bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Microseismic Monitoring as a Real Time Completions Diagnostic Tool in Unconventional Reservoirs: Field Case Studies
Authors: Ajayi Babatunde , Walker Kirby , Sink John , Wutherich Kevin , Downie Robert
Published: December 2011

Horizontal wells drilled in unconventional gas reservoirs are often completed by combining multiple perforation clusters in a hydraulic fracture treatment stage. Each treatment stage is typically prevented from communicating by using an isolation plug. It is a challenge to design a limited entry completion that comprehensively ensures that all perforation clusters are equally stimulated within a treatment stage (Miller et al, 2011, Mcdaniel et al, 1999). Slippage or failure of isolation plugs have also been known to occur during treatment execution and in many cases, these failures are discovered only after the well stimulation has been completed. This paper presents three case studies in the Marcellus Shale where real-time microseismic Hydraulic Fracture Monitoring (HFM) was used to evaluate the behavior and development of the induced fracture and a need for the corrective intervention was observed. In one of the cases, an innovative corrective action was implemented and microseismic results show that the intervention was successful.

This study shows how real-time microseismic monitoring can been used for not only evaluating fracture geometry and azimuth but can also be used as a diagnostic tool for observing operational failures in completion tools as well as making real-time changes to completion design in order to improve completion efficiency. Some of the potential failures that may be diagnosed using HFM analyzed in this study include loss of isolation between hydraulic fracture stages, breach in casing integrity, poor cement bond in annulus and confirmation of plug ball seating.

The first case study describes a hydraulic fracture treatment where the real-time HFM interpretation was useful in identifying a failure in the isolation plug between completion stages. This observation during the treatment execution was later confirmed by tagging the depth of the plug during coiled tubing operations. A production log was also run in the well and showed limited production contribution from the stage with the plug failure. The other two case studies address the use of real-time HFM interpretation to identify undesired fracture growth into an already stimulated region. Subsequent intervention by using an isolation plug between perforation clusters as a means of diversion was implemented in one of the cases.

These examples clearly show how real-time microseismic monitoring can be used to adapt conventional completion designs to the dynamic nature of completion operations in the field. The paper also highlights the innovative use of an isolation plug as a diversion mechanism during fracture treatment.
Modeling and Simulation of Gas and Liquid Flow in Tight Gas Sand
Authors: Khlaifat Abdelaziz , Qutob Hani , Arastoopour Hamid
Published: December 2011

Gas production from tight gas sands is vital for developing secure unconventional sources of energy. The porous media considered in this paper belong to tight gas reservoirs characterized by extremely low permeability (range of microdarcies) and low porosity (less than 7%) matrix. The transient, three dimensional, two-phase numerical model is presented for simulating the simultaneous gas and water flow through tight gas sand. The solved continuity and momentum equations treat both fluids as incompressible and immiscible. Darcy's and nondarcy's laws were incorporated into the equations to couple them by a fluid transfer term which depends on the potential difference between different specified physical domains. Also, the model accounted for the effect of capillary pressure and relative permeability. The numerical solution was obtained using the modified CFX-Flow3D code. Finite volume approach was used to discretize the equations. The set of discretized and linearized equations were solved using the inter-phase slip algorithm (IPSA) method. The simulation was applied to some obtained results in the laboratory experiments and predicted two-phase flow behavior. Calculated two-phase flow rates reflect the sensitivity of fluid flow to gas and liquid permeability in tight gas sand. The calculated flow behavior agrees reasonably well with experimental drainage, imbibition and two-phase flow behaviors.
The Role of Formation Damage in Hydraulic Fracturing Shale Gas Wells
Authors: Guo Boyun , Gao Deli , Wang Quanjun
Published: December 2011

Producing natural gas from shale gas presents a unique challenge to the petroleum engineers because of the low permeability nature of this type of gas reservoirs. Large scale hydraulic fracturing operations are often required for enhancing gas well productivity. Due to the shally characteristics of the reservoir rock, the productivity of the hydraulically fractured gas wells is very vulnerable to the damage by the fracturing fluids. The damaging mechanisms have been recognized to include fluid invasion, proppant embedment, gel filter cake at the fracture face, and the gel residue in the proppant pack. The relative significances of the well damage due to different mechanisms are not clear. It is highly desirable to have an analytical method for predicting the relative importance of different types of damage and optimizing fracturing treatment accordingly. This paper presents such a model and observations from model analyses.

A new mathematical model was developed in this study to predict the effects of fracture fluid filtration, proppant embedment, gel filter cake at the fracture face, and the gel residue in the proppant pack on the productivity of fractured gas wells in shale gas reservoirs. A unique feature of the new model is that it considers reservoir-fracture cross-flow in wells with long fractures and non-linear influx to wells with short fractures. Sensitivity analyses with the model show that, among the investigated four mechanisms, the fluid invasion should have the most detrimental effect, while the formation of proppant-embedment layer should have a negligible effect on the productivity of fractured wells in shale gas reservoirs.
Case Studies: Improved Performance of High Brine Friction Reducers in Fracturing Shale Reserviors
Authors: Paktinat Javad , O'Neil Bill , Tulissi Michael
Published: December 2011

The primary purpose of friction reducers (FR’s) used in stimulating shale reservoirs is to overcome tubular friction pressure and establish high pumping rates. Slickwater (or water frac treatments where friction reducers are used as main source of reducing tubular pressure) fracturing has increased significantly with the advent of horizontal shale stimulation. Technologies, including multi-stage fracturing of horizontal wells have increased frac volume requirements per well. Recent restrictions limiting fresh water usage and environmental concerns of flowbacks have created challenges for operators to adopt mechanical and chemical water treatment means to remove impurities from flowbacks for reuse in slickwater fracturing. However, most treatments do not remove brines from the water requiring development of high brine tolerant friction reducer to maintain high performance.

This study presents experimental and case studies of various cationic and anionic FR’s of the similar molecular weight in high brine flowbacks collected from two major shale plays. Finger print water analyses of shale reservoirs were used as brine source for evaluation. Dynamic friction loop flow apparatus was used to evaluate the rheological properties and formation damage of the FR where high brine waters are being used as the main source of slickwater fracs.

Field data collected for two case histories document the ability of the high brine tolerant friction reducers to perform at a level consistent with traditional products used in fresh water. This confirms the experimental flow data obtained from dynamic friction loop investigations. Results obtained from this study can be used to optimize slickwater frac treatments where flowbacks are the main source of frac water. Primary objectives include.Comparison studies of new high brine tolerant friction reducer with conventional FR’s used in the oilfield.Experimental data illustrating the performance of newly developed FR’s in high brine shale flowbacks. Cost advantage can be realized by using less polymer, while reducing fresh water and disposal of the flowbacks.(will be addressed at a later publication)Case studies of wells treated with the new friction reducers show performance in brines similar to these achieved with conventional FR’s when used in fresh water.
Recent Stimulation Results in the Weir Sandstone
Authors: Hoffman Kurtis Z. , Tellers John H. , Krcek Robert H.
Published: December 2011

The Weir zone in West Virginia is comprised of three separate sandstones that are Lower Mississippian in age and fall within the Price formation. The Weir sandstone of southeastern West Virginia is characterized by a near shore fluvial dominated delta front environment causing a gas bearing reservoir. Stimulation of the Weir sandstones is necessary for economic recovery of gas reserves.

This study provides background on the Upper Weir sandstone of McDowell, Mercer and Wyoming counties of West Virginia and focuses on historical stimulation treatments involving parameters such as amount of proppant and injection rate influencing the Estimated Ultimate Recovery (EUR). An extensive database containing geology, completion, stimulation and production data from the Upper Weir sandstone in southeastern West Virginia was utilized in this study. Single zone completion and adequate production history, greater than 12 months, were the criteria for well selection from the database of Weir wells in the southeastern West Virginia area. The total proppant placed was the major contributing factor in the resultant EUR. Increasing the total proppant not only increases the EUR but also decreases the number of wells to effectively drain the reservoir. From the results, economic analysis was completed to provide guidelines to achieve economic recovery from the Upper Weir sandstone in southeastern West Virginia.
DoReMi-A Passive Geophysical Monitoring Technique for CO2 Injection
Authors: Chen Shen-En , Liu Yangguang , Wang Peng
Published: December 2011

The carbon dioxide (CO2) injection at the Citronelle Oil Field in Alabama has been deployed since December 2009. The injection of the first 7,500 tons of CO2 has been completed in September 2010. To monitor the CO2 injection process and determine the potential for geological changes that may occur because of the injection, geophysical testing has been used at the site: a Derivative of Refractive Microtremor (DoReMi) method using wireless sensor has been conducted for acquiring ground motion in October 2008, January 2009 and June 2009, prior to injection, and again in December 2009, March 2010, May 2010 and September 2010, during injection, and after injection in November 2010, March 2011 and May 2011. The measurements were made at well sites along two linear arrays running from north - south and from northeast - southwest. The outcomes of the geophysical monitoring at the Citronelle Oil Field are shear-wave velocity profiles that are correlated to the static stress distribution at different injection stages. It is noticed that the pressure in the oil production layer and overburden strata at the time of water injection and CO2 injection has already built up in the entire monitored region. The results of the geophysical monitoring for the pilot injection will aid oil field operators in decision making for the future commercial-scale reservoir management strategies.
Pressure Transient Characteristics of Hydraulically Fractured Horizontal Shale Gas Wells
Authors: Cheng Yueming
Published: December 2011

Shale gas wells require a long horizontal lateral intersecting multiple hydraulic fractures to be economically viable. Because of the nature of ultralow permeability of shale matrix, it would take a significant long period of time for a well producing in transient flow regimes. Therefore, pressure transient characteristics for such a gas well is of considerable importance in both evaluation of fracturing treatment by estimating fracture and reservoir parameters and prediction of the long-term production behavior of wells in gas recovery.

The pressure transient response for a horizontal shale gas well with multiple transverse fractures is controlled by a specific combination of reservoir properties and well configuration. Focused on Marcellus shales, this paper investigates the characteristics of pressure transient response under a number of factors and flow mechanisms. The factors that are considered include matrix permeability, conductivity of hydraulic fractures, cluster spacing, and size/enhanced permeability of stimulated zone. The impacts of gas desorption and stress-dependent fracture conductivity on pressure transient behavior are also illustrated. This study provides insights into the pressure transient characteristics during shale gas well production.
Modeling Chemically Induced Pore Pressure Alterations in Near Wellbore Region of Shale Formations
Authors: Huang Lu , Yu Mengjiao , Miska Stefan , Takach Nicholas , Bloys J. B.
Published: December 2011

Instability issues often occur when water-based muds are applied to shale formations. Failure to predict the pore pressure accurately has been widely accepted as one of the major reasons causing shale instability. Water activity is a key factor to control the pore fluid moving in and out of the formation due to osmotic effects. Ideal and single-solute models have been developed in the past to predict the pore pressure by considering chemical osmotic effects. However, due to their complex nature, pore fluids/drilling fluids rarely behave as ideal solutions. A new model has been developed to predict pore pressure in shale formations that takes into account the non-ideality and multiple solutes of both drilling fluid and pore fluid. Transient pore pressure profiles and water activity are obtained from the coupled equations developed in this study. A Shale-Fluid Interaction Testing Cell (SFITC) has been developed in this study to test the interaction between the drilling fluid and the pore fluid. Parameters involved in the model, such as hydraulic conductivity, membrane efficiency and ion diffusion rate can be obtained through experimental data curve fitting. Model predictions have been compared with lab data and good agreement has been achieved. Water activity is found to be crucial for pore pressure control in shale formations. Simulation results explain the fact that salinity of drilling fluids has to be controlled in order to achieve shale stability. Results of this study can benefit drilling fluid design. Shale instability can be reduced by "balancing" the water activities of shale and drilling fluid. This can be achieved through changing the type of solutes and their concentrations based on information of the initial water activity of the shale. Wellbore stability models can obtain more accurate results by including the proposed pore pressure propagation model, which considers drilling fluid-induced chemical osmotic in-situ stress.
Numerical Dispersion Impact on Local Mixing in Heterogeneous Reservoirs
Authors: Rouzbeh Ghanbarnezhad M.
Published: December 2011

Dispersive mixing degrades field-scale miscible displacements through dilution of the injected solvent. This paper examines how local mixing owing to pore scale heterogeneity compares with the apparent mixing caused by numerical dispersion in heterogeneous permeable media. The numerical dispersion is associated with the truncation error inevitably introduced in finite difference approximations of the conservation equations.

In this study, the finite difference form of the convection-dispersion equation is derived to determine the numerical dispersion coefficients when flow velocity varies with distance. In addition, a simulation approach is used to evaluate local mixing in heterogeneous permeable media. The simulation models consist of an injector and a producer located at the ends of a two-dimensional grid. The simulations are performed with a fixed total dispersivity and different ratios of numerical to physical dispersivities. The local mixing for each grid block is determined through matching the concentration history to solution of the convection-dispersion equation.

Furthermore, spatial distribution of the local mixing caused by dissimilar sources of dispersivity is examined; geostatistics functions (the autocorrelation coefficient function and the semivariance) are determined for different separation distances. Autocorrelogram and variogram plots illustrate the variation of dispersivity in the longitudinal direction.

It turns out that the off-diagonal elements of the numerical dispersivity tensor are twice as large as in homogeneous reservoirs when the velocity changes with distance. Furthermore, the results indicate that the local mixing and the corresponding spatial distributions are considerably different when dissimilar ratios of numerical to physical are implemented. The different spatial distribution of local mixing explains why the growth of mixing zone is not characterized properly when considerable numerical dispersion is present. In addition, the results suggest that adjusting the size of grid blocks to account for the physical dispersivity is not appropriate in heterogeneous permeable media.
Channel Hydraulic Fracturing and its Applicability in the Marcellus Shale
Authors: Ajayi Babatunde , Walker Kirby , Wutherich Kevin , Sink John
Published: December 2011

Gas wells in the Marcellus shale are usually completed with a hydraulic fracture treatment in order to create a conductive proppant pack for fluid flow to the wellbore thus effectively increasing well productivity. A novel hydraulic fracture technique which creates a network of open channels within the created fracture has recently been introduced to the oil and gas industry with over 1400 successful treatment stages pumped in other ultra-low permeability, gas-bearing unconventional reservoirs. Channel fracturing boasts higher fracture conductivity and better fracture cleanup amongst its other claims. This paper reviews the applicability of the novel hydraulic fracturing technique in the Marcellus shale and details a case study investigating the possible production gains that may be obtained when channel fracturing is applied in this play.

This feasibility study briefly describes the Channel Hydraulic Fracturing technique and investigates the geophysical properties of the Marcellus shale to see if Channel fracturing is applicable in the play. The methods employed involves analyzing over 160 well logs spread across the Marcellus shale in order to create a grid map of counties and regions within the Marcellus Shale area that meet the criteria required for the applicability of the new technology. The technique is then compared to conventional hydraulic fracturing by reviewing initial production results from a Marcellus well with a conventional hydraulic fracture and performing production analysis and history matching using a production analysis software package. The conventional hydraulic fracture parameters are then replaced with channel fracturing parameters to obtain incremental production estimates.

The results of the study indicate that the Channel Fracturing technique is applicable without in most areas of the Marcellus shale play. The results of the simulation and case study show increased gas production from the new technique over conventional fracturing methods.
Perforation Shaped Charge Design for Shale Produces Improved Tunnel Geometry
Authors: Hardesty J. , Clark N. , Bell M. R. , Zaleski T.
Published: December 2011

The perforation of wellbore casing is a critical step in establishing communication between the wellbore and formations of interest. The effectiveness of this communication is dependent upon both the geometry of the perforations and the permeability distribution of altered material surrounding them. To date, our understanding and modeling of this geometry and permeability distribution has been limited to simple representations consisting of cone-shaped tunnels surrounded by a damaged layer exhibiting a constant, reduced permeability - typically of constant thickness. These models are based mainly on performance evaluations conducted in cement targets, and less frequently upon performance tests with stressed sandstone targets. This methodology influences our thinking regarding many post perforation process, including fracture completions, but breaks down when estimating perforation performance in shale formations.

This paper describes a body of experimental work with perforation simulation in a state of the art API RP-19B Section 4 facility. Tests are conducted in shale targets with a variety of shaped charge designs. The perforation tunnels are evaluated for geometry and performance using next generation CT scan imaging techniques. The results of this study show that perforation geometry produced in shale targets is significantly different from that produced in cement or sandstone targets commonly used to estimate perforation performance and that changes in shaped charge design can produce significant geometry improvements not recognizable by selection and evaluation in conventional targets.

In addition a field case comprised of 14 wells and 81 stimulation stages is presented demonstrating the potential improvement that can be obtained by using shaped charges designed for maximum performance in shale formations. When comparing wells perforated with improved charges to conventionally perforated offsets, a reduction in breakdown pressure gradient of between 13% and 29% is observed. Subsequent treating pressures are reduced by 6% to 15%.
Improved Predictions of Porosity from Microresistivity Logs in a Mature Field through Incorporation of Pore Typing
Authors: Teh Woan Jing , Willhite GP , Doveton JH , Tsau JS
Published: December 2011

The value of m is critical in making estimates of water saturation. "Rule of thumb" values of cementation might lead to errors in water saturation on either the optimistic or the pessimistic side. In a mature field, developed during the 1950s, no porosity logs were available from sources other than the flushed zone resistivity Rxo. The microresistivity porosity was calibrated with the core porosity to yield an accurate estimate of the porosity. However, the procedure of calibrating the porosity with Rxo for a linear regression model may not be sufficiently predictive without an understanding of the pore types in the reservoir interval. A thorough investigation of the pore types, based on the lithofacies description obtained from the core analysis, and its role in obtaining a good estimate of porosity is demonstrated in the Ogallah field. Therefore, the objective of this paper is to separate the porosity-microlog data into pore-type based zones with characteristic cementation exponents (m) in this multi-petrotype reservoir with a complex mixture of Arbuckle dolomite and sandstone rock.

The rock types in the Ogallah contain interparticle/intercrystalline, vugs and fractures distributed through the rock-facies, which influence the values of cementation factor. Rock fabric numbers and flow zone indices have been identified for classification of dolomite and sandstone, respectively. The analysis brings out characteristic cementation factors for distinct pore types in the Arbuckle rock. The analysis results also compliment the petrofacies delineation using discrimant analysis in this complicated rock layout as a quality control of the statistical application. The comparison between the predicted and core porosities shows a significant improvement over using a single m-value for carbonates and sandstones which will lead to improved description of a matured field.
The Impact of Stress and Formation Properties on the Outcome of Fracture Operations in Horizontal Shale Wells
Authors: Bilgesu H. I. , Yusuf A.
Published: December 2011

The natural gas production is gaining importance as a clean source of energy. Several potential sources exist for gas production in the Appalachian Basin with the Marcellus shale being the largest resource in the U.S. This covers several states in the Eastern U.S. and plays a vital role in the future of gas production. As a result operators are interested in the development of the shale resources mostly with multi-stage fractures using a horizontal well. However, the lack of commercially available information on well and treatment designs is rather vague. This information is critical in the determination of economics of gas production from shale wells.

In this study, simulations have been conducted to determine the gas production from horizontal shale wells when limited data is used in the design of fracturing operations. Some of the parameters studied include horizontal and vertical stresses, the amount of fracture stages and formation properties along with others. The same treatment can yield different fracture geometry due to changes in formation properties; however, the gas production values after a single fracture treatment were similar for cases considered in this study.
Successful Geosteering in Low Resistivity Contrast Reservoirs of the Permian Basin
Authors: Kok Jeffrey , DeJarnett Jeff , Geary Daniel , Vauter Eric
Published: December 2011

The Permian Basin of West Texas and New Mexico is a prolific brownfield that produces from numerous clastic and carbonate horizons. Some of these reservoirs are composed of several separate thin tight sands ranging from 6 to 11 feet. Historically, these thin bed formations were bypassed because of lack of production in vertical wells. To economically exploit hydrocarbon reserves from these thin beds, maximum reservoir contact within a single layer or commingled across reservoir layers off a horizontal well path is necessary. To maintain or steer the well within these thin reservoirs, distinct log responses across the reservoir is needed for lateral correlations and well trajectory steering. Unfortunately in the thin reservoir realms such as those encountered in the Permian Basin, a lack of contrast in log measurements, such as gamma ray and resistivity, often results in poor geosteering decisions with the consequence of high costs in well construction. Advances in horizontal and LWD technology now offers real-time placement accuracy using proactive bed boundary mapping technology that incorporates a sophisticated arrangements of resistivity transmitter-receiver arrays. It is well understood in the technical domain that log measurements require a degree of change in formation log response for steering applications. However, in low log measurement contrast reservoirs, deep directional curve measurements are currently the optimum alternative for well positioning interpretation.
Pressure-Pressure Deconvolution Analysis of Multiwell-Interference and Interval-Pressure-Transient Tests
Authors: Onur M.. , Ayan C.. , Kuchuk F.J.. J.
Published: December 2011

This paper investigates the use of pressure-pressure (p-p) deconvolution for interpretation of conventional multiwall-interference and wireline-formation-tester (WFT) interval pressure-transient tests (IPTTs). The investigation is limited to interference tests for which only a single source/sink well exists in a single-layer system. It is shown that the recent deconvolution algorithms developed for pressure-rate (p-r) deconvolution based on the same assumptions (i.e., a single source/ sink well) can also be used for performing p-p deconvolution by simply replacing the rate data in p-r deconvolution algorithms by the pressure data recorded at a source/sink location or at one of the observation locations. We apply p-p deconvolution to both synthetic and field-transient test data sets from IPTTs and multiwall-interference tests. Specifically, we investigate the applicability of p-p deconvolution for inconsistent data sets, where wellbore storage and skin may change from one flow period to another one. The results show that the impulse functions deconvolved from p-p deconvolution have signatures for various flow regimes (e.g., radial, spherical, linear) that are similar to from p-r deconvolution except from the pseudosteady-state (pss)-flow regime. Therefore, p-p deconvolution can also be used for model identification in the similar way based on p-r deconvolution algorithms, without requiring the flow-rate information.
Water Mixing During Waterflood Oil Recovery: The Effect of Initial Water Saturation
Authors: Graue Arne , Fernø Martin A. , Moe Robert W. , Baldwin Bernard A. , Needham Riley
Published: December 2011

This work studies the mixing of injected water and in-situ water during waterfloods and demonstrates that the mixing process is sensitive to the initial water saturation. The results illustrate differences between a waterflooded zone and a preflooded zone during, for example, water-based EOR displacement processes. The mixing of in-situ, or connate, water and injected water during laboratory waterfloods in a strongly water-wet chalk core sample was determined at different initial water saturations. Dynamic 1D fluid-saturation profiles were determined with nuclear-tracer imaging (NTI) during waterfloods, distinguishing between the oil phase, connate water, and injected water. The mixing of connate and injected water during waterfloods, with the presence of an oil phase, resulted in a displacement of all connate water from the core plug. During displacement, connate water banked in front of the injecting water, separating (or partially separating) the injected water from the mobile oil phase. This may impact the ability of chemicals dissolved in the injected water to contact the oil during secondary recovery and EOR processes. The effect of the connate-water-bank separation was sensitive to the initial water saturation (Swi). The time difference between breakthrough of connate water and breakthrough of injected water at the outlet showed a linear correlation to the initial water saturation Swi. The results obtained in chalk confirmed earlier findings in sandpacks (Brown 1957) and thus demonstrated the generality in the results.
Wettability Studies Using Low-Salinity Water in Sandstone Reservoirs
Authors: Alotaibi M.B.. B. , Nasralla R.A.. A. , Nasr-El-Din H.A.. A.
Published: December 2011

The ionic strength of injection water can have a major impact on oil recovery resulting from the use of low-salinity brines. Understanding how the water and oil chemistry affects the final recovery from a physicochemical point of view is necessary in order to optimize low-salinity waterflooding. It is clear from the literature that wettability is a key factor in achieving the low-salinity effect. Optimum ionic strength and conditions for low-salinity flooding with respect to wettability are still uncertain.

In this paper, we studied fluid/rock interactions at different salinity levels and elevated temperature conditions in terms of wettability and surface charge. Wettability is determined by a high-temperature/high-pressure (HT/HP) contact-angle method and zeta-potential technique. Outcrop rocks and stock-tank crude-oil samples were used in all experiments. Synthetic formation brine water, aquifer water, and seawater were evaluated under high-pressure conditions. Zeta potential of sandstone rocks and selected clay minerals was measured as a function of ionic strength.

Wettability of oil/brine/sandstone systems depends on salinity, temperature, and rock mineralogy. Using aquifer water in Berea sandstone improved the wettability toward a water-wet condition. The same aquifer water behaved in a different way when a different sandstone surface was tested. In Scioto sandstone, aquifer water changed the wettability to a neutral state. Low-salinity water expanded the double-layer thickness and eventually increased the zeta-potential magnitude. As a result of this expansion, it provides a greater opportunity to alter the wettability and enhance oil recovery. This study indicates that clay content in sandstone rocks can significantly alter the wettability either toward water-wet or intermediate. On the basis of the results obtained from this study, it is clear that low-salinity waterflooding can improve oil recovery in the field.
Successful Laboratory Testing of Practical Methods of Hydraulic-Control-System Failure Diagnosis Using Valve Signatures
Authors: An Hailing , Tanju Baha
Published: December 2011

The two hydraulic-diagnostic methods detailed in this paper can monitor the "health" of a subsea hydraulic-control system, diagnose or predict a system problem (particularly leaking or clogging problems), and locate its source by using readily available valve-signature data.

The methods were tested in a laboratory environment using a hydraulic system with simulated clogging and leaking mechanisms. Leak detection was performed using both signature-matching and mass-balance methods. The results showed a mean accuracy of 93% for mass-balance method and 82% for the signature-matching method. Clog detection by signature matching showed high accuracy in the controlled laboratory condition. The difference between the simulated and actual clogging is within 1%.

The methods provide a monitoring tool for detecting and locating potential leaks, blockages, and other system changes or anomalies, which could be used to estimate the potential high cost of intervention, possible downtime, and lost revenue.
A Comprehensive Model of High-Rate Matrix-Acid Stimulation for Long Horizontal Wells in Carbonate Reservoirs: Part II—Wellbore/Reservoir Coupled-Flow Modeling and Field Application
Authors: Furui K.. , Burton R.C.. C. , Burkhead D.W.. W. , Abdelmalek N.A.. A. , Hill A.D.. D. , Zhu D.. , Nozaki M..
Published: December 2011

Successful acid stimulation of long-horizontal-well intervals in carbonate reservoirs requires effective acid distribution along the entire reservoir length. Such treatments also require large volumes of acid and seawater/brine injection at sufficiently high injection rates to drive the acid wormholes deep into the reservoir. Under these flowing conditions, significantly large tubing friction loss is anticipated unless optimal friction reducer performance in the tubing is maintained throughout the pumping operation. Because prediction of wormhole penetration and corresponding skin factor depends on analysis of downhole-injection pressures at the reservoir face, it is crucial to properly account for these hydrostatic and friction changes prior to evaluation of wormhole length and skin factor.

In this study, an integrated flow model has been developed to predict the wellbore-pressure profile and wormhole distribution by tracking the movement of the acid in the wellbore and the formation. The wellbore-flow model is based on steady-state, 1D, pressure-based nodal method. The segmented wellbore in the reservoir interval is then coupled with analytical transient reservoir-flow models. The wormhole propagation in the formation is calculated based on the modified Buijse-Glasbergen correlation and upscaling model developed in our earlier work. The resultant wormholing skin factor is calculated by simulating and updating the changing well injectivity along the entire injection interval at every timestep. The model developed in this work is applicable for both fully completed wells (i.e., radial flow) and selectively completed perforation-cluster wells (i.e., spherical flow) typically employed in carbonate reservoirs.

Analysis of injection rates and pressures during acid treatment provides engineers with a way to determine the varying injectivity and tubing friction as stimulation proceeds. The model presented here can be used as a forward model for analyzing real-time treatment rate and pressure histories and can also be used to review past treatments to improve future treatment designs. Using actual field-stimulation data, we also discuss key elements to successful stimulation planning and the diagnosis of matrix-acid treatments to achieve effective wormhole coverage for horizontal completions in carbonate formations.
Promoting Job Safety for Workers with Intellectual Disabilities: The Staying Safe at Work Training Curriculum
Authors: Dewey Robin
Published: December 2011

In the United States, approximately 125,000 people with disabilities are employed through Community Rehabilitation Programs in manufacturing, assembly, and service jobs. These jobs have significant hazards and, consequently, the workers are at risk of injury. Training that empowers workers to participate in prevention efforts can help reduce work-related injuries. In general this kind of health and safety training in the United States is limited. It is even more so for workers with intellectual disabilities, in part because there have not been programs for teaching individuals with cognitive challenges health and safety skills, adapted to their learning needs. This paper describes the development and promotion of the Staying Safe at Work curriculum of UC Berkeley's Labor Occupational Health Program, which is designed for use by support agencies and employers of workers with intellectual disabilities. The goal of this program is to teach these workers essential occupational safety and health skills in a manner they can understand.
Ban Asbestos Phenomenon: The Winds of Change
Authors: Kazan-Allen Laurie
Published: December 2011

The shift in the public perception of asbestos from “magic mineral” to “deadly dust” owes much to the mobilization by asbestos victims, ban-asbestos activists, health and safety campaigners, and individuals concerned about the global asbestos death toll. Cognizant of the proven links between asbestos and disease, governments of industrialized countries banned further use, as a result of which consumption shifted to developing countries; between 2000 and 2010, asbestos use in Asia grew dramatically. In the face of a powerful industry lobby, members of the ban-asbestos network have lobbied national governments to outlaw asbestos use, challenged industry propaganda, and cooperated with social partners on coordinated multinational initiatives. Major developments in the campaign to end the mining, sale, and use of asbestos which have taken place over the last 50 years are delineated in this paper.
How do International Financial Flows to Developing Countries Respond to Natural Disasters?
Authors: David Antonio C.
Published: December 2011

This paper uses multivariate dynamic panel analysis to examine the response of international financial flows to natural disasters. The models estimated for a large sample of developing countries point to differentiated responses of specific types of financial flows. The results show that remittance inflows increase significantly in response to shocks to both climatic and geological disasters, thus confirming their compensatory nature. The models suggest a nuanced role for foreign aid. While the responses of aid flows to natural disaster shocks in general tend not to be statistically significant, international assistance to low income countries increases following geological disaster shocks. Furthermore, the results show that typically, other private capital flows (bank lending and equity) do not attenuate the effects of disasters and in some specifications, even amplify the negative economic effects of these events.
Prognostic significance of tympanosclerotic plaques localization and their morphological and histological characteristics for the outcome of surgical treatment
Authors: Milojevic Milanko , Djeric Dragoslava , Bijelic Dusan
Published: December 2011

Background/Aim. Tympanosclerosis is a sequela of inflammation of the middle
ear usually causing conductive hearing loss. The aim of the study was to
determine the significance of tympanosclerotic plaques localization in the
middle ear and their morphological and histological characteristics for
surgical treatment outcome. Methods. This retrospective study included a
total of 73 patients operated on for tympanosclerosis in the Clinic for
Otorhinolaryngology, Military Medical Academy (MMA) in a period 1996-2010.
The results of surgical treatment as well as the last audiometry findings
were analyzed. considering follow-up periods of 6 months to 8 years. The
patients were divided into 4 groups according to tympanosclerotic plaques
localization in the middle ear and the classification suggested by Wieling
and Kerr. The patients were also divided based on intraoperatively noticed
morphological characteristics of tympanosclerotic plaques, while the third
division was done as per histological findings. Surgical success was assessed
using the suggestions of the Japan Otological Society. Results. The analyzed
results showed the surgical success especially in the group II according to
Wieling and Kerr, while histological findings had no impact on the outcome of
the surgery. Conclusion. Surgical treatment has good results especially in
patients with the mobile stapes. Results are satisfactory in other
localizations, while various morphological and histological characteristics
do not have impact on the surgery outcome.
Exploiting and Sharing Tax Benefits: Seagram and DuPont
Authors: Erickson Merle M. , Wang Shiing-wu
Published: December 2011

In April 1995, Seagram sold 156 million DuPont shares back to DuPont for $8.8 billion to finance its acquisition of MCA. Clever structuring of DuPont's redemption generated tax savings of approximately $1.8 billion for Seagram and DuPont. DuPont captured about $800 million of the total tax benefits in return for facilitating the tax-saving structure. In spite of tax benefits of approximately $1 billion, Seagram's equity value declined by more than $2.5 billion in response to the DuPont redemption/MCA acquisition. Our analyses provide some evidence that a portion of these wealth effects are attributable to the loss of DuPont's earnings, which accounted for approximately 65 percent of Seagram's reported profits. As part of the financial accounting for the DuPont sale, Seagram recorded a $1.5 billion deferred tax liability and this financial accounting liability appears to be significantly overstated in economic terms.
Discussion of Economic Foundations of Valuation Discounts
Authors: Macnaughton Alan
Published: December 2011

The purpose of the Sansing (1999) paper is to bring some rigor to the fuzzy and contentious area of valuation discounts. This is worthwhile as valuations are seldom dispassionate searches for the truth. Sometimes the taxpayer's goal is to inflate the value, as in the case of a charitable donation; in other situations, such as for estate and gift taxes, the desire is to obtain a low value.

The first part of the discussion considers discounts for lack of marketability, while the second part considers minority discounts and integrates the two types.
The Effect of the Formulary Apportionment System on State-Level Economic Development and Multijurisdictional Tax Planning
Authors: Lightner Teresa
Published: December 2011

This paper examines the effect of the formulary apportionment system on state-level economic development. All three apportionment factors, when combined with the corporate tax rate employed by each state, are shown to have a significant negative association with the percentage change in manufacturing employment. However, further analysis suggests that the corporate tax rate, and not the apportionment formula, may be driving employment growth. Also, the findings do not support the importance of the throwback rule or the recent trend to overweight the sales factor in attracting economic development to a state.
Discussion of Contextual Features of Tax Decision-Making Settings
Authors: Cloyd C. Bryan
Published: December 2011

Tax practice has evolved over the past decade from being predominantly concerned with tax compliance to a major focus on tax planning. Significant challenges for researchers interested in tax professional judgment and decision making (JDM) are (1) understanding the current environment of tax professionals, (2) identifying research questions that are relevant to this environment, and (3) appropriately capturing the essential elements of the current environment in the experimental setting.

The research question addressed in Magro (1999) is related to this first challenge—understanding the current environment or context in which tax professional JDM occurs. Specifically, the research question addressed in this study is whether experienced tax professionals perceive differences between certain contextual features of tax-planning and compliance tasks.
The Influence of Tax Costs on Organizational Choice in the Natural Resource Industry
Authors: Omer Thomas C. , Plesko George A. , Shelley Marjorie K.
Published: December 2011

This study investigates the influence of TRA86, pre-TRA86 tax strategies, and firm characteristics on S conversions in the natural resource industry. TRA86 shifted substantial individual tax costs to corporations, inviting conversions, but also lowered corporate marginal tax rates and changed aspects of the built-in gain provision to reduce conversion benefits. Built-in gain changes affect industries differently because of differences in asset composition and economic conditions. The natural resource industry had substantial built-in gain potential and was consolidating and restructuring during the mid-80s, making built-in gain realization likely. Our results suggest that built-in gains negatively influenced conversions in the natural resource industry. This study enhances our understanding of the interaction between TRA86 rate changes and other provisions on incentives to convert from C to S corporate status. It also contributes to the organizational form literature by identifying factors related to TRA86, S corporation operating restrictions, firm characteristics, and tax strategies that influence conversion decisions.
Capital Investment Effects of Dividend Imputation
Authors: Black Ervin L. , Legoria Joseph , Sellers Keith F.
Published: December 2011

We examine the effects of dividend imputation on corporate capital investment in New Zealand and Australia. The empirical findings indicate that: (1) dividend imputation stimulated corporate capital investment in both countries; (2) the positive impact of dividend imputation on capital investment overshadowed any negative effects arising from the new capital gains tax imposed in Australia; and (3) the dividend imputation effects on capital investment are most pronounced for highdividend-paying firms. In summary, we demonstrate the positive impact of dividend imputation on corporate capital investment. Our findings support the conclusions of the U.S. Treasury that the “traditional” double tax on corporate distributions increases the cost of equity capital to the corporate sector and creates a bias against investment by the corporate sector.
Confirmation Bias in Tax Information Search: A Comparison of Law Students and Accounting Students
Authors: Cloyd C. Bryan , Spilker Brian C.
Published: December 2011

Tax professionals frequently perform research to evaluate the strength of client favorable tax positions. Prior research suggests that when performing research, tax professionals tend to focus their attention on precedents with conclusions consistent with their client's preferred outcome and attend less to precedents with conclusions inconsistent with this outcome. This confirmation bias causes professionals to be overly optimistic about the strength of the authoritative support for clientpreferred positions. Despite the potential problems that may arise with confirmation bias, research has yet to consider factors that may mitigate this behavior. Using an experiment that compares the information search behaviors of law students and accounting students, this study provides evidence that the nature of academic training influences the extent to which tax researchers are subject to confirmation bias. Specifically, we find that when conducting research to resolve an ambiguous tax issue, law students are less prone to the bias in certain situations than are Masters of Accounting students. The finding that training may mitigate confirmation bias in tax research has implications for tax professional education and tax practice.