bluuebunny/crossref_metadata_2025_split huggingface dataset:
Develop a New Model for Saturation Calculation in Streamline Simulation
Authors: Nourozieh H. , Kariznovi M. , Jamialahmadi M. , Shahrabadi A. 
Published: March 2008

Abstract
Streamline simulation becomes an accurate and fast method for reservoir simulation nowadays. This method is based on decouple the pressure equation from saturation equation and transform the 3D equation to 1D equations therefore it introduces a speed up factor in respect to conventional simulation.
Tracing streamlines in the reservoir is a main step in streamline simulation. As a streamline is traced, it passed through many grid blocks. The numerical approach to 1D saturation equation requires picking up the saturation in each grid block when a streamline traced. In this way, saturation versus time of flight information recorded for each streamline traced from injector to producer. This information is defined on an irregular time of flight space.
Past efforts to move the saturation forward was based on transforming the irregular time of flight space onto a regular space. Transforming onto a regular 1D grid results in averaging of saturations, and represents one source of numerical diffusion in the streamline method.
In this paper we present a new method to move the saturation forward based on irregular time of flight space and compared the results with the common method. The result of saturation with this method will be more accurate and averaging of saturations and numerical diffusion will be decreased.
Modeling of the Stability of Multibranch Horizontal Open Holes
Authors: Manriquez Alberto Lopez , Podio Augusto L. , Sepehrnoori Kamy 
Published: March 2008

AbstractThis investigation was focused on studying the complex problem of stability of multi-branch horizontal openholes in a complete three-dimensional anisotropic in-situ stress field simulating drilling, completion, and production conditions.Previous work on this subject consisted of parametric analyses placing the junction in the overburden. Whenever reservoir management requires the construction of a specific multilateral scenario such as a multibranch horizontal inside a producing formation, a complex analysis is required. In this work, stress- displacement analysis in steady-state was coupled with transient phenomena to compute stress behaviors and changes in pore pressure due to disturbances created during simulated drilling and production conditions. This coupled analysis allowed for the inclusion of time dependent non-linear processes that influence behavior of the system compounded by rock, fluids contained in the rock, and in-situ stress field.
Applications of Ultra Low Density, Operationally Simple, Non–Foamed Cement Slurries — Case Histories
Authors: El Shaari N. , Myers Scott H. , Dajani Ragib , Doherty Dale Robert 
Published: March 2008

Abstract
Technical and product enhancements in well cementing have allowed the introduction of non-foamed cement systems mixed at densities as low as 7.5 ppg that attain ultimate compressive strengths as high as 1,000 psi. These non-foamed ultra low-density slurries are simplifying blending and mixing operations. In California oilfields and oilfields throughout the world, drilling wells into weak and low-pressure formations, has always been an industry challenge. Successful cement placement in these types of well environments is also a challenge. Lost circulation and partial fluid returns is major culprit to poor cement bonding in addition to higher well costs. Operators in many California fields are forced to drill wells "blind", for example, drilling without mud returns. Drilling "blind" does not preclude the challenging need to properly cement these wells to obtain zonal isolation.
The process of foaming cement systems to reduce slurry densities has been applied successfully over the years in wells throughout the world. Though foamed- cementing has been successful, the design and execution add components of operational and technical challenges. These would include accurate metering of nitrogen, uncertainty of actual cement density within the wellbore, additional equipment and personnel requirements, and special drilling rig components. The need for simplicity has allowed the introduction of non-foamed ultra low- density cement systems. In California, successful cement jobs were pumped using non-foamed systems at densities as low as 10.0 ppg. In Colorado, 8.9 ppg slurry was successfully pumped that had ultimate compressive strength of over 1,400 psi. In both cases, these systems provided simpler and an economic alternative choice. These ultra low-density slurries can be designed to meet wide range well temperatures and depth applications. The paper will discuss these systems along with field applications and case histories from California and other parts of the world.
Northern California Gas Sands — Hydraulic Fracture Stimulation Opportunities and Challenges
Authors: El Shaari N. , Minner W. A. 
Published: March 2008

Abstract
Hydraulic fracturing is a stimulation technique successfully applied in formations throughout the world to increase production rates and enhance hydrocarbon recovery. The process involves creating a crack by pumping fluids at pressures above formation fracturing pressures, and then filling the crack with proppant to create a high conductivity connection to a large formation area. Hydraulic fracturing stimulates production by overcoming restrictions imposed by formation permeability, drilling and completion damage, production-induced damage and, an incomplete reservoir connection across laminated intervals. The process has been applied to a large scale in many Central and Southern California fields to enable economic development and reasonable hydrocarbon recovery. Example formations include the Belridge Diatomite, Stevens Sands, Etchegoin, Antelope shale, McLure shale, McDonald shale, Point of Rocks sands, Kreyenhagen shale, Ranger sands, the UP Ford shale, and the Monterey shale. Despite the routine application of fracturing in many fields, there has been very little fracturing experience in the gas-producing formations of Northern California. Example formations such as the Martinez, Forbes, Winters, and the K-1 are generally laminated sand intervals with low to moderate permeability (less than 1 mD and up to 10 mD), that are easily damaged by completion and production operations. Despite the hydraulic fracturing potential for stimulating production rates, improving gas recovery, and increasing reserves by extending the economic development area, it has been only sparingly employed. General formation properties are reviewed – what are the implications for hydraulic fracture potential, treatment design and placement challenges? Several treatments are reviewed to provide examples of fracture treatment behavior and response. Based on the initial experience and formation properties, it is believed that hydraulic fracturing has a significant potential in many Northern California gas reservoirs.
The Effect of Drillpipe Rotation on Pressure Losses and Fluid Velocity Profile in Foam Drilling
Authors: Duan Mingqin , Miska Stefan , Yu Mengjiao , Takach Nicholas , Ahmed Ramadan , Hallman John 
Published: March 2008

Abstract
Foam is gaining increasing applications in both drilling and cementing. Typical applications include drilling operations in naturally fractured formations and depleted or patially depleted reservoirs. The unique pressure profile created by foam makes it an ideal drilling fluid in many areas where a narrow operating window exsits between pore pressure and fracture pressure. While rotary drilling is the most widely used drilling technique, there has been no study on foam drilling with drill pipe rotation. This study was undertaken to identify the effect of pipe rotation on pressure losses and velocity profiles of foam flow in both concentric and eccentric annuli. The effects of pressure, foam quality and pipe eccentricity were also investigated.
For the first time, pipe rotation effects on foam flow were experimentally studied on a flow loop consisting of a pipe viscometer and an annular test section. Pipe rotary speeds were varied from 0 to 400 RPM with foam qualities ranging from 60% to 90% at different flow rates. Computational Fluid Dynamics simulations were performed to compare with experimental results. A flow-through rotational viscometer was used to investigate foam rheology at higher pressures and verifiy the results of the pipe viscometer.
Results show that pipe rotation increases pressure drop by more than 30% for low quality (below 70%) foams in a concentric annulus. It has no noticeable effects on medium quality (70%-80%) foams, and slightly decreases pressure drop for high quality foams. In an eccentric annulus, pipe rotation clearly shifts the maximum axial velocity core along the pipe rotation direction. When there is a cuttings bed, however, the velocity core shifts to a direction that is opposite to the pipe rotation direction, which has a tremendous impact on hole cleaning. Unlike incompressible fluids, the absolute pressure also affects foam rheology and pressure drop for a given quality foam. The results of this study are particularly useful for drilling and cementing design calculations for underbalanced and managed pressure drilling operations.
Underbalanced Drilling: "Remedy for Formation-Damage, Lost-Circulation, and Other Related Conventional-Drilling Problems"
Authors: Rafique Maqsood Ahmad 
Published: March 2008

Abstract
The economics of exploration and production (E&P) continue to encourage use of new methods to reduce problems and costs. Underbalanced technology is one such method, which offers effective solution to conventional drilling problems. Underbalanced drilling or UBD is a procedure used intentionally to drill oil and gas wells where the equivalent circulating density (ECD) of the drilling fluid is less than the pore pressure in the formation being drilled. Underbalanced drilling (UBD) has been used with increasing frequency to minimize problems associated with invasive formation damage, which often greatly reduce the productivity of oil and gas reservoirs, particularly in openhole horizontal well applications. UBD, when properly designed and executed, minimizes or eliminates problems associated with the invasion of particulate matter into the formation as well as a multitude of other problems such as adverse clay reactions, phase trapping, precipitation, and emulsification, which can be caused by the invasion of incompatible mud filtrates in an overbalanced condition. In many UBD operations, additional benefits are seen because of a reduction in drilling time, greater rates of penetration, increased bit life, a rapid indication of productive reservoir zones, and the potential for dynamic flow testing while drilling.
Development and Exploration Well Permitting
Authors: Rivera P. V. , Gough G. N. , Dixon W. H. , Ashley B. J. 
Published: March 2008

Abstract
The protection of endangered species and sensitive habitat through the performance of biological surveys and the implementation of mitigation measures is critical when obtaining regulatory agency permit approvals for development and exploration wells within the San Joaquin Valley. Certain Federal and State listed endangered species, such as the blunt-nosed leopard lizard (BNLL), also known as Gambelia sila, are fully protected (West's Annotated California Codes, 1992). A new Best Management Practice (BMP) for protection of BNLL was developed in 2004 in a cooperative effort between Occidental of Elk Hills, Inc. (OEHI) and the U.S. Bureau of Land Management (BLM) to facilitate permitting an exploration well on a BLM mineral estate in western Kern County.
The BMP mitigation measure was developed under BLM's Programmatic Biological Opinion which provides for Federal incidental take authority pursuant to Section 7 of the Endangered Species Act. The BMP involved installing an exclusion fence around a proposed new well site. A trench approximately six inches deep was cut around the area to be enclosed using a walk behind trencher. The exclusion fence was constructed of 18-inch flashing, buried six-inches in depth and reinforced with stakes. Sections of flashing were joined by overlapping the materials and sealing them with a silicon based adhesive. A sliding gate was constructed using similar materials and a steel plate was placed across the threshold of the entrance to assist gate operations. As a contingency plan for discovery of BNLL within the excluded area, silt fencing would be used to isolate smaller areas inside the exclusion area. The plan specified that a section of the main exclusion fence would be removed, if necessary, to allow the lizard to leave. The exclusion fencing remained intact until drilling and sump closure activities were completed.
In summary, no harm came to the endangered BNLL or any other listed species during the course of this project. Since the development and successful implementation of this BMP, the Bakersfield, CA BLM Field Office and other Federal/State wildlife agencies have required other applicants to utilize this mitigation measure on federal and private lands that contain BNLL, as well as for other threatened and endangered species.
An Integrated Study of Mature Low Permeability Reservoir in Daqing Oil Field, China
Authors: Xu Yunting , Pu Hui , Shi Lianjie 
Published: March 2008

Abstract
Chaoyanggou oilfield is the largest low permeability oilfield of Daqing, and has been under production since 1981. Because of it’s complex geological characteristics, significant difference in physical properties of reservoir and crude oil in different blocks, the development effect is not desirable. In this paper, the reasons for the low development effect are analyzed, and the infill drilling is regarded as an effective way to improve the oil recovery and development effect. Through the study, the limit for infill drilling technology was determined, which includes such influential factors as well density, waterflood control degree, low limit of reservoir permeability, and effective displacement coefficient, etc. Also an integrated geological study has been carried out. The primary goal of the study was to develop an integrated reservoir description for targeted infill drilling and improve recovery in a low-permeability reservoir. The field application of infill drilling is very successful and the predicted ultimate oil recovery can be improved by 8.9+OOIP.
The study of this low permeability reservoir in the Daqing field is an excellent opportunity to: (1) demonstrate the economic importance of this zones, (2) guide the infill drilling program in other blocks, and (3) help the company to find additional reserves in the Songliao Basin.
A Method for Characterization of Flow Units Between Injection-Production Wells Using Performance Data
Authors: Lee Kun-Han , Ortega Antonio , Mohammad Nejad Amir , Ershaghi Iraj 
Published: March 2008

Abstract
This paper presents a novel data mining method to characterize the flow units between injection and production wells in a waterflood, using carefully implemented variations in injection rates. The method allows the computation of weight factors representing the influence of any of the injectors surrounding a given producer. The weight factors are used to characterize the effective contribution of injection wells to the total gross production in surrounding production wells. A wavelet approach is used to design the perturbation in the injection rates and to analyze the observed variations in the gross production rates.
Tracking the contribution of injectors to various producers can help in balancing voidage-replacement in waterflood optimization. A second application is reservoir characterization, where information provided by the proposed procedure can help in mapping high permeability flow units such as channels and fractures as well as flow barriers between wells. The method was successfully calibrated and tested for simulated line drive and five spot patterns with various assumed flow units and flow heterogeneity conditions. The paper also includes a case study for a tight formation waterflood where the weight factors are intended to delineate the pattern of natural fractures causing preferential flows.
Micromechanics of Hydrate Dissociation in Marine Sediments by Grain-Scale Simulations
Authors: Holtzman Ran , Silin Dmitriy B. , Patzek Tad W. 
Published: March 2008

Abstract
We seek to quantify the impact of hydrate dissociation on the strength of hydrate-bearing sediments. Dissociation of gas-hydrates in marine sediments converts the solid hydrate structure into liquid water and gas. Together with the associated pore pressure increase, this process reduces the stiffness of the sediments, which may fracture or be fluidized. If sediment failure occurs, seafloor subsidence and landslides can severely damage offshore infrastructure.
To evaluate the mechanical properties of a sediment sample, we simulate loading of a disordered pack of spherical grains by incremental displacements of its boundaries. The deformation is described as a sequence of equilibrium configurations. Each configuration is characterized by a minimum of the total potential energy. This minimum is computed using a modification of the conjugate gradient algorithm. We verify our model against published data from experiments on glass beads. Our simulations capture the nonlinear, path-dependent behavior of granular materials observed in experiments.
Hydrates are modeled as load-bearing solid particles within the pores. To simulate the consequences of dissociation, we reduce the solid fraction by shrinking the hydrate grains. The effect of the associated excess pore pressure is modeled by isotropic compression of the solid grains, and reduction in macroscopic effective stress. Weakening of the sediment is quantified as a reduction of the effective elastic moduli.
Incentives and Penalties Related to Earnings Overstatements that Violate GAAP
Authors: Beneish Messod D. 
Published: March 2008

This paper investigates the incentives and the penalties related to earnings overstatements primarily in firms that are subject to accounting enforcement actions by the Securities and Exchange Commission (SEC). I find (1) that managers in treatment firms are more likely to sell their holdings and exercise stock appreciation rights in the period when earnings are overstated than are managers in control firms, and (2) that the sales occur at inflated prices. I do not find evidence that earnings overstatement in these firms is motivated by concerns about debt covenant violations or the cost of external financing. The evidence suggests that the monitoring of managers' trading behavior can be informative about the likelihood of earnings overstatement.
Many economists believe that insider trading is an efficient method of compensating managers for their efforts. These economists argue that reputation losses would preclude managers from making profitable trades before periods of poor corporate performance. Consequently, this paper also investigates the employment and monetary penalties imposed on managers after the earnings overstatement is publicly discovered. This evidence reveals that (1) managers' employment losses subsequent to discovery are similar in firms that do and do not overstate earnings and (2) that the SEC is not likely to impose trading sanctions on managers in firms with earnings overstatement unless the managers sell their own shares as part of a firm security offering. The evidence suggests that neither employment or SEC-imposed monetary losses are effective in preventing the managers in these firms with extreme earnings overstatements from selling their stake in their firms in the face of declining performance.
The Influence of Potentially Fraudulent Reports on Audit Risk Assessment and Planning
Authors: Newman D. Paul , Patterson Evelyn , Smith Reed 
Published: March 2008

We consider how auditors assess the risk of fraudulent financial reporting and plan their audit where a possibly fraudulent auditee anticipates the assessment and planning process. The auditor uses the auditee's (possibly fraudulent) earnings report to revise his beliefs about the likelihood of fraud when formulating an audit plan.
We find that as underlying earnings increase, a fraudulent auditee increases reported earnings. In turn, as the auditee's reported earnings increase, the auditor increases audit effort. We also find that the auditee (who knows the auditor will use the report for audit planning) selects reports that increase his own expected payoff, relative to reports he would select if the auditor did not observe the report before finalizing the audit plan. By contrast, the auditor is no better off using the auditee's report for audit planning. Inherent risk, detection risk, and overall audit risk can increase when the auditor uses the auditee's report. Thus, because of the dynamic interaction between the auditor and auditee, procedures that aid in assessing audit risk may not reduce that risk or result in more efficient audits.
Management's Incentives to Avoid Negative Earnings Surprises
Authors: Matsumoto Dawn A. 
Published: March 2008

Recent reports in the business press allege that managers take actions to avoid negative earnings surprises. I hypothesize that certain firm characteristics are associated with greater incentives to avoid negative surprises. I find that firms with higher transient institutional ownership, greater reliance on implicit claims with their stakeholders, and higher value-relevance of earnings are more likely to meet or exceed expectations at the earnings announcement.I also examine whether firms manage earnings upward or guide analysts' forecasts downward to avoid missing expectations at the earnings announcement. I examine the relation between firm characteristics and the probability (conditional on meeting analysts' expectations) of having (1) positive abnormal accruals, and (2) forecasts that are lower than expected (using a model of prior earnings changes). Overall, the results suggest that both mechanisms play a role in avoiding negative earnings surprises.
Executive Target Bonuses and What They Imply about Performance Standards
Authors: Indjejikian Raffi J. , Nanda Dhananjay (DJ) 
Published: March 2008

We provide evidence that CEOs' and lower-level business unit executives' target bonuses are negatively associated with a proxy for measurement noise in accounting-based performance measures, and positively associated with proxies for firms' growth opportunities and the extent of executives' decision-making authority. Non-CEO executives' target bonuses are also positively associated with their CEO's target bonus.
In addition, we compare executives' actual and target bonuses over two consecutive periods to draw inferences about how firms revise executives' performance standards. If firms adjust performance standards to fully reflect executives' past performance, then we expect an executive's chances of earning an above-target bonus to be independent of his past performance. We find evidence to the contrary; an executive is more likely to receive an above-target bonus if he received an above-target bonus in the prior year than if he did not. This suggests that firms do not adjust standards to fully reflect executives' past performance, consistent with agency-theoretic arguments that a firm can better motivate its executives if it discounts executives' past performance in setting their future compensation.