bluuebunny/crossref_metadata_2025_split huggingface dataset:
First 12 Months’ Experience of Disconnectable Mooring System for H221/H226 FPSO
Authors: Davison Christopher , Wang Heng Qi , Holzle R. G. 
Published: December 2007

Abstract
The development of the HZ 21 and HZ 26 oilfields offshore People's Republic of China incorporates a tanker based FPSO. The FPSO is moored by means of a disconnectable mooring system which allows the FPSO to leave the site in the event of an approaching typhoon.
The mooring system is one of a novel design in which the mooring buoy floats below sea level when disconnected, and in the connected mode is joined to a turret in the tanker's forepeak. The system was commissioned during early September 1990, and this paper gives a description of the design, construction and installation of the system and resumes the experience gained during the first twelve months of operation.
Horizontal Well Operations at Prudhoe Bay
Authors: Broman W. H. , Schmohr D. R. , Schnorr D. R. 
Published: December 2007

Abstract
An evaluation of the current status of horizontal wells at Prudhoe Bay which focused on recent developments in the areas of well performance, surveillance and wellwork results has been recently completed. BP Exploration currently operates 17 horizontal wells at Prudhoe Bay. Their performance analysis is an integral component in the future decision processes of reservoir management and further drilling opportunities as the field matures.
Horizontal well performance data at Prudhoe Bay has shown an increase in oil production rate and accelerated recovery from a majority of the wells in comparison to offset vertical wells. The productivity of the horizontal wells is controlled by both the reservoir description and the well completion. Results from horizontal well workovers and stimulations have been varied. Analysis of the procedures employed has resulted in recommendations to follow in conducting future operations on horizontal wells. Case studies from two horizontal well workovers are included in this paper to highlight the risks, techniques and options available.
Horizontal well surveillance analysis is complicated by production logging tool limitations, horizontal multiphase effects and completion designs. Three production log analyses that illustrate the technical challenges associated with logging horizontal wells are discussed in this paper.
Evaluation of Loose Formations by Means of Constant Pressure Underbalance During Perforation Cleanup
Authors: Puntri P. L. N. , Ceci G. , Obondoko G. 
Published: December 2007

ABSTRACT
This paper presents a case history of a technique utilized in a loose sand fontation to keep constant pressure underbalance during tubing fill-up after TCP shooting.
The method allows a good evaluation of the formation characteristics scon after the TCP shooting, providing an early knowledge of the formation productivity before the final completion with gravel-pack and Electric Submersible Pumps. Moreover, it gives the means for a correct pump design and the evaluation of the gravel pack efficiency.
This technique developed by Agip Recherches Congo was applied to shallow reservoirs consisting of loose sands filled with rather viscous oil. All the wells are completed with gravel packs and electric submersible pumps (ESP).
Prior to shooting the tubing is filled with nitrogen and the pressure is discharged to have desired under-balance. To keep underbalance constant during tubing fill up, WPH is discharged to decrease backpressure.
The fact that a practically constant pressure underbalance occurs during perforation clean up allows a reliable interpretation of the bottom hole pressure transient.
A Geostatistical Well Correlation Method That Can Identify Faults
Authors: Yang An-Ping 
Published: December 2007

Abstract
To effectively produce oil and gas from a reservoir we need to locate faults. A geostatistical method is developed to correlate wells mathematically to determine their relative stratigraphie alignment. With more than two wells the change in dip angle is used to identify a fault. Uncertainty can be reduced when more wells on both sides of the fault are included in the analysis. The major advantages of this new method are: (1) more data can be correlated at the same time to detect otherwise unidentifiable faults, (2) the analysis can be done quickly on a computer, and (3) the correctable range of well spacing can be determined from geostatistical theory with the variogram.
Wellbore Stability and Drilling Results From the First Horizontal Well in the Kotter Field Offshore The Netherlands
Authors: Fuh G-F. , Deom D. B. , Turner R. D. 
Published: December 2007

ABSTRACT
This paper presents the method and analysis of borehole stability prior to drilling the first horizontal well located in Block K/18 of the Dutch Sector of the North Sea. Field data from eight previous wells drilled in the area were analyzed and used to construct a geomechanics model for numerical simulations of potential behavior of the horizontal well under design. The challenge was to drill a high-angle hole through the highly reactive and potentially overpressured Vlieland Shale, then into the partially depleted (6.8 ppg equivalent mud weight) underlying Vlieland Sandstone. Borehole stability analysis provided useful information for well plan and drilling considerations.
The horizontal well was a great success technically and economically. The excellent results can be attributed to prewell planning and good communications between operating personnel and associated service companies. In addition, drilling practices, adopted as a result of the understanding of borehole mechanics, helped overcome problems in borehole instability. Details of drilling and completion operations are included in this paper.
The Design of Steerable BHA's To Minimize the Adverse Effects of Motor Imbalance and Drilling Forces
Authors: Harvey P. , Wassell M. 
Published: December 2007

ABSTRACT
Drilling forces from the bit, drill string and mud motor rotor imbalance adversely affect the performance of steerable bottom hole assemblies (BHAs). Proper BHA design can significantly enhance tool reliability and drilling performance. Positioning of stabilizers and the use of drill collar flex sections to minimize the effects of rotor imbalance are of particular importance when designing steerable BHAs.
Evaluation of the performance of steerable BHAs run in a 17-1/2″ diameter hole indicates that the evolution from low torque/high speed mud motors to high torque/low speed mud motors has introduced connection fatigue problems associated with increased response of the latter to mud motor rotor imbalance.
High torque/low speed motors are characterized by the use of multilobe rotors. These rotors orbit eccentrically about the center of the motor housing at speeds several times greater than the output shaft speed. This creates large cyclic imbalance forces which impart large dynamic loads onto the BHA.
Proper positioning of stabilizers and the use of flex-sections in the BHA reduce the adverse cyclic bending moment levels below those of the low torque/high speed motors, thus eliminating their contribution to connection fatigue.
In addition to critical mud motor imbalance loads, natural lateral frequencies must be considered in the BHA design in order to avoid bit bending and whirling excitations. Finite element modal analysis of the proposed BHA design can determine these critical speeds, as well as speeds that may result in undergauge stabilizers bouncing from side to side in the hole.
Bit Balling and Wellbore Instability of Downhole Shales
Authors: Ledgerwood L. W. , Salisbury D. P. 
Published: December 2007

ABSTRACT
While oil-base muds have given satisfactory performance in the past, environmental concerns motivate the further development of water-base muds. Often associated with water-base muds are operational problems such as bit balling, high torque, and stuck pipe. Tests commonly used to evaluate muds are typically conducted on nonpreserved, unstressed shale and disparate formations. There is a need, therefore, for means of evaluating non-oil mud systems in the laboratory to predict relative performance under field conditions.
This paper describes two methods of testing water-base muds on preserved, stressed shale specimens. One test method utilizes the Microbit Drilling Rig (MDR) to study bit balling characteristics of shale in a given mud system. The test results showed that the clay matrix of the rock can influence balling. The type of cations present are critical, whereas cation exchange capacity and moisture content are not directly correlatable to bit balling. Analysis of the rock to determine composition and plasticity can be used to determine the tendency of a given formation to ball the bit.
The second method utilizes the Downhole Simulation Cell (DSC) to study wellbore instability resulting from exposure of shale to drilling muds under downhole temperature and stress conditions. An elasto-plastic model is presented showing how mud type can affect wellbore stability. These results caution against reliance on tests of unconfined shale particles (cuttings) or even unconsolidated shale specimens when studying effects of muds on shale instability.
Tests results from the MDR and DSC test equipment can be used to develop data bases for the selection of mud system and bit type and to suggest hydraulics to prevent balling of PDC bits. The data has been applied to the selection of a water-base mud that reduced both mud and operation costs when drilling deviated wells in the Gulf of Mexico.
A New Method for the Quantitative Determination of the PHPA Polymer Content of Drilling Fluids and Other Aqueous Systems
Authors: McCulley L. Z. , Malachosky E. 
Published: December 2007

Abstract
The need for a reliable, quantitative analytical method for the determination of the partially hydrolyzed Polyacrylamide (PHPA) polymer content, of drilling mud and other water-base fluids has been evident for some time. Previous methods have been based on either the precipitation of the anionic PHPA molecule or alkaline hydrolysis of the amide nitrogen to form ammonia. All these methods are semiquantitative determinations and are subject to a wide variety of interferences. Another severe limitation, in the case of drilling fluids, is that a portion of the mud filtrate is used for analysis. The free polymer content of the filtrate is rarely, if ever, the same as the unfiltered liquid phase of the whole mud.
The method described in this paper is truly quantitative and is an absolute rather then an empirical method. It is based on the total oxidation of all organic material in a sample of the liquid phase of a water-base drilling fluid. The amide nitrogen in the polymer molecule forms ammonium ions during the digestion and oxidation process. These ammonium ions are then measured with an ammonia gas-sensing electrode after conversion to ammonia by means of a simple pH adjustment.
In addition, a sampling technique has been developed which enables the analyst to obtain a solids-free portion of the liquid phase of a drilling mud sample without filtering the liquid through the mud filter cake. Thus, the method assures measurement of the available free polymer content of the fluid phase of the whole mud.
The method described is ideally suited to the determination of the PHPA content of any aqueous solutions including those encountered in wastewater treatment and sludge dewatering operations. The results of both laboratory and field evaluations of the method are presented.
Wellbore Fluids Model Provides Basis for Drilling Optimization
Authors: Swanson B. W. , Heritage J. R. , Lawsoh D. 
Published: December 2007

ABSTRACT
Current drilling engineering applications programs generally consider only one aspect of the drilling process and therefore allow drilling optimisation in terms of only one variable. In reality, however, drilling is a highly complex and interactive process in which optimisation of one parameter in isolation can have significant and possibly detrimental effects on another.
This paper describes a novel computer program, the Wellbore Fluids Model, that allows a realistic replication of the interacting processes that occur as drilling fluid flows around the wellbore; these include, for example, cuttings transport, hydraulic pressures and fluid property changes with temperature and pressure. By considering these interactions simultaneously the model can provide a more realistic foundation on which to base engineering decisions to ensure optimum rate of penetration.
The paper provides a comparison of the model predictions against field measured data. A simulation which illustrates the complex interactions that occur whilst drilling is presented.
The EC Social Charter, Professional Standards, and New Engineering Entrants
Authors: Harnett Brian , Taylor Simon 
Published: December 2007

Abstract
The aim of this paper is first, to give a brief overview of the EC Social Charter highlighting its achievements to date and second, to focus on the Community’s attempts to harmonize the divergent national rules governing professional standards and the recognition of diplomas with emphasis on the engineering sector.
The Social Charter seeks to establish a code of fundamental social rights to be enjoyed by Community workers. However, it is no more than a political declaration of principles and intent. It has no legislative effect nor does it extend the legislative powers of the Community Institutions. Indeed it was only signed by eleven out of twelve Member States. The United Kingdom, under Margaret Thatcher’s intransigent leadership, refused to approve a document which it saw as an attempt by European socialists such as Jacques Delors, the President of the Commission and Vasso Papandreou, the EC Social Affairs Commissioner to introduce socialism "by the back door" thus undermining the U.K.’s duly elected conservative government.
Although the mutual recognition of diplomas and professional experience was listed in the Social Charter as a fundamental social right, it is easily distinguished from many of the other, more politically controversial, rights. It will be seen below that the central idea behind the Social Charter is to protect workers from the cut-throat capitalism of the free market system by creating a safety net of workers’ rights. Its opponents see it as a socialist threat to the success of the EC "single market" programme which is due to be completed by 1992. The recognition of diplomas is, on the other hand, a central aspect of the EC rules governing the free movement of persons in the Community. The Treaty of Rome, which is the constitution of the European Community, obliges Member States to ensure that persons, including workers and professionals, can move freely and establish themselves without hindrance anywhere in the Community. This principle, along with the free movement of goods, services and capital, is a prerequisite to the success of the EC "single market". The idea is that without this freedom of movement throughout the Community the desired pan-European economies of scale cannot be achieved. For example, an engineering firm, based in one Member State but wishing to branch out and operate throughout the Community, would suffer a commercial handicap if its engineers, qualified in the original Member State were unable to offer their professional services or be relocated in other Member States.
Flow Visualization of Viscous Fingering in Heterogeneous Porous Media
Authors: Brock D. C. , Orr F. M. 
Published: December 2007

ABSTRACT
Flow visualization experiments and numerical simulations were performed to investigate the combined effects of viscous fingering and permeability heterogeneity in four different two-dimensional glass bead packs. In each model, unstable displacements were performed at three different flowrates and mobility ratios. The experiments were also simulated numerically, using a particle tracking simulator.
In the homogeneous model, fingers grew through the mechanisms of spreading, splitting, shielding and coalescence. Fingering patterns were sensitive to mobility ratio but not to flowrate. Analysis of pressure distributions in and around fingers showed that viscous crossflow drives the finger growth mechanisms.
In the heterogeneous models, flow was largely determined by the patterns of heterogeneity. In all experiments, flow followed high permeability paths seen in the Μ=1 displacements, with viscous fingering effects overlain, despite the fact that permeability contrasts were mild (four-to-one). Simulations yielded finger patterns remarkably similar to those seen in the experiments. Thus, the simulator used represents with reasonable accuracy the physics of finger growth in heterogeneous porous media.
Fair Market Value: Theory vs. Practice
Authors: Williams J. 
Published: December 2007

Abstract
This paper presents an examination of fair market value concepts as they pertain to producing petroleum properties. Conventional petroleum economic theories of fair market value are examined in light of recent work on the market value of long-life reserves. Their work is expanded to show that sellers rely on comparable sales data for estimating FMV. Both results are used to suggest that current practices over-emphasize the discounted cash flow approach to estimating fair market value.
A Statistical and Economic Analysis of Incremental Waterflood Infill Drilling Recoveries in West Texas Carbonate Reservoirs
Authors: French R. L. , Brimhall R. M. , Wu C. H. 
Published: December 2007

Abstract
This paper presents empirical infill drilling forecast models and infill well economics for Permian Basin Clearfork and San Andres waterflood units. Four infill recovery indicators were analyzed: 1) ultimate recovery, 2) incremental recovery, 3) recovery per well, and 4) recovery per acre-ft. It was estimated from these forecast models that an additional 6.9% OOIP or 710 MMSTB could be recovered by infill development to 10 acre well spacing in those units studied.
Infill recovery forecast models developed have waterflood recovery and fraction reduction in well spacings as independent variables. The forecast results match actual field data reasonably well. Reductions in well spacings seemed to play a more significant role in determining infill performance in Clearfork than in San Andres.
Economic analyses were performed on an infill well basis. Breakeven economic analysis was conducted for the first guantile reserve level of 70 MSTB and by varying initial production rates. A set of curves were generated for each formation as a quick reference.
A Comparison of Steam- and "Cold"-Gas-Foams in Terms of Thin Liquid Film Stability
Authors: Hatziavramidis D. T. 
Published: December 2007

Abstract
Generation and destruction of steam foam in porous media are governed by the stability of evaporating/condensing thin liquid films, with a surface active solute, in contact with the pore wall (wall films) and sandwiched between two liquid/gas interfaces (free films or lamellae), respectively. The surface tension at the film interface is allowed to vary as a result of temperature (thermocapillarity) and surface excess concentration gradients (surfactant effect). A comparison of evaporating/condensing films associated with steam foams to isothermal films associated with "cold" gas foams is made in terms of stability characteristics.
CT Imaging of Steam and Steam/Foam Laboratory Experiments
Authors: Demiral B. M. R. , Castanier L. M. , Brigham W. E. 
Published: December 2007

Abstract
The CT imaging technique together with temperature and pressure measurements were used to follow the steam propagation during steam and steam foam injection experiments in a three dimensional laboratory steam injection model. During the design period, the advantages and disadvantages of different geometries were examined to find out which could best represent radial and gravity override flows and also fit the dimensions of the scanning field of the CT scanner. As a result of this analysis a 3D rectangular box with dimensions 20x20x7.5 cm was constructed. This box simulates one quarter of a five spot pattern. Aluminum, Teflon™ and Fiberfrax™ were chosen as supporting and insulating materials. Teflon™ was placed between the porous medium and the aluminum shell so that the rate of heat transfer in the porous medium would be much faster than that in the aluminum during a steam injection run. During experiments, steam was injected continuously at a constant rate into the water saturated model and CT scans were taken at six different cross sections of the model. Pressure and temperature data were collected with time at three different levels in the model. CT pictures and three dimensional temperature distributions were compared and analyzed in terms of observed steam zone at each section. To do that, CT numbers within the scan section were used to determine the steam and water zones, and with the aid of x-ray pictures the position and propagation of the steam zone were determined. In addition, using the three dimensional temperature distribution measurements at the same times, steam displacement fronts could be drawn at the scan section locations. These pictures and drawings were used to compare the results obtained from classical temperature-pressure monitoring and from CT scans.
During steam injection experiments the saturations obtained by CT matched well with the temperature data. That is, the steam override as observed by temperature data was also clearly seen on the CT pictures.
During the runs where foam was present, the saturation distributions obtained from CT pictures showed a piston like displacement. However, the temperature distributions were different depending on the type of steam foam process used. During the experiment which included non-condensible gas (nitrogen) injection, the temperature distributions, contrary to the saturation distributions, still indicated the presence of steam override, although the override was reduced by the foam. However, when there was no nitrogen the temperature distributions followed the saturation distributions. This may possibly indicate that the nitrogen foam ahead of steam foam caused the difference between temperature and saturation distributions. These results clearly show that the pressure/temperature data alone are not sufficient to study steam foam in the presence of non-condensible gas.
A Laboratory and Field Injectivity Study: CO2 WAG in the San Andres Formation of West Texas
Authors: Prieditis J. , Wolle C. R. , Notz P. K. 
Published: December 2007

ABSTRACT
Laboratory measurements of CO2 and brine injectivities in restored San Andres carbonate cores at reservoir conditions are reported. Included are results both with unsaturated CO2 and brine as well as with brine equilibrated with CO2 and CO2 equilibrated with brine. A waterflood, oilflood, and miscible flood followed by many cycles of CO2 and brine injection were done. Important results are the following: endpoint CO2 relative permeabilities were substantially smaller than both water and oil endpoint relative permeabilities making CO2 less mobile than would be anticipated just from viscosity ratios, the irreducible water saturation increased after an oilflood and persisted during subsequent CO2 floods, residual CO2 saturations to saturated brine were about the same magnitude as the residual oil saturations to waterflood, and the injectivity of unsaturated brine was much higher than saturated brine because of absorption of the CO2 phase.
The laboratory work was done in support of an injectivity field trial. The results of an injection of two cycles of CO2 and of brine into a well in the Mabee Field in the San Andres formation are reported. Both the CO2 and the brine field injectivities were significantly greater than the pre-CO2 waterflood injectivity on a volumetric basis. Field injectivities were somewhat greater than would be anticipated from the laboratory data. A simple analytical injectivity model could approximate some of the features of the field test but was not completely satisfactory.