bluuebunny/crossref_metadata_2025_split huggingface dataset:
Practical Application of Safety Cultures
Authors: Spadaccini Danny , Robinson Scott 
Published: December 2007

Abstract
The Asia Pacific region consists of 1600 employees, 14 countries, 30 locations, 5 spoken languages with various socio political and cultural differences. The region includes the countries of Australia, New Zealand, Papua New Guinea, Indonesia, Singapore, Malaysia, Thailand, China, Philippines, Saklin Islands, India and Brunei. The HSE Team for Asia Pacific reviewed surveys, administration and implementation of the HSE management systems for the region. This review included traditional HSE data such as LTI's, TRIR, systems / infrastructure auditing in addition to measures of participation in HSE systems. The key findings of the review were: Levels of HSE performance where unacceptable for the region;Participation of personnel in HSE was low; andSystems and infrastructure to support participation was lacking.
It was recognised that no improvements to HSE could be achieved without the relevant infrastructure, training, systems and tools. It would be a waste of time to be seeking participation from personnel in HSE when the organisation has not provided the basics to support HSE. A plan was developed and broken into two key parts being infrastructure and implementation programs.
The HSE systems and infrastructure implemented have become an integral part of day to day business. The systems and processes have been designed and implemented by the personnel who will use them; accordingly the sustainability and continual improvement of the processes will be maintained. The performance improvement has included a TRIR improvement from 4.39 in 2002 to 0.46 in 2005.
The improvements in safety performance have occurred across a wide spectrum of activities, statute laws, cultures and political climates. The participation of all personnel has been the critical element to the success achieved.
Formation Damages Caused by Emulsions During Drilling With Emulsified Drilling Fluids
Authors: Fjelde Ingebret 
Published: December 2007

Abstract
The potential for macroemulsions to cause formation damages during drilling with emulsified drilling fluids (OBM) have been studied for consolidated low-medium permeable sandstone. Two types of emulsified drilling fluids were used, one with mineral base oil and one with synthetic base oil.
The emulsions in tested OBM were found to be stabilized both by emulsifiers and particles (organoclay and drilled solids). At low shear rates, aggregates of water droplets and particles were observed by microscopy. The potential for emulsion invasion will be highest during the spurt period, especially if the emulsions in the muds are not stable. The risk for emulsion invasion will increase with filtration pressure.
In bulk experiments, the stability of emulsions formed by mixing of mud filtrates and reservoir fluids was found to depend on the compositions of emulsified drilling fluid and crude oil. These emulsions were found to cause severe formation damages in core-floods at 90°C. The damages were partly removed during aging at higher temperatures (120°C and 150°C). At 90°C the emulsions appeared to be more stable in cores than in bulk. The potential for creation of emulsion in the oil reservoirs will be highest at high shear rates, e.g. in the spurt period and in the start of the oil production. The risk will increase with the concentrations of emulsifiers in the mud filtrate and reservoir oil.
Formation damages caused by emulsions can be non-permanent. Since emulsions are thermodynamically unstable, the potential for permanent damage caused by emulsions will usually be lower at higher temperatures. Mechanisms for stabilisation and thereby also breaking of emulsions, depend on the compositions of the mud filtrate and the reservoir fluids. If the damaged area is swept by the produced oil, removal of emulsions by dilution with the oil can be possible.
Use of synthetic oil in stead of the crude oil in laboratory experiments, can give incorrect estimates of the potentials for formation damages caused by emulsions. Short laboratory experiments can also give too high estimates of the potential for permanent emulsion related formation damages.
Conformance and Mobility Control: Foams vs. Polymers
Authors: Zhang Guoyin , Seright R. S. 
Published: December 2007

Abstract
This paper considers whether foams can be superior to polymers for improving vertical sweep efficiency in reservoirs. Our focus is on vertical sweep improvement during waterflooding and chemical flooding rather than gas flooding. Both linear and radial flow geometries were considered, with and without crossflow. We found that foams can provide improved sweep compared to polymer solutions if (1) foam forms in high permeability zone(s) but not in low permeability zone(s), (2) no crossflow occurs between high and low permeability zones, AND (3) the foam resistance factor in the high permeability zone(s) is sufficiently high to overcome the permeability contrast and the unfavorable mobility ratio between the gas bank and the oil/water bank in the less permeable zones. Foams will generally not be superior to polymers under other circumstances unless gravity effects provide a fortuitous benefit. Other limitations for foams must be recognized, including (1) challenges with formulating foams to meet the above requirements, (2) limitations on foam propagation, especially due to surfactant retention, (3) compression costs during foam injection, and (4) limitations on foam stability under reservoir conditions.
The paper also examines limitations for polymers. Historically, permeability reduction by polymers was advocated as advantageous since reduction in polymer mobility was greater than anticipated based on solution viscosity. However, this permeability reduction generally increases with decreasing permeability, thereby diminishing sweep efficiency. Applications in linear flow (i.e., fractured wells) can be reasonably forgiving of this effect if the permeability contrast and the polymer solution resistance factors are sufficiently large. For radial flow (i.e., wells that do not intersect fractures) with crossflow between layers, the effect has little consequence. However, for radial flow with no crossflow, the effect is quite damaging to sweep.
Oxidation as a Rheology Modifier and a Potential Cause of Explosions in Oil and Synthetic-Based Drilling Fluids
Authors: Shahbazi K. , Mehta S. A. , Moore R. G. , Ursenbach M. G. , Fraassen K. C. V. 
Published: December 2007

Abstract
In drilling directional and horizontal wells, the oil and synthetic-based drilling fluids are required to exhibit high viscosity at low shear rates to properly suspend the weighting materials and drilling cuttings and to prevent sag and settling of weighting materials. This can be achieved by employing different rheology modifiers such as dimeric and trimeric fatty acids, imidazolines, amides, and synthetic polymers. Moreover, the safety of the drilling operation has been one of the main concerns of drilling companies.
Since oil and synthetic-based drilling muds are widely used in high pressure high temperature wells, a set of drilling fluids commonly used in Western Canada were examined to study the effect of long exposure of the drilling mud with air. They consist of three oil base liquids (Diesel, Drillsol, and Distillate) and one synthetic base liquid (Envirodrill) together with water scavengers, viscosifiers, wetting materials, fluid loss controllers, and weighting materials. The drilling fluids were aged in stationary reactors in the presence of one charge of air for 52 hours at 150°C and 13.5 MPa initial pressure.
This paper presents the results related to changes in rheological properties and occurrence of explosion in the drilling fluids employed. The results at different shear rates, ranging from ultra low shear rates to high shear rates, are presented. It is shown that the aged drilling fluid systems exhibited a tremendous increase in viscosity at ultra-low shear rates and relatively low increases at medium and high shear rates. Furthermore, the amounts of solids precipitated in the base liquids were correlated with the mononuclear aromatics content. While rapid heat releases or explosions in the synthetic-based drilling fluids were observed with 0.5 – 1.6 hours induction delay times with gradual increase in liquid phase temperature, oil-based systems were safe under the conditions tested.
These experimental results imply that oxidation serves as a rheology modifier and induction delay time can be used as a warning parameter for an impeding explosion. Moreover, the impact of each chemical on the extent of increasing the viscosity and the occurrence of explosion is given.
Application of Viscoelastic Surfactants as Mobility-Control Agents in Low-Tension Surfactant Floods
Authors: Lakatos Istvan , Toth Janos , Bodi Tibor , Lakatos-Szabo Julianna , Berger Paul D. , Lee Christie 
Published: December 2007

Abstract
Since the recent trend of oil price opened new vistas in IOR/EOR scenario, the laboratory study looked at different new type of super (S) and viscoelastic (Sv) surfactants that provide both IFT lowering and mobility control. The paper is basically focusing on evaluation of viscoelastic surfactants as mobility controlling agents used as pre-flush, co-surfactant and post-buffer media. The experimental work is extended to their effects on bulk phase and interfacial rheological properties, surface and interfacial tension, phase behavior, wettability, flow properties in porous media and displacement efficiency using various injection protocol. Beside determination of mobility, mobility ratio, normal and differential displacement curves, the solution structure was analyzed by transmission and backscattering photon correlation spectroscopy.
Measurements and core studies confirmed that the viscoelastic surfactants might be used to replace traditional mobility controlling agents (polymers) over a wide temperature and pressure range. Their sensitivity to shear rate and other degrading effects is much less than found for high molecular weight synthetic and biopolymers. Thus, the viscoelastic surfactants may offer an excellent opportunity for mobility control in various enhanced oil recovery techniques independent of injection protocol. Their positive influence on recovery efficiently can be explained by mobility control, front stabilization (buffering) and profile correction. The viscoelastic surfactants may also improve the "microscopic displacement efficiency", which is not widely recognized as a significant part of the displacement mechanism, and hence the recovery efficiency. General conclusion of the laboratory studies is that viscoelastic surfactants may open new vistas in chemical flooding.
Nanoemulsions: A New Vehicle for Chemical Additive Delivery
Authors: Del Gaudio Lucilla , Bortolo Rossella , Lockhart Thomas P. 
Published: December 2007

Abstract
Nano-emulsions are emulsions where the droplet size of the internal phase is 500 nm or less. Because of the small drop size, they are not subject to gravity-driven separation owing to the density differences of the two phases. Nano-emulsions constitute a rapidly expanding field of study, with perceived or consolidated applications to drug delivery, cosmetics, food products, etc. To date, most processes for generating nano-emulsions have relied on brute force mechanical methods (ie., based on high mixing energy in order to overcome the high surface energy generated), including several developed for the E&P industry. These generate nano-emulsions with a broad droplet size distribution and, in general, limited stability. While low energy processes based on phase inversion are well-known, the lack of general preparation methods has limited their applications to specific, high value-added industries.
We report a general, transitional phase inversion method for the preparation of mono-disperse nano-emulsions of very small drop size (30-80 nm) which should prove useful for the delivery of oilfield chemicals in a variety of applications. The nano-emulsions possess very long lifetimes and can be charged with one or more oilfield chemicals. Parameters governing nano-emulsion formation and their properties and stability are reported. Nano-emulsions containing oilfield chemicals may find applications to well treatments (scale inhibition, acidizing, etc.), flow assurance (eg., multiple additive packages), and deposit removal/clean-up. Their long-term stability and ease of preparation from a concentrated precursor are compatible with oilfield logistics requirements.
ICD Screen Technology Used to Optimize Waterflooding in Injector Well
Authors: Raffn A. G. , Hundsnes S. , Kvernstuen S. , Moen T. 
Published: December 2007

Abstract
This paper presents an innovative completion technology, fine tuned by reservoir simulations, for balancing the water injection profile into various sand formation zones in an open-hole completed injector well, increasing sweep efficiency.
Traditional injection wells often suffer from the risk of sanding in, hence sand control is beneficial or even required. Another major challenge is to achieve even distribution of the injected water into all zones along the well-bore. Injector wells are often designed to penetrate, and give pressure support to, several reservoir intervals with various permeabilities which challenges the reservoir management. Permeability contrasts, heel-toe effect, formation damage, creation of thief fractures and well bore injectivity changes need to be managed to avoid early breakthrough in adjacent production wells. Smart-well systems are highly complex and costly, and for this particular case, where raw seawater is used, the high corrosion resistance requirement was considered a show stopper.
The solution was to qualify and install special screens with integrated flow control devices, tailor-made for injection wells, and with correct nozzle sizes for this particular case. These screens were made of materials selected to withstand the corrosive environment and high rate of unfiltered water during lifetime of the well. The screens where gravel-packed to restrict annular flow and give zonal isolation, which optimizes regulation of reservoir heterogeneities.
This new technology is representing a quantum leap forward in field economics, by marrying all the benefits realized with this simple robust and reliable self-regulating injection management system.
The paper will discuss the qualification program inclusive focus on risk of erosion, plugging and corrosion. Further, the completion design of the well, with flow distribution simulations and sensitivities inclusive comparisons with actual field date is also reviewed together with economic value analysis. Future potential, applications and scenarios will also be discussed.
Assisted and Manual History Matching of a Reservoir With 120 Wells, 58 Years Production History and Multiple Well Recompletions
Authors: Gruenwalder Markus , Poellitzer Stefan , Clemens Torsten 
Published: December 2007

Abstract
The 16th Torton horizon of the Matzen Field is the largest oil reservoir in Austria. Oil production commenced in 1949. Up to now, 42 mn m3 have been produced from this reservoir. The reservoir is characterised by transgressive sands and calcite layers extending laterally several meters to several tens of meters. These layers are effective vertical flow barriers. To optimise oil recovery, wells were first completed in deeper sections of the sands which are up to 70 m thick and later perforated in upper sections.
To identify infill drilling locations in this 58 year old field, an integrated study was performed 2005 – 2006. To achieve a good history match, permeabilities and the extent and presence of thin limestones, the so-called "hard layers", were modified (vertical flow barriers). Four infill drilling locations were identified.
To assess the uncertainty in the production forecast for these four wells, assisted history matching and forecasting was performed. Assisted history matching achieved several good matches. Using history matches with the smallest error, several forecasts were generated. In all of the forecasts, the production rates from the infill wells would result in economically attractive projects – hence the four drilling locations were included in the drilling schedule for 2007.
Comparing results of the manual and assisted history matching shows that assisted history matching leads to as good as or better global matches for production rates and pressures. Furthermore, assisted history matching gives a range of forecasts which can be used to quantify uncertainty. However, in this reservoir with multiple re-completions and small scale heterogeneities, the well by well history match was better in manual history matching than in assisted history matching. In addition, manual history matching resulted in significantly improving the understanding of the reservoir behaviour and in identifying wells which suffer from poor cementation.
Using Microgels To Shut Off Water in a Gas Storage Well
Authors: Zaitoun A. , Tabary R. , Rousseau D. , Pichery T. , Nouyoux S. , Mallo P. , Braun O. 
Published: December 2007

Abstract
The present paper describes the first field application of a new water shutoff technology using size-controlled microgels for the treatment of a gas storage well.
The treatment was designed from an integrated study combining laboratory coreflood experiments and near-wellbore reservoir simulations. The candidate well (open hole completion with liner) was drilled in a sandstone reservoir formation made of a succession of layers with different petrophysical quality all connected each other. The presence of a thin high-permeability streak located in the bottom part of the open interval was assumed to be the main factor of excessive water production. A bullhead option was chosen for the treatment. Microgel size (around 2 micron) favored their placement in the high-permeability layer, whereas the penetration in the rest of the reservoir was expected to be very superficial.
The treatment was performed in June 2005. Due to pressure constraints, the volume of the treatment had to be reduced to 26 m3 only. A backflush of gas was necessary to recover gas injectivity. The well was kept on production during the whole winter season 2005-2006. Water production was significantly reduced thus enabling higher gas rate production. A positive impact on sand production was also observed. Well behavior was in good agreement with model predictions.
Effect of Production-Induced Stress Field on Refracture Propagation and Pressure Response
Authors: Weng X. , Siebrits E. 
Published: December 2007

Abstract
In this work, the propagation of an orthogonal fracture and reopening along the initial fracture during a refracture treatment is studied by taking into account the production induced stress field surrounding the initial fracture. It is shown that the propagation pressure of the orthogonal fracture quickly increases to above the closure stress on the initial fracture due to the fracture penetrating into the higher stress region, which leads to fracture reopening along the initial fracture plane (called in-plane frac hereafter). A dual-frac PKN model is developed to predict the growth of the two intersecting fractures in a variable stress field and the associated pressure response in order to obtain an insight into the refracture process. The modeling results show that a refracture treatment can undergo three distinct periods of fracture growth:
Period I: Dominant orthogonal fracture propagation. It exhibits a rapid pressure increase due to the stress increase at the tip of the orthogonal fracture.
Period II: Reopening of the initial fracture. This period shows a relatively flat pressure since the stress at the fracture tip is nearly constant.
Period III: Extension of the initial frac and the orthogonal frac. It exhibits steeper pressure increase (tip screen-out like pressure response) as the stress at the tip increases when the in-plane fracture propagates past the initial fracture tip. The in-plane fracture length growth is significantly slowed.
Two field cases from the Barnett Shale are evaluated by comparing the model prediction to the pressure response. The model prediction agrees well with the observed pressure response and surface tiltmeter observations. The production-induced stress has significant implications on refracture design and candidate selection and they are discussed for various reservoir scenarios.
Three-Phase Equilibrium Calculations for Compositional Simulation
Authors: Haugen K. B. , Sun L. , Firoozabadi A. 
Published: December 2007

Abstract
The combination of successive substitution and the Newton method provides a robust and efficient solution to the non-linear iso-fugacity and mass balance equations for two-phase split computations in compositional simulations. In the successive substitution, the non-linear Rachford-Rice equation introduces some complexity, but the Newton method in combination with the bisection method provides a robust solution. For three-phase split calculations, the literature indicates that the computed three-phase region is smaller than the measured data. Some of the computed results also show some inconsistency in the phase diagram when there is three-phase region. We have found that the solution to the two Rachford-Rice equations in three phases can solve the problem. Our proposal is deceptively simple. We use a two-dimensional bisection method to provide good enough initial guesses for the Newton method in solving the two Rachford-Rice equations. In this work, we provide examples of various degree of complexity to demonstrate how powerful the combined bisection-Newton method is in three-phase split calculations. The proposed method is both infallible and efficient. To the best of our knowledge, the use of the bisection method in two variables has not been attempted in the past.
Evaluation of a Renewable, Environmentally Benign Green Solvent for Wellbore and Formation Cleaning Applications
Authors: Berry Sandra L. , Boles Joel L. , Cawiezel Kay E. 
Published: December 2007

Abstract
Traditional aromatic and chlorinated solvents typically utilized in oilfield applications are facing stricter governmental and environmental restrictions for their use and disposal. Concerns about flammability, acute toxicity, and environmental contamination have made their use less attractive. Furthermore, many countries in Central and South America have begun to closely monitor and regulate the manufacture, importation, and storage of typically utilized oilfield solvents such xylene and toluene due to their utilization in the manufacture of illicit drugs.
In an effort to be environmentally and socially responsible, greener alternative solvents from renewable resources are continually being investigated as possible cleaning and solvent solution substitutes. This paper discusses the properties and evaluation of a 100% biodegradable non-toxic solvent blend that is derived from two renewable resources produced both in the U.S. and world. In the past, due to its price and limited availability, the solvent’s use has been limited to specialized cleaning applications in the electronics industry. However, due to improved manufacturing processes, the product is more available and affordable for wider applications. The totally biodegradable solvent blend is currently being utilized heavily in paint and coatings removal, ink and graffiti removal, and electronics component cleaning. It has a Kauri Butanol (KB) solvency value of approximately 500 and is a EPA approved SNAP solvent.
This paper discusses the evaluation of the biodegradable solvent blend to replace traditional solvents in stimulation packages for wellbore and formation cleaning applications. Laboratory studies were conducted to evaluate the solvent’s efficiency to dissolve and remove pipe dope materials and OB/SOB mud residues and films at room temperature and 150°F. The solvent was also evaluated to determine its efficiency to dissolve and disperse paraffin and asphaltene solids, and to reduce the viscosity and enhance the flow characteristics of heavy crude oils.