bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Lumped-Parameter Model for Transient Two-Phase Gas-Liquid Flow in a Wellbore
Authors: Fairuzov Y. V. , Guevara J. Gonzalez , Barradas G. Lobato , Velázquez R. Camacho , Nucamendi F. Fuentes 
Published: December 2007

Summary
In this study, a lumped-parameter model of transient two-phase gas/liquid flow in a wellbore is presented. The model is based on the assumption that the flow process is essentially one-dimensional so that an area's average properties can be represented as a function of one space variable and time. The wellbore is divided into a number of control volumes (nodes) that are connected by junctions (flow paths). A mass equation is formulated for each control volume, and an approximate momentum equation is used to calculate the flow rate at each junction. A numerical algorithm for coupling the wellbore model with a reservoir model is proposed. Calculations were carried out to determine the behavior of the wellbore flow during a pressure-buildup test. The results obtained from these calculations are compared to previously published theoretical results.
Matrix Treatment Employs New Acid System for Stimulation and Control of Fines Migration in Sandstone Formations
Authors: Thomas R.L. , Crowe C.W. 
Published: December 2007

Summary
A matrix acidizing system employing fluoboric acid (HBF4) has been developed to stimulate problem sandstone formations. The fluoboric acid hydrolyzes to generate hydrofluoric acid (HF), thus achieving deeper live-acid penetration. Laboratory tests also show that spent fluoboric acid reacts with undissolved clay to reduce cation exchange capacity greatly and render the clay insensitive to incompatible fluids.

Introduction
Sandstone matrix acidizing long has been used as a means of improving production of oil. and gas by removing formation damage and increasing permeability of the zone immediately around the wellbore. Laboratory and field studies1–4 have demonstrated the effectiveness of this type of treatment. In spite of widespread use, however, many formations do not respond satisfactorily to conventional HCl/HF treatments. This normally is attributed to rapid spending of HF near the wellbore. Some wells initially show good stimulation but later experience an unusually rapid decline in production rate. Such production declines commonly are observed in wells producing from both consolidated and unconsolidated sands. The declines usually are attributed to plugging by migratory clays and other fines.
Formation plugging by migratory fines was demonstrated by Krueger et al.5 in both laboratory and field studies. Core test results revealed that high flow rates caused dislodgment of fines with resulting loss of permeability. Krueger also reported field studies in which the production decline rate was accelerated by flowing wells above an optimal rate.
As the production rate was increased, a corresponding increase in inorganic solids content of the produced oil also was observed. These observations strongly support the theory of formation damage from fines migration. Migratory fines apparently are released first by exposure to strong acid and later by mechanical forces resulting from the increased flow of produced fluids. Various treatments and production techniques6 have been devised in an effort to control or minimize this problem. Krueger et al.5 and Templeton et al.7 described treating techniques in which wells, following stimulation, were returned to production at a gradually increasing rate to minimize fines migration. Various clay stabilizing agents8,9 also have been applied in an effort to control movement of fines. Also, delayed acting acidizing systems7,10 have been developed to provide deeper live-acid penetration and, thus, remove damaging fines some distance from the wellbore.
Multivariate Optimization of Surfactant Systems for Tertiary Oil Recovery
Authors: Vinatieri James E. , Fleming Paul D. 
Published: December 2007

Abstract
A new method of optimization has been developed for tertiary oil recovery systems employing surfactants. This method simultaneously adjusts all composition variables in a manner which greatly reduces the total number of compositions which need to be investigated experimentally. This multivariate optimization technique has been applied to two petroleum sulfonate systems, one containing a pure hydrocarbon and the other containing a crude oil. In both cases, significant reductions of interfacial tensions were achieved relative to those obtained by conventional optimization with respect to salinity alone.
Surfactant systems for tertiary oil recovery commonly involve at least five components: oil, water, surfactant, cosurfactant, and electrolyte. The optimization of such systems is hindered by this large number of components and because interpolation of behavior is often difficult. Previously, such systems have been optimized by adjusting concentrations of individual components empirically. These empirical optimizations have indicated that surfactant systems which form three phases are preferred for oil recovery although they are not necessarily fully optimized. As stated by the Gibbs phase rule, a five-component, three-phase system has only two degrees of freedom at constant temperature and pressure. These two degrees of freedom can be identified mathematically by making use of chemical analysis of a three-phase sample. Thus, optimization of three-phase surfactant systems can be accomplished by adjusting only two variables, resulting in a dramatic reduction of time and effort required to optimize such systems.
For the systems studied, both the volume per unit mass of surfactant and the viscosity of the microemulsion phase are increased significantly even though the optimization was based on interfacial tension only. These bonuses should lead to improved sweep efficiency in the displacement process.
Compaction and Permeability of Oil-Shale Aggregates at High Temperatures
Authors: Trimmer D. , Heard H. C. 
Published: December 2007

Abstract
We have measured the change in bulk volume and permeability of an oil-shale aggregate subjected to high temperatures and pressures in a one-dimensional strain loading configuration. At stresses of 0.69 to 6.2 MPa and temperatures as high as 700°C, the 6-liter sample may compact by as much as one-third, and permeability may decrease by factors of 10 to 100. There is no simple relationship between strain or porosity and permeability. Attempts to analyze the data in terms of a Kozeny-type equation were unsuccessful.
Optimizing High-Temperature Kill Pills: The Åsgard Experience
Authors: Svoboda Charles 
Published: December 2007

Summary
Historically, the survival rate for conventional, nondamaging polymer/carbonate kill pills under elevated temperatures was limited. Accordingly, a development program was instituted to develop a new high-temperature kill pill that would possess superb bridging characteristics on a high-permeability proppant while remaining thermally stable at temperatures exceeding 165°C (329°F).
This paper describes the development of a sodium formate kill pill geared specifically for the demanding Åsgard development in the Norwegian North Sea. The pill was engineered and successfully applied in a high-temperature application to seal a high-permeability (400 to 500 darcys) frac-pack sand in the Smørbukk field. In the field, the newly engineered formate-based pill proved to be thermally stable while providing sufficient leakoff control. Furthermore, the development reinforced the critical role of proper particle-size distribution (PSD) in minimizing fluid invasion.
With an emphasis on the PSD, this paper reviews the relative formation-damage potential testing procedure of the new formulation on simulated fracture packs. In the laboratory, the fluids demonstrated excellent thermal stability after long-term exposure to temperatures exceeding 150°C (300°F). The aging process was started simultaneously with two samples of each pill and concluded at the end of 16 and 72 hours, respectively. Leakoff tests were performed on 16/30 proppant at 165°C (329°F), resulting in minimal filtration. This paper also examines the unusually demanding conditions at Åsgard relative to other Norwegian fields and details the application and performance of the new kill pill in this hostile downhole environment.
Profiling Water Injection Wells by the Brine-Fresh Water Interface Method
Authors: Holbert Don R. 
Published: December 2007

Abstract
In order to attack the problem of channeling in water injection wells, it was felt necessary to have an accurate injection profiling means as a basic step. The means had to be capable of profiling injection wells that are permanently completed with cement-lined tubing which are heavily shot to produce highly irregular wellbores. The brine-fresh water interface method was chosen. The equipment and techniques developed for profiling by this method are described.
Experience has shown that the accuracy of the method is chiefly dependent upon the precision of the flow control systems and on allowing adequate time for stabilization of interface position. These operating limitations are discussed. The interface method can be broken down into the moving interface technique and the constant interface technique. The two techniques have been found to be complementary for obtaining injection profiles over a wide variety of conditions. For the constant interface technique, precision to .01 ft relative to other stations is common. This unusual degree of accuracy has led to the discovery of many instances where significant volumes of water are injected in very small vertical intervals. This indicates that channeling can be a problem even at moderate or low injection rates. In some cases the volumes of water injected have been so large and the formation intervals so small that flow through fractures rather than permeable streaks was considered probable.
It is possible that remedial procedures for fracture conditions could be quite different than remedial measures for permeable streak thief zones. The method accuracy and possible workover potential make interface profiling of practical significance for all types of water injection wells.

Introduction
In order to efficiently water flood a formation it is desirable that the injected water enter uniformly into all strata of the formation. If this is not the case, but a substantial portion of the injected water channels through fractures or excessively permeable zones, the oil production will be associated with excessive amounts of water. This obviously would adversely effect the economics of the operation.
An Improved Model for Predicting Separation Efficiency of a Rotary Gas Separator in ESP Systems
Authors: Harun A. F. , Prado M. G. , Shirazi S. A. , Doty D. R. 
Published: December 2007

Summary
An improved model capable of predicting the separation efficiency of a rotary gas separator (RGS) in electric submersible pump (ESP) systems is presented. The model incorporates a new, two-phase, flow-inducer model capable of calculating the inducer head. The inducer head, generated by an RGS, has been identified as a key parameter that distinguishes between a separator's high-and low-efficiency regions. This information was previously determined empirically but can now be calculated. The new model more accurately predicts the maximum liquid rate at which an RGS should be installed. A comparison of the model's predictions with water/air and hydrocarbon/air experimental data indicates that the improved model performs better than earlier ones.
Automation System Case Study of Coalbed-Methane Development
Authors: Robertson Steve K. , Pool Mike , Farrens Michael J. , Butts Tammie J. 
Published: December 2007

SummaryCan an independent producer fulfill a vision to develop and produce a coalbed methane (CBM) gas field that covers 200 square miles in a remote desert plateau in the western United States? This paper will answer that question as well as provide answers to other pertinent questions, such as:What tools would be available to the operator to efficiently and safely produce the wells? Will the tools allow for future expansion and/or allow new technologies to be incorporated into the system in a cost-effective manner?This case study will show how River Gas Corp. was able to successfully meet its needs with an automation system that was jointly developed with an engineering/manufacturing company. All phases of the project, from its inception in 1991 with a 13-well pilot project to a planned 600-well development, are discussed. Innovative solutions successfully answered the previous questions and allowed the system to evolve to meet the continuing changes in expansion and production needs.
An Analysis of Methods for Leasing the U.S. Outer Continental Shelf
Authors: Marsh G. Rogge 
Published: December 2007

New U.S. laws require the use of many different offshore leasing methods. A computer program has been developed to analyze these alternatives. Economic characteristics are reviewed. Criteria are suggested for judging leasing systems. The most effective methods use cash bonus as the bid variable and a small fixed royalty or net profit share.

Introduction
The recently passed amendments to the Outer Continental Shelf Lands Act of 1953 enable the use of several different methods for leasing the U.S. offshore (Table 1). The U.S. Dept. of Interior, charged with the administration of the OCS, is required to use systems different from the current bonus-bid-plus-fixed-royalty method for at least 20%, but no more than 60%, of future leasing.Questions arise as one looks over this list. How will these alternative methods operate? How will they affect offshore operations? Are some systems better than others? The purpose of this paper is to try to answer these questions by (1) analyzing economic and operational effects of each leasing system, (2) examining the problems of selecting the "best" system, (3) proposing criteria for judging leasing systems, and (4) evaluating these systems.

EXXALT - An OCS Leasing Model
The tool used for this analysis is EXXALT, a Fortran IV program developed specifically to analyze alternative leasing methods. It is an extensively revised version of a program written at Cornell U.

Bidder's Attitude in Model
Any economic model of OCS operations must be concerned primarily with the formulation of the bid to win the tract. Because of this, the attitude of the bidder is a major concern. How will he act?The model assumes the bidder's view of the prospect is that it is either wholly contained oil one tract or unitized, it has some chance of being dry (though the basin is productive), and the range of possible reserve sizes is described by an input lognormal distribution.The bidder will make the largest possible bid to maximize his chance of winning the lease. This maximum bid results in a zero average net present value (ANPV) profit after discounting the expected net cash flow at the bidder's required discounted cash flow rate (DCFR).The bidder will ignore all other variables that may influence his bid, such as amount and nature of competition, "flinching" (a bidder's reluctance to bid above a certain monetary level), or other constraints imposed by a company's unique financial situation.

How Model Works
The flowchart in Fig. 1 shows how the program calculates a bid for a prospect. Offshore cost data and operational data (number of platforms and wells, amount of installed capacity, etc.) can be expressed as functions of field reserve size, water depth, and reservoir depth. These three parameters are the most significant.
JPT
P. 1262＾
Full-Scale Well-Model Tests of a New Chemical Plug System for Zone Isolation in Horizontal Wells
Authors: Gomez J. A. , Mamora D. D. , Lilledal L. O. 
Published: December 2007

SummaryA new method for zone isolation in horizontal wells with chemical packers has been developed and tested with a 60-ft-long, full-scale horizontal-well apparatus. The method involves setting two chemical wellbore plugs in the horizontal section to straddle the problem zone, squeezing gel into the problem zone, and cleaning out the borehole before production. A crosslinked hydroxyethyl cellulose was used as the wellbore plug, while a monomer gel was used to shut off the problem zone. Tests confirmed the viability of the new zone-isolation method.
Petroleum For Our Future Progress
Authors: Gonzalez Richard J. 
Published: December 2007

Abstract
Since oil and gas supply two-thirds of the energy consumed in the United States, the availability of petroleum is a matter of vital concern for our economic progress and national security. A review of this subject is timely because of some recent predictions that the domestic industry cannot long sustain substantially increased production and that the United States will soon begin to run out of oil.
Fortunately, domestic crude oil production could be sustained at a rate more than 2,000,000 B/D above that of Oct., 1956, for a period of three years or more even with a substantial reduction in drilling. Drilling at current or higher levels will mean continuation of the past upward trend in domestic petroleum availability for the foreseeable future.
Recent estimates that the United States will only produce 150 to 200 billion bbl of oil will prove conservative because of improved producing techniques and additional discoveries in old and new provinces. The Dept. of Interior considers 300 billion bbl as the ultimate reserves of the United States to be a reasonable figure, and even that may seem conservative in another 20 years. As more oil is discovered, the estimate of ultimate production in the United States will continue to be pushed upward and the predicted date of running out of oil will be pushed further into the future.
The amount of oil to be found and produced in the United States will be affected by national policies on imports and on taxation of domestic production. A reasonable volume of imports will serve as all effective stimulus to efficiency in domestic operations but an undue volume of imports will have a damaging effect on our progress and security. Reasonable tax provisions on petroleum production are also essential to provide increasing quantities of oil for the future. The provisions applicable to petroleum production illustrate differential treatment that does not constitute a preferential tax advantage because it is related to the unusual risks in the search for oil. The existing rate of depletion comes close to measuring the capital value of oil in the ground while a lower rate would fall far short of recognizing the capital value that should be protected from taxation as ordinary income. National policies should be designed to encourage development of domestic resources in order that we may have sufficient petroleum for our future progress.
Lead Deposits in Dutch Natural Gas Systems
Authors: Hartog F. A. , Jonkers G. , Schmidt A. P. , Schuiling R. D. 
Published: December 2007

Summary
During the production of natural gas from Dutch Rotliegend and Kupferschiefer sediments that are next to "conventional" carbonate and sulphate scales, lead deposits sometimes also form. These deposits, which vary in composition from galena (lead sulphide) to elemental (metallic) to lead and complex lead (hydr)oxides, may form a serious threat to operations because they tend to block production equipment or injection pumps and tubing. In some cases, radioactive lead (lead-210 with a half-life of 22.3 years) is incorporated into these compounds at levels greater than regulatory concern, which necessitates additional safety measures during operations and maintenance.
In sour gas wells, the deposition of galena can be explained by local supersaturation (caused by a sudden temperature or pressure drop) where bisulphide anions react with lead cations in the produced water, in which concentrations of up to 150 mg lead per liter brine have been detected. In the absence of hydrogen sulphide and even in "dry" gas wells, the deposition of metallic lead has been observed locally at rates of 10 g/D or more. An electrochemical mechanism is held responsible for lead deposition on carbon steel tubing: iron from the tube wall is oxidized by lead ions in solution, leading to corrosion of the wall and deposition of lead scales in thicknesses of 10 mm or more. Under unfavourable conditions or during maintenance operations, metallic lead is easily converted into secondary lead minerals.
Detailed knowledge on the geological origin, the transport pathways to surface facilities, and the mechanisms of lead scale formation might enable the future development of techniques that can prevent lead deposition.
Prediction of the Damping-Controlled Response of Offshore Structures to Random Wave Excitation
Authors: Vandiver J. Kim 
Published: December 2007

AbstractA method is presented for predicting the damping-controlled response of a structure at a known natural frequency to random wave forces. The principal advantage of the proposed method over those in current use is that the explicit calculation of wave forces is not required in the analysis. This is accomplished by application of the principle of reciprocity: that the linear wave force spectrum for a particular vibration mode is proportional to the radiation (wave-making) damping of that mode. Several example calculations are presented including the prediction of the heave response of a tension-leg platform. The directional distribution of the wave spectrum is included in the analysis.
Specifying Lengths of Horizontal Wells in Fractured Reservoirs
Authors: Gale Julia F.W. 
Published: December 2007

Summary
New methods have been developed to constrain optimal horizontal drilling distance in fractured reservoirs in which opening-mode fractures are dominant. Studies of opening-mode fractures in Austin Chalk outcrops and core reveal that open fractures are commonly clustered, with the distance between clusters ranging from approximately 1 m to more than 300 m, depending on the horizon in question. Aperture-size distributions follow power laws, and spacing-size distributions are negative logarithmic or log-normal. The aperture size at which fractures are open to fluids is variable and site-specific (0.14 to 11 mm). Scaling properties of fracture attributes were used to calculate fracture permeability and to constrain well-length fracture-permeability relationships. Fracture permeability depends on the scale of measurement; it has been determined at 9.2 darcies for 14 m of lower Austin Chalk core and 286 darcies for 300 m of upper Austin Chalk outcrop.
Champion East: Low-Cost Redevelopment of Shallow, Stacked, and Faulted Heavy-Oil Reservoirs
Authors: van Kessel Onno 
Published: December 2007

Summary
The Champion East area offshore Brunei Darussalam consists of approximately 50 stacked, shallow, and intensely faulted heavy-oil reservoirs. These reservoirs have been under development since 1975 and have to date produced just 9% of the oil initially in place. Over the period 1998–2003, Brunei Shell Petroleum (BSP) is embarking on a major redevelopment with the aim of converting a further 30 million m3 of oil-in-place volume into commercial reserves.
An overview will be given of how new technology is adding value to the total redevelopment, supported by actual application results and learning points.
The primary development of Champion East is now nearing completion. The use of existing facilities and ultrashallow, long-reach horizontal wells—with innovative sand exclusion and down-hole intelligence—has achieved a 60% unit cost reduction over previous drilling campaigns in the area.
The only way to unlock another 5 to 15% of the oil-in-place volume is to start secondary recovery through water injection, in combination with the use of electric submersible pumps (ESPs).