bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Interimplant Distance (2 and 3 mm) on the Height of Interimplant Bone Crest: A Histomorphometric Evaluation
Authors: Elian Nicolas , Bloom Mitchell , Dard Michel , Cho Sang‐Choon , Trushkowsky Richard D. , Tarnow Dennis 
Published: March 2011

Background: Implants restored according to a platform‐switching concept (implant abutment interface with a reduced diameter relative to the implant platform diameter) present less crestal bone loss than implants restored with a standard protocol. When implants are placed adjacent to one another, this bone loss may combine through overlapping, thereby causing loss of the interproximal height of bone and papilla. The present study compares the effects of two interimplant distances (2 and 3 mm) on bone maintenance when bone‐level implants with platform‐switching are used.Methods: This study evaluates marginal bone level preservation and soft tissue quality around a bone‐level implant after 2 months of healing in minipig mandibles. The primary objective is to evaluate histologically and histomorphometrically the affect that an implant design with a horizontally displaced implant–abutment junction has on the height of the crest of bone, between adjacent implants separated by two different distances.Results: Results show that the interproximal bone loss measured from the edge of the implant platform to the bone crest was not different for interimplant distances of 2 or 3 mm. The horizontal position of the bone relative to the microgap on platform level (horizontal component of crestal bone loss) was 0.31 ± 0.3 mm for the 2‐mm interimplant distance and 0.57 ± 0.51 mm above the platform 8 weeks after implantation for the 3‐mm interimplant distance.Conclusions: This study shows that interimplant bone levels can be maintained at similar levels for 2‐ and 3‐mm distances. The horizontally displaced implant–abutment junction provided for a more coronal position of the first point of bone–implant contact. The study reveals a smaller horizontal component at the crest of bone than has been reported for non‐horizontally displaced implant–abutment junctions.
Living Cellular Construct for Increasing the Width of Keratinized Gingiva: Results From a Randomized, Within‐Patient, Controlled Trial
Authors: McGuire Michael K. , Scheyer E. Todd , Nevins Marc L. , Neiva Rodrigo , Cochran David L. , Mellonig James T. , Giannobile William V. , Bates Damien 
Published: March 2011

Background: The standard of care for increasing keratinized gingiva adjacent to teeth that do not require root coverage is the free gingival graft (FGG). A pilot study indicated that the use of a living cellular construct (LCC) could be effective in this clinical scenario.Methods: A pivotal, multicenter, randomized, within‐patient, controlled, open‐label trial was conducted (N = 96 patients). After removing the mucosa and keratinized gingiva from the test site, either an LCC or FGG was applied. The primary efficacy endpoint was the ability of the LCC to regenerate ≥2 mm keratinized gingiva at 6 months. Secondary measures were the same color and texture as the adjacent tissue, a 1‐mm width of keratinized gingiva at 6 months, patient treatment preference, surgical site sensitivity at 1 week, and patient‐reported pain after 3 days. Safety was assessed by reports of adverse events.Results: At 6 months, the LCC regenerated ≥2 mm of keratinized gingiva in 95.3% of patients (81 of 85 patients; P <0.001 versus a 50% predefined standard). As expected, the FGG generated more keratinized gingiva than the LCC (4.57 ± 1.0 mm versus 3.2 ± 1.1 mm, respectively). The gingiva regenerated with the LCC matched the color and texture of the adjacent gingiva. All patients achieved ≥1 mm keratinized gingiva with the LCC treatment by 6 months, and more patients preferred treatment with the LCC than with the FGG. No difference in sensitivity or pain was noted between the treatments. The treatments were well tolerated, and reported adverse events were typical for this type of periodontal surgery.Conclusion: The use of an LCC may provide a safe and effective therapy for augmenting the zone of keratinized gingiva.
Interactions of Enamel Matrix Derivative and Biomechanical Loading in Periodontal Regenerative Healing
Authors: Nokhbehsaim Marjan , Deschner Birgit , Bourauel Christoph , Reimann Susanne , Winter Jochen , Rath Björn , Jäger Andreas , Jepsen Søren , Deschner James 
Published: March 2011

Background: Although enamel matrix derivative (EMD) has been shown to promote periodontal regeneration, it is unknown whether the actions of EMD are modulated by occlusal loading. This in vitro study was performed to investigate whether biomechanical forces regulate the response of periodontal ligament (PDL) cells to EMD.Methods: Human PDL cells were treated with EMD in the presence and absence of cyclic tensile strain (CTS) of various magnitudes for ≤14 days. Synthesis of transforming growth factor (TGF)‐β1, vascular endothelial growth factor (VEGF), growth factor receptors, collagen, and runt‐related transcription factor 2‐ (RUNX2), cell numbers and adhesion, wound fill rate, and calcium accumulation were analyzed by real‐time polymerase chain reaction, enzyme‐linked immunosorbent assay, a wound healing assay, and alizarine red S staining.Results: Wound fill rate, cell numbers and adhesion, and expression of TGF‐β1, VEGF, collagen, and RUNX2 were significantly increased by EMD. In the presence of CTS, the EMD‐induced effects were significantly reduced. The inhibition of the EMD‐upregulated VEGF expression by CTS was blocked by a specific inhibitor of nuclear factor‐kappa B signaling. Moreover, CTS downregulated receptors for growth factors involved in the actions of EMD. CTS also antagonized significantly the EMD‐induced calcium deposition.Conclusions: These in vitro findings suggest that the beneficial actions of EMD on PDL cell functions critical for periodontal regeneration are jeopardized by biomechanical loading. Clinical studies should clarify whether protection of teeth against occlusal forces in the early healing stage may positively affect the outcome of regenerative therapy with EMD.
Detection of Periodontal Bacteria in Atheromatous Plaque by Nested Polymerase Chain Reaction
Authors: Figuero Elena , Sánchez‐Beltrán María , Cuesta‐Frechoso Susana , Tejerina Jose María , del Castro Jose Antonio , Gutiérrez Jose María , Herrera David , Sanz Mariano 
Published: March 2011

Background: In recent years, increasing evidence regarding the potential association between periodontal diseases and cardiovascular diseases has been identified. The available evidence underlines the importance of detecting periodontal pathogens on atheromatous plaque as the first step in demonstrating the causal relationship between the two conditions. The main aim of this investigation is to detect periodontitis‐associated bacteria from carotid artery atheromatous plaque from patients who received an endarterectomy using strict sample procurement and laboratory procedures.Methods: Atheromatous plaque from endarterectomies from carotid arteries were scraped and homogenized, and bacterial DNA was extracted. To obtain a representative concentration of amplicons, two amplifications of the bacterial 16S ribosomal‐RNA gene were carried out for each sample with universal eubacteria primers by a polymerase chain reaction (PCR). A nested PCR with specific primers for the target bacteria was performed next. Statistical tests included the χ2 test.Results: Forty‐two atheromatous plaque were analyzed. All of them were positive for ≥1 target bacterial species. The bacterial species most commonly found was Porphyromonas gingivalis (78.57%; 33 of 42), followed by Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) (66.67%; 28 of 42), Tannerella forsythia (previously T. forsythensis) (61.90%; 26 of 42), Eikenella corrodens (54.76%; 23 of 42), Fusobacterium nucleatum (50.00%; 21 of 42), and Campylobacter rectus (9.52%; four of 42). The simultaneous presence of various bacterial species within the same specimen was a common observation.Conclusion: Within the limitations of this study, the presence of DNA from periodontitis‐associated bacteria in carotid artery atheromatous plaque retrieved by endarterectomy is confirmed.
Method To Generate Full-Bore Images Using Borehole Images and Multipoint Statistics
Authors: Hurley Neil F. , Zhang Tuanfeng 
Published: March 2011

Summary
Borehole-image logs, which are produced by tools being lowered into a well, provide oriented electrical and acoustic maps of the rocks and fluids encountered in the borehole. Electrical borehole images in water-based (conducting) and oil-based (nonconducting) muds are generated from electrodes arranged in fixed patterns on pads that are pressed against the borehole wall. Depending on the borehole diameter, gaps nearly always occur between pads. Because of these gaps, it is common to have nonimaged parts of the borehole wall.
Full-bore images are complete, 360° views of the borehole wall. They are generated by "filling in the gaps" between the pads in borehole-image logs. This method uses the Filtersim algorithm of multipoint statistics (MPS) to generate models, or realizations. Measured (incomplete) borehole images themselves are used as "training images." Recorded data are perfectly honored (i.e., the models are conditioned to the real data). Gaps are filled with patterns similar to those seen elsewhere in the log. Patterns in the gaps match the edges of the pads. The frequency distribution of continuously variable pixel colors in the gaps matches the distribution of pixel colors in the measured images.
Full-bore images facilitate visualization and interpretation of borehole-image logs in any lithology, although case studies shown in this paper are developed in vuggy and fractured rocks. These images can be used to draw closed contours around electrically resistive or nonresistive patches in the borehole wall. Full-bore images can be used to repair logs with bad electrodes, low pad pressure, or poor acoustic reflections. Therefore, they can be used to enhance any commercially available electrical or acoustic borehole images.
A New Well-Pattern-Optimization Procedure for Large-Scale Field Development
Authors: Onwunalu J.E.. E. , Durlofsky L.J.. J. 
Published: March 2011

Summary
The optimization of large-scale multiwell field-development projects is challenging because the number of optimization variables and the size of the search space can become excessive. This difficulty can be circumvented by considering well patterns and then optimizing parameters associated with the pattern type and geometry. In this paper, we introduce a general framework for accomplishing this type of optimization. The overall procedure, which we refer to as well-pattern optimization (WPO), includes a new well-pattern description (WPD) incorporated into an underlying optimization method. The WPD encodes potential solutions in terms of pattern types (e.g., five-spot, nine-spot) and pattern operators. The operators define geometric transformations (e.g., stretching, rotating) quantified by appropriate sets of parameters. It is the parameters that specify the well patterns and the pattern operators, along with additional variables that define the sequence of operations, that are optimized. A technique for subsequent well-by-well perturbation (WWP), in which the locations of wells within each pattern are optimized, is also presented. This WWP represents an optional second phase of WPO. The overall optimization procedure could be used with a variety of underlying optimization methods. Here, we combine it with a particle-swarm-optimization (PSO) technique because PSO methods have been shown recently to provide robust and efficient optimizations for well-placement problems.
Detailed optimization results are presented for several example cases. In one case, multiple reservoir models are considered to account for geological uncertainty. For all examples, significant improvement in the objective function is observed as the algorithm proceeds, particularly at early iterations. The use of well-by-well perturbation (following determination of the optimal pattern) is shown to provide additional improvement. Limited comparisons with results using standard well patterns of various sizes demonstrate that the net present values (NPVs) achieved by the new algorithm are considerably larger. Taken in total, the optimization results highlight the potential of the overall procedure for use in practical field development.
Inflow Performance of a Cyclic-Steam-Stimulated Horizontal Well Under the Influence of Gravity Drainage
Authors: Wu Z.. , Vasantharajan S.. , El-Mandouh M.. , Suryanarayana P.V.. V. 
Published: March 2011

Summary
In this paper, we present a new, semianalytical gravity-drainage model to predict the oil production of a cyclic-steam-stimulated horizontal well. The underlying assumption is that the cyclic steam injection creates a cylindrical steam chamber in the upper area of the well. Condensed water and heated oil in the chamber are driven by gravity and pressure drawdown toward the well. The heat loss during the soak period and during oil production is estimated under the assumption of vertical and radial conduction. The average temperature change in the chamber during the cycle is calculated using a semianalytical expression. Nonlinear, second-order ordinary differential equations are derived to describe the pressure distribution caused by the two-phase flow in the wellbore. A simple iteration scheme is proposed to solve these equations. The influx of heated oil and condensed water into the horizontal wellbore is calculated under the assumption of steady-state radial flow.
The solution from the semianalytical formulation is compared against the results from a commercial thermal simulator for an example problem. It is shown that the model results are in good agreement with those obtained from reservoir simulation. Sensitivity studies for optimization of wellbore length, gravity drainage, bottomhole pressure, and steam-injection rate are conducted with the model. Results indicate that the proposed model can be used in the optimization of individual-well performance in cyclic-steam-injection heavy-oil development. The semianalytical thermal model presented in this work can offer an attractive alternative to numerical simulation for planning heavy-oil field development.
Optimizing Fracture Spacing and Sequencing in Horizontal-Well Fracturing
Authors: Roussel Nicolas P. , Sharma Mukul M. 
Published: March 2011

Summary
Horizontal wells with multiple fractures are now commonly used in unconventional (low-permeability) gas reservoirs. The spacing between perforations and the number and orientation of transverse fractures all have a major impact on well production.
The opening of propped fractures results in the redistribution of local Earth stresses. In this paper, the extent of stress reversal and reorientation has been calculated for fractured horizontal wells using a 3D numerical model of the stress interference induced by the creation of one or more propped fractures. The results have been analyzed for their impact on simultaneous and sequential fracturing of horizontal wells.
Our results demonstrate that a transverse fracture initiated from a horizontal well may deviate away from the previous fracture. The effect of the reservoir's mechanical properties on the spatial extent of stress reorientation caused by an opened crack has been quantified. The paper takes into account the presence of layers that bound the pay zone but have mechanical properties different from those of the pay zone. The fracture vertical growth into the bounding layers is also examined.
It is shown that stress interference, or reorientation, increases with the number of fractures created and depends on the sequence of fracturing. Three fracturing sequences are investigated for a typical field case in the Barnett shale: (a) consecutive fracturing, (b) alternative fracturing, and (c) simultaneous fracturing of adjacent wells. The numerical calculation of the fracture spacing required to avoid fracture deviation during propagation, for all three fracturing techniques, demonstrates the potential advantages of alternate fracture sequencing and zipper fracs to improve the performance of stimulation treatments in horizontal wells.
Design Methodology and Operational Practices Eliminate Differential Sticking
Authors: Dupriest Fred E. , Elks William C. , Ottesen Steinar 
Published: March 2011

Summary
This paper discusses a successful initiative begun 6 years ago to eliminate differential sticking across global operations. In the 5-year period from 2004 through 2008, there were only three differential-sticking events in 3,476 wells drilled with the recommended practices. There were an additional 17 sticking events with designs that did not conform to recommended practices, and 14 of these were freed. The drilling environment was diverse. Overbalances in excess of 1,000 to 2,000 psi were common in multidarcy rock and at high angle, and depleted reservoirs have been drilled with overbalance as high as 7,800 psi in vertical wells.
The early focus of the stuck-pipe-avoidance practices was the elimination of differential sticking. However, some level of sticking occurs routinely in drilling operations, and these events become problematic only if the force required to initiate pipe movement exceeds what can be delivered to the stuck point. It is now accepted that sticking cannot be prevented and that elimination of sticking is not a proper design objective. The philosophical objective has now shifted from elimination of sticking to "maintaining conditions that allow the pipe to be pulled free," assuming that it will become differentially stuck. The desire to maintain this ability to move the pipe has required the implementation of a range of practices, some of which were not common in the industry.
Changes were made in bottomhole assembly (BHA) design, fluid design, real-time cake-shear-strength recognition, and realtime cake-remediation practices. A finite-element (FE) model was also applied to redesign new systems or applications that lie outside the operator's previous experience. The stochastic model predicts cake growth and sticking force and the probability that it will be possible to deliver a force that can free the pipe for any given still-pipe time. The model inputs were calibrated through pullout tests with a variety of fluids to determine mechanical cake-strength properties, the rate at which those properties develop, changes in the pressure transient through the cake as it matures, and the cake contact areas and geometry at any point in time.
Engineering and operations training also contributed greatly and allowed relatively uniform implementation to be achieved across a large, globally diverse operation in less than 1 year. A small number of noncompliant designs continued to be used, and these contributed greatly to the incidence of stuck pipe in the first 3 years. Last year, there was only one incident of stuck pipe with a noncompliant design.
The paper describes the underlying sticking concepts, the engineering design and field practices used, the modeling capability, and the field results.
Automation of Mud-Pump Management: Application to Drilling Operations in the North Sea
Authors: Cayeux Eric , Daireaux Benoît , Dvergsnes Erik Wolden 
Published: March 2011

Summary
Drilling in the North Sea is confronted with an ever more challenging pressure-management issue because of narrow geopressure windows in depleted reservoirs. Further, the occurrence of packoffs can cause serious damage to the formation and contribute to nonproductive time. To address these problems, automation of mud-pump management has been developed over the last 4 years to minimize the chance of fracturing the formation while starting the mud pumps or circulating. To account for abnormal flow restrictions in the annulus, automatic actions are also an integral part of the mud-pump automation described in this paper.
Since the downhole conditions are continuously changing (e.g., depth, temperature, flow-rate, gel time, cuttings proportion), the necessary safeguards to operate the mud pumps need to be updated constantly. Advanced transient temperature and hydraulic models are used to estimate, in real-time, the downhole situation. On the basis of the current context, evaluations of maximum pump rates and acceptable flow accelerations are performed and sent to the mud-pump control system to be used as an envelope of protection. Furthermore, to assist the driller during connections, the pump-startup procedure has been semiautomated to decrease connection time. Finally, an automatically triggered pump-shutdown procedure is also available to minimize the consequences of a packoff on formation fracturing.
A first version of the system has been tested during the drilling of one well in 2008 in the North Sea. Based on the initial experience, a revised version has been used during the drilling of three wells drilled on the Norwegian continental shelf in 2009. The feedback from the drillers involved in the testing has been used to improve the user friendliness of the system. The automation of the mud-pump management has been well accepted by the drilling crews. However, the testing has shown that additional instrumentation at the rigsite is necessary before such automation can be rolled out safely.
The Influence of Data Quality on Workflows and Decision Making in Well Delivery
Authors: Sawaryn S.J.. J. , Whiteley N.. , Deady A.. , Borresen A.. , Gibson N.. 
Published: March 2011

Summary
The paper discusses how data quality influences workflows and decision making in drilling and completions and examines the use of semiautomated processes for quality assurance. With poor data, additional steps are required and workflows must be repeated. In even relatively simple situations, controlled tests suggest that small changes or omissions may have a significant influence on the work efficiency or outcome.
In earlier work, the quality of any data stream has been described in terms of identity, presence, measurement frequency, accuracy, continuity, units, and associated metadata. For some of these, a degree of self-checking is possible, applying simple algorithms to the data stream to detect presence and bounds, with alarms to alert the operator if these are transgressed. In other cases, such as the change in drag and torque with depth, the stream must be checked against a trend, called a pseudolog, determined from the physics. These calculations are performed by "smart agents" directly in real time on the wellsite information transfer standard markup language (WITSML) data feed from the rig. The paper describes the early work in developing smart agents to address data quality and structure of the associated tool kit that can be used to construct more- complex agents from a wider selection of data sources, including system-generated ones. The computational resources required are also discussed.
The increase in digital data and skills shortage makes manual assurance of all the data streams neither practical nor cost effective. Because current applications are not tolerant of errors and omissions, a step change in data quality is needed if more-automated workflows are to be achieved. Greater assurance of the data at source and an improved understanding of the workflows will help.