bluuebunny/crossref_metadata_2025 huggingface dataset:
The Lévy flight paradigm: random search patterns and mechanisms
Authors: Reynolds A. M. , Rhodes C. J.
Published: March 2009

Over recent years there has been an accumulation of evidence from a variety of experimental, theoretical, and field studies that many organisms use a movement strategy approximated by Lévy flights when they are searching for resources. Lévy flights are random movements that can maximize the efficiency of resource searches in uncertain environments. This is a highly significant finding because it suggests that Lévy flights provide a rigorous mathematical basis for separating out evolved, innate behaviors from environmental influences. We discuss recent developments in random‐search theory, as well as the many different experimental and data collection initiatives that have investigated search strategies. Methods for trajectory construction and robust data analysis procedures are presented. The key to prediction and understanding does, however, lie in the elucidation of mechanisms underlying the observed patterns. We discuss candidate neurological, olfactory, and learning mechanisms for the emergence of Lévy flight patterns in some organisms, and note that convergence of behaviors along such different evolutionary pathways is not surprising given the energetic efficiencies that Lévy flight movement patterns confer.
Survivorship curves and their impact on the estimation of maximum population growth rates
Authors: Lynch Heather J. , Fagan William F.
Published: March 2009

Previous efforts to use the Euler equation to estimate maximum population growth rates (variously symbolized as eitherr,rm, orrmax) have used simplified models of survivorship that neglect differences in survivorship schedules among species. In particular, several recent analyses have used either an exponential model of survivorship or a step function model in which all individuals live until a fixed age of death. Using a flexible alternative based on the beta distribution and a compiled data set of mammalian survivorship curves for 58 species, we explore the influence of survivorship shape and scale on the estimation ofr. We show that the Euler equation paired with an exponential model of survivorship can be used to calculate an unbiased estimate ofrover a large range of body sizes, whereas the more commonly used step function survivorship model results in severely inflated estimates ofr, especially for mammals with large maximum population growth rates. Finally, we demonstrate that, despite producing different absolute estimates ofr, the three survivorship models examined yield similar allometric scaling coefficients relatingrto biomass. These allometric scaling relationships are highly sensitive to the inclusion or exclusion of bats (Chiroptera), which exhibit life‐history traits (long life spans, small litter sizes, and relatively long litter intervals) inconsistent with their small body size.
Evidence for the evolution of reduced mycorrhizal dependence during plant invasion
Authors: Seifert Elizabeth K. , Bever James D. , Maron John L.
Published: March 2009

Introduced species inevitably experience novel selection pressures in their new environments as a result of changes in mutualist and antagonist relationships. While most previous work has examined how escape from specialist enemies has influenced herbivore or pathogen resistance of exotic species, post‐introduction shifts in exotic dependence on mutualists have not been considered. In a common environment, we compared dependence on AM fungi of North American and European populations of Hypericum perforatum (St. John's Wort), a forb native to Europe. Introduced North American populations responded less to inoculation with AM fungi than did European populations. Root architecture was strongly correlated with mycorrhizal response, and introduced populations had finer root architecture than native populations. Finally, introduced populations exhibited decreased root and increased reproductive allocation relative to European populations, consistent with a transition to a weedier life history; however, biomass allocation patterns were uncorrelated with mycorrhizal response. These findings are the first demonstration of a genetically based reduction of mycorrhizal dependence and shift in root architecture in an introduced species.
Diversity has stronger top‐down than bottom‐up effects on decomposition
Authors: Srivastava Diane S. , Cardinale Bradley J. , Downing Amy L. , Duffy J. Emmett , Jouseau Claire , Sankaran Mahesh , Wright Justin P.
Published: March 2009

The flow of energy and nutrients between trophic levels is affected by both the trophic structure of food webs and the diversity of species within trophic levels. However, the combined effects of trophic structure and diversity on trophic transfer remain largely unknown. Here we ask whether changes in consumer diversity have the same effect as changes in resource diversity on rates of resource consumption. We address this question by focusing on consumer–resource dynamics for the ecologically important process of decomposition. This study compares the top‐down effect of consumer (detritivore) diversity on the consumption of dead organic matter (decomposition) with the bottom‐up effect of resource (detrital) diversity, based on a compilation of 90 observations reported in 28 studies. We did not detect effects of either detrital or consumer diversity on measures of detrital standing stock, and effects on consumer standing stock were equivocal. However, our meta‐analysis indicates that reductions in detritivore diversity result in significant reductions in the rate of decomposition. Detrital diversity has both positive and negative effects on decomposition, with no overall trend. This difference between top‐down and bottom‐up effects of diversity is robust to different effect size metrics and could not be explained by differences in experimental systems or designs between detritivore and detrital manipulations. Our finding that resource diversity has no net effect on consumption in “brown” (detritus–consumer) food webs contrasts with previous findings from “green” (plant–herbivore) food webs and suggests that effects of plant diversity on consumption may fundamentally change after plant death.
INDIVIDUAL DIFFERENCES, INTELLIGENCE, AND BEHAVIOR ANALYSIS
Authors: Williams Ben , Myerson Joel , Hale Sandra
Published: March 2009

Despite its avowed goal of understanding individual behavior, the field of behavior analysis has largely ignored the determinants of consistent differences in level of performance among individuals. The present article discusses major findings in the study of individual differences in intelligence from the conceptual framework of a functional analysis of behavior. In addition to general intelligence, we discuss three other major aspects of behavior in which individuals differ: speed of processing, working memory, and the learning of three‐term contingencies. Despite recent progress in our understanding of the relations among these aspects of behavior, numerous issues remain unresolved. Researchers need to determine which learning tasks predict individual differences in intelligence and which do not, and then identify the specific characteristics of these tasks that make such prediction possible.
AN INEXPENSIVE INFRARED DETECTOR TO VERIFY THE DELIVERY OF FOOD PELLETS
Authors: Pinkston Jonathan W. , Ratzlaff Kenneth L. , Madden Gregory J. , Fowler Stephen C.
Published: March 2009

The reproducibility of experimental outcomes depends on consistent control of independent variables. In food‐maintained operant performance, it is of utmost importance that the quantity of food delivered is reliable. To that end, some commercial food pellet dispensers have add‐on attachments to sense the delivery of pellets. Not all companies, however, offer such add‐ons. Aside from availability, cost and temporary reduction in throughput may be a problem for smaller labs. The present paper outlines our recent development of a simple, inexpensive infrared device to detect and confirm the delivery of pellets. The in‐line construction of the detector routes the falling pellet through a barrel so that it passes between an infrared emitter and receiver. The circuitry was designed to be compatible with all commercially available behavioral measurement systems, and so may be retrofit to any existing system. Our tests with the detector so far have shown that it is 100% accurate in detecting pellet delivery. The individual unit cost is approximately 25 dollars. The low cost and versatility of the device offer an easy method to ensure the integrity of food delivery in operant settings.
TOLERANCE TO EFFECTS OF COCAINE ON BEHAVIOR UNDER A RESPONSE‐INITIATED FIXED‐INTERVAL SCHEDULE
Authors: Weaver Matthew T. , Branch Marc N.
Published: March 2009

Tolerance to effects of cocaine can be modulated by schedules of reinforcement. With multiple ratio schedules, research has shown an inverse relationship between ratio requirement and amount of tolerance that resulted from daily administration of the drug. In contrast, tolerance to the effects of cocaine on behavior under multiple interval schedules generally has developed regardless of interval value. Under interval schedules reinforcement depends on the animal making one response following a time interval. Thus, as time to respond increases, the time to reinforcement decreases. On the other hand, fixed ratio schedules require a specified number of responses to be made prior to reinforcement. Therefore, delaying the initiation of responding does not coincide with a significant decrease in the time to reinforcement. In the current experiment, 6 pigeons were trained to respond under a three‐component multiple schedule, with a different tandem fixed‐ratio 1 fixed‐interval schedule in each component. The multiple schedule required one response, which was followed by one of three fixed‐interval values (5, 15, or 60 s). Thus, the multiple schedule was interval‐like because after the fixed‐ratio 1, only one more response was required for reinforcement, but it was also ratio‐like because the length of the pause at the beginning of each interreinforcer interval affected the time until the next reinforcer. Acute administration of cocaine generally resulted in dose‐dependent decreases in responding. Chronic (i.e., daily) administration of a rate‐decreasing dose resulted in tolerance patterns similar to those usually obtained with multiple ratio schedules. That is, the magnitude of tolerance was related inversely to schedule size. These results suggest that delay to reinforcement from the initial response may play a role in the development of schedule‐parameter‐related tolerance.
Cellular Effects of Enamel Matrix Derivative Are Associated With Different Molecular Weight Fractions Following Separation by Size‐Exclusion Chromatography
Authors: Johnson Dwight L. , Carnes David , Steffensen Bjorn , Cochran David L.
Published: March 2009

Background: Enamel matrix derivative (EMD) was shown to enhance soft tissue healing and regeneration of the periodontium; however, the mechanisms of this action are unknown. It is assumed that amelogenin, the most abundant protein in EMD, is the protein primarily responsible for the effects of EMD. The purpose of this study was to fractionate EMD and associate its specific cellular effects with different molecular weight fractions following size‐exclusion chromatography.

Methods: Freshly dissolved EMD was fractionated by gel filtration, and forty‐five 7‐ml fractions were collected, desalted, lyophilized, and resuspended. These fractions were analyzed for their effects on the differentiation of osteoprogenitor cells (C2C12) and the proliferation and differentiation of human microvascular endothelial cells (HMVECs). Alkaline phosphatase activity (C2C12) was measured as a marker for osteogenic differentiation before and after preincubation of the fractions with the bone morphogenetic protein (BMP) decoy receptor, noggin. Angiogenesis (HMVEC) was evaluated as a marker for endothelial cell differentiation. Enzymographic assays used polyacrylamide gels copolymerized with denatured type I collagen to determine gelatinolytic activities in each fraction.

Results: EMD fractionated into three major protein peaks following size exclusion chromatography with cross‐linked dextran particle matrix. Peak I was associated with the column void volume, whereas peak III eluted near the salt volume. Peak II eluted between these two peaks. Proliferation and angiogenic activities were associated with peaks II and III for the microvascular cells. The differentiation of osteoprogenitor cells, indicated by alkaline phosphatase activity, was induced by EMD components present in peak I and the leading edge of peak II. The additional observation that this differentiation was inhibited by prior treatment of the fractions with noggin suggested the activity was induced by BMP rather than amelogenin or other unknown proteins. Gelatinolytic activities were detected in the early fractions of peaks I and II of gel‐fractionated EMD.

Conclusions: The cellular activities stimulated by EMD are not associated with a single molecular weight species. The fact that noggin abolishes C2C12 alkaline phosphatase activity suggests that effects on osteoprogenitor cell differentiation are the result of a BMP‐like protein(s), whereas effects on proliferation and angiogenesis are associated with lower molecular weight species present in peaks II and III. Finally, unheated EMD displays gelatinolytic activities that are also detectable following size‐exclusion separation of its constituents. The masses of these activities were consistent with those reported for latent and active matrix metalloproteinase‐20.
Periodontal Therapy Reduces the Severity of Active Rheumatoid Arthritis in Patients Treated With or Without Tumor Necrosis Factor Inhibitors
Authors: Ortiz P. , Bissada N.F. , Palomo L. , Han Y.W. , Al‐Zahrani M.S. , Panneerselvam A. , Askari A.
Published: March 2009

Background: Rheumatoid arthritis (RA) and periodontitis are common chronic inflammatory conditions. Recent studies showed a beneficial effect of periodontal treatment on the severity of active RA. This study was undertaken to further examine the effect of non‐surgical periodontal treatment on the signs and symptoms of RA in patients treated with or without anti‐tumor necrosis factor‐alpha (anti‐TNF‐α) medications. The effect of anti‐TNF‐α therapy on periodontitis also was assessed.

Methods: Forty participants diagnosed with moderate/severe RA (under treatment for RA) and severe periodontitis were randomly assigned to receive initial non‐surgical periodontal therapy with scaling/root planing and oral hygiene instructions (n = 20) or no periodontal therapy (n = 20). To control RA, all participants had been using disease‐modifying anti‐rheumatic drugs, and 20 had also been using anti‐TNF‐α before randomization. Probing depth (PD), clinical attachment level (CAL), bleeding on probing (BOP), gingival index (GI), plaque index (PI), RA disease activity score 28 (DAS28), and erythrocyte sedimentation rate (ESR) were measured at baseline and 6 weeks later. Linear mixed models were used to identify significant differences between subjects who received periodontal treatment and those who did not.

Results: Patients receiving periodontal treatment showed a significant decrease in the mean DAS28, ESR (P <0.001), and serum TNF‐α (P <0.05). There was no statistically significant decrease in these parameters in patients not receiving periodontal treatment. Anti‐TNF‐α therapy resulted in a significant improvement in CAL, PD, BOP, and GI.

Conclusions: Non‐surgical periodontal therapy had a beneficial effect on the signs and symptoms of RA, regardless of the medications used to treat this condition. Anti‐TNF‐α therapy without periodontal treatment had no significant effect on the periodontal condition.
Hand and Ultrasonic Instrumentation in Combination With Root‐Coverage Surgery: A Comparative Controlled Randomized Clinical Trial
Authors: Zucchelli G. , Mounssif I. , Stefanini M. , Mele M. , Montebugnoli L. , Sforza N.M.
Published: March 2009

Background: The role of vigorous root planing in the surgical treatment of gingival recession was recently questioned. The aim of the present randomized controlled split‐mouth clinical study was to compare the effectiveness, in terms of root coverage, of hand and ultrasonic root instrumentation in combination with a coronally advanced flap for the treatment of isolated‐type recession defects.

Methods: Eleven systemically and periodontally healthy subjects with bilateral recession defects (≥3 mm) of similar (≤1 mm) depth affecting contralateral teeth were enrolled in the study. Only Miller Class I gingival recession with no deep cervical abrasion or root caries/demineralization were included in the study. Control root exposures were treated with curets, whereas test roots were instrumented with ultrasonic piezoelectric devices. Randomization for test and control treatment was performed by a coin toss immediately prior to surgery. All recessions were treated with a coronally advanced flap surgical technique. The clinical reevaluation was made 6 months after surgery.

Results: The two approaches resulted in a high percentage of root coverage (95.4% in the control group and 84.2% in the test group) and complete root coverage (82% in the control group and 55% in the test teeth), with no statistically significant difference between them. Clinical attachment level gains were clinically significant in both groups (3.36 ± 0.92 mm in the control group and 2.90 ± 0.70 mm in the test group), with no statistically significant difference between them. The increase in keratinized tissue height was statistically significant in both groups (0.55 ± 0.52 mm in the control group and 0.36 ± 0.67 mm in the test group), with no difference between them.

Conclusions: The present study failed to demonstrate any superiority, in terms of root‐coverage results, for hand instruments over ultrasonic treatment of the root surface in combination with coronally advanced flap mucogingival surgery. Further studies of longer‐term duration and larger sample size could help to establish the superiority of one form of root instrumentation in conjunction with root‐coverage surgery.
Comparing Suture Strengths for Clinical Applications: A Novel In Vitro Study
Authors: Vasanthan Asvin , Satheesh Keerthana , Hoopes Wyeth , Lucaci Patrick , Williams Karen , Rapley John
Published: March 2009

Background: The purpose of this study was to compare the tensile strengths of commonly used sutures over a 2‐week period under simulated oral conditions.

Methods: Three suture materials (chromic gut [CG], polyglactin [PG], and polyglactin‐fast absorbing [PG‐FA]) were used in 4‐0 and 5‐0 gauges. After pretensioning, 252 suture samples (42 of each material and gauge) were used. A biologic simulation was created in vitro by mixing 9 ml sterile human saliva and human serum in a 1:1 ratio in a petri dish maintained at a pH of 7.4 to 8.1 at 37°C. All samples were tested preimmersion and 1 hour and 1, 3, 7, 10, and 14 days postimmersion. The tensile strength was assessed using a microtensile tester, and the maximum load required to cause suture breakage was determined. The point of breakage in the samples and the samples themselves were also assessed.

Results: During the first 24 hours of immersion, all 4‐0 and 5‐0 samples of CG and PG maintained their initial level of tensile strength; PG‐FA 5‐0 decreased in strength, which was statistically significant (P = 0.001). Between days 1 and 3, the tensile strength of PG and PG‐FA decreased significantly, with PG‐FA 5‐0 showing a greater and more precipitous decrease than PG‐FA 4‐0; the tensile strength of CG changed little during this time. After 7 days of immersion, PG 4‐0 had significantly greater tensile strength than CG, and both were significantly greater than that of PG‐FA. By day 10, CG and PG had statistically greater strength (P = 0.01) than PG‐FA, and values were similar for the 4‐0 and 5‐0 gauge materials. All samples of PG‐FA 5‐0 and most samples of the PG‐FA 4‐0 exhibited 0.00 N strength (i.e., they had disintegrated) at the 10‐ and 14‐day periods of evaluation.

Conclusions: 4‐0 sutures are stronger and have greater tensile strength than 5‐0 sutures. CG seems to sustain its strength better than PG and PG‐FA after 2 weeks. PG‐FA may not be a desirable suture if tensile strength is required after 10 days. Appropriately designed clinical studies are necessary to confirm this finding in an in vivo environment.
Circulating Interleukin‐6 and High‐Sensitivity C‐Reactive Protein Decrease After Periodontal Therapy in Otherwise Healthy Subjects
Authors: Marcaccini Andrea M. , Meschiari César A. , Sorgi Carlos A. , Saraiva Maria C.P. , de Souza Ana M. , Faccioli Lúcia H. , Tanus‐Santos José E. , Novaes Arthur B. , Gerlach Raquel F.
Published: March 2009

Background: Periodontal disease has been associated with many chronic inflammatory systemic diseases, and a common chronic inflammation pathway has been suggested for these conditions. However, few studies have evaluated whether periodontal disease, in the absence of other known inflammatory conditions and smoking, affects circulating markers of chronic inflammation. This study compared chronic inflammation markers in control individuals and patients with periodontal disease and observed whether non‐surgical periodontal therapy affected inflammatory disease markers after 3 months.

Methods: Plasma and serum of 20 controls and 25 patients with periodontal disease were obtained prior to and 3 months after non‐surgical periodontal therapy. All patients were non‐smokers, they did not use any medication, and they had no history or detectable signs and symptoms of systemic diseases. Periodontal and systemic parameters included probing depth, bleeding on probing, clinical attachment level, hematologic parameters, as well as the following inflammatory markers: interleukin (IL)‐6, high‐sensitivity C‐reactive protein (hs‐CRP), CD40 ligand, monocyte chemoattractant protein (MCP)‐1, soluble P‐selectin (sP‐selectin), soluble vascular adhesion molecule (sVCAM)‐1, and soluble intercellular adhesion molecule (sICAM)‐1.

Results: There were no differences in the hematologic parameters of the patients in the control and periodontal disease groups. Among the tested inflammatory markers, IL‐6 concentrations were higher in the periodontal disease group at baseline compared to the controls (P = 0.006). Therapy was highly effective (P <0.001 for all the analyzed clinical parameters), and a decrease in circulating IL‐6 and hs‐CRP concentrations was observed 3 months after therapy (P = 0.001 and P = 0.006, respectively). Our results also suggest that the CD40 ligand marker may have been different in the control and periodontal disease groups prior to the therapy (P = 0.009).

Conclusions: In apparently otherwise healthy patients, periodontal disease is associated with increased circulating concentrations of IL‐6 and hs‐CRP, which decreased 3 months after non‐surgical periodontal therapy. With regard to the CD40 ligand, MCP‐1, sP‐selectin, sVCAM‐1, and sICAM‐1, no changes were seen in the periodontal disease group between baseline and 3 months after therapy.
Working With Coiled Tubing in H2S and CO2 Wells: A Global Perspective
Authors: Hampson R. , Moir C. , Freeney T.
Published: March 2009

The use of coiled tubing (CT) in wells containing hydrogen sulfide gas (H2S) has associated problems because of the potential for sulfide stress cracking (SSC) of the CT material. Carbon dioxide (CO2) can also contribute to general corrosion or intensify any H2S-related corrosion because of chemical reactions resulting in acid. However, with the right precautions, equipment, and procedures, this type of operation can be carried out safely and successfully.

The various problems associated with working with CT in H2S and CO2 wells are discussed and a general best practice taken from locations working regularly with H2S and CO2 is presented. This paper shows the equipment, chemical inhibitor, quantity and method of inhibitor application, and other precautions taken to carry out the work safely and successfully. An alternative approach is also highlighted for some situations whereby any H2S is bullheaded into the well before coiled-tubing intervention. This alternative approach avoids any contact of H2S with CT to prevent corrosion. A number of case histories are shown for different H2S and/or CO2 locations around the world, which detail the type of operations, quantity of H2S and CO2, procedures used, frequency of operations, and the overall success of these methods in ongoing operations.

This paper presents a review of methods and equipment currently being used around the world to work in potentially corrosive and dangerous H2S and/or CO2 wells.
Corrosion Fatigue of Grade-90 Pipe in 15% and 28% Hydrochloric Acid With and Without Inhibitor
Authors: Ehtesham Asif , Freeney Timothy , Hampson Richard
Published: March 2009

Coiled tubing (CT) is routinely exposed to different concentrations of acid in stimulation and cleanout jobs. Routine maintenance measures are generally taken, such as the use of inhibitors and proper cleanup and storage practices. However, a large number of CT strings suffer from corrosion and corrosion-fatigue related damage. Though it is difficult to isolate string damage solely from corrosion fatigue, this paper addresses the effect of acid with and without inhibitors on corrosion-fatigue properties of the grade-90 pipe through experimental testing. The results of testing demonstrate that exposure to acid without an inhibitor and during fatigue had the most pronounced effect on fatigue life. The simultaneous action of corrosion and fatigue produced more pits and cracks than would have occurred by corrosion or fatigue separately.

CT exposure to acid before, during, and after bending can have different effects on fatigue life. This paper describes an experimental study that was conducted to observe these effects. A strip of metal, 1-in. wide and 6-in. long, was cut from a round 1.75-in. OD, 1.56-in. wall thickness of 90-ksi yield CT and underwent one-way, bent-beam fatigue testing. This paper will present S-N curves generated for samples in three environments: air, acid, and acid with inhibitor at deflection levels ranging from 0 to 40 mm. Finite element analysis (FEA) was used to correlate deflection to strain range levels of 0.5 to 4.0%.
Damaged Control Line Replacement Safety Valve System: Thru-Tubing
Authors: Bolding Jeff L. , Embrey Mark R. , Mondelli Max E. , Sanders Don L.
Published: March 2009

Description: A wireline insert, Surface Contror permission to publish this paper. A special thanks to BJ tools specialiolled Sub-Surface Safety Valve (SCSSV), has been successfully installed for an operator in the Gulf of Mexico, in a well, which had lost control line integrity. The new Control line was installed "thru-tubing", using capillary tubing and wireline disciplines.

Application: The Minerals Management Service (MMS) reluctantly grants variances to oil and gas operators who request permits to install storm chokes, on wells which have lost control line integrity. Storm chokes do not allow for surface control and are less safe than the mandated SCSSV's. The new system has been MMS approved and offers operators a safer alternative, which is less costly than a workover and more flexible than a strom choke or velocity valve.

Results, Observations, Conclusions: The new system was installed and the well is flowing trouble free whilst having complete surface control capability. Subsequently, the operator has had the flexibility to substantially increase the production rate avoiding the necessity of adjusting differential pressure settings as with a velocity type valve.

This system has an enormous impact on the environment and economics. The most reliable method of controlling a subsurface safety valve is with a direct hydraulic system. Preserving use of a direct control system has historically been a focus of operators and encouraged by governing bodies. Reconnecting direct control of the safety valve relieves operators and governing officials from having to make difficult decisions regarding a safety issue. Aside from the apparent safety advantage, the system presents economical advantages as well. Operators maintain the option for flowing at maximum rates and are relieved of frequent maintanence expenses associated with velocity type devices. Case in point, the operator has had the ability to adjust production rates from 1 mmcfd to 5.2 mmcfd.

Significance of Subject Matter: This system has an enormous impact on economics and the environment. Considering the single pod well, the operator now has the option to negate the bi-annual inspection of a storm choke or velocity valve, which would require a lift boat operation each time. Additionally, this API 14A product will prevent the necessity of a workover, avoiding costs which may render the remaining reserves, uneconomic.
Success Story of Regaining Full-Bore Access to Formation Following Failure of Attempted Cement Squeeze Using Thru Tubing Under Reaming Technology
Authors: Ghani Siti Alsyah Binti Abdul , Haner Kyle , Robinson Larry , Rossing Mike
Published: March 2009

A certain Field development is located offshore Malaysia in 60 meters of water. Well B-10 was drilled in 1991 with deviations up to 69° and was completed as a dual string producer from sands E-12/13 in the short string and E-14 in the long string via two strings of 2-7/8" tubing in 9-5/8" 40 lbs/ft casing. In 2008, the E-14 sand was no longer productive with a water cut of 95% and so a water shut-off initiative was performed using a coiled tubing cement squeeze. The job resulted in failure probably due to the less than expected rate of cement fluid loss into the formation resulting in its unintentionally plugging the casing and tubing and blocking access to the formation for reperforating.

To regain access to the casing and the E-14 sand, it was necessary to perform two procedures with coiled tubing (CT); to mill the cement in the tubing and to underream the 9-5/8" casing thru the 2-7/8" tubing. The extended reach required to clean the tubular down to the casing wall posed a major challenge with the possibility of getting the underreamer stuck in the tailpipe, being unable to retract it to re-enter the tubing or damaging the tubing and/or the completion equipment during retrieval. The milling and under-reaming job were successfully carried out despite the challenges, including milling cement in the 9-5/8" casing, high 69°deviation, high tool expansion requirement from 2-7/8" tubing to 9-5/8" casing and the use of nitrogen as a motor drive fluid.

In this paper the authors will review the history of the well and the problems that lead to the cement job being performed, the reasons for the subsequent problems and the consequences of failure. Subsequently, the paper will review in detail the risks involved in the proposed procedure and the new technology offered. The paper will also discuss the cleanout procedure which was performed successfully and re-established full bore access to the perforations.
New Performance-Tracking System Enhances Knowledge Management and Provides Valuable Assistance in Well Planning and Procedure Evaluation on a Global Basis
Authors: Rossing Mike , Hammond Blake Thomas , Green Steve
Published: March 2009

To this day the words "we tried that before and it didn't work then either" are too often heard when a procedural problem occurs. This is arguably because work records have historically been stored on a well by well basis in filing cabinets or on field service engineer's hard drives with no centralized, globally accessible capability to allow gathering and comparison of data pertaining to similar operations anywhere in the world. As a result a means of making cross reference to what happened on other wells when a given procedure or product application is being considered can be difficult, if not impossible. There is clearly a need for a different approach to procedural and product performance record keeping that will facilitate comparison with previous applications on a global basis and provide a means of evaluating the risk and the chances of success.

The adoption of the Internet by business provided the opportunity to create a single database from a multitude of desktop databases and spreadsheets. With this end in mind the Performance Tracking System (PTS) was conceived to provide a method of storing product utilization and performance data on a global basis that could provide instant access to the results obtained, allowing a means to evaluate and plan any given procedure based on historical performance. This in turn allows an evaluation to be made as to how the product or procedure could be expected to perform when used in a given set of parameters. This system, which has been in use now since 2002 and is now implemented company wide, provides a means of cataloging performance across a full spectrum of product lines and well conditions and as the body of accumulated data has grown so it can provide comparative analysis for any given worldwide operational area, regardless of end user, to the benefit of all operations. It utilizes the features of a simple "asset tracking system" while providing a means of resolving the myths and perceptions associated with the phrase. The PTS provides a means of answering thousands of independent questions but perhaps foremost among them, "has this been done this way before and how successful was the outcome" can be answered with certainty.

In this paper the authors will discuss the concept of the PTS, how it was designed and the methods used to implement the gathering and storage of data in an instantly recoverable manner. They will go on to provide examples of how the system has been used to assist in well planning, to resolve disagreements on procedural matters and to set up a position ahead of the curve in knowledge management to the benefit of working relationships between supplier and customer.
Applying Well-Remediation Techniques to Subsea Flowlines in Deepwater Gulf of Mexico
Authors: Hudson Lisa A. , Bowen Gregor J. , Breithaupt Truman A.
Published: March 2009

Flow assurance in subsea production flow lines is becoming more prevalent as deepwater well developments continue to grow. Coiled tubing (CT), though traditionally used in wellbore environments, can be utilized to address flow assurance.

Complications are possible when applying CT technology in a nonconventional environment. Connection tie-ins and available deck area are typically incompatible with intervention-type activities, and challenging issues such as weight limitations, nature of blockage, and weather sensitive environments lead to the need for elaborate planning with multiple contingencies to address the uncertainties. Our study investigated the operational planning and logistical requirements associated with the radiation of the flow assurance for the Serrano flowline.

The Serrano flowline is located in the Gulf of Mexico (GOM), in 3,500 ft of water and is tied back 6 miles to the Auger TLP. Three subsea wells have produced through the electrically heated Serrano flowline since 2001. In November 2006, there was an unplanned shutdown of the flowline and despite numerous attempts to restart, the wells had failed to flow.

In December 2007, after 6 months of intensive and complex planning, a standalone CT operation was successfully performed while drilling operations continued on the main rig. The operations consisted of utilizing a unique small footprint compensation frame to allow access to the flowline from a confined area. Then a 1-1/2-in CT string was deployed into the flowline to retrieve a sample of the blockage for diagnostic purposes. The analysis of the sample dictated the optimal cleanout strategy which was to combine a specialized rotary nozzle with pumping diesel and solvents to successfully clean out the flowline. The blockage was breached at a depth of 3,700 ft after cleaning almost 1,000 ft in less than 24 hours. The flowline was reinstated and gas production restored to >2,000 bbl/d and 8 MMcf, thus preventing the client from losing the lease.
Wireline Tractor Milling Operations From a Riserless Light-Well Intervention Vessel at the High-Temperature Åsgard Field
Authors: Juel Henning , Ranum Håvard , Mjaaland Svein , Varne Terje , Solberg Dag Birger , Bjorndal Rune
Published: March 2009

Intervention with scale milling on subsea wells have traditionally been performed with semi submersible rigs and heavy intervention equipment as coiled tubing. Riserless Light Well Intervention (RLWI) with wireline has so far been a practical and cost efficient alternative in the subsea intervention marked. The on-going development of wireline tractor technology including milling bits has increased the scope of work for RLWI to include mechanical scale removal.

This paper describes a case history of first time use of wireline tractor scale milling technology in a well on the high temperature Åsgard field deployed from a RLWI vessel. The well had a history of calcium carbonate scale build in the production liner first seen in 2003. The well had been intervened using coiled tubing in 2003 without being able to remove all the scale bridges completely.

The objective of the intervention was to remove a 23 m calcium carbonate scale bridge to provide access for installation of a high pressure high temperature (HPHT) bridge plug and permit subsequent additional perforation work. An electric wireline conveyed tractor with a rotational assembly was chosen to perform the job.

A qualification test programme was performed to confirm that the selected wireline tractor and milling assembly could operate reliably in an environment up to 166 °C for extended periods without tool failures. The maximum well temperature was 152 °C. Following successful trials in the test facility the equipment was mobilized to the RLWI vessel.

The scale bridge of 23 m was milled in 3 runs with a 5.72" custom designed milling bit. Subsequent operations were successful with installation of a HPHT bridge plug and completion of four additional perforation runs.

The production results after the intervention was an oil increase from 468 Sm3/d to 1204 Sm3/d. The Gas Oil Ratio was decreased from 3500 Sm3/Sm3 to 2750 Sm3/Sm3. The successful operation by scale milling on the Smørbukk field has demonstrated that wireline tractor scale milling technology can be used on high temperature wells using the RLWI concept.
Subsea-Pipeline Intervention With Coiled Tubing From a Supply Vessel
Authors: Pepin Alexandre , Spadaro Angelo
Published: March 2009

Coiled tubing (CT) pipe has been successfully used in the past to clean and abandon in situ subsea pipelines in offshore areas where conventional industrial approaches (i.e., pigging, flushing or suction) were not feasible. The technique of using CT has been explored before and the subject has been covered in previous SPE papers1. The basis of the previous work relies on the CT pipe's strength to be pushed through long, horizontal lines and its ability to convey tools and fluids at once.

One of the main limitations, however, in using CT for pipeline interventions in offshore environments as opposed to the traditional methods is the amount of equipment required on board. In most cases, deck space, loading constraints and operational factors such us seabed, heave, or current direction, fixed have posed significant challenges. These challenges have been addressed in some specific cases for production platforms, jack-up boats, or dynamically positioned (DP) monohull vessels. However, traditional coiled tubing intervention will not always provide a feasible solution.

A particular operationally challenged subsea pipeline intervention exists in the Congo delta. The pipeline, which linked two production platforms, had been plugged with organic deposits and two pigs from an initial cleanup attempt in November 2004.

Subsequent conventional trials failed to break through these obstructions, so CT was proposed as a feasible alternative. The platform's deck space and crane load capacity, 4-knot sea currents rich in alluviums and products from the Congo river, and 46-ft seabed that used either jack-up boats or DP vessels not an option. This paper discusses the unique solution developed to address the operational and technical challenges of this difficult environment
Successful Milling and Removal of a Permanent Bridge Plug With Electric-Line Tractor-Conveyed Technology
Authors: Stragiotti Stephen , Karlsen Ole Eddie
Published: March 2009

A new application of running wireline stroker technology in combination with wireline milling technology has been proven successful in the Norwegian Sector of the North Sea. In August 2008, on an offshore platform, a wireline stroker and wireline milling rotational unit were used to mill out and remove a permanent type bridge plug at 1,264m (approximately 4,147 ft) MD (50° deviation).

The 3.25" high expansion bridge plug was inadvertently set in the tubing in March 2008 at 1,264 m. It was decided to attempt to mill out the plug on electric wireline to regain production from the well. A study was initiated to evaluate if it would be feasible to develop a wireline conveyed stroker and milling system capable of removing the plug. During a two months design period, several different bits and milling tools where designed and tested. It was confirmed that by combining a wireline miller with a modified wireline stroker to act as feed control, it should be possible to mill out the retaining rings and collapsing the plug. The milling system included a control unit allowing the WOB (weight on bit) to be optimized for each application. In addition it also controls the reactive torque and force generated when the milling bit engages the plug.

The offshore operation was successfully completed in three days.

The milling tool has proven to be an effective solution to down hole problems that require milling of metal or hardened materials. The technical solution was developed within the design parameters and in accordance with the timeline set out for the project. This new method for milling well completion hardware and other well bore obstructions offers a cost-efficient alternative technology to existing methods using coil tubing or snubbing. The success of the milling operation is a significant milestone and has pushed the limits for what is possible to achieve on electric wireline.

By applying new technology, the well was quickly put back in production. The operation was conducted as a live well intervention without the need for using the drilling derrick.

This paper will examine the challenges and solution chosen in an operation of milling a bridge plug on electric wireline.
Engineering Development to Improve Tubular Cutting Ability in High-Ductility Metallurgy Strings With Low-Torque Motors
Authors: Guimaraes Zacarias , Barros Robledo , Franca Cicero , Costa Filipe , Camargos Wyvis , Gerena J. Alexander , Raulino F. , Henrique Afonso , Ponte Vitor , Teles J. Marcelo , Costa Necesio
Published: March 2009

During the restoration process of a high temperature gas producer well, offshore Brazil, it was detected that its production tubing was stuck due to scale deposition. An attempt to pull the string using an offshore completion rig was unsuccessful. The use of alternative methods like wireline chemical cutters, string shots and thru-tubing tools with elastomer rubbers was not possible due to the high bottom hole temperature of the well (363 °F). With this scenario, the solution was to use coiled tubing in order to cut the string above the free point.

The first challenge for this coiled tubing intervention was the production tubing metallurgy, Cr-22, which has highly ductile and carbides embedded in its matrix. These properties cause the adherence of chips on the cutter blades and contribute to accelerated wear on the mechanical cutter.

The second challenge was the constraint of having to use lower torque metal-metal motor, because the high torque (rubbers) stator for positive displacement motors, available in Brazil do not work over 300 °F.

In order to overcome all of these challenges and optimize the cutting process, tests were performed before the job in a similar Cr-22 tubing sample, using a standard two blades pipe cutter attached to a 2-1/8" metal-metal motor. After the failure in the first test, improvements in the pipe cutter were done until reaching an effective cutting system.

This paper presents in details all steps in the pipe cutter design development and summarizes the operational procedures executed in this successful job using 1-1/4 inch coiled tubing, metal-metal motor and optimized pipe cutter.

It will be of value to point out other (more expensive) options that the customer normally would have had to use, i.e. snubbing unit with spaghetti pipe.
A Successful Application of Fiber-Optic-Enabled Coiled Tubing With Distributed Temperature Sensing DTS Along With Pressures to Diagnose Production Decline in an Offshore Oil Well
Authors: Parta P. E. , Parapat A. , Burgos R. , Christian J. , Jamaluddin A. , Rae G. , Foo S. K. , Ghani J. , Musa M.
Published: March 2009

In this paper, we present a field example where pressure and distributed temperature measurements enabled understanding of reservoir characteristics and fluid movement causing production hindrance in an offshore horizontal well. The field example comprises a horizontal well in the South China Sea that was completed as an openhole monobore oil producer using a slotted liner.The well began production with an initial oil rate of 1,800 bbl/d. Oil production quickly dropped to 1,000 bbl/d and gradually declined to 200 bbl/d. During this period, the gas oil ratio (GOR) steadily increased from 200 scf/bbl to 2,200 scf/bbl.To arrest production decline, a chemical treatment to remove suspected emulsions and polymers during drilling was conducted. Immediate post treatment, production increased to 2,200 bbl/d, but dropped dramatically and stabilized at pretreatment rates soon after. Formation of emulsions and asphaltenes were believed to be the cause of the production decline. However, with inadequate information, the diagnosis was inconclusive. Consequently, a fiber-optic-enabled coiled tubing string along with real-time bottomhole pressure and temperature gauges were used to acquire distributed temperatures and pressures of the entire horizontal section of the wellbore.

Results of the pressure survey revealed that the well was receiving insufficient pressure support from the water injector, which, in turn, was causing gas cap expansion. The distributed temperature survey indicated excessive gas production from the toe of the horizontal section as a result of this expansion, thus limiting liquid production. The combination of gas rates with oil and water production has also created tight emulsions, further hindering production performance.It was concluded that the high gas production from the toe could not be selectively shutoff or controlled in the horizontal openhole slotted liner completion to perform an effective stimulation program and treat the tight viscous emulsions.