007

Abstract
A correlation of the bubble point pressure for black oil systems is developed using the standard physical-chemical equations of solutions. The correlation is based on 158 experimentally measured bubble point pressures of 137 independent systems and is expressed in terms of the usually measured field parameters-flash separation gas-oil ratio, rank oil gravity, total gas gravity, and reservoir temperature.
The data were obtained on systems produced in Canada, Western and Mid-Continental United States, and South America. The average error (algebraic) in the representation is 3.8 per cent, and the maximum error encountered is 14.7 per cent.

Introduction
In the absence of experimentally measured properties of reservoir fluids, it is often necessary for the field engineer to make estimates regarding the fluid properties based on the usually measured producing parameters. To aid in these estimations, various correlations have appeared in the literature in recent years. Among the pertinent properties of interest is the bubble point pressure. A correlation for this parameter has been reported by Standing. However, this correlation was based essentially on California produced crudes and this limitation was pointed out with its presentation. The correlation presented in this paper utilized data on crude oil systems from Canada, Western and Mid-Continental United States, and South America.
Modeling the Number of Bids Received for Outer Continental Shelf Leases by Poisson-Type Models (includes associated papers 12296, 12297. 12338, 12369, 12570 and 12710 )
Authors: Bruckner Lawrence A. , Nachtsheim Christopher 
Published: December 2007

Summary
Since 1954, the U.S. federal government has held hydrocarbon lease sales for areas on the Outer Continental Shelf (OCS). The U.S. DOE is charged with developing lease sale policies designed to increase competition on the offered tracts, Increased competition has been assumed synonymous with increased number of bids (NOB). To study the influence of alternative bidding systems on the number of bids received, a mixed Poisson-type model has previously been employed. Here we show why this model is not statistically supportable. A truncated model is proposed and is shown to be statistically justified for the number of solo bids over all sales and marginally supported for the number of joint bids on sales before the joint-bidding ban.

Introduction
Since 1954 the federal government has held hydrocarbon lease sales for areas in the OCS region of the U.S. In a typical sale, from 75 to 300 tracts were offered and 30 to 90% of these tracts received bids. The number of sealed bids received by tracts varied from 0 to 18 with approximately exponentially decaying frequency. The U.S. DOE is charged with developing bidding systems that will increase competition on the offered tracts. At present, if one sale generates a larger average number of bids per tract than another sale, the first sale is considered to have been more competitive.
Dougherty and Lohrenz rightly question the efficacy of judging different bidding alternatives "by comparing the average number of bids per lease" alone. Their paper attempts to address this inadequacy by developing a model for the number of bids received considering classes of differing" bidder interest." (A related model has been developed independently by Engelbrecht- Wiggans.)
Unfortunately, the Dougherty-Lohrenz model was not properly tested for goodness of fit. In the next section of this paper we statistically evaluate and reject the mixed Poisson model as proposed. Then, in the ensuing sections, a number of departures from the previous approach are considered. Solo and joint bidding patterns are examined separately. Then, certain ambiguities regarding the interpretation of the number of tracts that were offered but received no bids are discussed. The removal of such tracts from consideration led to the formation of a new, truncated Poisson-type model that provided some significant improvements in goodness of fit. Later we examine the effects on the distribution of NOB of the 1975 ban on joint bidding among major oil companies.

The Dougherty-Lohrenz Model
Dougherty and Lohrenz proposed a Poisson-type model of the following form to fit the number of bids (NOBS) on offered tracts.
Pk=F1 k+F2P(N=k/ 2)+F3P(N=k/ 3),
........................ (1)
JPT
P. 1263^
The Effect of Temperature on the Flow Properties of Clay-Water Drilling Muds
Authors: Srini-Vasan S. , Gatlin Carl 
Published: December 2007

Introduction
In the past few years the hydraulic aspects of rotary drilling have received considerable attention. It is generally recognized that accurate prediction of circulating pressures is desirable, particularly in those areas where a delicate pressure balance is necessary to prevent both blowouts and lost circulation. For calculation purposes the standard hydraulic equations for the pipeline flow of Newtonian fluids have been altered to facilitate similar calculations for non-Newtonian or plastic fluids. This latter classification includes most colloidal types of drilling muds.
Two properties: plastic viscosity, and Bingham yield value, are commonly used to define the flow characteristics of a plastic fluid. These are commonly obtained with multispeed viscosimeters such as the Fann V-G meter: Normally these measurements are obtained at some surface temperature, and are not corrected to circulating temperatures for calculation purposes. This may result in considerable error, particularly in the laminar flow calculations which commonly apply to the drill pipe-borehole annulus. The purpose of this study was to investigate the effect of temperature on the flow properties of some water-base muds.

Experimental Procedure
A laboratory model Fann V-G meter was used for measurement of viscosities, yield values and gel strengths. An aluminum water jacket with O-ring seals was machined to fit around the mud cup of the Fann meter.
All mud samples were prepared by thorough mixing in a Hobart mixer. Viscosity and gel strength measurements were made with the Fann meter using standard procedures. Flow properties of muds were studied at 80, 120, 160 and 180°F.
The compositions of the test samples are given in Table 1.

Results

Effect of Temperature on Flow Properties
The typical effect of temperature on the flow properties of these drilling muds is illustrated by Fig. 1. It was found that plastic viscosity and apparent viscosity decreased with an increase of temperature. However, the curves were not linear, and did not appear to follow any definite trends or patterns. Yield point data showed much more scattering.
Since a usable method for predicting drilling mud flow behavior with temperature was desired, an attempt was made to find a simple relationship between these variables.
CO2 Mobility Control
Authors: Dellinger Stan E. , Patton John T. , Holbrook Stan T. 
Published: December 2007

Abstract
As early as 1955, surfactants were recognized for their effectiveness in lowering gas mobility in reservoir cores by in-situ foam generation. For commercial field application a specific surfactant must have several important characteristics. It must be (1) highly effective with low cost, (2) chemically stable, soluble, and surface active in oilfield brines, and (3) unaffected by contact with crude oil or reservoir minerals.
A static foam generator, an adaptation of a conventional blender, was used to screen more than 150 candidate surfactants. Promising additives were then ranked in a unique dynamic test, developed at New Mexico State U., that involves sequential liquid/gas flow in a vertical tube packed with glass beads. Conventional flow tests in tight, unconsolidated sandpacks show good correlation with the dynamic and static screening tests, especially those data obtained in the dynamic experiment. Some synergism exists between additives with amine oxides and amides having the most beneficial effect on foam stability and gas mobility control.
The utility of cosurfactant stabilization was demonstrated in linear, two-phase flow tests through tight, unconsolidated sandpacks involving brine and gas. A solution containing 0.45% Alipal CD-128™ and 0.05% Monamid 150-AD™ can decrease gas mobility over 100-fold. The effect appears to be time-independent, indicative of good foam stability. Alipal CD-128 alone reduces gas mobility even more, usually by a factor of two. The moderating influence of a cosurfactant could be beneficial in avoiding "overcontrol" of mobility, especially in low-permeability reservoirs.
Rheology of Mobility-Control Foams
Authors: Patton J. T. , Holbrook S. T. , Hsu W. 
Published: December 2007

Abstract
Enhanced oil recovery (EOR) studies have consistently demonstrated the need to mitigate gas channeling in processes involving use of gas to displace crude oil. The use of foam for gas mobility control was first investigated in 1955, and an early field test by Union Oil Co. of California indicated significant merit in the concept. Work was undertaken at New Mexico State U. to provide rheological data of in-situ-generated foam in an attempt to define the mobility-lowering mechanism.
A capillary viscometer was constructed to measure the rheological properties of the most promising foams made with commercially available additives. Data collected at different shear rates show that foams are pseudoplastic in nature and several orders of magnitude more viscous, 10 to 100 cp (0.01 to 0.1 Pa·s) than their gas or liquid fractions. Significantly, foam viscosities are generally an inverse function of foam density, which is very advantageous in oil-displacement processes. In areas where gas fingering is pronounced, foam viscosity would be expected to increase with gas saturation and, thereby, would tend to mitigate further gas channeling.
The spontaneous generation of a viscous foam phase may also serve to reduce the flowing gas saturation and, thus, lower gas mobility because of the relative permeability effect. This technology is easily adapted to the water-alternating-gas (WAG) process involving CO2 or rich-gas displacement of oil.
Criteria for Structuring Surfactants To Maximize Solubilization of Oil and Water: Part 1—Commercial Nonionics
Authors: Graciaa Alain , Fortney Lester N. , Schechter Robert S. , Wade William H. , Yiv Seang 
Published: December 2007

Abstract
The phase behavior of nonionic surfactants having the same hydrophilic/lipophilic balance (HLB) but differing molecular weights has been studied. It is shown that the optimal alkane carbon number (ACN) depends on the HLB, but that increasing the hydrophobe molecular weight narrows the middle phase region, increases the solubilization parameter, and decreases the interfacial tension (IFT).
We found that the width of the three-phase region is in simple inverse proportion to the solubilization parameter at optimal salinity and that the multiple of IFT times the square of the solubilization is a constant. We also found it possible to synthesize nonionics that rival anionics in the properties mentioned above.
Effect of Mud Filtrate Invasion on Apparent Productivity in Drillstem Tests in Low-Permeability Gas Formations
Authors: Holditch S.A. , Lee W.J. , Lancaster D.E. , Davis T.B. 
Published: December 2007

Summary
This paper shows that mud-filtrate invasion prior to drillstem testing in low-permeability gas formations can cause significant reduction of gas flow rate observed during the test. In addition, apparent gas permeabilities determined from test data can be much lower than the true values. These conclusions are supported by simulator results and field data.

Introduction
Interpretation of drillstem tests (DST's) in low-permeability gas formations is difficult. and this difficulty leads to uncertainty in identifying formations that, when stimulated, could become commercial completions. Operators have tong suspected that mud-filtrate invasion into these low-permeability formations could contribute to these uncertainties because of significant alterations in relative permeability and capillary pressure. These uncertainties led us to a study of the effects of mud-filtrate invasion on response in a DST; this paper reports the results of that study.
In this investigation, we used a two-phase, two-dimensional, fully implicit reservoir simulator to model DST's. The input data for the simulator were obtained from special core analyses. openhole tops, and DST's from the Falher sandstone in western Canada.

Model Description
The two-dimensional, two-phase model used in this study has been described previously in the literature. The model simulates the flow of gas and water in the formation using a simultaneous determination of saturations and pressures from finite-difference approximations of the gas and water flow equations. Capillary pressure and relative permeability data are input into the model; the model is therefore capable of simulating imbibition, water blocking, and cleanup effects. These effects are potentially important in DST performance.
To simulate a DST, uniform initial pressures and saturations were established in the model for all reservoir cells. To model the imbibition of filtrate into the formation prior to the DST, the pressure in the wellbore was set equal to (and maintained at) the hydrostatic mud pressure, and the water (filtrate) saturation was maintained at 100%. Water saturations and pressures around the wellbore increased during the imbibition period as filtrate moved into the reservoir. To model a mud filter cake, the permeabilities in the formation adjacent to the wellbore were reduced.
Following the imbibition period, a flow period was simulated. During the flow period, the pressure in the wellbore was maintained at a fixed pressure and the wellbore volume was set equal to the value of a typical drillpipe open to flow. Following the flow period, a pressure buildup test was simulated, with the wellbore volume set equal to a typical volume below the shut-in valve in a DST tool assembly .
JPT
P. 299^
Gravel Packing Controls Unconsolidated Sand in Venezuela Field
Authors: McReynolds Preston S. 
Published: December 2007

Abstract
Sand control has been the major problem encountered in producing oil from the unconsolidated Miocene sands in the Lagunillas area of Venezuela. One of the first completions developed to prevent excessive sand production was the combination oil string in which pre-perforated casing was employed. In most cases this method was unsuccessful in controlling sand and was replaced in 1951 by a special slotted liner completion. The slotted liner technique has been effective in controlling sand and in obtaining high volume producers in the Bachaquero sand member. However, as a satisfactory completion depends upon the ability to wash the well into production outside the liner, this technique will soon become obsolete because of the declining reservoir pressure in the Bachaquero field.
A program to evaluate gravel packing as a replacement for the slotted liner technique (see Fig. 1) and to provide a sand control method for use inside existing pre-perforated completions was initiated in April, 1956.
Forty-three wells have been gravel packed in the Lagunillas Dist. through Sept. 25, 1957, with two jobs considered as failures. Thirty of these wells are producing at an average rate of 520 B/D of 12 to 180 API gravity crude as compared to 268 BOPD for the average offset well. Eight wells are awaiting installation of production equipment and are expected to be satisfactory producers when opened to production.
Various problems concerning fluids, liner slot sizes and loss of gravel to the formation have been encountered. Solutions to these problems have been found and procedures for both open-hole and inside gravel packs have been developed that can be applied with confidence to the sand control problems that exist in the Bolivar coastal fields.

Introduction
A program to evaluate the applicability of gravel packing as a sand control method to wells in the Lagunillas Dist. was initiated in April, 1956.
Hydraulic Fracture Propagation in Layered Rock: Experimental Studies of Fracture Containment
Authors: Teufel Lawrence W. , Clark James A. 
Published: December 2007

Abstract
Fracture geometry is an important concern in the design of a massive hydraulic fracture for improved natural gas recovery from low-permeability reservoirs. Determination of the extent of vertical fracture growth and containment in layered rock, a priori, requires an improved understanding of the parameters that may control fracture growth across layer interfaces. We have conducted laboratory hydraulic fracture experiments and elastic finite element studies that show that at least two distinct geologic conditions can inhibit or contain the vertical growth of hydraulic fractures in layered rock: (1) a weak interfacial shear strength of the layers and (2) an increase in the minimum horizontal compressive stress in the bounding layer. The second condition is more important and more likely to occur at depth. Differences in elastic properties within a layered rock mass may be important—not as a containment barrier per se, but in the manner in which variations in elastic properties affect the vertical distribution of the minimum horizontal stress magnitude. These results suggest that improved fracture treatment designs and an assessment of the potential success of stimulations in low-permeability reservoirs can be made by determining the in-situ stress state in the producing interval and bounding formations before stimulation. If the bounding formations have a higher minimum horizontal stress, then one can optimize the fracture treatment and maximize the ratio of productive formation fracture area to volume of fluid pumped by limiting bottomhole pressures to that of the bounding formation.