bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Parametric Study of Compressional and Shear Wave Velocities in Ekofisk Reservoir Chalk
Authors: Pedersen Sean H. , Rhett Douglas W. 
Published: December 2007

Abstract
A parametric study of compressional and shear wave velocity was conducted on Ekofisk reservoir chalk to gain more insight in the acoustic response of the chalk to changes in temperature, stress state and fluid saturations. The information from the study is used to interpret seismic signature changes associated with a Repeated Seismic Monitoring Program. Three factors have been identified to have a possible impact on acoustic velocities as a result of a waterflooding process. These three factors are 1) changes in effective stress state, 2) changes in water saturation, and 3) changes in temperature. It would appear that these 3 effects act together to increase the compressional wave velocity. Laboratory measurements show that the largest effect on velocity is a reduction in porosity, which results from an increase in stress and/or an increase in water saturation. Changes in temperature and fluid saturation are secondary effects which also produce increases in acoustic velocities. Together, these two parameters can account for about 5% increase in compressional wave velocity. However, compaction alone accounts for approximately 3-4% increase in compressional wave velocity. Experimental data indicate that the low frequency Biot-Gassmann relation predicts compressional and shear wave velocities to within ±2% of the measured values when appropriate rock moduli are used. This relation has therefore been considered to be a suitable approach for modeling fluid substitution in Ekofisk chalk.
Monitoring and Management of Fractured Reservoirs Using Induced Microearthquake Activity
Authors: Jupe A. , Jones R. , Dyer B. , Wilson S. 
Published: December 2007

Abstract
The potential value of induced microearthquake (microseismic) imaging for the monitoring and management of fractured hydrocarbon reservoirs is illustrated using a high quality data set obtained during development of the European Hot Dry Rock (HDR) geothermal energy project, Soultz-sous Forets, Alsace, France. This development has involved massive hydraulic fracturing Operations (MHF), waterfloods and water extraction in a naturally fractured rock mass. The characteristics of the development, operation and hydraulic behaviour of this system are in many ways analogous to those of fracture dominated hydrocarbon reservoirs. The data set consists of 28,000 located microseismic events detected during two phases of reservoir development, comprising a total injected fluid volume of 1 50,000m3. The microseismic data has provided detailed images of the 500Mm3 reservoir volume, successfully identifying the hydro-mechanical controls on fracture dominated flow an isotropy, enabling the successful targeting of a production well and allowing delineation of the principal flow paths. The analysis of microseismic connectivity has recently been used to successfully construct a reservoir simulator grid for modelling the long term performance of the reservoir.
P. 493
A Conceptual Model for Correlating Ultrasonic Attenuation to Deformational Behavior
Authors: Couvreur J.F. , Thimus J.F. , Lousberg E. , Vervoort A. , King M.S. 
Published: December 2007

Abstract
A number of laboratory tests (uniaxial, triaxial and hydrostatic) were conducted on a dry porous limestone. A conceptual model is proposed to correlate deformation and damage fields with the variation of ultrasonic velocities and quality factors. This correlation is presented in a stress deviator versus confining pressure diagram. In this way, the successive steps occurring in the damage process of this rock are well described. In particular, the quality factor of the S wave distinguishes clearly the onset of the initially stable cracking, while velocity of the S wave and strain measurements are sensitive to dilatancy which appears later in the damage process of the studied limestone.
P.187
An Experimental Study of Elastic Wave Propagation an Isotropy and Permeability an Isotropy In an Illitic Shale.
Authors: Jones C. , Meredith P. 
Published: December 2007

Abstract
Shales are highly anisotropic and are generally characterized by very low permeabilities. In this paper we report results of an experimental study of the relationship between elastic wave propagation anisotropy and permeability anisotropy of an illitic shale.
Elastic wave velocity was measured as a function of angle relative to the bedding plane orientation. Radial compressional and shear wave velocities were measured around the circumference of a core taken parallel to the bedding of the shale. The shale was highly anisotropic.
Permeability measurements were then taken for cores oriented in the directions of the maximum and minimum velocities. The permeability was measured using a novel steady-state-flow permeameter capable of measuring extremely low flow rates of water, brine, or oil. At low effective pressure the shale was highly anisotropic, but the anisotropy reduced to zero at high effective pressure.
We compare the shale results with those from measurements on a sandstone and a tuff, where permeability anisotropy is maintained even up to the highest effective pressures used.
P. 307
Reservoir-Scale Fracture Permeability in the Dixie Valley, Nevada, Geothermal Field
Authors: Barton C.A. , Hickman S.H. , Morin R. , Zoback M.D. , Benoit D. 
Published: December 2007

Abstract
Borehole televiewer, temperature, and flowmeter data recorded in six wells penetrating a geothermal reservoir associated with the Stillwater fault zone in Dixie Valley, Nevada, were used to investigate the relationship between reservoir permeability and the contemporary in situ stress field. Data from wells drilled into productive and nonproductive segments of the Stillwater fault zone indicate that permeability in all wells is dominated by a relatively small number of fractures striking parallel to the local trend of the fault. However, Coulomb failure analysis using our fracture orientations in conjunction with stress orientations and magnitudes determined by Ref. 1 suggests that fault zone permeability is high only when individual fractures as well as the overall Stillwater fault zone are optimally oriented and critically stressed for frictional failure. Fracture geometry may also play a significant role in determining reservoir productivity. The well-developed populations of low-angle fractures present in wells drilled into the producing segment of the fault are not present within the relatively impermeable segment of the Stillwater fault zone.
P. 315
Cracking and Compaction Behavior of Sandstone
Authors: Braun Roland , Jahns Eberhard 
Published: December 2007

Abstract
Compression and extension tests with measurement of permeability and elastic wave velocity were made on two different sandstones. Distinctly different cracking and compaction behavior were observed in the two types of test. Conclusions are drawn for the choice of wellbore orientation and allowable pressures. The results also enable the stress conditions and fracturing in the area around a wellbore to be characterized on the basis of measurements in the same direction of shear and compression wave velocities.
P. 339
Prediction of In-Situ Formation Compressibility from Production Data
Authors: Yildiz Turhan 
Published: December 2007

Abstract
This study presents simple graphical methods (0 predict itt-situ formation compressibility from production data. The graphical methods are based on the conventional material balance equation for oil reservoirs. The material balance equation is recasted into several straightline formats such that either the intercept or the slope of the straightline yields an estimate of formation compressibility. Also, floe information from the straightline plots can be used to predict oil-in-place.
The new predictive methods were applied to field data from a depletion/compaction drive reservoir. The formation compressibility and oil-in-place values predicted by the proposed methods were compared with those from other sources and methods, resulting in excellent agreement.
The proposed graphical techniques are limited to depletion/compaction drive reservoirs and cannot be applied to reservoirs subject to strong water-drive.
P. 357
Water/chalk (or Collapsible Soil) Interaction: Part I. Comprehensive Evaluation of Strain and Stress Jumps at the Waterfront
Authors: Piau J.-M. , Bois A.-P. , Atahan C. , Maury V. , Halle G. 
Published: December 2007

Abstract
Ekofisk, Valhall and other North Sea reservoirs are made of water sensitive rocks such as pure high porosity chalk (Andersen 1). Production of these fields may imply water- flooding which has two important consequences. On one hand water-flooding seems to fracture the reservoirs, hence increasing their gross permeability, while compaction drive becomes one of the main mechanism for production. On the other hand, compaction may endanger well completions and subsidence surface facilities.
In order to perform reliable predictions of compaction and subsidence when water-flooding such reservoirs, it is necessary to take into account not only the deformations that come from the compressibility of the reservoir rocks but also to include additional deformations induced by water-flooding.
This paper presents two constitutive models that predict such additional deformations. The first model is an elastoplastic model which depends continuously on the water saturation (WS) while the second is a particular case of the first model where the water-flow is assumed to be piston-like and water saturation jumps from Swi (not water-flooded) to Swf (water-flooded), at the waterfront. These constitutive models have not been developed taking into account any specific microscopic mechanism at waterfront. They can be used even if more than one mechanism is responsible for the water effect.
P. 419
A Two-Domain, 3D, Fully Coupled Fluid-Flow/Geomechanical Simulation Model for Reservoirs With Stress-Sensitive Mechanical and Fluid-Flow Properties
Authors: Osorio Jose G. , Chen Her-Yuan , Teufel Lawrence W. , Schaffer Steve 
Published: December 2007

Abstract
A 3D finite-difference, fully implicit model has been developed to represent the physical phenomena occurring during the production from reservoirs with stress-sensitive mechanical and fluid-flow properties. The model considers two different physical domains:
an inner domain representing the reservoir, where fluid-flow and rock deformation occur, and an outer (surrounding) domain representing the extended stress-disturbed region caused by reservoir depletion.
The inclusion of the surrounding domain leads to realistic modeling of the actual geomechanical boundary conditions taking place in the subsurface. The reservoir is treated as a multiphase poroelastic system consisting of a deforming solid skeleton and a moving compressible pore fluid. Non-linear elastic deformation ts assumed for both domains. The governing equations describing the deformation of the surrounding domain, the deformation of the reservoir solid skeleton and the motion of the pore fluid are fully coupled.
Simulation results clearly show that the permeability of stress-sensitive reservoirs may significantly change through the reservoir producing life. Different reservoir conditions yield different degrees of permeability reduction. In general, permeability decreases as production time increases. Zero- displacement boundary conditions yield less permeability reduction than constant stress boundary conditions. The permeability reduction decreases as the rock elastic moduli of the outer domain increase. The "arch effect" has a strong influence on reservoir permeability behavior.
P. 455
Targeting a 'Step Change' in Offshore Safety Performance
Authors: Cosad C. , Donald M. , Davies T. , MacChesney R. 
Published: December 2007

Abstract
A North Sea industry-wide initiative has set out a framework to target a 'step change' in offshore safety performance, broadly defined as a 15% year-to-year improvement. To achieve this, one major operator and alliance partners have focused on behavioral and cultural issues, underpinned by an innovative training program. This step change is being pursued in an environment of strong industry growth and high personnel mobility and turnover, adding to the challenge.
Initial training goals are to: train individuals to stop any operation because of uncertainty or safety concerns; institute open, low-level incident reporting and communication; and instill personal ownership of individual and colleague safety.
A number of 'tools' have been put in place to promote these behavioral changes, with supervisors trained to provide better communication and counseling on safety matters.
There are four main elements to supervisor training. Safety Leadership comes first. This session is reinforced by three other courses: Risk Assessment, Auditing in Safety, and Accident/Incident Investigation. Supervisor training is conducted with a 'diagonal slice', from senior onshore to frontline rig management, with a side benefit of improved interpersonal understanding and communications.
One training innovation uses actors role-playing a scene offshore subsequent to an accident. Those being trained have the opportunity to demonstrate their skills, both interpersonal and investigative, to manage the situation and discover root causes. 'Freeze the action', 'living playback' and behavioral coaching of actors allow participants a learning experience not found in the real world: 'If only I had a chance to do that again.' This paper presents a summary of the strategy, tools, obstacles and results to date.
Towards a Learning Organization
Authors: Kaspersen Bjoerg 
Published: December 2007

Abstract
Ever since Phillips Petroleum Company Norway (PPCoN) started operating in Norway, the company has invested heavily in training. The majority of this training has been safety related courses and equipment courses, many of them internal and focusing on specific equipment, systems or procedures.
However, in the 90's the world changed. There were changes in the political as well as in the economical situation. The advances in IT technology facilitated a different way of working and cooperating, but also required a higher level of knowledge. As systems become more and more integrated, it was felt that a better understanding was critical in order to operate safely and efficiently.
All of this required a whole new look at competence development, focusing on learning rather than training, on responsibility rather than entitlement, on education rather than courses and on teams rather than on individuals.
The presentation will focus on how the company managed to change the culture and people's attitude with it, and what the results are so far.
Management of Wellbore Instability & Formation Damage by Improved Drilling Mud Design
Authors: Azizi T. , Chen H. , Rahman S.S. 
Published: December 2007

Abstract
Wellbore instability and formation damage are the two major problems encountered by the petroleum industry. It is commonly accepted that formation damage is mainly caused by fluid-rock interaction due to the change in pore fluid chemistry which is caused by invading mud filtrate. Invasion of mud filtrate can be reduced by forming a tight filter cake on the wellbore wall. A tight filter cake can also provide support to the wellbore wall and prevent wellbore collapse. Therefore, the most effective option for solving wellbore instability and formation damage problems is to design a drilling mud that is compatible with formations in relation to both fluid-rock interaction and mud caking characteristics. This paper considers a number of mud systems with novel features and investigates their potential use in drilling and completion of tight gas formations in Central Australia, which are highly susceptible to formation damage. Among the four (4) muds investigated, ester based mud has been found to be the most effective in reducing formation damage by producing a tight filter cake on the wellbore wall.
P. 113
Investigation of Blast Furnace Slag Addition to Water-Based Drilling Fluids for Reduction of Drilling Fluid Invasion into Permeable Formations
Authors: Tare Uday A. , Growcock Frederick B. , Takach Nicholas E. , Miska Stefan Z. , Davis Neal 
Published: December 2007

Abstract
Granulated quick-quenched blast furnace slag (BFS or slag) in water-based drilling mud systems has been studied before, mainly from the perspective of mud-to-cement (MTC) conversion. However, the concept of using slag in a drilling mud for an effective low permeability filter cake, which minimizes formation damage, has not been explored.
This work explores the potential of using slag to consolidate filter cakes, thereby achieving reduced filter cake permeability. Also investigated is the overall impact on the reduction in formation damage by selective activation of BFS in dynamically deposited filter cakes. Studies were conducted on lignosulfonate, partially hydrolysed polyacrylamide (PHPA) and CaCO3 Drill-In fluids with BFS as a mud additive. Various mud properties, such as rheology (ambient as well as high pressure/high temperature), pH, filtrate loss and initial spurt loss are reported for muds containing variable loadings of BFS, and a control containing no BFS.
This study demonstrates the possibility of reducing invasion of mud into permeable formations through addition of small quantities of BFS to drilling mud. BFS appears to produce a more consolidated filter cake, which can be very useful for reducing wellbore stabilization problems in formation intervals that exhibit lost circulation and poor zonal isolation. In some cases BFS-containing drilling fluid appear to reduce formation damage in the near -wellbore environment.
P. 195
New Generation Wireline Logging Tools Enhance Rig Efficiency, Safety and Formation Evaluation
Authors: Davis R.J. , Benson R.H. , Boser D.J. 
Published: December 2007

Abstract
The traditional wireline formation evaluation tool has been redesigned to provide a driller friendly' tool providing standard log readings. Platform Express (PEx), the new design, integrates sensors used for formation evaluation into a short, highly reliable and efficient logging system. In addition, the new design allows for more robust measurements with higher resolution to be logged at a much higher speed than was possible in the past.
The new generation equipment is less than half the length and weight of the triple-combo equipment making setup and calibration of the tool much faster and safer. Through the use of integrated sensors, flex joints that improve pad contact, and other innovative technology, not only traditional triple-combo resistivity and porosity measurements can be collected, but also high-resolution micro-resistivity and imaging measurements, plus tool movement measurements for speed correction and depth matching. The hardware has been designed to meet LWD shock standards. This results in greatly improved reliability with as many as three times the number of jobs between failures as previously attained. Re-engineering of the sensors allows twice the logging speed while delivering better data than the previous generation tool.
This paper will present the results of operations and logs since the equipment's introduction in Indonesia. Setup and logging times are compared with those of the conventional tool string and several log examples are discussed to show the benefits of the new logging system both in terms of wellsite efficiency and more robust data acquisition.
P. 207
Density Behavior of Drilling Fluids During High Pressure High Temperature Drilling Operations
Authors: Kårstad Eirik , Aadnøy Bernt S. 
Published: December 2007

Abstract
In this study, we present an analytical model for the density-pressure-temperature dependence for drilling fluids. This generalized equation of state is valid for oil- and water based drilling fluids and also for completion fluids. The model is compared to other models already proposed, and is found to represent the measured data more accurately than the other models. In the application of the model we study the transient density behavior during drilling operations.
Innovative Perforating Techniques Show Promising Results in Problematic Deep Depleted Gas Sands
Authors: Dyer George , Gani Setiawan Rudy , Gauntt Gary 
Published: December 2007

Abstract
VICO's tighter gas sands in the 12000- to 13000-ft. depths have proven to be very difficult to produce efficiently. During the past two decades, hydraulic fracturing and acid stimulation of these zones has proven to be economically, mechanically, and logistically impractical. Recent evaluations of the damage mechanisms in these formations have indicated that crushed zone effects after perforating might be playing a larger role in some zones than previously thought. Thus, new techniques to increase production efficiency have been sought. Two perforating techniques are showing particular promise.
Extreme overbalance perforating, incorporating proppant with some of the highest pressures used to date (nearly 15,000 psi surface and 19,000 psi at depth), have been successfully executed and the results using this method have been encouraging.
The other new perforating method is the extreme underbalance technique, This method employs a specially designed modular gun system. and has been used in monobore completions. Underbalance as high as 4700 psi was achieved. The jobs have resulted in some of the most prolific wells in these reservoirs.
For the first time in the industry, new equipment technology that allows a true comparison between underbalance and extreme overbalance techniques has also been employed.
Multi-Lateral Case Histories in the Thailand, Malaysia and Brunei Area
Authors: Emerson A. Brent , Jones Rich C. , Lim S.B. 
Published: December 2007

Abstract
Multilateral well technology utilization continues to increase in the Asia Pacific Region. There is a significant variety to the level of complexity chosen in order to fulfill the requirements of a particular application. The key to a successful implementation of a multilateral well begins at the well selection phase based on the reservoir and ends with a team approach during operations and a thorough, post-job analysis. This paper will discuss the case histories of 5 Multilateral wells that have been completed in Thailand, Malaysia and Brunei. It will discuss lessons learned and thus the continuous improvement on multilateral technology.
P. 253
Why Not Use Aluminum in Drilling?
Authors: Akgun Ferda , Maidla Eric E. , Basovich Vladimir , Gelfgat Michail Y. 
Published: December 2007

Abstract
Using light weight drill and casing strings in drilling may cut down drilling costs by allowing the selection of smaller and/or cheaper equipment.
Drilling components are designed to meet or exceed certain load conditions and operational constraints (e.g. stress, strain, overall stretching limits, fatigue, corrosion, etc.). An important parameter that greatly impacts on the overall design is the material density of drilling tubulars, here limited to casing and drill string. Tubular density affects both stress (axial, bending and von Mises) and strength of the tubular itself and impacts on derrick compression and rotary torque that are determining factors for rig selection.
This study investigates the stress and strength behavior of aluminum based drill and casing strings and compares with steel based conventional ones.