bluuebunny/crossref_metadata_2025 huggingface dataset:
An Investigation of PVT Effects on Geochemical Fingerprinting of Condensates From Gas Reservoirs
Authors: Al-Meshari Ali A. , Kokal Sunil L. , Jenden Peter D. , Halpern Henry I.
Published: March 2009

One of the tools used for the characterization of gas reservoirs is the geochemistry of gas condensates. The fingerprinting of gas condensates by gas chromatography, in particular, may provide information regarding reservoir compartmentalization, which can be a major uncertainty at the early-field-appraisal stage. An important concern is the capture of suitable liquid samples. When the flowing bottomhole pressure falls below the dewpoint pressure, for example, condensate will drop out near the wellbore and the captured sample may not be representative of the formation fluid.

We conducted two sets of tests simulating the effect(s) of gas-/ liquid-phase fractionation on fingerprinting analyses: (1) at different pressures (all below the dewpoint) at reservoir temperature (RT) region in order to simulate dropout of liquids in the near-wellbore area and (2) to investigate the effect of variations in separator temperature and pressure.

Geochemical fingerprints obtained on our laboratory-fractionated samples show that condensates obtained from gas wells with flowing bottomhole pressures below dewpoint may not be suitable for compartmentalization studies. Differences in separator pressure and temperature affect the fingerprints of gas condensates, but the effects are small and unlikely to alter conclusions regarding potential fluid-flow barriers. We suggest a number of best practices for the collection and analysis of gas condensates for fingerprinting studies.
A Simple Mechanistic Model for Void-Fraction and Pressure-Gradient Prediction in Vertical and Inclined Gas/Liquid Flow
Authors: Khasanov Mars , Khabibullin Rinat , Krasnov Vitaly , Pashali Alexander , Guk Viatcheslav
Published: March 2009

A new mechanistic model for two-phase flow in vertical and inclined pipes was proposed on the basis of the drift-flux approach. The proposed model, unlike the other mechanistic models [Ansari et al. (1994); Xiao et al. (1990); Zhang et al.(2003)] that incorporate a system of nonlinear equations to solve, uses an explicit equation for liquid-holdup prediction, thus reducing computation time significantly. Coupled with some simplified assumptions on pressure/volume/temperature (PVT), such a simple form of a liquid-holdup-prediction formula enables an analytical integration of the pressure gradient in two-phase flow along the pipe. This procedure is used usually to speed up the calculation of bottomhole pressure (BHP) for a large number of wells for oil-production-optimization purposes (Khasanov et al. 2006).

The drift-flux approach can predict liquid holdup for bubbly flow quite accurately. However, for slug flow, it usually underestimates the void fraction. Because slug flow is the most common flow in producing wells, this leads to the pressure drop being overestimated significantly; this can be proved by comparing computational results to the experimental data and mechanistic models. Small gas bubbles in liquid slugs should be accounted for when predicting liquid holdup for slug flow more accurately. Gas in the slug body is considered by adding a proper term to the void-fraction expression. This term is based on the correlation for liquid holdup in the slug body. The model was evaluated with Rosneft's field data and the Tulsa University Fluid Flow Projects (TUFFP) databank. The model was evaluated by comparing it with three mechanistic models for multiphase flow.
Predicting Accelerating Subsidence Above the Highly Compacting Luconia Carbonate Reservoirs, Offshore Sarawak Malaysia
Authors: Dudley J. W. , van der Linden A. J. , Mah K. G.
Published: March 2009

Sarawak Shell Berhad has a number of offshore gas fields that produce from the Luconia carbonate formation, which can exhibit high-compressibility pore-collapse deformation. Recent accelerated subsidence has been observed at several of these fields, which extrapolates to final subsidence values well above previous estimates. This paper describes a geomechanical study involving core work to determine if the Luconia formation compressibility is sensitive to brine flow from the rising aquifer and a 3D geome-chanical finite-element model developed to predict future subsidence and lateral movements for the F23 platform.

Compaction tests were performed on the Luconia core from three different gas fields. Tests on twin plugs were conducted—one plug undergoing a standard uniaxial zero-lateral-strain compaction test, while its twin has several pore volumes of simulated-formation brine flowed through it (at virgin in-situ stress conditions) before the compaction loading. Four sets of compaction tests on twin plugs were completed. The higher-porosity samples showed characteristic pore-collapse behavior consistent with previous measurements on Luconia mouldic limestone core. No sensitivity to brine flow was observed. In-situ compaction logs in the field also do not show increased compressibility in sections flooded by the rising gas-water contact (GWC). The geomechanical model uses a relatively simple structural model comprised of four layers—two overburden formations, the Luconia carbonate and one underburden formation. A nonlinear deformation model for the Luconia formation captures the accelerating pore-collapse response observed in the core and in-situ compaction measurements. The model is calibrated to GPS-measured platform subsidence and is consistent with measured core- and field-compaction properties. The results predict that platform subsidence rates with depletion would level off, with a maximum subsidence of 18.5 ft +/− 1 ft at an abandonment pressure of 300 psi. Platform subsidence in the two years following the work continues to follow the predicted values.

This work illustrates the importance of integrated geomecha-nical core testing, field-monitoring measurements, and modeling to accurately predict compaction and subsidence effects in highly compacting environments.
Inverted-Convection Proppant Transport for Effective Conformance Fracturing
Authors: dos Santos J. A. C. M. , Cunha R. A. , de Melo R. C. B. , Aboud R. S. , Pedrosa H. A. , Marchi F. A.
Published: March 2009

In mature fields, a continuous challenge for operators is to maximize hydrocarbon recovery while minimizing associated water production. Water production causes several problems, including scaling, fines migration or sand-face failure, tubular corrosion, and increased hydrostatic loadings. Thus, although water production is almost an inevitable consequence of oil production, it is usually desirable to defer its onset, or its rise, as long as possible.

Proper stimulation is required to prove many reservoirs commercially, including dirty sandstones and lower-permeability layered formations in waterdrive reservoirs and/or with nearby water zones. The focus on water avoidance has made conformance fracturing an interesting prospect in mature fields because it combines synergistically a relative permeability modifier (RPM) with a fracturing fluid to enhance production and reduce water cut in one step. However, if a water zone is below the zone being fractured, fracture invasion may create a conductive path for water production. For example, proppant convection and settling can result in heavier treatment stages displacing rapidly downward from the perforations to the bottom of the fracture. This may occur when treatments call for large pad volumes, high proppant concentrations, or stage density contrasts.

An important technique used to avoid this problem is known locally as inverted proppant convection. It requires proppant buoyancy in the selected fracturing fluid, as is possible when using ultralightweight proppants (ULWPs) with specific gravities (SG) from 1.054 to 1.75. The technique involves pumping a high-density fluid pad with SG higher than the proppant carrier fluid, which in turn has SG slightly higher than the selected ULWP.

This paper describes the design approach, operational procedures, and evaluation of field case histories demonstrating the synergism of conformance fracture and inverted proppant convection as applied in northeast Brazil, with the potential to impact field-development strategies worldwide.
Predicting Undulating-Well Performance
Authors: Kamkom R. , Zhu D. , Bond A.
Published: March 2009

Undulating wells are one of the alternatives to horizontal wells in field developments for extremely low-vertical-permeability formations. Undulating wells offer higher reservoir exposure, and they do not depend on vertical permeability as much as horizontal wells do. This makes an undulating well trajectory sometimes more attractive than horizontal wells.

In this paper, we will present two different approaches to predicting undulating-well performance: (1) an analytical model that uses a segmented vertical-well model with a slanted skin factor to account for the effect of undulation and (2) a more-comprehensive model that evaluates undulating-well performance in a parallelepiped reservoir on the basis of a line-source solution. The analytical model is simple and works well under certain formation- and well-structure conditions. The line-source model is more flexible on permeability assumptions and well location. We compared the results of the two approaches to identify the conditions in which the analytical model can be applied.

Field examples are used in the paper to illustrate optimizing undulating-well performance by the model. The Cosmopolitan field, Cook Inlet Alaska, and the Oooguruk field, North Slope, Alaska, are planned for development with undulating horizontal wells. Both reservoirs are challenged with relatively low permeability, low kV/kH ratios, and moderate-viscosity oil. Undulating horizontal wells are needed to overcome these issues and deliver commercial production rates. The performance model developed in this study demonstrated the additional value of an undulating well over a conventional horizontal well, which provided key support in the well-design and field-development plans.
Sorption-Induced Permeability Change of Coal During Gas-Injection Processes
Authors: Lin W. , Tang G. -Q. , Kovscek A. R.
Published: March 2009

Our study has two features. First, laboratory experiments measured the change of the permeability of coal samples as a function of pore pressure and injected-gas composition at constant effective stress. Second, adsorption-solution theory described adsorption equilibria and aided interpretation. The gases tested include pure methane (CH4), nitrogen (N2), and carbon dioxide (CO2), as well as binary mixtures of N2 and CO2 of different compositions. The coal pack was initially dry and free of gas, then saturated by each test gas at a series of increasing pore pressures at a constant effective stress until steady state was reached. Thus, the amount of adsorption varied, while the effective stress was held constant. Results show that, (i) permeability decreases with an increase of pore pressure at fixed injection-gas composition, and, (ii) permeability change is a function of the injected-gas composition. As the concentration of CO2 in the injection gas increases, the permeability of the coal decreases. Pure CO2 leads to the greatest permeability reduction among all the test gases. However, 10 to 20% by mole of N2 helps to preserve permeability significantly. According to the mixed-gas adsorption isotherms, adsorption and the selectivity of a particular gas species on coal surfaces is a function of pressure and the gas composition. Therefore, we conclude that loading coal surfaces with adsorbed gas at constant effective stress causes permeability reduction. Finally, gas adsorption and permeability of coal are correlated, simply to extend the usefulness of study results.
Real-Time Performance Analysis of Water-Injection Wells
Authors: Izgec B. , Kabir C. S.
Published: March 2009

This work presents a complete reformulation of the Hall method involving both pre- and post-breakthrough situations. Two approaches involving both transient and pseudosteady-state methods produced very similar solutions, which were verified with the results of coupled geomechanical/fluid-flow simulations. The new formulations allow tracking the expanding water-bank radius from inception to breakthrough. Pressure of this bank at the water/oil interface is evaluated at every timestep, thereby allowing continuous update of the ‘external pressure’ in Hall's formulation. We show that Hall's formulation is a particular case of the proposed approach. Several simulated and field examples demonstrate the value of reformulated Hall analysis.

Because Hall formulation involves an integral, the resultant signature, by nature, is insensitive in revealing clues about subtle changes that may occur during formation fracturing or plugging. We observed that the derivative of the modified-Hall integral, obtained analytically, provides definitive signatures about fracturing or plugging.

The new interpretation approach is particularly suitable for projects at the inception of flooding. Mature projects can benefit equally from the new tool. Perhaps the biggest appeal of the proposed tool lies in the green fields where real-time data are readily available.
Improving LWD Image and Formation Evaluation by Using Dynamically Corrected Drilling-Derived LWD Depth and Continuous Inclination and Azimuth Measurements
Authors: Bordakov G. A. , Kostin A. V. , Rasmus J. , Heliot D. , Laastad H. , Stockhausen E. J.
Published: March 2009

The paper illustrates the improvements in logging while drilling (LWD) images and subsequent formation evaluation by using a new methodology for depth and survey measurements corrections.

LWD depth measurements are often considered inaccurate and, therefore, not as reliable for well-to-well correlations, correlations with data acquired with wireline measurements and formation layer thickness determinations. The reasons for these inaccuracies generally originate from the traditional practice that LWD depth is purposely made equal to the driller's depth, which is a static pipe length measurement made by tape at the surface.

There is almost always a difference between the actual measured depth (MD) of the LWD sensor downhole and this static pipe measurement, because downhole the drillpipe is subject to an environment that is not representative of the derrick (e.g., varying drilling mechanical conditions and temperature changes). Here, we demonstrate the applications of the method, which allows dynamic driller's depth correction for the effects of drillstring weight, downhole friction, weight on bit, thermal expansion, residual rig heave, and tide.

Another significant inaccuracy source is a standard practice of calculating borehole position from stationary survey points typically taken every 90 feet (ft) using the minimum curvature method. Neglecting the complex borehole shape between survey stations can lead to a systematic error in determining the borehole position. We consider using continuous inclination and azimuth measurements along with stationary surveys to correct these errors.

We provide comparisons of LWD images before and after the depth and survey corrections to illustrate how the measurement errors affect formation dips interpreted from the images. We demonstrate how improved accuracy allows filtering out the artifacts and provides more decisive and accurate identification of geologic features. We show how using the corrected 3D position improves accuracy of the formation thicknesses calculations and therefore improves the reservoir summation results.

As a result, we propose a borehole 3D position measurement that is accurate, consistent between wells (regardless of rig type or bottomhole assembly [BHA] configuration), and independent of the drilling mode. Using this new measurement significantly improves the quality of the formation evaluation.
Case Studies Illustrating the Use of Reservoir Simulation Results in the Reserves Estimation Process
Authors: Rietz Dean , Usmani Adnan
Published: March 2009

Continuous improvements in reservoir simulation software and the availability of high performance computing equipment are making the use of simulation models commonplace for field development and planning purposes. Naturally, this trend has also increased interest in the use of reservoir simulation model results in the oil and gas reserves estimation process.

As simulation specialists who work in a primarily reserves-evaluation company, the authors are routinely asked to evaluate, and in many cases incorporate, simulation results in the reserves estimation process. In addition, the authors are required to opine on the approach and tactics used by clients while they incorporate numerical models in their reserves bookings. Because limited published discussion exists on this topic, the purpose of this paper is to provide some examples of the approach used by the authors. We believe this approach to be appropriate and within the spirit of reserves interpretation as used by typical reserves regulatory bodies such as the U.S. Securities and Exchange Commission (SEC).

Papers previously published have discussed the use of models in the reserves process, including the evaluation of the models themselves (Palke and Rietz 2001; Rietz and Usmani 2005). In contrast, this paper provides three case studies that illustrate how results from various models have been used to assist in quantifying reserves. Two of the examples are based on history-matched models, while the third focuses on a pre-production reservoir where no adequate history is available and probabilistic methods were incorporated to help understand the uncertainty in the forecasts.

While there is no "cookbook" or step-by-step procedure for using simulation results to estimate reserves, the case studies presented in this paper are intended to both show some examples and also spark some debate and discussion. Undoubtedly there will be some disagreement with our techniques, but an open discussion should prove to be beneficial for both reserves evaluators and simulation specialists.
Long-Term Field Development Opportunity Assessment using Horizontal Wells in a Thin, Carbonate Reservoir of the Greater Burgan Field, Kuwait
Authors: Ambastha Anil K. , Matar Al Dawood , Ma Eddie
Published: March 2009

The Mauddud reservoir in the Greater Burgan field is a thin, carbonate reservoir containing light oil in a 10 to 20-feet (ft) target zone with "good" porosity. Matrix permeability is low, and natural fracture density can be variable in this reservoir. Thus, this reservoir must be exploited using horizontal wells. In the early 1990s, 16 horizontal wells were drilled in this reservoir. Five more horizontal wells have been drilled in 2005 and 2006 in an effort to scope out the long-term potential of this reservoir. However, only three of these five new wells had a production history of a few months that could be used in our history-matching effort. Thus, the history-matching effort concentrated on 19 wells (16 old plus 3 new wells).

In conjunction with the drilling of recent horizontal wells, a comprehensive reservoir characterization program culminating into a full-field reservoir simulation model has been completed. The 24-million cell geological model was scaled up to a 9-million cell model at a 164-ft by 164-ft areal grid level to properly incorporate flow characteristics of horizontal wells into the simulation model. Matrix permeability of the scaled-up model was enhanced by using a unique process based on analytical solutions for short fractures and fracture density/orientation mapping for the entire field. This reservoir simulation model has been history-matched for the 13-year production history of 16 1990s horizontal wells along with a production history of a few months for 3 new wells using only a global-permeability multiplier and water relative-permeability curve shape modification. This model has been used in the forecast mode to assess long-term field development opportunity for the Mauddud reservoir. Primary depletion results show that horizontal wells drilled in an intelligent manner in this difficult reservoir hold the key to economic development of this reservoir.
Modeling Conformance as Dispersion
Authors: Coats K. H. , Whitson C. H. , Thomas L. K.
Published: March 2009

For decades the effect of physical dispersion (in-situ mixing) in porous media has been of interest in reservoir engineering and groundwater hydrology. Dispersion can affect the development of multicontact miscibility and bank breakdown in enriched-gas drives and miscible solvent floods of any mobility ratio.

The magnitude or extent of dispersion is quantified by the rock property physical dispersivity, α, which is on the order of 0.01 ft for consolidated rocks and several times smaller for sandpacks, as found in many laboratory measurements.

Numerical studies of the effect of dispersion on enriched-gas drives and field tracer tests often use input values of a scale-dependent dispersivity 100 to 1,000 or more times larger than ≈0.01 ft. These large scale-dependent dispersivity values stem from large apparent dispersivities (αa) determined by matching the 1D convection/diffusion (C/D) equation to production-well-effluent tracer-concentration profiles observed in field tracer tests.

A scale-dependent dispersivity can be used only as a fitting factor to match or explain the effluent profile of a single producer at a fixed distance from an injector. It cannot represent physical dispersion to justify the conclusions reached by its use in simulations of enriched-gas-drive, field-tracer-test, or other reservoir displacement processes. It has no predictive value in any numerical simulation.

The scale-dependent apparent dispersivities reflect conformance or other behavior not governed by the 1D C/D equation and should not be used to justify large dispersivities as input to numerical studies. This paper shows that large apparent dispersivities observed in field tests can result with physical dispersivity no larger than the ≈0.01-ft laboratory-measured value.

Heterogeneity alone (no physical dispersivity or molecular diffusion) causes no in-situ mixing and cannot explain observed large apparent echo-test dispersivities. Large apparent dispersivities for two reported echo (single-well inject/produce) tracer tests are shown to result from a model with drift alone and no dispersion.

The widely reported scale dependence of apparent dispersivity is a simple and necessary consequence of mis-applying the 1D C/D equation, with its single parameter of Peclet number, L/α, to conformance it does not describe. The conformance portion, aac, of apparent dispersivity, αa, is scale-dependent, but physical dispersivity is a rock property independent of scale and time. The value of αa approximately obeys an additive dispersivity principle, αa≈α + αac, where αac is dispersivity representing conformance and αaG>>α in field displacements.
Discussion of Interrelationship of Temperature and Wettability on the Relative Permeability of Heavy Oil in Diatomaceous Rocks
Authors: Dietrich J. K.
Published: March 2009

Schembre et al. (2006) interpret the effects of temperature on diatomite wettability and relative permeability for a specific set of laboratory conditions. These researchers imply that countercurrent imbibition (CCI) of hot water and oil–driven by capillary-pressure forces–is the dominant mechanism in the thermal recovery of heavy oil from diatomite. While their results are appreciated and of theoretical interest, additional experimental work would seem to be necessary before conclusions can be drawn about fieldscale key mechanisms and achievable-oil-displacement efficiencies.

Several features of the testing procedures used by Schembre et al. (2006) prevent scaling their results from the laboratory to the field: extracted rather than preserved core material was used, deadoil rather than live-oil was used, and the cores were not stressed during testing. Bennion et al. (1985) demonstrated the importance of measuring relative permeabilities using preserved core material, overburden stress conditions, and live crude oil. These types of relative permeability functions–rather than those measured using dead-oil and extracted cores that were unstressed–were very similar to those developed empirically by Coats et al. (1977) and Dietrich (1981) to reproduce cyclic-steam field performance. Bennion et al. (1985) found that laboratory-measured relative permeability curves from preserved core, when performed at reservoir conditions, do not need to be adjusted downward to match low water production typical of cyclic-steam response.

Regarding the effects of stress, heating amorphous Opal-A diatomite has been shown to be capable of causing a sample compression of 25% or more and a severe reduction in permeability (Dietrich and Scott 2007). Heating in the absence of a change in effective stress from the initial equilibrium condition causes compaction; heating at elevated effective-stress levels causes much more compaction (Fig. D-1). Sample compression of 25% or more is expected to severely alter the primary pore structure and, hence, the relative-permeability and capillary-pressure characteristics of the diatomite. Wilson (1956) showed that an overburden stress causing only a 5% reduction in porosity of a sandstone core can produce a sufficiently large change in pore size distribution to affect the relative permeability of the core.
Authors' Reply to Discussion of Interrelationship of Temperature and Wettability on the Relative Permeability of Heavy Oil in Diatomaceous Rocks
Authors: Kovscek A. R. , Schembre J. M. , Tang G. -Q.
Published: March 2009

Dietrich's discussion is wide ranging. We agree that oil recovery from diatomite rocks is influenced by a variety of mechanisms, that compaction plays a role, and that more work in the area of recovery mechanisms and their representation within a reservoir simulator is warranted. His critique of our work, however, incorrectly summarizes our experimental procedures and it misrepresents the importance that we attribute to hot-water imbibition in relation to the other mechanisms that contribute to thermal oil recovery. His discussion of the simulation of field-scale recovery processes does not appear to acknowledge the need for upscaling or the inherent nonuniqueness present in history-match results. Our work highlights the role of fines detachment as well as silica and mineral dissolution combined with compressive stress (Schembre et al. 2006; Ikeda et al. 2007; Ross et al. 2008). We have found that rock wettability evolves favorably to a more water-wet state with elevated temperature. This change in wettability contributes positively to recovery.
CT Study of Liquid Diversion With Foam
Authors: Nguyen Q. P. , Zitha P. L. J. , Currie P. K. , Rossen W. R.
Published: March 2009

The mobility and flow distribution of liquid injected after foam control the effectiveness of foam/acid matrix well-stimulation treatments and the injectivity of liquid in many foam improved-oil-recovery processes. We present a computed-topography (CT) study of liquid injection following foam, in which both mobility and the sweep of liquid are determined directly, the latter by CT imaging. Earlier experimental work is extended in that the effects of foam quality, foam-injection rate, post-foam liquid-injection rate, and core heterogeneity on liquid mobility and displacement pattern are observed directly. CT images show that liquid fingers through foam rather than displacing it evenly. As a result, 1D models for the displacement cannot represent the process accurately. The formation of the finger is at least partly stochastic: In different experiments in the same core, with similar initial foam states, the liquid finger took markedly different paths through the core. Liquid injected after foam does not follow simply the path of mobile gas in the foam. In these experiments, post-foam brine injection was not qualitatively less effective than post-foam surfactant injection, though there were differences in both post-foam mobility and fingering pattern. Implications of field application of foam-acid diversion in matrix-stimulation treatments are discussed.
Predicting Horizontal-Openhole-Completion Success on the North Slope of Alaska
Authors: Erwin Michael D. , Ogbe David O.
Published: March 2009

The Colville River field represents the first widespread and successful application of horizontal openhole completions on the North Slope of Alaska, and one of the first in the world. The purposes of this paper are to examine why this completion technique was selected and identify key parameters that favored its successful application in the Colville River field. The optimal completion technique for a candidate well is determined by reservoir properties, geologic setting, rock mechanics, development plan, and completion design. In this paper, we will review the unique advantages and disadvantages of horizontal openhole completions in the Colville River field.

Three key parameters were critical to the success of horizontal openhole completions and could be applied broadly in other situations. Using these three criteria, other major North Slope reservoirs were evaluated to determine their potential for horizontalopenhole-completion applications. Focus areas in this evaluation include in-situ reservoir parameters, development plans, fluid contacts, and wellbore geometries. The results show that only one other major field on the North Slope could have benefited from horizontal openhole completions.

The results of this paper are meant to provide guidelines for future application of horizontal openhole completions on the North Slope of Alaska and elsewhere.
A Hybrid Approach To Improve Reserves Estimates in Waterdrive Gas Reservoirs
Authors: Yildiz Turhan
Published: March 2009

The conventional reserves estimate methods for waterdrive reservoirs are well established. Typically, the techniques proposed by Havlena and Odeh (1963 and 1964) and McEwen (1962) are used. In general, the reserves estimated from these procedures are not unique since the recorded historical production data are simultaneously solved for aquifer parameters and reserves. Normally, multiple combinations of reserves and aquifer parameters match the field data equally well. Hence, a range of reserves—rather than a unique value—is found. The upper and lower limits of the reserves range may vary several-fold.

In this paper, a hybrid approach that makes use of available methods is used to narrow the reserves range estimates in water-drive gas reservoirs. The hybrid approach combines the McEwen method, apparent gas-in-place (GIP) vs. time, the modified Roach (1981) method, and the modified Havlena and Odeh method for partial waterdrive.
The Impact of Client and Auditor Gender on Auditors’ Judgments (Retracted)
Authors: Gold Anna , Hunton James E. , Gomaa Mohamed I.
Published: March 2009

SYNOPSIS: This study assesses the influence of client gender and auditor gender on auditors’ judgments. In an experimental task, a client offers unverified explanations as to why the auditor’s initial proposed adjusting journal entry (AJE) to lower the inventory value should not be recorded. The design includes one randomly manipulated variable (client gender: male or female) and one measured variable (auditor gender: male or female). The dependent variable assesses the influence of the client’s explanations on the auditor’s final proposed AJE recommendation. The results indicate that both male and female auditors exhibited a male favorability; that is, they were persuaded more by a male than female client to change their initial AJE recommendation. Furthermore, female auditors were more influenced by a male client and less influenced by a female client than male auditors. Using an expert panel’s consensus opinion as a benchmark for the “best” solution, the male auditors were more accurate than female auditors, irrespective of client gender. Additional research will aid in substantiating, determining the limits, and generalizing the findings.
IFRS and the Accounting Consensus
Authors: Sunder Shyam
Published: March 2009

SYNOPSIS: A broad consensus in accounting favors principles over rules to guide creation of a uniform high-quality set of standards for use everywhere, and granting monopoly power to a single body for this purpose. If implemented into policy, this consensus will discourage discovery of and evolution toward better methods of financial reporting, make it difficult to conduct comparative studies of the consequences of using alternative methods of accounting, promote substitution of analysis and thinking by rote learning in accounting classes, help discourage talented youth from collegiate programs in accounting, and probably endanger the place of accounting discipline in university curricula. Because the presumed benefits in the form of increased comparability of financial reports internationally or stateside are unlikely to be realized, the wisdom of undertaking these burdens remains questionable. The paper calls for a re-examination of the accounting consensus.
Industry Specialization by Global Audit Firm Networks
Authors: Carson Elizabeth
Published: March 2009

ABSTRACT: This study investigates the role of global audit firm networks in the market for audit services. Underlying theory suggests that there are benefits from the use of network structures, which enable these firms to expand efficiently into the global audit market and to develop global industry specializations. I identify global and national industry specialist auditors via market share metrics based on client assets audited, and use a large sample of 15,583 clients from 62 countries in 2000 and 14,628 clients from 60 countries in 2004. I find in both periods that audit fee premiums are consistently associated with global specialist auditors, irrespective of whether those audit firms are or are not national specialists.
The Performance of Analysts with a CFA® Designation: The Role of Human-Capital and Signaling Theories
Authors: De Franco Gus , Zhou Yibin
Published: March 2009

ABSTRACT: This study compares the performance of sell-side equity analysts with and without a Chartered Financial Analyst® (CFA) designation. Using a large sample of forecasts, our tests indicate that CFA charterholders issue forecasts that are timelier than those of non-charterholders. The results for accuracy are mixed. We establish that while charterholders perform at statistically significant higher levels than non-charterholders in some tests, the economic significance of these differences is questionable. For a subsample of analysts, we find evidence that charterholders improve along the dimension of timeliness after they receive their CFA charter. This result provides support for a human-capital explanation in which charterholders improve their productivity during the CFA program. Finally, we show that the market reaction for smaller firms is stronger for charterholders than non-charterholders after controlling for timeliness, boldness, accuracy, and optimism. This result provides evidence consistent with “credentialism,” a variant of signaling theory in which a professional's education level provides a signal about the professional's quality to his or her clients.
Hurdle Rates and Project Development Efforts
Authors: Dutta Sunil , Fan Qintao
Published: March 2009

ABSTRACT: We examine the optimal choice of hurdle rates in a capital budgeting setting in which a manager receives superior information regarding the profitability of an investment project. Unlike the prior capital budgeting literature that treats the distribution of investment returns as exogenous, we consider a scenario in which the manager can engage in upfront project development activities to improve the quality of investment opportunity. To motivate the project development effort while ensuring truthful information flow, the optimal hurdle rate is always lower than what it would be if the manager's project development effort were directly observable. We show that the optimal hurdle rate can even be below the firm's cost of capital under plausible circumstances. We also examine how the optimal hurdle rate varies with the ex ante quality of the firm's investment opportunities, and find that optimal hurdle rates will be higher in firms whose investment opportunities are relatively good or relatively poor than in firms with investment opportunities of intermediate quality.
The Impact of Shareholder Activism on Financial Reporting and Compensation: The Case of Employee Stock Options Expensing
Authors: Ferri Fabrizio , Sandino Tatiana
Published: March 2009

ABSTRACT: We examine the economic consequences of more than 150 shareholder proposals to expense employee stock options (ESO) submitted during the proxy seasons of 2003 and 2004, the first case in which the SEC allowed a shareholder vote on an accounting matter. Our results indicate that these proposals affected accounting and compensation choices. Specifically, (1) targeted firms were more likely to adopt ESO expensing relative to a control sample of S&P 500 firms, (2) among targeted firms, the likelihood of adoption increased in the degree of voting support for the proposal, and (3) non-targeted firms were more likely to adopt ESO expensing when a peer firm was targeted. Additionally, (1) CEO pay decreased in firms in which the proposal was approved relative to a control sample of S&P 500 firms, and (2) among targeted firms, approval of the proposal was associated with decreases in CEO compensation and the use of ESO in CEO pay. Our findings reveal an increasing influence of shareholder proposals on governance practices.
Former Audit Partners on the Audit Committee and Internal Control Deficiencies
Authors: Naiker Vic , Sharma Divesh S.
Published: March 2009

ABSTRACT: This study examines the association between internal control deficiencies (ICDs) reported under Section 404 of the Sarbanes-Oxley Act (SOX, U.S. House of Representatives 2002) and the presence of former audit partners on the audit committee who are affiliated (AFAPs) and unaffiliated (UFAPs) with the firm's external auditor. We find a negative association between AFAPs and UFAPs on the audit committee and ICDs. We also find results that suggest the NYSE and NASDAQ three-year “cooling-off” rule applying to AFAPs may be unwarranted and deserves further empirical and regulatory attention. Further tests suggest AFAPs do not allow management to circumvent the disclosure of ICDs when conditions appear to suggest this may be so, and that AFAPs are negatively related to performance-adjusted discretionary accruals. Collectively, we interpret these findings to suggest that AFAPs and UFAPs on the audit committee are associated with more effective monitoring of internal controls and financial reporting.
Effect of Dual Cure Composite as Dentin Substitute on Marginal Integrity of Class II Open-Sandwich Restorations
Authors: Koubi S. , Raskin A. , Dejou J. , About I. , Tassery H. , Camps J. , Proust J-P.
Published: March 2009

Clinical Relevance

Dual-curing composites may present a good alternative to RMGIC in open-sandwich restorations and they act as a dentin substitute. However, this study showed that RMGIC remains the best intermediate material when open-sandwich restorations are indicated.
The Effect of Preoperative Ibuprofen on Tooth Sensitivity Caused by In-office Bleaching
Authors: Charakorn P. , Cabanilla L. L. , Wagner W. C. , Foong W-C. , Shaheen J. , Pregitzer R. , Schneider D.
Published: March 2009

Clinical Relevance

The use of an analgesic may help to reduce tooth sensitivity during in-office bleaching. Within the limitations of this study, Ibuprofen (600 mg, PO single dose) reduced tooth sensitivity during, but not after the treatment period.
Effect of 2% Chlorhexidine Digluconate on the Bond Strength to Normal Versus Caries-affected Dentin
Authors: Komori P. C. P. , Pashley D. H. , Tjäderhane L. , Breschi L. , Mazzoni A. , de Goes M. F. , Wang L. , Carrilho M. R.
Published: March 2009

Clinical Relevance

Attempts to use CHX adjunctively with conventional etch-and-rinse adhesives may play a clinically relevant role in the preservation of resin-dentin bonds.
Deproteinization Effects of NaOCl on Acid-etched Dentin in Clinically-relevant vs Prolonged Periods of Application. A Confocal and Environmental Scanning Electron Microscopy Study
Authors: Sauro S. , Mannocci F. , Tay F. R. , Pashley D. H. , Cook R. , Carpenter G. H. , Watson T. F.
Published: March 2009

Clinical Relevance

Complete removal of the collagen matrix prior to dentin bonding procedures has been proposed as a strategy to prevent later degradation, which may jeopardize the longevity of resin-dentin bonds. This study demonstrates that a complete removal of the exposed collagen matrix from the etched dentin surface can be achieved by applying a 12 w/v% NaOCl solution, but at this concentration, it requires a far longer reaction time than is clinically acceptable.
A Clinical Evaluation of Two In-office Bleaching Regimens With and Without Tray Bleaching
Authors: Matis B. A. , Cochran M. A. , Wang G. , Eckert G. J.
Published: March 2009

Clinical Relevance

In-office tooth bleaching, followed by at-home bleaching with trays, was shown to be more effective than in-office bleaching without at-home bleaching. Three 15-minute applications of an in-office bleaching agent were more effective than one 40-minute application.
Influence of Power Density on Polymerization Behavior and Bond Strengths of Dual-cured Resin Direct Core Foundation Systems
Authors: Oto T. , Yasuda G. , Tsubota K. , Kurokawa H. , Miyazaki M. , Platt J. A.
Published: March 2009

Clinical Relevance

The dentin bond strength and polymerization behavior of the dual-cured core foundation resins tested in this study were affected by the power densities of the curing unit. When using dual-cured core foundation systems, practitioners should consider power densities for getting optimal bond strength.
Effect of Operator-specific Handling on Tooth-composite Interface and Microleakage Formation
Authors: Schneider H. , Busch I. , Busch M. , Jentsch H. , Häfer M.
Published: March 2009

Clinical Relevance

After calibration of the restoration procedure, three operators experienced differences in tooth-composite interface morphology and microleakage formation. These differences reflect technique-sensitivity of the etch-and-rinse adhesive. The lowest microleakage on dentin was related to an enhanced interface integrity. After additional application of an adhesive component, sealing of the enamel and dentin was partially enhanced, but microleakage formation did not decrease. These results are helpful in the comparative evaluation of other bonding systems.
Computational Investigations on the Dynamics of Tires Rolling on Rough Roads
Authors: Brinkmeier M. , Nackenhorst U.
Published: March 2009

Finite element methods are well established for the mechanical analysis of tires in industry. For stationary rolling contact analysis a relative kinematics description based on a mixed spatial–material description provides a suitable framework for efficient computations of quite detailed tire models. Despite these advantages, special effort is necessary for the reliable treatment of tractive rolling with friction, or even when inelastic material properties have to be considered. An additional challenge is the simulation of high-frequency response for comfort analysis, for example.

This paper focuses mainly on the latter aspect, namely, the transient dynamics response with respect to rolling noise prediction. The theoretical basics have been outlined in prior publications; this presentation concentrates on a systematic analysis of the transient dynamic behavior of rolling tires based on a modal analysis first. Based on computed eigenvectors, a partial modal energy criterion is introduced to judge the influence of different assembly parts on the dynamics of rolling tires. The capability of the suggested approach will be outlined in a second part, where the transient dynamic response due to the excitation from different road surface textures and bridge connection constructions are discussed. The sensitivity of these computations with regard to the excitation mechanism will be shown, from which a much higher potential in road construction regarding traffic noise reduction is concluded.

The presented results are the partial outcome of research project “Leiser Straßenverkehr 2,” funded by the Federal Ministry of Economics and Technology (BMWi) and organized by the Federal Highway Research Institute (BAST). This research was performed in close cooperation between tire manufacturers, road construction companies, and universities.
Analiza Modalna Pękającej Łopatki Sprężarki
Authors: Witoś Mirosław
Published: March 2009

Analiza Modalna Pękającej Łopatki Sprężarki

W artykule przedstawiono problematykę wiarygodnego rozpoznawania i prognozowania stanu technicznego stalowych łopatek sprężarki. Omówiono symptomy pęknięcia pióra łopatki i metody jego identyfikacji, stosowane w eksploatacji i remoncie turbinowego silnika odrzutowego typu SO-3. Przedstawiono optyczną metodę laserowego pomiaru drgań pióra łopatki na wzbudniku, wdrażaną w Wojskowych Zakładach Lotniczych nr 3 (WZL-3). Omówiono spostrzeżenia z jej weryfikacji. Wskazano na nowe możliwości badawcze wdrażanej metody, a w tym identyfikowanie wczesnych symptomów zmęczenia materiału (fazy umocnienia i osłabienia) i inicjacji pęknięcia. Omawianą tematykę zobrazowano przykładami z pomiarów właściwości modalnych dobrych i uszkodzonych łopatek oraz prób zmęczeniowych, prowadzonych wg profili LCF i HCF. Wykazano, że analiza kształtu charakterystyki rezonansowej danego modu umożliwia wiarygodne różnicowanie zmęczenia od pęknięcia materiału.
On the Modal Analysis of a Cracking Compressor Blade
Authors: Witoś Mirosław
Published: March 2009

On the Modal Analysis of a Cracking Compressor Blade

The paper deals with issues related to reliable recognition and prediction of health of steel compressor blades. It outlines symptoms that indicate the blade cracking, and identification methods that can be used during operation, maintenance and repairs/overhauls of turbine jet engines of the SO-3 type. An optical method involving laser measurements of blade vibration while on the excitation source is presented in details as it is implemented in the WZL-3 (Military Aviation Works No. 3). The method has been verified in practice and some findings from the verification process are discussed. Next, new testing capabilities offered by the method are presented, including identification of early symptoms of material fatigue (the strengthening and the weakening of the material) and the crack initiation. The topics under discussion have been illustrated with some examples taken while measuring modal properties typical of both defect-free and faulty blades as well as from fatigue tests conducted according to the LCF and HCF profiles. It has been proved that the analysis of resonance responses for specific modes of operation allows of reliable differentiation between material's fatigue and cracking.
Badania Struktury I Mikrotwardości Warstwy Konstutuowanej Laserowo NA Stali Konstrukcyjnej
Authors: Kłysz Sylwester , Bień Anna
Published: March 2009

Badania Struktury I Mikrotwardości Warstwy Konstutuowanej Laserowo NA Stali Konstrukcyjnej

W pracy przedstawiono wyniki badań makro- i mikroskopowych struktury i pomiarów mikrotwardości warstwy wierzchniej próbek ze stali do ulepszania cieplnego 50H, poddanej laserowemu utwardzaniu. Na podstawie badań rentgenowskich przeprowadzonych na dyfraktometrach DRON-4 i Seifert XRD 3003 określono parametry sieci krystalograficznej i ilościową zawartość poszczególnych faz.