bluuebunny/crossref_metadata_2025 huggingface dataset:
Efeito da utilização de laterita nas propriedades físicas e mecânicas de cerâmica vermelha
Authors: Vieira C.M.F. , Intorne S.C. , Alexandre J. , Alves M.G. , Monteiro S.N.
Published: December 2007

Este trabalho tem por objetivo avaliar a incorporação de até 40% em peso de laterita a uma argila visando à fabricação de cerâmica vermelha. Inicialmente a laterita foi submetida a ensaios de caracterização mineralógica, química e física. Em seguida foram preparados corpos de prova por prensagem uniaxial a 20 MPa para queima em forno de laboratório a 700, 900 e 1100ºC. As propriedades físicas e mecânicas avaliadas das cerâmicas queimadas foram: retração linear, absorção de água e tensão de ruptura à flexão. A plasticidade das composições foi avaliada pelo método de Atterberg. Os resultados indicaram que a laterita contribuiu para melhorar a trabalhabilidade da argila. Com relação às propriedades de queima, foi observado que nas temperaturas de 700 e 900ºC a incorporação da laterita reduziu ligeiramente a absorção de água e a retração linear da argila. Por outro lado, a resistência mecânica da argila também foi reduzida. Já a 1100ºC, a laterita apresentou um efeito significativamente deletério nas propriedades avaliadas da argila. Por fim, os resultados indicaram que a laterita apresenta um potencial para utilização como componente de massa de cerâmica vermelha em temperaturas na ordem de 700 e 900ºC.
Briefing: Implementation and implications of Water Framework Directive
Authors: Brooke J.
Published: December 2007

The European Union (EU) Water Framework Directive (WFD), which was transposed into law in most member states in 2003, introduces a new, integrated regime of protection, improvement and management to all water bodies. These include rivers and canals, coastal and estuarine waters and, in some countries, large marine areas. The WFD also aims to prevent further deterioration in water status and to reduce or phase out pollution from certain named ‘priority and priority hazardous substances’ (these are being identified as part of the process of agreeing a separate ‘daughter Directive’ to the WFD). Another key objective of the WFD is to ensure that water bodies reach ‘good status’ by the end of 2015. Reaching good status requires not only chemical but also new ecological targets to be met. Implementation of this ambitious Directive is continuing apace in both the UK and at EU level. Stakeholder participation is a key element of the provisions of the Directive and the navigation sector is ensuring that it gets involved in this process at all levels. This briefing note provides a short overview of these activities.
Realignment in low-lying coastal areas: UK experiences
Authors: Pontee N. I.
Published: December 2007

The present paper reviews the context of realignment in the UK from both a coastal process and policy context, and explains the approaches that can be adopted to implement realignment. A number of case studies are then presented covering both estuarine managed realignment schemes involving the removal of flood embankments; and natural barriers beaches where realignment is likely. The paper demonstrates that while realignment leads to more natural coasts, such approaches are not without their disadvantages. The breaching of coastal defences, be they natural or man-made, has environmental, social and economic implications. Although policies involving realignment might be the most sustainable solutions in theory, this does not mean that they will be immediately embraced by the public, when they have come to expect continued flood protection. It is suggested that the promulgation of policies involving realignment requires a number of elements including increasing public awareness of coastal change, floodproofing properties, providing temporary defence measures, restricting the development of new properties and considering governmental compensation for affected home owners.
Safety of a deep water marine riser under random loads
Authors: Khan R. A. , Ahmad S.
Published: December 2007

The safety of a deep water marine riser subjected to high axial and bending stresses was addressed with respect to potential fatigue failure. A three-dimensional non-linear dynamic analysis of a marine riser was carried out for response calculations. The response histories so obtained were employed for the study of the fatigue reliability analysis of the riser under random wave and random wave plus top vessel motion. A fatigue damage estimation of the riser was made using Miner–Palmgren's rule (S–N curve approach). A non-linear limit state function based on the above approach was derived in terms of random variables. The advanced first-order, second-moment method (Afosm) and Monte Carlo simulation technique were employed for reliability estimation. The design point important for probabilistic design is located on the failure surface. The influence of various random variables on overall probability of failure was studied through sensitivity analysis. The effect on riser fatigue reliability of uncertainties in various random variables is highlighted.
The Contracts (Rights of Third Parties) Act 1999
Authors: Winter J.
Published: December 2007

This article describes how the cost and inconvenience of collateral warranties can be avoided by inserting provisions giving rights to third parties in construction contracts. Those third party rights are now enforceable following the introduction of the Contracts (Rights of Third Parties) Act 1999.
Managing risk to maximise profit in an engineering environment
Authors: Betteley K.
Published: December 2007

Engineers in the modern world are only too aware that they are in a money-making business. Whereas for many their calling is an art, the vulgar reality of profit is never far away. Nevertheless, the two do not need to be incompatible. This article discusses how risk management can improve profitability and bridge the creative gap.
Pyrolysis of biodegradable wastes using microwaves
Authors: Robinson J. P. , Kingman S. W. , Snape C. E. , Shang H.
Published: December 2007

The pyrolysis of biodegradable wastes using microwaves was studied as a potential technology to divert waste streams from landfill by converting the biomass into a high-value char, with a potential market as a co-firing media in pulverised fuel power stations. It is demonstrated that pyrolysis can be achieved using inherent moisture as the microwave absorbing phase and that complete char formation can be attained. The efficiency of the process is dependent on the microwave cavity used and it was found that microwave pyrolysis is governed primarily by the rate at which energy is supplied to the waste material. When the heating rate is maximised, the calorific value of the produced pyrolysis gases is greater than the total microwave energy required, meaning that the process is potentially self-sustaining. The dielectric properties of other waste materials are presented and these are used to identify the prevalent design criteria for translating the pyrolysis process to pilot scale.
Development and Implementation of a Scale-Management Strategy for Oseberg Sør
Authors: Fleming Niall , Ramstad Kari , Eriksen Synnøve H. , Moldrheim Erlend , Johansen Thomas Rudberg
Published: December 2007

Oseberg Sør field, operated by Hydro Oil & Energy, is situated 130 km west of the Norwegian coast on the eastern flank of the Viking Graben structure. It comprises a sequence of fault-bounded structural units of varying geological complexity. Within these units, the reservoir intervals are of moderate to poor quality and can exhibit strong contrasts in permeability and formation water composition. Reservoir support is provided by combined injection of gas and Utsira aquifer water. The wells are a combination of platform and subsea and comprise extended reach horizontals with complex geometry and lesser numbers of vertical wells.

Detailed scale predictions have been performed to identify the scaling risk for each producer. From these, it was identified that the major risk to well performance and integrity was CaCO3 precipitation in the upper tubing with potential failure of the downhole safety valve. The risk varied from negligible to severe and reflected the variable composition of the produced water and well operating conditions. The scale predictions provided the basis for a technical and economic evaluation to identify an appropriate scale-management strategy for Oseberg Sør. For those wells completed with downhole chemical injection lines, the option to use these for scale inhibition was considered cost effective. In other wells where this option was not available, scale inhibitor injection into the gas lift system or squeezing using a viscosified treatment was considered viable.

The paper will provide the technical and economic reasoning for the scale-management strategy selected along with field case histories for each treatment type (i.e., experience with treatment using chemical injection lines, injection of scale inhibitor into the gas lift system, and squeezing).
Field Case Studies: Damage Preventions Through Leakoff Control of Fracturing Fluids in Marginal/Low-Pressure Gas Reservoirs
Authors: Paktinat J. , Pinkhouse J. A. , Williams C. , Clark G. A. , Penny G. S.
Published: December 2007

The primary purpose of surfactants used in stimulating sandstone reservoirs is to reduce surface tension and contact angle and provide leakoff control. However, many of these chemicals adsorb rapidly within the first few inches of the sandstone formations, reducing their effectiveness in deeper penetration. This phenomenon causes surfactants to adsorb or plate-out, reducing their effectiveness in post-fracturing fluid recovery.

This study describes experimental and field-case studies of various surfactants used in the oilfield. Several different surfactants, including a nonionic ethoxylated linear alcohol, a nonyl phenol ethoxylate, an amphoteric, a cationic, and a microemulsion system were investigated to determine their adsorption properties when injected into a laboratory sandpacked column. A laboratory-simulated comparison study of commonly used surfactants and microemulsion was used to identify their leakoff and waterrecovery properties from gas wells.

Field data collected from Bradford, Balltown, and Speechley sandstone formations confirmed experimental sandpacked column and core-flow investigations. Reservoirs treated with microemulsion fluids demonstrate exceptional water recoveries when compared with conventional surfactant treatments. Wellhead pressures, flowing pressures, and production data were collected and evaluated using a production simulator to show effective fracture lengths, damage surrounding the fractures, and drainage areas with various fluid systems. These investigations and presented case studies can be used to minimize formation damage.
An Integrated Technique for Production Data Analysis (PDA) With Application to Mature Fields
Authors: Gaskari R. , Mohaghegh S. D. , Jalali J.
Published: December 2007

The most common data that engineers can count on, especially in mature fields, is production rate data. Practical methods for production data analysis (PDA) have come a long way since their introduction several decades ago and fall into two categories: decline curve analysis (DCA) and type curve matching (TCM). DCA is independent of any reservoir characteristics, and TCM is a subjective procedure.

State of the art in PDA can provide reasonable reservoir characteristics, but it has two shortcomings: First, for reservoir characterization, the process requires bottomhole or wellhead pressure data in addition to rate data. Bottomhole or wellhead pressure data are not usually available in most of the mature fields. Second, a technique that would allow the integration of results from hundreds of individual wells into a cohesive fieldwide or reservoirwide analysis for business decision making is not part of today's PDA tool kit.

To overcome these shortcomings, a new methodology is introduced in this paper that has three unique specifications:

It does not "require" pressure data, bottomhole or wellhead (but it can make use of it, if available, to enhance accuracy of results). It integrates DCA, TCM, and numerical reservoir simulation or history matching (HM) to iteratively converge to a near unique set of reservoir characteristics for each well. It uses fuzzy pattern recognition technology to achieve fieldwide decisions from the findings of the analysis.
Scale Inhibitor Squeeze Treatments Deployed From an FPSO in a Deepwater, Subsea Fields in the Campos Basin
Authors: Bogaert P. , Berredo M. C. , Toschi C. , Jordan M. M. , Frigo D. M. , Morgenthaler L. , Bryson B. , Afonso M.
Published: December 2007

This paper describes field experience and lessons learned from scale control operations in a deepwater subsea development in the Campos Basin, Brazil; specifically, from bullheading scale-inhibitor squeezes from the FPSO host, along the production flowlines, into four low-watercut, horizontal subsea wells, completed with sand control.

The relatively small number of high-cost, highly productive wells, coupled with a very high barium-sulfate scaling tendency upon breakthrough of injection water, meant that not only was effective scale management critical to achieve high hydrocarbon recovery, but even wells at low water cuts were deemed to be at sufficient risk to require squeeze application.

Use of conventional, water based squeezes have been known to cause significant damage to productivity in low-watercut wells, including those showing a fines-migration tendency, as was the case here. Hence, on the basis of risk mitigation, supported by an extensive program of laboratory testing, it was decided that for the initial treatments, only the mainflush would be water based, with a mutual-solvent preflush and marine-diesel overflush.

Other key challenges associated with treating from the host included the remote location of the wells, the potential to form hydrates, the cleanliness of the lines along which the treatment would pass, the achievement of effective placement over a long producing interval, as well as the need to deploy the chemical package via a support vessel adjacent to the FPSO. All had to be managed because of the high cost and low availability of a deepwater rig that could deploy the treatments directly to the subsea wellheads.

This paper will explore in detail the issues associated with inhibitor-squeeze deployment in deepwater, subsea fields, many of which are currently being developed in the Campos basin, Gulf of Mexico, and West Africa, and are a good example of best-practice sharing from another oil basin.
Author's Reply to Discussion of A Practical Method for Anticipating Asphaltene Problems
Authors: Buckley Jill
Published: December 2007

The authors appreciate Dr. Civan's interest in our predictions of asphaltene-onset pressures. It is interesting to see that well-established temperature correlations can fit our example predictions, but we would like to emphasize that the onset pressures in our Fig. 7d are predictions, not measured data. Perhaps the temperature correlations should be used with the measured data (i.e., the onset solubility conditions at atmospheric pressure) from which predictions can be made for the onset of asphaltene instability at any temperature and pressure.
Theoretical and Experimental Studies of Rate-Dependent Two-Phase Immiscible Flow
Authors: Allen F. R. , Puckett D. A.
Published: December 2007

Theoretical predictions are obtained with both Eulerian and Lagrangian methods for calculating saturation profiles in two-phase immiscible displacements in the presence of capillary pressure effects. The one-dimensional (1D) simulator WFLOOD is described with Lagrangian and Eulerian options for refined calculations of saturation distributions throughout all stages of a linear core flood. WFLOOD calculations are presented to demonstrate typical waterflood performance in a 1-m [3.3-ft] core with two different capillary-pressure functions at high and low flow rates.

Steady-state and dynamic brine/tetradecane displacement experiments are described with Clashach sandstone cores that have radioactive ferrocene in the oil phase to measure saturation by a new nucleonic method. Some of the nonuniform character of these cores has been revealed by measurements.

The PORES reservoir simulation model is used for a theoretical analysis of the experiments in which the nonuniform initial saturation distributions must be represented. It is shown that PORES, used in conjunction with measured steady-state relative permeabilities and measured static capillary pressure data, reproduces the time-dependent saturation profiles to within the accuracy of the measurements at high and low flow rates. The Lagrangian treatment in WFLOOD provides a theoretical benchmark that defines the levels of numerical dispersion present in the PORES Eulerian finite-difference calculations.

A theoretical analysis is used to derive a constraint on the form of krw(dpc/dSw), as a function of Sw, which is valuable when capillary pressure functions Pc = Pc(Sw) are chosen for numerical modeling of immiscible displacements.
Percolation Theory of Two-Phase Relative Permeability
Authors: Heiba A. A. , Sahimi Muhammad , Scriven L. E. , Davis H. T.
Published: December 2007

This paper uses statistical concepts, some borrowed from the percolation theory of disordered media, to develop a theory of two-phase relative permeabilities in regimes in which one phase is strongly wetting. Inputs to the theory are a network model of pore space, the distributions of pore-throat radii, and functions that relate pore-throat conductance and volume to its radius. The theory with a network model of pore space and several simple statistical distributions of pore dimensions, is found to predict all observed trends in two-phase relative permeabilities of systems in which one phase is strongly wetting. Moreover, the inputs to the theory can be adjusted to fit experimental data closely.
Determining Fracture Orientation From Pulse Testing
Authors: Tiab Djebbar , Abobise Edwin O.
Published: December 2007

This paper presents a procedure for determining a complex orientation of a vertical fracture and the formation permeability from pulse testing. Generalized correlations relating the quotient of dimensionless response amplitude and dimensionless cycle period (ΔpD/ΔtcycD) to dimensionless time lag are presented. The correlations can be used for analyzing pulse-test pressure response at an un-fractured observation well resulting from pulsing a vertically fractured active well. Detailed procedures for the design and analysis of pulse testing of a vertically fractured well are presented.
New Oil Mud Passes Environmental Tests
Authors: Hinds Aston A. , Clements William R.
Published: December 2007

In recent years, there has been a substantial incréase in the use of oil-based drilling fluids. This widespread use results primarily from the ability of oil muds to handle a variety of potential drilling problems. They have excellent thermal stability, can tolerate solids, salts, and acid-gas contamination, and provide excellent borehole stability. The major concern about oil muds has been their toxicity, especially in regard to marine life when used offshore. Current regulations prohibit the discharge of oil muds and unwashed cuttings offshore.

This paper discusses the performance characteristics of a new, nontoxic oil-mud system. This system employs a nontoxic-mineral seal oil as the base fluid. The emulsifiers are formulated to give minimum toxicity while retaining the excellent temperature and contaminant stability normally associated with invert-emulsion drilling fluids.
The Relationship of Thickening Time. Gel Strength, and Compressive Strength of Oilwell Cements
Authors: Sabins Fred L. , Sutton David L.
Published: December 2007

A previous investigation1 of the effect of thickening times on early compressive-strength and gel-strength development has been expanded to include a wider range of well conditions, a greater variety of slurry types, and a more thorough evaluation of static gel strength.

No positive relationship between thickening time and the onset or the rate of static-gel-strength development could be found. With few exceptions, all slurries tested developed values greater than 48 Pa [100 lbf/100 sq ft] gel strength in less than 20 minutes. Data presented show that times needed to develop a specific static gel strength are more closely related to the type of slurry than to thickening time. A calculation method is given for estimating shutdown factor from static-gel-strength data.

New data confirm that 12- and 24-hour compressive strengths are not significantly reduced by reasonable increases in thickening time. The maximum single-stage cement interval without an unreasonable waiting-on-cement (WOC) time for specified compressive strength has been redefined in terms of interval temperature differences.
The Remote-Controlled, Multiangle Bent Sub for Drilling Trajectory Control and Corrections
Authors: Boulet J.G. , Morin P.E.
Published: December 2007

A downhole, adjustable, multiangle bent sub, called Telepilote, has been developed for remote control of the wellbore path on a real-time basis without changing the general bottomhole assembly (BHA) configuration. Different modes of actuation for changing the bent sub correspond to different types of construction. The tool is available in 6 3/4-, 7 3/4-, 8-, and 9 1/2-in. [17.1-, 19.7-, 20.3-, and 24.1-cm] nominal sizes. It can be set at six positions, from zero (or straight position) to a maximum angle position of 2 deg. 2 deg.30', or 3 deg. according to nominal sizes. The main construction features and different drilling applications are presented. In addition, the T-3000 Telepilote is described, which features the Telehydrocom (THD) actuator system. This system makes an immediate, direct hookup in the drillstring between the sub and all survey instruments, including measurement-while-drilling (MWD) systems, possible.

Introduction

Worldwide application of directional drilling methods proves that drilling the complete trajectory of a given hole proves that drilling the complete trajectory of a given hole size requires BHA changes. These can be achieved in either rotary drilling or downhole motor drilling with fixed-angle bent subs for controlling and correcting the two basic complementary directional parameters: drift angle and azimuth. Accurate controls and corrections of azimuth are impossible in rotary drilling, while methods with downhole motor and fixed-angle bent subs do not permit the optimization of the drift angle for the hole permit the optimization of the drift angle for the hole profile. Therefore, the application of a downhole deviation profile. Therefore, the application of a downhole deviation tool that is adjustable from the surface makes directional drilling more efficient, saves time, and is more accurate. Such equipment will extend current standard methods for directional control.

The Telepilote is associated with a turbine in a downhole motor. It allows drilling of the complete buildup zone and of the constant-drift-angle zone with the same BHA by a modification of only the multiangle-bent-sub angle from the surface. Thus the need of a round trip either to install an angle sub for the kickoff or to change the BHA is eliminated. A wide variety of applications are foreseeable because of the remotely controlled variable configuration from surface, which can respond to a large variety of worldwide drilling programs and formations with accuracy and efficiency.
Critical Water-Free Production Rates and Gravity-Drainage Rates for Multiwell Systems
Authors: Lehner F. K.
Published: December 2007

A formal analogy with plane potential flow is established for the steady or semisteady free-surface flow of a compressible reservoir fluid in horizontally bounded reservoirs or reservoir sections where the permeability is allowed to vary with depth. This leads to simple analytical estimates of critical (maximal) water-free production rates in the presence of bottomwater or of gravity-drainage rates in the presence of a gas cap for single wells and multiwell systems. Reservoir fluid compressibility is shown to have little effect on these rates in most practical situations.
Laboratory Drying Procedures and the Permeability of Tight Sandstone Core
Authors: Soeder Daniel J.
Published: December 2007

Core analysis of identical, side-by-side samples of Rocky Mountain tight sandstone indicates that laboratory drying technique strongly affects the measured core permeabilities to gas. Samples dried to constant weight at 140°F [60°C] in a vacuum oven or in an unhumidified conventional laboratory oven have significantly higher permeabilities than identical samples dried to constant weight at 140°F [60°C] under 45% relative humidity. Drying the samples maintains the proper hydration states of swelling (smectite) clays present in "dry" gas-bearing tight sands in the ground. Drying in an unhumidified oven removes this hydration water, causes the clays in the flow paths to collapse, and increases the permeability of the core. This clay damage is irreversible. We recommend that Rocky Mountain tight sands be dried in a controlled-humidity chamber at 140°F [60°C] under 45% relative humidity until the samples reach stable weight. This drying technique will remove all free pore water while maintaining the proper hydration state of swelling clays. Cores dried with this procedure will reflect more accurately the properties of actual tight gas sand reservoirs.
New Skin and Wellbore Storage Type Curves for Partially Penetrated Wells
Authors: Kuchuk Fikri J. , Kirwan Paul A.
Published: December 2007

An analytic solution is derived for the transient pressure behavior of a partially penetrated well when wellbore storage and skin effects are significant. New type curves, generated by this solution, enable the engineer to analyze well test data from partially penetrated wells and to discriminate between near-wellbore damage and pseudoskin caused by partial penetration.
Analysis of Fractured Wells Producing at High Flow Rates Using Late-Time Data
Authors: Guppy Kern H.
Published: December 2007

This paper presents a method for analyzing late-time data for high-flow-rate wells that cause turbulent flow within the fracture. Fracture conductivity has been determined on the basis of early-time pressure data. The pseudoradial flow period, however, can be used to check the fracture conductivity by identifying the semilog straight line and by determining the total skin factor. Late-time analysis will increase the confidence in the fracture conductivity. In small fractures, early-time data may not be long enough to calculate fracture conductivities. In these cases, late-time data are the only option available for calculating these fracture parameters.

In high-flow-rate wells, the calculated fracture conductivity is significantly lower than the true fracture conductivity. Methods have been presented for correcting these apparent values to obtain the true fracture conductivity. We have found that early-time correlations cannot be used to correct apparent fracture conductivities obtained in the late-time analysis. This is because the flow regime has changed significantly between the early and late periods. Examples are presented that use either both early- and late-time data or only late-time data for determining the true fracture conductivity.
Electromagnetic Wave Resistivity MWD Tool
Authors: Rodney Paul F. , Wisler MacMillan M.
Published: December 2007

This paper is an overview of the development of a 2-MHz [2×106-cycle/sec] measurement-while-drilling (MWD) resistivity logging tool. This tool uses propagating electromagnetic waves rather than the pseudostatic fields of its low-frequency counterparts. The basic theory of operation is presented along with a discussion of the factors that affect tool response and the compromises that led to the specific embodiment. Field data are presented from which a comparison is made between this tool and wireline tools. It is seen that it is often possible to obtain a direct reading of true formation resistivity, Rt, with this tool.
An Efficient Finite-Difference Method for Simulating Phase Segregation in the Matrix Blocks in Double-Porosity Reservoirs
Authors: Gilman J. R.
Published: December 2007

An efficient finite-difference method is presented for simulating unsteady-state multi phase flow in the matrix blocks (primary porosity) of naturally fractured systems or other reservoirs that have two different porosities. The scheme obtains pressure and saturation distributions in the matrix blocks (rather than average values) by dividing the matrix into subdomains. The method is an extension of the double-porosity concept in which fractures are the continuum for fluid flow and the matrix rock is the primary storage medium that acts as a source term to the fractures. Examples show that this subdivision results in different recoveries from the conventional double-porosity models when phase segregation in the matrix blocks is important to the recovery mechanism.

In this formulation, the fracture medium is the major flow path to the wellbore with the matrix subdomains as source terms. The matrix subdomains can be connected to each other or to the fractures in any way desired to conform to the physics of the reservoir. This approach lends itself to an efficient scheme for reducing the system of flow equations to the same structure as conventional single-porosity simulators. The method is presented for a fully implicit, one-dimensional (1D), two-phase (oil/water) simulator.
Use of Capillary-Pressure Data for Rapid Evaluation of Formation Damage or Stimulation
Authors: Amaefule J. O. , Masuo S. T.
Published: December 2007

Foreign fluids and/or entrained solids introduced during various phases of well development reduce the intrinsic reservoir productivity by blocking the effective flow path. Oil/gas recoveries, therefore, can be enhanced significantly if better quality control is established for all well treatment fluids by assessing rock/fluid and fluid/fluid compatibilities before field use.

A capillary-pressure method, developed for evaluating the formation damage or stimulation potential of well treatment fluids, uses relative changes in pore-entry pressure, shape of the capillary-pressure curve, and residual wetting-phase saturations as measures of damage or stimulation in core plugs exposed to various treatment fluids.
Surfactant Flooding Carbonate Reservoirs
Authors: Adams Wilton T. , Schievelbein Vernon H.
Published: December 2007

Some of the most difficult yet most attractive EOR targets are found in the west Texas carbonate reservoirs, where tertiary recovery is complicated by characteristically very low permeability coupled with high hardness and salinity of the reservoir brine. This paper presents data obtained in two well-pair surfactant floods undertaken in the San Andres formation, Bob Slaughter Block, Hockley County, Texas.

To provide the most data in the least time, a close well spacing and relatively large production/injection ratios were used. For each well pair, a different surfactant system was developed, tailored to resist the local aquifer brine salinity and hardness. Consequently, neither system required a preflush. Each test consisted of a large slug of surfactant, followed by biopolymer, fresh water, and formation brine, together with appropriate nonadsorbent tracers. The large slug sizes were intended to allow subsequent designs to be made by interpolation rather than extrapolation. The data provided by these tests demonstrate that (1) low-permeability carbonate reservoirs can be chemically flooded, (2) polymer can be injected and propagated in these reservoirs without any biodégradation, (3) these systems can mobilize tertiary oil effectively at a chemical consumption near that observed in the laboratory, and (4) two-well tests can provide a quick field evaluation of surfactant systems proposed for large-scale use.
A Postflood Evaluation Test of the North Burbank Surfactant/Polymer Pilot
Authors: Lorenz P. B. , Trantham J. C. , Zornes D. R. , Dodd C. G.
Published: December 2007

In a follow-up evaluation to a surfactant/polymer pilot in the North Burbank field of Osage County, OK, a test program was designed to determine the relative importance of the various detrimental factors—heterogeneity, crossflow, ion exchange, and partitioning—that lead to nonconformance and degradation of surfactant and polymer slugs. A diagnostic well was drilled within the drainage area of one of the best producing wells for tertiary oil. The location was selected because (1) there was good communication between the injector and producer in this quadrant, (2) it was close to an injector and probably would be swept by injected chemicals, and (3) simulation suggested that a well at this location could encounter several zones swept by surfactant, polymer, and fresh water. Rock, brine, and oil samples were taken and analyzed for sulfonate, polyacrylamide, alcohol, calcium, and residual oil. Comparisons were made with core analyses on adjacent wells at the start of the project and with fluids produced from them.

Chloride and residual oil were low, indicating that the region had been swept and oil displaced. Sulfonate and alcohol were surprisingly high. Surfactant and cosurfactant were segregated, and the slug was markedly displaced toward the Type II+ direction from optimality. No polyacrylamide was detected in the brine or on the rock, suggesting a change in flow patterns that diverted polymer around the region so that sulfonate and alcohol were not fully displaced. These observations indicate that the performance of the pilot was influenced by both heterogeneity and degradation of the chemical slug.
Viscosity and Phase Behavior of Petroleum Sulfonate Solutions in the Liquid Crystalline Region
Authors: Benton W. J. , Baijal S. K. , Ghosh O. , Qutubuddin Syed , Miller C. A.
Published: December 2007

Aqueous solutions of two petroleum sulfonate surfactants, a pure sulfonate surfactant and one mixed with an ethoxylated sulfate surfactant, were studied with polarizing microscopy, polarized light screening (PLS), and viscometry. The same sequence of phases was seen with increasing salinity for the various surfactants—i.e., transformation from an isotropic micellar solution to a lamellar liquid crystalline phase to an isotropic phase that scattered light and exhibited streaming birefringence. Addition of calcium ions to the petroleum-sulfonate/ethoxylated-sulfate mixtures led to the same basic sequence of transformations, but the effect of calcium was about 11.5 times as great as that of sodium on a molar basis. Many small crystalline particles were also observed when calcium was present.

A cone-and-plate viscometer was used to measure the apparent viscosity of the various solutions. A maximum in apparent viscosity was always found in the transition region between a dispersion of spherulitic liquid crystalline particles in an aqueous phase and a single liquid crystalline phase. The maximum occurred whether the transition was brought about by changes in salinity, divalent cation concentration, oil content, or other compositional variables. Apparent viscosity generally decreased with increasing temperature, although dependence on temperature was not monotonic at high salinities.

Apparent viscosity decreased with increasing shear rates and was time-dependent at a given shear rate. At low salinities, apparent viscosity generally decreased with time. At high salinities, apparent viscosity frequently increased with time.
MWD: A Case Study in Applying New Technology in Norwegian Block 34/10
Authors: Teige T. G. , Undersrud E. , Rees M.
Published: December 2007

Developments in measurement while drilling (MWD) technology have led to the successful operation of a multisensor, negative-pulse telemetry system in the Norwegian sector of the North Sea. This paper describes the MWD system and discusses its application on three wells drilled in Block 34/10 and its advantages over a more conventional drilling program. Particular attention is paid to Well 34/10-20, where the simultaneous drilling, logging, and hole-opening of the 26-in. [66-cm] tophole section was performed for the first time.

We believe that as multisensor MWD systems become more reliable, substantial savings in rig time and increased drilling control and rig safety will result.
Characterization of Pore Space by Quantitative Image Analysis
Authors: Ruzyla K.
Published: December 2007

A quantitative image analysis system has been configured for characterizing pore space of reservoir rocks. The technique can be applied to a magnified image of a rock thin section or polished section. With this system, numerous accurate measurements of porosity, pore size, shape, and internal rock-surface area can be obtained and easily summarized as distributions of pores. This quantity and quality of information is not attainable with conventional thin-section point-count techniques. Porosity values obtained by image analysis are in agreement with those obtained from core-plug analysis.
Porosity, Permeability, and Pore Structure of the Tight Mesaverde Sandstone, Piceance Basin, Colorado
Authors: Soeder D. J. , Randolph P. L.
Published: December 2007

Special core analyses on 44 tight Mesaverde sandstone samples from the U.S. DOE Multiwell Experiment (MWX) were combined with petrographic investigations to relate the porosity and permeability of the cores to the pore structure of the rocks. Core analysis was performed on 1-in. [2.54-cm] -diameter horizontal plug samples with a computerized steady-state-flow measuring device that routinely measures gas flow rates with a resolution of better than 10−6 std cm3/s.

All samples were selected from intervals expected to be gas-productive on the basis of wireline well logs and were taken from the portion of the interval that showed the lowest gamma ray log response. The core plugs were measured for dry permeability to gas, relative permeability at various water saturations, porosity to gas, and PV compressibility. Petrographic samples were taken directly off the plug ends and were analyzed with both an optical microscope and a scanning electron microscope (SEM). The petrographic study was explicitly directed toward observing the flow paths and pore structure deduced from the core analysis data.

Petrographic observations revealed that the pore geometry of tight sandstone falls into three general categories: grain-supported primary pores, secondary solution pores connected by narrow intergranular slots (the most common pore structure in the Mesaverde), and matrix-supported grains. Reservoir properties measured from core analysis correlated fairly well with the observed pore geometry and showed trends associated with various depositional environments in the formation.
An Improved Method for Viewing Micropore Systems in Rocks With the Polarizing Microscope
Authors: Gies R. M.
Published: December 2007

Blue dye, mixed with epoxy resin and used to impregnate rock thin-sections to reveal porosity, is replaced by a fluorescent dye, rhodamine B. Incident-light illumination is provided by a special attachment available for polarizing microscopes. The intense autofluorescent-light response makes even the smallest micropores and microfractures visible in sharp detail.
Mathematical Modeling of a Gravel-Pack Logging Tool
Authors: Boyce James R. , Carroll James F.
Published: December 2007

This report discusses a sophisticated mathematical model of a gravel-pack logging tool that has a gamma ray source and a single gamma ray detector. We use a generalized Monte Carlo computer code, called MCNP, to model photon transport in three-dimensional (3D) geometries. Our approach includes a technique called variance reduction, which both reduces computational time and increases the precision of the results.

The mathematical model is verified by comparison of calculated results with measurements made in laboratory simulations of gravel-pack completions. Laboratory measurements reported previously1 included a wide selection of fluids of various materials and densities, several screens, tubings, and two casing sizes. Comparison of the modeling results with experimental data reveals excellent agreement, giving a high level of confidence to the model.

This study had three major objectives: (1) to expand our understanding of the physical processes involved, (2) to verify and to interpret the laboratory data, and (3) to provide a method by which tool responses can be obtained for a variety of borehole and gravel-pack conditions not measured in the laboratory. Thus, we were able to develop a generalized interpretation method that predicts downhole conditions as a function of tool response. A field example showing this interpretation procedure is presented.
Particle Transport in Viscous and Viscoelastic Fracturing Fluids
Authors: Acharya A. (Ruma)
Published: December 2007

Particle settling velocity as related to fluid rheology in fracturing fluids is an important parameter in the determination of the final distribution of propping agent in a fracture. This paper describes theoretical and experimental analyses that account for viscous and elastic properties of the fluid to predict proppant settling characteristics and reviews existing theoretical models used to correlate proppant settling data.

A closed-form expression for the terminal settling velocity of a single particle as derived from an approximate analysis is compared with experimental data and with data from the literature. The theoretical results are combined with the experimental data to obtain a correlation that is useful in the prediction of the settling velocity of a particle in viscous fluids at an intermediate Reynolds number.
PDC Bit Performance for Rotary, Mud Motor, and Turbine Drilling Applications
Authors: Black A. D. , Walker B. H. , Tibbitts G. A. , Sandstrom J. L.
Published: December 2007

During laboratory drilling tests at simulated downhole conditions in shale, the performance of a polycrystalline-diamond-compact (PDC) bit was measured over a wide range of rotational speeds covering rotary, positive-displacement-motor (PDM), and turbine drilling applications. Tests were conducted at a constant borehole pressure with a standard water-based mud. Rate of penetration (ROP), torque, and mechanical horsepower at the bit were determined as functions of rotational speed, bit weight, and flow rate. From the test results, the cost benefit of higher rotational speeds achieved with PDM and turbine drilling was examined in terms of break-even costs relative to rotary drilling.
Bulk CO2 Removal Achieved Through Membrane Separation
Authors: Dinello M. S. , Narayan R. S. , Patton C. J.
Published: December 2007

A pilot CO2 recovery system was installed in a major west Texas field to confirm the operation and performance of commercial-size coated hollow-fiber membrane gas separators. Data were gathered to verify predicted membrane performance on the basis of earlier demonstration tests. Such parameters as feed pressure, temperature, and CO2 content in the feed gas were evaluated. Removal of CO2 from a casinghead gas stream containing 40 to 80 vol% CO2 was successfully demonstrated with minimum pretreatment of the feed gas. The data taken compared favorably with predicted performance curves based on earlier demonstration unit results.
Development and Application of a Shear-Ram Tubing-Head System for Increased Offshore Platform Safety
Authors: Elkins Hugh L. , Adamek Frank C.
Published: December 2007

Concurrent drilling and production operations on offshore platforms increase the potential for blowouts and subsequent fires. Present wellhead and Christmas tree designs address the potential for production equipment to resist flame impingement for limited exposure periods, but new technology is required to eliminate the source feeding the flame.

A new concept incorporates a blowout preventer (BOP) shear-ram system permanently installed in the wellhead to shear and to seal the tubing in the event of an emergency. Wellhead equipment and BOP systems provide a tandem hanger system that incorporates metal-to-metal sealing and tubular support, tubular shearing, fish retrieval, and tieback re-entry capability.

This report details the design, manufacture, installation, and full-scale laboratory testing that successfully confirmed the ability of the shear-ram tubing-head system to suspend, tie back, shear, and seal 7-in., 32-lbm/ft [17.8-cm, 47.6-kg/m] N-80 tubing at 5,000-psi [34.47-MPa] maximum service pressure.
A Parametric Study of the Effects of Coal Seam Properties on Gas Drainage Efficiency
Authors: Remner David J. , Ertekin Turgay , Sung Wonmo , King Gregory R.
Published: December 2007

A parametric study is conducted to investigate the effects of reservoir properties on gas drainage efficiency. It is found that when a coal seam is opened to production, the gas desorption and production rates increase to a maximum value and then decline. The magnitude of the early desorption peak was found to be a function of (1) the ability of the micropore matrix to supply gas to the macropore system, and (2) the coal seam's conductivity to water. The desorbing gas was observed to create a localized, high-gas-saturation bank in the area enclosed by the pressure transient. The gas bank provided an internal pressure maintenance to the reservoir, while it decreased the relative permeability to brine. This created a competing effect with respect to water production. Because water removal strongly influences the pressure decline and, consequently, the desorption rate, a unique production mechanism was observed.

The study explored the interference effects on gas and water flow in multiple-well systems. It was found that the pressure drawdown caused by the multiple wells enhanced the desorption of gas into the macropore system and caused a positive interference effect on the gas flow rate. The water rate, however, encountered the more conventional negative interference effect.
Discrimination of Crude Oil and Water in Sand and in Bore Cores With NMR Imaging
Authors: Blackband S. , Mansfield P. , Barnes J. R. , Clague A. D. H. , Rice S. A.
Published: December 2007

Nuclear magnetic resonance (NMR) imaging techniques were used to study the mobile proton content in prepared samples containing mixtures of crude oil, water, and sand. The measured proportions of viscous crude oil agree well with the actual values. Discrimination of light crude oil and water was demonstrated by proton chemical shift differences. A bore core sample also was examined and gave clear images from its oil content.
Clear Brine Drilling Fluids: A Study of Penetration Rates, Formation Damage, and Wellbore Stability in Full-Scale Drilling Tests
Authors: Doty P. A.
Published: December 2007

The performance of CaCl2/CaBr2 clear brine fluid was compared with that of lignosulfonate-water-based and oil-invert-emulsion-based fluids in a series of full-scale laboratory drilling tests. Sandstone and shale rock samples were drilled with a clean CaCl2/CaBr2 brine, a solids-contaminated CaCl2/CaBr2 brine, a water mud, and an oil mud, all at 13-lbm/gal [1558-kg/m3] density. Penetration rates were measured under various conditions of weight on bit, fluid flow rate, and differential wellbore/pore pressure. Drilling fluid filtration into the sandstone was measured under both drilling and circulating (nondrilling) conditions. After drilling, 2-in. [5.08-cm] radial cores taken from the sandstone specimens were studied for permeability damage caused by the drilling fluids. In a separate test, shale specimens were exposed to circulating drilling fluids to examine wellbore stability effects.