bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Theoretical Model Of The Polymerization Of Silica In Aqueous Media
Authors: Peck Lawrence B. , Axtmann Robert C. 
Published: December 2007

Abstract
Despite three decades of experimentation, no general, quantitative description of the polymerization of silicic acid in aqueous solutions has emerged. An accurate mathematical model could have a seminal effect on the solution of many problems in the utilization of geothermal resources, e.g., in the prevention of silication in boreholes, energy conversion equipment and reinjection wells. In addition, such a model might advance understanding of hydrothermal alteration in geothermal reservoirs.
We report here an analysis that divides the overall reaction into successive regimes that are limited in rate by nucleation; chemical reaction; and diffusion of monomer to growing polymer particles.
In the case of homogeneous nucleation, an analogy with the theory of condensation suggests that RN, the rate of formation of critical nuclei, isEquation 2
where Î3 and Vo are the surface tension and specific volume of the solid, respectively; S C/Ce where C is the concentration of monomer and Ce is its solubility; and A is a constant. Exploration of the properties of equation (2) leads to the prediction of maxima and minima in the polymerization rate as a function of temperature and of the temperature-dependent induction times that have been observed in the laboratory and in nature.
The dimensionless ratio rfko/D serves as a useful index of whether diffusion or chemical reaction exerts the dominant influence over silica particle growth. rf is a characteristic length; ko is the surface specific, forward, rate constant; and D is the monomer diffusivity. For rfko/D 1, the reaction rate is very rapid, diffusion is limiting, and particle growth is described byEquation 36
where Rp is the particle radius divided by rf; Co=Ciâ?'Ce, where Ci is the initial monomer concentration; and Ï? tD/rf2.
In the chemical reaction-limited regime, rfko/D 1 and the appropriate solution becomesEquation 42
For both diffusion-limited and reaction-limited regimes, the relationshipEquation 37
holds and allows the calculation of C vs. time from equation (36) or (42).
The agreement between theory and extant laboratory data on natural and synthetic silica solutions is excellent. The analysis indicates, moreover, that a priori evaluation of the ratio rfko/D would permit the wily experimentalist to avoid diffusion limitations whilst attempting to measure chemical kinetic rates.
Performance of One of the Iranian Carbonate Reservoirs
Authors: Jamshidnezhad Mohammad 
Published: December 2007

Abstract
More than ninety percent of Iranian petroleum reservoirs are carbonate. In order to investigate Iranian petroleum reservoirs, one of the Iranian carbonate fields has been analyzed. This field is located in Southern Iran with 23 km long and 7 km wide, and contains two reservoirs,I1 and II2.One of these reservoirs sits over another and an impermeable zone separates two reservoirs. In this field, horizontal and directional drilling have been experienced. Production from this field was started 10 years ago,and it is estimated for naturally depletion 80 years must be considered.At the present,out of 28 drilled wells,6 wells are horizontal,7 wells are directional,and 15 wells are vertical.Except one well,all horizontal wells are on stream.Average daily rate of horizontal and directional wells respectively are about 3.1 and 3.5 percent of overall field rate.Nevertheless,in this field and other Iranian carbonate field,there are numerous problems for horizontal wells,such as high losses of drilling mud,troubles in petrophysical logging,need to high cost and time.
In this paper, after investigating geological studies,PVT, static pressure,well testing experiments,performance of horizontal,vertical and directional wells and overall performance of this field,the ways for rate increasing have been proposed.As far as possible,wells be drilled vertically(especially in second reservoir,II2) and horizontal drilling be done only in first reservoir,I1.Also,using of artificial lift (such as installation of electrical submersible pumps in wells) is recommended.
Real Time, Real Fast: Drilling Horizontal Wells in a Heavy Oil Environment
Authors: Balke Scott C. , Rosauer Mark S. 
Published: December 2007

Abstract
The presence of producible hydrocarbons in Orinoco Tar Belt of Eastern Venezuela was confirmed as early as 1936. Today this accumulation is thought to contain more than 1.2 trillion barrels of heavy and extra heavy oil in a giant stratigraphic trap 320 miles long by 40 miles wide. Even though this region has a tremendous volume of oil it has remained marginally cost effective to produce due to the significant costs of development. Using the latest technology and innovative techniques the Hamaca Project, centrally located in the Orinoco Tar Belt, will be able to effectively and economically develop a portion of these reserves.
The Hamaca area covers some 250 square miles and Petrolera Ameriven has a commitment to develop and produce the 165,000 acres defined under the association agreement at a rate of 190,000 BOPD for the life of this project. The oil, when cooled and degasified, resembles more a tar or asphalt that one would use to pave a road than the oil you would put in your crankcase. Adding to the complexity of this project is that the major reservoirs within the field were deposited in major low stand and transgressive systems tracts, comprised of meandering fluvial to fluvial-tidal deltaic deposits.
Hamaca utilized a system of LWD, satellite links, continuous updating and real-time visualization to assess and mitigate risks while drilling. This system allowed extremely accurate placement of the shoe in the build sections, for real-time directional control in the laterals and has multi-rig capability allowing for better utilization of resources. Some examples of the situations encountered and their remedies were: the identification of sand/shale interfaces and the redirection of the bit, non-pay zones were identified and avoided and planned well paths revised to encounter better pay.
The methodologies developed along with the technology used were effective in minimizing developmental costs that greatly enhanced the financial viability of the project.
The Effect of Clay Fraction on Heavy Oil Depletion Test
Authors: Andarcia L. , Kamp A. M. , Huerta M. , Rojas G. 
Published: December 2007

Abstract
Primary production of heavy oil from unconsolidated sand reservoirs is a process that is not well understood. Laboratory depletion experiments of sand packs, which mimic the field situation at a laboratory scale, show that production behavior of heavy oils under solution gas drive depend in a complex way on diverse parameter such as: depletion rate1,2, fluid properties 3, porous medium properties45, etc.
This work focuses on understanding the effect of the clay fraction in the sand pack on the recovery process. Experimental results from depletion tests at constant total volumetric production rate are presented. The porous media consisted of synthetic sands with different proportions of clay, except for one of the experiments, where reservoir sand was used. The oil was extra heavy crude (8 ºAPI) from the Venezuelan Orinoco Belt.
Pressure, pressure drop over the core, and oil and gas production were measured as a function of time. It was found that critical gas saturation and recovery factor increase with increasing clay content, whereas the supersaturation or the deviation from thermodynamic equilibrium decreases. This is interpreted in terms of an increasing number of nucleation sites at increasing clay concentration. More activated nucleation sites lead to more and smaller bubbles that allow a lesser mobility for the gas phase. Gas then becomes significantly mobile at larger gas saturations. This hypothesis is supported by previously published data from micromodel experiments doped with clay particles6.
The fact that critical gas saturation and recovery factor depend on the composition of the reservoir sand may strongly affect the evaluation of reservoir production capacity, because large regional heterogeneities related to clay content are often present in oil-producing "sands".
Dynamic Fracture Modelling Approach for Cold Lake Cyclic Steam Stimulation
Authors: Lebel J. Pierre 
Published: December 2007

Abstract
In Imperial Oil’s Cold Lake field, Cyclic Steam Stimulation (CSS) is used to recover bitumen from the Clearwater formation. At initial reservoir conditions, fluids are essentially immobile due to high bitumen viscosity and due to very low relative permeability to water. The injection of steam is achieved by injecting at pressures that induce hydraulic fractures in the formation. Numerical simulation techniques typically handle fracturing by imposing a large increase in permeability as the pressure exceeds a fracture pressure.
Standard simulation approaches using an ExxonMobil in-house simulatori to modeling fracturing require an excessive pressure gradient in order to propagate a fracture. As a result, the pressure of the fracture blocks is overestimated, resulting in an unrealistic overestimate of leak-off from the fracture. The fracture area is thereby significantly underestimated and possible fluid communication between wells is not properly modeled.
The term "dynamic fracturing" refers to an approach that improves hydraulic fracture modeling by using a variation of upstream weighting to calculate the effective permeability between fracture blocks. The upstream weighting is done indirectly using changes in void ratio, which is a measure of pore dilation due to pressure change. The method has been calibrated with field data from two Cold Lake pads.
Early attempts to use this method encountered numerical stability problems. This resulted in very slow run times, and in many instances, cases could not be completed. The method has been improved using a simple dampening scheme making it practical to use in multi-well models. This approach is aimed at improving predictions of fluid distribution in early cycles of CSS including predictions for infill well performance. More realistic fluid communication modeling improves subsequent infill performance predictions. Useful comparisons of performance from different steam strategies require good predictions of fluid distribution caused by each strategy. This work has imporved our ability to model the CSS process and to predict field behaviour.
Certification Of The Heather Platform
Authors: George Philip John , Sladden Peter Richard 
Published: December 2007

Abstract
This paper describes the results of foundation analyses carried out by Lloyd's Register of Shipping as part of its independent appraisal of the Union Oil Company Heather platform, which was installed in the North Sea in 1977. The studies described were made in partial fulfillment of the requirements incorporated in the 'Offshore Instalations (Construction and Survey) Regulations'1 for the issue of a Certificate of Fitness.
The paper discusses the validity of using currently accepted empirical design methods of predicting pile capacity and behaviour in the very hard boulder clays encountered in the Heather field. The results of tests on boulder clay from other sites both on and offshore are compared with the Heather soils.

Introduction
The very hard boulder clays found in the Heather field and at other locations in the North Sea have presented problems to platform designers insofar as the undrained shear strengths are beyond the range of those normally experienced onshore. This brings into question the commonly used relationships of undrained shear strengths with ultimate capacity and stress-strain relationships.
The paper compares the behaviour of similar boulder clays from onshore sites and from other North Sea locations and makes use of the derived relationships in the soil/structure interaction models.
The analyses presented consider:the interaction of the piles within the pile group using boundary element methods, and assuming an equivalent three-dimensional elastic continuum;the interaction of piles with the structure using two-dimensional non-linear finite element analyses.
In addition, a pile axial load transfer analysis is discussed which assumes non-linear load deflection characteristics and compares the Heather foundation behaviour with pile load test data from the B.P. West Sole field.
The primary objective of the analyses discussed is to establish the loads and deformations within the foundation, and to provide the pile load response relationship to be utilized in the superstructure analysis.
A companion paper by Durning et al (1978)2 describes in detail the foundation design history and site conditions.
Predicting Pile Driveability: Heather As An Illustration Of The "Friction Fatigue" Theory
Authors: Heerema Edward P. 
Published: December 2007

Abstract
In the series of papers on the Heather Field pile foundation, this paper presents the backgrounds of the driveability prediction made by Heerema Engineering Service. The prediction was made according to the 'friction fatigue' theory, which is based on the assumption that skin friction in clay is gradually lost along the pile shaft as driving proceeds.
A laboratory test is described which illustrates this phenomenon.
A mathematical model is given for the shape of the horizontal stress distribution along the pile shaft; parameters needed in this formulation have been empirically determined, partly from laboratory tests and partly from computer post-analyses of driving experiences. This was necessary as it is as yet net possible to quantify horizontal soil stresses acting on the pile wall during driving on an analytical basis.
The friction fatigue theory presented here proves to be consistent for all pile driving experience in stiff and hard clay in the North Sea investigated by the author, and it is believed, therefore, that it will in general lead to improved pile driving predictions as compared to other available methods.

1. Introduction
Pile driving at Heather Field was one of the most interesting piling cases of the past few years in the North Sea. The soil consisted of very heavily overconsolidated clay at shallow depths, with undrained shear strength values up to 800 KN/m2, twice the values encountered so far in the North Sea.
At depths near to design penetration of the piles, however, the clay had rather common shear strength values.
It was therefore difficult to make a reliable prediction of the driveability. By conventional means of predicting (i.e., through the use of ultimate static bearing capacity calculations), it was to be expected that it was impossible to drive to the required penetration of 46 m with the hammers available.
The author's research group was nevertheless optimistic about the possibility to reach design penetration. Their prediction was that it should be possible to reach design penetration with the second-largest hammer available, the Menck 8000. This proved to be correct. Although the blow count was considerably higher than expected over most of the piles' penetration depth, the expected blow count range near design penetration was correct. (fig. 1; discussion in section 7).
Thermal Decay Time Logging At Ekofisk, Case Study Of A Multiple Use Tool
Authors: Golder George David 
Published: December 2007

Abstract
Thermal decay time (TDT) logging has proven to be a multiple use tool in the thick carbonate reservoirs at Ekofisk and nearby fields. Phillips Petroleum Company Norway has initiated a program to take a baseline log in each development well shortly after it has been put on production, to be followed by periodic future logs.
The original reason for obtaining a baseline log was to determine the TDT response at initial conditions in each well for comparison against future TDT logs, i.e., the usual 'time-lapse' technique, to monitor changes in water, gas and oil saturations at various stages of depletion. The Danian and Maestrichtian limestone reservoirs are commonly acid-fractured during completion in wells in the Ekofisk Area fields, so the baseline TDT log was also intended to determine how much correction for the 'acid effect' would have to be applied in each well.
The baseline TDT logs by themselves, however, are proving to be useful tools in applications other than those originally planned. The effect of acid on TDT log response has allowed the logs to be used to evaluate the effectiveness of acidizing and diverting techniques. Restimulations have been recommended and evaluated using TDT logs in conjunction with cased hole production logs. The usefulness of the TDT log in tracking the horizontal and vertical distribution of injection gas is also being evaluated.
Phillips believes that thermal decay time logging will be a basic, multiple use reservoir monitoring tool throughout the life of the Ekofisk Area fields.

INTRODUCTION
Soon after Phillips Petroleum Company Norway began development drilling in the Ekofisk Area fields (Ekofisk plus 5 other major carbonate reservoir fields and one small sandstone reservoir field) the need was recognized to gather data about initial conditions in each well to provide the basis for future reservoir monitoring efforts. A program was established, therefore, to obtain, in addition to normal openhole logs and completion tests, cased hole production logs and a baseline thermal neutron decay time (TDT*) log soon after the start of production in each well. Initially it was believed that the baseline TDT logs would be of limited use until comparisons could be made with future TDT logs, in the usual time lapse technique, to observe fluid saturation changes in the reservoir. In practice, however, the baseline TDT logs have proven useful in several unexpected ways.

THE TDT LOG
Since the development and introduction in the late 1960's of pulsed neutron logs to measure thermal decay times, TDT logs and, even more importantly, the techniques for their use and interpretation have matured greatly. TDT logging is now one of the most useful reservoir monitoring tools available to the industry.
When first introduced by Dresser Atlas as the 'Neutron Lifetime Log', and later by Schlumberger as the 'Thermal Neutron Decay Time Log', TDT logs were basically used for locating undepleted oil and gas zones behind casing in older fields or determining the source of high water cut production.
Importance Of Large-Scale LNG Operations To International Energy Supply
Authors: Coppack C.P. 
Published: December 2007

Introduction
This is to be a talk about the liquified natural gas business, its potentialities and possibilities. It is a new business and one which can hardly be said to have started yet, as the first regular commercial cargo of liquefied natural gas has not yet been shipped. Nevertheless and in spite of this, I think that it is already reasonable to say that it is a business which will develop very considerably, in all probability on a worldwide scale. I do not think it would be going too far to describe its present stages as the birth of a whole new industry.
The first full scale commercial LNG venture will start operations this summer moving natural gas from Algeria to England. The liquefaction plant at Arzew near Oran will have a capacity of about 150/MM/CFD; two thirds of this capacity is for British Market and two ships are now nearing completion to carry this gas to the terminal installation in England which is being constructed by the Gas Council of Great Britain. About one third of the output of the liquefaction plant is destined for the French gas market and the French are now building a third LNG ship to carry this. I do not propose to describe this project and its history in detail.
The Development Decision For Frontier Areas: The North Sea
Authors: Warren Joseph E. 
Published: December 2007

Abstract
Despite the restrictions imposed by the hierarchial organization of most oil companies, including national companies, the exploration process does not logically end with a discovery. At least in high-risk, frontier areas, the contribution of exploration should continue until the development decision is made. This decision is the most economically significant one that must be faced during the course of establishing new productive capacity — the real goal of exploration.
Most frontier areas — deep, stormy waters far offshore or remote arctic regions — require massive capital investments for development; therefore, the development decision must be made in a timely manner even though available estimates of reserves and costs may be very uncertain. If the uncertainty involved is quantified, it is possible to specify a procedure that will yield optimal design parameters for any assumed level of reserves — optimality, in this sense, may be predicated on any chosen economic criterion. Then, taking into account the uncertainty in the estimated reserves, per se, an expected value for the chosen economic criterion can be determined for each assumed level of reserves. Finally, on the basis of these expected values, the optimal reserve value, for design purposes, can be found; and, the development decision may purposes, can be found; and, the development decision may be made by considering the distribution of the chosen economic criterion associated with the optimal design level of reserves.
A procedure for the determination of the optimal level of reserves, a discussion of the economic criteria that may be used, and an analysis of the development decision are presented in this paper. A simple numerical example is presented in this paper. A simple numerical example is also included.
Offshore Trials Of A Prototype Subsea Head Chamber
Authors: Hingston D.L. 
Published: December 2007

Hingston, D.L., Vickers-Interek Ltd. UK.

Introduction
Vickers-Intertek Limited was formed in May 1976 in order to promote the demonstration and marketing of applications of the Neutrabaric method of working underwater in a one-atmosphere water-filled environment. Intertek are the inventors of the Neutrabaric system, which has now been patented in several other countries and Vickers were one of the first companies to develop the use of manned submersibles with lock-out capability. In January 1977, Vickers-Intertek launched a multisponsor project to design and build a prototype subsea wellhead chamber which would demonstrate an important application of the Neutrabaric system. The sponsors included American, Norwegian and British Oil Companies who made a significant contribution to the project through a Technical Advisory Committee which supervised the design, construction and trials ensuring that the prototype was designed to incorporate the latest developments in subsea technology and tested to meet all current and future oilfield requirements. Trials of the prototype were successfully completed in September 1978. The unit was installed first in 80 ft and then in 400 ft of water at a site near Kyle-of-Lochalsh off the West Coast of Scotland and was hydrostatically tested to 700 ft for Lloyds Certification. A diverless installation was demonstrated using hydraulic handling tools operated remotely from the surface. The unit was accessed on several occasions at each depth by men working at one atmosphere pressure from a manned submersible. A number of typical installation and maintenance tasks(and some unscheduled tasks) were demonstrated and the unit was recovered to the surface using the same diverless handling techniques.

DESIGN PHILOSOPHY
The fundamental philosophy behind the system is that standard oilfield equipment and standard techniques are used such as would apply to a wet-exposed tree subsea completion.