bluuebunny/crossref_metadata_2025 huggingface dataset:
Global Gene Expression in Coprinopsis cinerea Meiotic Mutants Reflects Checkpoint Arrest
Authors: Anderson Erika , Burns Claire , Zolan Miriam E
Published: October 2012

The basidiomycete Coprinopsis cinerea is well-suited to studies of meiosis because meiosis progresses synchronously in 10 million cells within each mushroom cap. Approximately 20% of C. cinerea genes exhibit changing expression during meiosis, but meiosis and mushroom development happen concurrently and therefore differentially expressed genes might not be directly involved in meiotic processes. By using microarrays, we examined global gene expression across a meiotic time course in two mutants in which meiosis arrests but mushrooms develop normally. Genes differentially expressed in the mutants compared with the wild type are likely to be involved in meiosis and sporulation as opposed to mushroom development. In rad50-1, which arrests in late prophase, RNA abundance for a group of early meiotic genes remains high, whereas the expression of a group of late meiotic genes is never induced. In contrast, in msh5-22 (which fails to undergo premeiotic DNA replication), both early and late meiotic genes are underexpressed relative to wild type at late meiotic time points as the cells die. Genes that are differentially expressed relative to wild type in both mutants are particularly strong candidates for playing roles in meiosis and sporulation.
A Genetic Screen to Discover Pathways Affecting Cohesin Function inSchizosaccharomyces pombeIdentifies Chromatin Effectors
Authors: Chen Zhiming , McCroskey Scott , Guo Weichao , Li Hua , Gerton Jennifer L
Published: October 2012

Cohesion, the force that holds sister chromatids together from the time of DNA replication until separation at the metaphase to anaphase transition, is mediated by the cohesin complex. This complex is also involved in DNA damage repair, chromosomes condensation, and gene regulation. To learn more about the cellular functions of cohesin, we conducted a genetic screen in Schizosaccharomyces pombe with two different cohesin mutants (eso1-G799D and mis4-242). We found synthetic negative interactions with deletions of genes involved in DNA replication and heterochromatin formation. We also found a few gene deletions that rescued the growth of eso1-G799D at the nonpermissive temperature, and these genes partially rescue the lagging chromosome phenotype. These genes are all chromatin effectors. Overall, our screen revealed an intimate association between cohesin and chromatin.
PUF-8, a Pumilio Homolog, Inhibits the Proliferative Fate in theCaenorhabditis elegansGermline
Authors: Racher Hilary , Hansen Dave
Published: October 2012

Stem cell populations are maintained by keeping a balance between self-renewal (proliferation) and differentiation of dividing stem cells. Within the Caenorhabditis elegans germline, the key regulator maintaining this balance is the canonical Notch signaling pathway, with GLP-1/Notch activity promoting the proliferative fate. We identified the Pumilio homolog, PUF-8, as an inhibitor of the proliferative fate of stem cells in the C. elegans germline. puf-8(0) strongly enhances overproliferation of glp-1(gf) mutants and partially suppresses underproliferation of a weak glp-1(lf) mutant. The germline tumor that is formed in a puf-8(0); glp-1(gf) double mutant is due to a failure of germ cells to enter meiotic prophase. puf-8 likely inhibits the proliferative fate through negatively regulating GLP-1/Notch signaling or by functioning parallel to it.
Competition Between Conjugation and M13 Phage Infection inEscherichia coliin the Absence of Selection Pressure: A Kinetic Study
Authors: Wan Zhenmao , Goddard Noel L
Published: October 2012

Inter- and intraspecies horizontal gene transfer enabled by bacterial secretion systems is a powerful mechanism for bacterial genome plasticity. The type IV secretion system of Escherichia coli, encoded by the F plasmid, enables cell-to-cell contact and subsequent DNA transfer known as conjugation. Conjugation is compromised by phage infection that specifically targets the secretion machinery. Hence, the use of phages to regulate the spread of genes, such as acquired antibiotic resistance or as general biosanitation agents, has gained interest. To predict the potential efficacy, the competition kinetics must first be understood. Using quantitative PCR to enumerate genomic loci in a resource-limited batch culture, we quantify the infection kinetics of the nonlytic phage M13 and its impact on conjugation in the absence of selection pressure (isogenic set). Modeling the resulting experimental data reveals the cellular growth rate to be reduced to 60% upon phage infection. We also find a maximum phage infection rate of 3×10−11 mL phage−1 min−1 which is only 1 order of magnitude slower than the maximum conjugation rate (3×10−10 mL cell−1 min−1), suggesting phages must be in significant abundance to be effective antagonists to horizontal gene transfer. In the regime where the number of susceptible cells (F+) and phages are equal upon initial infection, we observe the spread of the conjugative plasmid throughout the cell population despite phage infection, but only at 10% of the uninfected rate. This has interesting evolutionary implications, as even in the absence of selection pressure, cells maintain the ability to conjugate despite phage vulnerability and the associated growth consequences.
SlWUS1; An X-linked Gene Having No Homologous Y-Linked Copy inSilene latifolia
Authors: Kazama Yusuke , Nishihara Kiyoshi , Bergero Roberta , Fujiwara Makoto T , Abe Tomoko , Charlesworth Deborah , Kawano Shigeyuki
Published: October 2012

The dioecious plant Silene latifolia has heteromorphic sex chromosomes, and comparison of the positions of sex-linked genes indicates that at least three large inversions have occurred during the evolution of the Y chromosome. In this article, we describe the isolation of a new sex-linked gene from S. latifolia, which provides new information on the evolution of this plant’s young sex chromosomes. By using reverse-transcription polymerase chain reaction degenerate primers based on the Arabidopsis thaliana sequence of WUSCHEL, a flower-development gene, we found two copies in S. latifolia, which we named SlWUS1 and SlWUS2. Southern blot and genetic segregation analysis showed that SlWUS1 is located on the X chromosome and SlWUS2 is autosomal. No Y-linked copy of SlWUS1 was found by either Southern blot analysis under low-stringency conditions or polymerase chain reaction with degenerate primers, so we conclude that SlWUS1 probably has no Y-linked homolog. It is unknown whether the Y chromosome lost the SlWUS1 copy by degeneration of this individual gene or whether deletion of a larger genome region was involved. Several tests lead us to conclude that dosage compensation has not evolved for this sex-linked gene. We mapped the ortholog in the nondioecious relative S. vulgaris (SvWUS1), to compare the location in a species that has no history of having sex chromosomes. SvWUS1 maps to the same linkage group as other fully X-linked genes, indicating that it was not added to the X, but was lost from the Y. Its location differs in the maps from the two species, raising the possibility that the X chromosome, as well as the Y, may have been rearranged.
A Fast and Efficient Approach for Genomic Selection with High-Density Markers
Authors: Pungpapong Vitara , Muir William M , Li Xianran , Zhang Dabao , Zhang Min
Published: October 2012

Recent advances in high-throughput genotyping have motivated genomic selection using high-density markers. However, an increasingly large number of markers brings up both statistical and computational issues and makes it difficult to estimate the breeding values. We propose to apply the penalized orthogonal-components regression (POCRE) method to estimate breeding values. As a supervised dimension reduction method, POCRE sequentially constructs linear combinations of markers, i.e. orthogonal components, such that these components are most closely correlated to the phenotype. Such a dimension reduction is able to group highly correlated predictors and allows for collinear or nearly collinear markers. Different from BayesB, which predetermines hyperparameters, POCRE uses an empirical Bayes thresholding method to obtain data-driven optimal hyperparameters and effectively select important markers when constructing each component. Demonstrated through simulation studies, POCRE greatly reduces the computing time compared with BayesB. On the other hand, unlike fBayesB which slightly sacrifices prediction accuracy for fast computation, POCRE provides similar or even better accuracy of predicting breeding values than BayesB in both simulation studies and real data analyses.
Prediction of Inflicted Brain Injury in Infants and Children Using Retinal Imaging
Authors: Minns Robert A. , Jones Patricia A. , Tandon Anamika , Fleck Brian W. , Mulvihill Alan O. , Elton Robert A.
Published: October 2012

BACKGROUND:

Retinal hemorrhages (RHs) occur in inflicted traumatic brain injury (ITBI), accidental traumatic brain injury (ATBI), and some medical conditions, although the reported number, distribution, type, and frequency vary greatly between these different etiologies. We hypothesize that these RH characteristics reliably help to distinguish ITBI from ATBI and nontraumatic etiologies.

METHODS:

A 6-year prospective observational study using wide-field retinal imaging (RetCam) was conducted within 24 hours of admission to PICU, on serially recruited children with traumatic and nontraumatic encephalopathies. “Definite” and “probable” ITBI cases were confirmed by multiagency child protection case conferences. Image analysis used digital color and grayscale images for retinal “zoning” and “layering” of hemorrhages.

RESULTS:

Significant differences were found between the mean numbers of hemorrhages in ATBI/ITBI, and ITBI/nontraumatic etiologies for the 3 retinal zones (range, P = .003–.009) and for the dot-blot hemorrhages (range P = .001–.002). The mean numbers of RHs per ITBI patient in the peripapillary, macula, and peripheral zones were 14, 28, and 31 respectively. RHs in ATBI were near the optic disc and more superficial than in ITBI, where hemorrhages involved deeper layers (range, P = .003–.039) and were more peripheral (P = .03). The positive predictive value for ITBI in children <3 years with >25 dot-blot (intraretinal) hemorrhages was 93%.

CONCLUSIONS:

This prospective study, which included all potential causes of RHs, with objective retinal methodology, has confirmed that a young age and a high dot-blot count are strong predictors of ITBI. This high predictive value may support medicolegal deliberations.
Sucrose for Procedural Pain Management in Infants
Authors: Harrison Denise , Beggs Simon , Stevens Bonnie
Published: October 2012

The use of oral sucrose has been the most extensively studied pain intervention in newborn care to date. More than 150 published studies relating to sweet-taste-induced calming and analgesia in human infants have been identified, of which 100 (65%) include sucrose. With only a few exceptions, sucrose, glucose, or other sweet solutions reduced pain responses during commonly performed painful procedures in diverse populations of infants up to 12 months of age. Sucrose has been widely recommended for routine use during painful procedures in newborn and young infants, yet these recommendations have not been translated into consistent use in clinical practice. One reason may be related to important knowledge and research gaps concerning analgesic effects of sucrose. Notably, the mechanism of sweet-taste-induced analgesia is still not precisely understood, which has implications for using research evidence in practice. The aim of this article is to review what is known about the mechanisms of sucrose-induced analgesia; highlight existing evidence, knowledge gaps, and current controversies; and provide directions for future research and practice.
Allowing Adolescents and Young Adults to Plan Their End-of-Life Care
Authors: Wiener Lori , Zadeh Sima , Battles Haven , Baird Kristin , Ballard Elizabeth , Osherow Janet , Pao Maryland
Published: October 2012

OBJECTIVE:

The objective of this study was to assess and compare the usefulness, helpfulness, and stress associated with reviewing a previously adapted advance care planning guide, My Thoughts, My Wishes, My Voice, in comparison with the widely used adult document Five Wishes by adolescents and young adults (AYAs) living with a serious illness.

METHODS:

Fifty-two participants (age 16–28) living with metastatic or recurrent cancer or HIV infection (acquired at birth or early in life) were presented pages randomly from My Thoughts, My Wishes, My Voice and, Five Wishes, and asked to rank 25 items on several factors, including how likely they would be to complete each statement. Participant opinion on suggested changes in content, design, format, and style was obtained and resulted in development of a new document.

RESULTS:

AYAs living with a life-threatening illness want to be able to choose and record (1) the kind of medical treatment they want and do not want, (2) how they would liked to be cared for, (3) information for their family and friends to know, and (4) how they would like to be remembered.

CONCLUSIONS:

AYA views of what should be included in an advance care planning guide were incorporated into a new document, Voicing My Choices, that provides youth, families and providers an opportunity to reduce the silence around the dying process by allowing an opportunity to share one’s voice. We provide guidance on how to incorporate this tool into care.
Clinical Prognostic Messages From a Systematic Review on Cerebral Palsy
Authors: Novak Iona , Hines Monique , Goldsmith Shona , Barclay Richard
Published: October 2012

OBJECTIVE:

To summarize evidence on the rates of co-occurring impairments, diseases, and functional limitations with cerebral palsy into succinct clinical messages.

METHODS:

A search was conducted of the databases PubMed, Medline, CINAHL, and PsycINFO, and the results were supplemented with hand searches. Two independent reviewers determined whether retrieved abstracts met the following inclusion criteria: human subjects; >90% were children or adults with cerebral palsy; published after 1999; and population-based data. Articles were appraised, analyzing design, participants, level of evidence, rates of impairments, and functional implications. Methodologic quality was rated by using a standardized checklist.

RESULTS:

A total of 1366 papers were identified in the search; 82 were appraised and 30 were included in the meta-analyses. High-level evidence existed, as rated on the Oxford 2011 Levels of Evidence: 97% of prevalence studies were level 1. The data were of a moderate to high quality grade (with the exception of sleep disorders), allowing plain English clinical messages to be developed.

CONCLUSIONS:

Among children with cerebral palsy, 3 in 4 were in pain; 1 in 2 had an intellectual disability; 1 in 3 could not walk; 1 in 3 had a hip displacement; 1 in 4 could not talk; 1 in 4 had epilepsy; 1 in 4 had a behavior disorder; 1 in 4 had bladder control problems; 1 in 5 had a sleep disorder; 1 in 5 dribbled; 1 in 10 were blind; 1 in 15 were tube-fed; and 1 in 25 were deaf.
Epignathus Teratoma with Duplication of Mandible and Tongue: Report of a Case
Authors: Tsai Yun-Ta , Cala-or Ma. Arlene Cirineo , Lui Chun-Chung , Wang Tzu-Jou , Lai Jui-Pin
Published: October 2012

We report a female infant with presentation of epignathus teratoma involving duplication of both the mandible and tongue. Epignathus with duplication of the mandible has rarely been reported in the literature thus far. The location and extent of the tumor, as well as the involvement of adjacent structures, resulted in trismus and upper airway obstruction at birth. Thus, staged operations including debulking and correction of anatomical anomaly were performed on this patient after life-saving tracheostomy. As a result, we not only prevented morbidity associated with the anomaly but also refined the patient's appearance and improved her quality of life.
Numerical Modeling of Induced Fracture Propagation: A Novel Approach for Lost Circulation Materials (LCM) Design in Borehole Strengthening Applications of Deep Offshore Drilling
Authors: Salehi Saeed , Nygaard Runar
Published: October 2012

Lost circulation caused by low fracture gradients is the cause of many drilling related problems. Typically the operational practice when lost circulation occurs is to add loss circulation materials (LCM) to stop mud from flowing into the formations. To improve the treatment for lost circulation caused by low fracture gradients, especially designed materials in mud system are used to seal the induced fractures around the wellbore. This operation is in the literature referred to as wellbore strengthening that has been found to be a very effective in cutting Non-Productive Time (NPT) when drilling deep offshore wells. Size, type and geometry of sealing materials are debating issues when different techniques are applied. Also the phenomenon is not truly understood when these techniques applied in different sedimentary basins.

This paper presents development and simulation results of a three-dimensional Finite-Element Model (FEM) for investigating wellbore strengthening mechanism. This study also describes a procedure for designing Particle Size Distribution (PSD) in field applications. To better understand the numerical results, the paper also reviews the connection between Leak of Tests (LOTs) and wellbore hoop stress and how these LOTs can mislead in fracture gradient determination.

A comprehensive field database was collected from different sedimentary basins for this study. Results demonstrate that the maximum attainable wellbore pressure achieved by wellbore strengthening is strongly controlled by stress anisotropy. Results also show that Particle Size Distribution (PSD) of wellbore strengthening should be designed in order to seal the fractures close to the mouth and at fracture tip. This will result both in maximizing hoop stress restoration and tip-screening effects. In addition this model is able to show the exact fracture geometry formed around the wellbore that will help to optimize the sealing materials design in wellbore strengthening pills. To support numerical modeling results, near wellbore fracture lab experiments on Sandstone and Dolomite samples were also presented. Laboratory experiments results reveal importance of rock permeability, tensile strength and fluid leak-off in wellbore strengthening applications.
Comparison of Stuck-Pipe and Lost-in-Hole Outcomes by Operator and Well Complexity in US Land Taken from a Global Bit Run Dataset
Authors: Robson Robert Ian
Published: October 2012

The loss of bottomhole assemblies (BHAs) in wellbores has always been a problem for drillers. A great deal has been written about the causes of stuck pipe, and many studies have been performed. Much of this work is anecdotal or localized. Until now, there has not been a very large dataset available in a format that allows performance to be compared for identifying causal relationships and risks.

A bit run summary database exists in which directional and measurement service crews can enter data related to the run location, objective, and operational outcome. These bit run summaries from 2005 through 2010, covering jobs run in US land operations (over 27,000 runs), were reviewed and classified. The reviewed data built a statistical picture of run outcomes that can be searched with a wide array of filters, including hole size, region, run length, date, operator, mud system, and combinations thereof.

Examination of these data has yielded several interesting relationships as well as general observations and conclusions. Tripping of pipe in the elevators (i.e., with no pumps) or reaming in and out of hole is seen to be the activity 40% of the time when a stuck or lost incident occurs. Interestingly, the likelihood of losing a BHA once it becomes stuck in US land is much less than the global rate; i.e., approximately one in three stuck BHAs are recovered.

The importance of planning the run with stuck pipe prevention in mind cannot be overstated. This dataset represents a valuable tool for risk analysis and job planning by comparing relative risk factors to both local and global datasets.
A Unique Electrical Submersible Reciprocating Pumping (ESRP) System Design Applied in Unconventional Oilfield
Authors: Wensheng Zhang , Lin Wang , Fengshan Wang , Youquan Huang , Gang Cao , Fengwu Zhang , Huaifeng Ren , Junwen Ge , Weiping Zhang , Ling Liu , Xinmin Wang
Published: October 2012

In recent years, a unique electrical submersible reciprocating pumping system (ESRP) was developed and has been applied in Daqing Oilfields. The main structure of ESRP is similar with ESP, consisting of an electrical submersible motor, pump, tubing and cable. The key equipments of ESRP are the reciprocating motor and the pump. The motor is a novel permanent magnetic line motor consisting of stator and mover. The pump is a special reciprocating pump. In operation, the mover slips in the stator from one end to the other periodically controlled by surface equipment, applying the power to the plunger of the reciprocating pump. Because of its small outerdiameter, the whole system could be run into the horizontal wellbore conveniently.

This unique lifting system was designed mainly for the production of satellite oilfields in Daqing Oilfield. Unlike the properties of the main blocks of Daqing Oilfield with thick pay zones, high permeability and shallow imbedded reservoir, these satellite oilfields distributed discontinuously, the layers are thin and imbedded deeply with poor permeability. The producers’ averaged production is below 35 bpd. Beam pumping system showed poor benefit due to the high investment and operating cost. PCPs and Bailing lifting systems were applied later in a larger scale. But the management was relatively complicated and still limited in horizontal wells. As the result, ESRP showed great advantages both in technical and economic respects in the production.

Till the end of 2010, ESRP has been applied in more than 30 wells in Daqing Oilfield. The longest running life has reached above 400 days. It showed remarkable advantages in the production of low displacement and deep reservoir, especially for horizontal wells.

With the improvement of displacement and other specifications, this unique lifting system design has great potential in the development of unconventional reservoir as well as mature oilfields.
Instilling Realism in Production Forecasting: Dos and Don'ts
Authors: Rajvanshi Avnish K. , Meyling Robert Gmelig , Haaf Danny ten
Published: October 2012

Historically, and across the E&P industry, several projects were found to underperform in their actual performance as compared to the promises made at the time of project approval. Investment decisions on upstream projects rely, to a large extent, on the robustness of the predicted ultimate recovery and production forecast associated with the chosen development concept. A 2010 upstream industry benchmarking consortium reviewed global performance of E&P projects and concluded that the majority of production forecasts presented at project approval were not attained. In many cases, this underdelivery resulted in eroded project economics and reputation damage with stakeholders.

The challenge for the E&P industry is to ensure that project approvals are based on realistic forecasts (P50 case). Modern technology has offered a paradigm shift in the amount of detail which can be included in the subsurface static and dynamic models. However, a universal truth is that no single model is the perfect representation of reality, and the recovery processes based on modelling are, therefore, always approximations of real life situations. Simulation models are guiding tools rather than sources of perfect answers.

This work is intended to increase awareness amongst the forecasters and the decision makers about pitfalls associated with production forecasting (especially those generated by dynamic models). It provides insight into the need to condition model input data or alternatively the model output to ensure that forecasts and resource volumes generated by these models are realistic. Root causes of unrealistic forecasts are identified. Dos and don'ts are described that help instil realism in the forecasting process. Pragmatic techniques to adjust the output obtained from dynamic modelling are illustrated using real-life examples.

This work presents a pragmatic approach to create reliable long-term production forecasts which can form the basis for sound business decisions.
Evaluation of Bakken Performance Using Coreflooding, Well Testing, and Reservoir Simulation
Authors: Kurtoglu Basak , Kazemi Hossein
Published: October 2012

The success of oil production in North Dakota Bakken should be credited to advanced completion and stimulation techniques. The abundance of data on well production, core analyses and flooding, geologic reservoir characterization, and pressure transient testing has enhanced reservoir evaluation. Understanding matrix and fracture contribution to daily oil production is the key to identifying reservoir drivers affecting the lifelong well productivity.

In this paper, we will present an application of core flooding, mini-frac and pressure build-up tests, decline curve analysis and reservoir simulation history matching to achieve reliable long-term reservoir performance predictions. This approach could lead to developing an integrated workflow for determining the performance drivers in the greater Bakken.

Information presented in this paper includes well performance data from several Bakken fields, displacement results on selected cores, mini-frac and pressure transient analyses, and history matching using decline curve analysis and numerical simulation.

Specifically, the matrix permeability from core measurements is on the order of 10-4 md while the permeability from well testing is on the order of 10-2 md. The latter represents the combined contributions of micro-fractures and matrix permeability. Reservoir simulation also shows that a single-porosity system, using only the matrix permeability from the core analysis, is not sufficient for matching well production performance without having a secondary permeability and porosity (micro-fractures). The dual-porosity nature of the reservoir was confirmed by a long-term pressure build-up test.
The Use of Real-Time Downhole Pressure and Distributed Temperature Surveying in Quantifying the Skin Evolution and Zone Coverage in Horizontal Well Stimulation
Authors: Balto Abdulelah A. , Qahtani Hassan B. , Kilany Khaled A , Baez Fernando , Elsherif Tamer
Published: October 2012

Fiber optic enabled coiled tubing (FOECT) has been commonly used in qualitatively evaluating reservoir matrix chemical treatment in real time during the past couple of years. During this period, attempts of transforming qualitative evaluations to quantitative ones were made. The quantitative evaluation is based on two simultaneous criterions. The first one is a downhole pressure diagnostic plot (pressure transient analysis) created instantinuously using real-time acquired data by the downhole gauges. The second is an estimate of the zonal coverage based on the resulting temperature profile plot before, during and after a pumping treatment. Pressure transient analysis gives the skin as a direct output, while the cooling down/warming up DTS profiles identifies where the treatment fluids went in the formation, hence identifying the damaged zones.

It is strongly recommended to combine well testing analysis techniques with zone coverage evaluation in highly deviated and horizontal completed wells in both clastic and non-clastic rocks. Basically, deriving the skin from the injectivity test (pretreatment) and the skin from the post flush (post-treatment) provides an evaluation matrix treatment effectiveness.

A comparison between formation damage "skin" before and after the treatment was performed on the spot, revealing positive results of nearly uniform distribution of treatment fluids, and skin value reduction across the 3400 ft horizontal section.

Following the innovative procedures executed in well-A, different techniques were proposed, providing time and cost savings; raising the operational excellence expectations levels higher than expected for an offshore environment. The application of FOECT technology helped to minimize uncertainties during treatmentevaluation, and enhanced treatment distribution and placement. In addition to establishing more accurate and reliable Nodal Analysis and production forecast models.
Integrating Casing Drilling and Conductor Sharing Technology To Optimize Brownfield Redevelopment Plans
Authors: Erivwo Ochuko , Roed Haakon , Javaid Muhammad Omer , Ngau Christie Usun , Pickup Duncan
Published: October 2012

An alliance was formed between PETRONAS Carigali and Schlumberger IPM to re-develop the mature Samarang field, offshore Malaysia. Integrated studies had identified opportunities to increase recoverable reserves in the 30 year old field by as much as 10% of STOIIP from infill drilling and EOR techniques. However, with 96 wells and 48 sidetracks already drilled, the number of additional slots that could economically be made available for potentially up to 33 new wells in the redevelopment campaign was limited.

Of the several options considered to address the challenge of limited slots, conductor sharing technology was preferred over multiple sidetracks and costly slot recoveries. The size constraint of the available 36 × 13-3/8 × 9-5/8 5ksi dual wellhead system was however a concern. Offset wells analyses showed losses, tight hole and stuck surface casing problems, with several casings set shallower than planned. These challenges had historically being mitigated with a shallow 18-5/8 casing to enable setting the 13-3/8 surface casing at planned depth. The elimination of this contingency casing implied increased exposure in getting the surface casings to bottom and was mitigated with the integration of directional Casing Drilling into the surface hole plans.

This paper presents the integration of Casing Drilling with Conductor Sharing technology in the phase 1 of the Samarang redevelopment project. It focuses on the key engineering considerations (casing API connection enhancement, geometrical separation, start-up rotary anti-collision etc) applied to address the concerns associated with the technology integration in a cost-sensitive environment. The paper also discusses the highlights, lessons learnt and recommendations from its successful execution. The unique integration of Casing Drilling and Conductor Sharing Wells in Samarang is believed to be the world's 1st combination of the technologies. It's success has provided opportunity to reduce construction costs for phase 2 of the project and opened up further well design optimization opportunities in the development of challenging brown fields.
Flow Capacity Evaluation in a Complex Carbonate Reservoir: Key to Understand Reservoir Productivity and Stimulation Effectiveness
Authors: Acharya Mihira N. , Kabir Mir R. , Al-Ajmi Saad H. , Dashti Qasem M. , Al-Anzi Ealian H. , Kho Djisan , Darous Christophe , Chakravorty Sandeep
Published: October 2012

Flow capacity evaluation in carbonate reservoirs is known to be challenging because of heterogeneity in the rock matrix. The original depositional texture and resulting pore structure is often altered by secondary diagenetic processes such as dissolution, leaching, cementation, and dolomitization, creating complicated pore systems with varying porosity to permeability relationship. Dolomitization in particular is known to be an important diagenetic process in carbonate reservoirs, typically enhancing porosity and permeability development and making the rock less susceptible to porosity reduction due to increasing effective stress during burial. Core data taken in deep carbonate reservoirs reveal a strong correlation between degree of dolomitization and reservoir quality.

Neutron-induced gamma-ray spectroscopy logging has proven to be a powerful tool for the evaluation of dolomite content, especially in wells drilled with barite-weighted mud where PhotoElectric Factor (PEF) is not reliable. Using methods developed on a core database, reservoir rock types can be identified and matrix permeability can be estimated from a combination of porosity and dolomite content derived from neutron-induced gamma-ray spectroscopy data and other common logs measurements. Predicted flow profiles and flow capacity of the reservoirs can be calculated from the estimated matrix permeability and can be verified by comparison with available production logs and test data.

Several examples will highlight the comparison between the predicted synthetic flow profiles and the flow profiles measured by production logs, as well as the comparison of estimated flow capacity with pressure transient analysis data. Such comparisons can be used to diagnose stimulation effectiveness, identify zones dominated by fractures, confirm solid bitumen effects, and identify zones with significant formation damage. Another important application is the selection of perforation and stimulation zones to achieve optimum production based on the expected permeability contrast. This integrated approach to flow capacity prediction is proving to be an effective tool in understanding the behavior of complex carbonate reservoirs.
Structured Mentoring: A Critical Component of a Global Talent Management Strategy
Authors: Rousseau Meta
Published: October 2012

Competing for market share in a dynamic international marketplace, the frontrunners are those who are able to build a skilled, global workforce through multi-faceted strategies that enable them to align training, mentoring, and coaching initiatives and implement cutting-edge practices such as social and mobile learning. Structured mentoring forms the foundation of a well-designed talent management strategy. Well-designed mentoring programs enable organizations to align and seamlessly integrate training, coaching and mentoringinitiatives into holistic, personalized offerings. It is through successful structured mentoring programs that organizations are able to sustain a uniquely skilled and internally motivated workforce that sets them apart from competition. In this paper, we will consider structured mentoring in context of seven topics:

Structured Mentoring Defined Value Added Through Structure Mentorship Types and Models The Structured Mentoring Process Structured Mentorship Teams The Structured Mentoring Program Toolkit Success Factors
Mobile Applications Development for Upstream Solutions
Authors: Al-Naim Hamad A. , Al-Qurtas Abdulrahman , Awan Mohammad , Rihabe Salim , Ibrahim Mohammad , Madani HusamAdDeen , Malik Pervaiz
Published: October 2012

The rapidly evolving tablet and mobile devices have proven their overwhelming popularity, not just as entertainment devices but as valuable productivity tools for enterprises and professionals. Furthermore, mobile computing is becoming an integral player in the Information Technology industry, thereby influencing the design of software applications required by oil and gas organizations.

The new generation of tablets and smartphones can be effectively utilized for real time data monitoring and reporting. This can be achieved through the deployment of Upstream software solutions, such as GIS supported reservoir performance monitoring applications, management reporting dashboards, and engineering analytical tools.

This paper provides an overview of an assessment project initiated by Saudi Aramco to evaluate the development and deployment of oil and gas Upstream software solutions on mobile devices. The assessment focused on capitalizing on the capabilities of these devices for adding business value and building in-house expertise in the area of mobile application development. The paper will summarize the assessment findings and recommendations for the future direction of applications development methodology and requirements.
Pushing The Limits Of Downhole Sand Control: E Field
Authors: Thilagalingam J. , Natasha M. S , Jadid M
Published: October 2012

The E Field, with depletion type reservoirs offshore Sabah, started first production in the early 1980's with no active sand control measures where all the wells, many of which were horizontal, were completed as cased hole and perforated. After some 25 years, most wells began to produce sand along with high gas production, causing supply curtailment with some wells requiring shut ins. A new development plan executed in August 2010 involved drilling five new wells from an existing platform to include active sand control as part of the overall strategy. Due to the costly gravel packing operation coupled with the potential high skin in such completion, a new sand control approach was adopted. The key to this approach was to limit the production drawdown to a certain level by maximizing the well productivity index (PI) through open hole completion and to avoid sand influx at the early stage. Stand alone screen (SAS) completion consisting of a selected screen of a specific slot size was installed in the open hole, acting as a second production barrier in the event sand influx occurs.

The geomechanic study on E field data suggested that with ongoing depletion, the new wells would exceed the critical drawdown pressure (CDP) and sand production is expected from day one as evident from sand production issues in the field. However, it was decided to test the limit of this study with consideration relying more on the inherent strength of the rock as reflected by the high unconfined compressive strength (UCS) data of over 5000psi and thus the wells were completed with SAS in open hole. Permanent downhole gauges (PDGs) were installed in all the SAS wells to monitor the production drawdown closely, especially during the initial production phase.

The target reservoir is semi-consolidated laminated sandstone with poorly sorted sand of uniformity coefficient (UC) value of over 15 and d10 finer size sand content of over 10%. Based on retention test results, the 175μm screen size was chosen as using the d10 particle size (92μm) option will likely result in excessive plugging during the projected sand failure phase. This alternative selection is effectively moving beyond the currently accepted screen selection criteria limits.

This paper highlights design considerations in E field aimed at optimising well productivity and reducing sand control cost by challenging current standards and limits commonly adopted in sand control completions. The well performance results following the revisit are also reviewed to support this unconventional approach. This is expected to contribute to the evolution of future sand control strategies. Lessons learnt during well cleanup and initial production phase with continuous monitoring from downhole PDGs are included to provide a holistic picture of this case study.
Torque and Drag Modeling Advanced Techniques and Troubleshooting
Authors: McCormick John , Liu Gefei
Published: October 2012

Extreme torque and drag (T&D), especially when unplanned, is a primary limiter to the reach of horizontal and extended-reach wells. Many engineers use T&D software models without a thorough understanding of how the input affects the calculations in the program. This paper describes best practices in complicated T&D modeling applications.

The discussion in this paper is applicable to wells with horizontal laterals, extended-reach wells, wells with difficult geometries, and all complicated well operations that require T&D models for planning and troubleshooting. Specifically applicable are operations that T&D programs have difficulty handling, such as running dual strings, expandable casing operations, drilling with casing, and jarring operations.

Most engineers involved in downhole operations from operators to service companies run either T&D models or base decisions related to their wells and operations on reports from these programs. Many of the engineers and managers in the oilfield can benefit from this guide on best practices for a commonly executed, but little understood, component to well planning.

Few papers address the practical application side of T&D modeling, and most engineers and managers have only a basic understanding of how to create a model or interpret the results. This paper disseminates technical information to increase global competence in a vital part of any challenging well drilled. Drilling extreme and challenging wells is becoming more common, and increased knowledge for T&D modeling and interpretation is needed.
Departure From the Norm in Polycrystalline Diamond Bit Design Allows Significant Performance Gains in Highly Erosive and Abrasive Formations
Authors: Deen Aron , Maw Jason , Knull Craig , Clegg John
Published: October 2012

PDC drill bits have grown from niche to mainstream products by gradual, subtle evolutions in design and materials technology. Occasionally, there have been more dramatic step changes in design or materials that have launched PDC bits into new applications. This paper will talk about such a step change: the design, manufacture and application of a contiguous blade of polycrystalline diamond. Rather than blades made up from individual cutters, as with a conventional PDC bit design, this bit has full-length, contiguous polycrystalline diamond coverage, without gaps between cutters on each blade. The advantages of this arrangement are many. Most obvious is the ability to drill erosive and/or abrasive formations without erosion. Often PDC bits, especially lighter set bits, can lose steel or matrix body material between the cutters due to erosion or abrasion, and this can be life-limiting. With no gaps between the cutters, this ceases to be a problem. Other possibilities include: bits for more conventional formations where a contiguous blade can be used instead of backup cutters, enhancing ROP and stability (Maw 2012). This represents a step change in bit design with the potential to redefine bit design across the applications spectrum.

This paper details some of the problems with the currently accepted PDC design paradigm, and proposes a novel solution to them by changing it. The hurdles in the way of making the concept a reality and their solutions are described, relating to new concepts in bit design, cutter selection, and new manufacturing process. The testing methodology used to prove the concept in the oil sands in northern Alberta, Canada, as well as the test results are presented. Finally, future planned developments based on the apparent advantages of the invention are forecast.
Results of the First Norne Field Case on History Matching and Recovery Optimization Using Production and 4D Seismic Data
Authors: Rwechungura Richard , Bhark Eric , Miljeteig Ola T. , Suman Amit , Kourounis Drosos , Foss Bjarne , Hoier Lars , Kleppe Jon
Published: October 2012

In preparation for the SPE Applied Technology Workshop, "Use of 4D seismic and production data for history matching and optimization – application to Norne (Norway)" held in Trondheim 14-16 June 2011, a unique test case (Norne E-segment) study based on real field data of a brown field offshore Norway was organized to evaluate and compare mathematical methods for history matching as well as methods on optimal production strategy and/or enhanced oil recovery.

The integrated data set provided an opportunity to discuss emerging and classical history matching and optimization methods after being tested using real field data. The participants of this comparative case study were expected to come up with a history matched model preferably using an integration of production and time-lapse seismic data and with an optimal production strategy for the remaining recoverable resources for the future period. Participants were allowed to suggest techniques to enhance recovery. Taking into account that the Norne benchmark case is a case study based on real data and no one exactly knows the true answer, participants and delegates were encouraged to discuss the methods, results and challenges during the course of the workshop, and thus in this case there are no winners or losers. Everyone who participated gained experience during the course of the exercise.

Participants were asked to history match the model until the end of 2004 and optimally predict the production (oil, water and gas rates) performance until the end of 2008. Participants were from different universities in collaboration with other research organizations namely Stanford University in collaboration with IBM and Chevron, TU Delft in collaboration with TNO, Texas A&M University, and NTNU in collaboration with Sintef. This paper summarizes the presented results from these groups and the outcome of the discussion of the workshop delegates.
The Challenges Facing Independent Companies Willing To Extract Crude Oil On The Periphery Of the Nariva Swamp, An Environmental Sensitive Area In Trinidad
Authors: Jaggernauth Deonarine J.
Published: October 2012

The Nariva Swamp (an Environmentally Sensitive Area in Trinidad) comprising 28,029 acres of wetland is located on the eastern side of the island. It is bordered by hilly terrain on the west and north sides, and the Atlantic Ocean on the east side. Several companies have extracted and continue to extract hydrocarbons from the Atlantic Ocean, and similarly on land in the southwest area.

The island of Trinidad was once part of South America, and separated maintaining its diversity of flora and fauna. Since it was difficult for these species to adapt, new sub-species emerged making areas like Nariva Swamp unique. The Nariva Swamp is one of the areas designated as a protective area to conform to the Ramsar Treaty of 1971. It is the largest fresh water ecosystem in Trinidad and is home to several species governed and protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

It is the belief of the geologists that there are substantial hydrocarbons located under the Nariva Swamp at depths greater than 3000 feet. They believe the northeast to southwest trends could substantiate their information. Independent companies have expressed the desire in exploring for these hydrocarbons, but due to the area being designated an ESA, the challenge will be to extract the hydrocarbons by using directional drilling on the periphery of the swamp to minimize interventions. In order to satisfy regulatory requirements for the local Environmental Management Authority (EMA) for any project approval, operators will have to demonstrate stringent environmental impact control measures that will be required for the drilling and production operations. This should include minimum environmental discharge, noise, and human activities using appropriate technologies. There are other sensitive areas in Trinidad where hydrocarbon extraction takes place with minimal disturbance to the environment that can provide the framework and necessary requirements for this area

To date one independent has undertaken the challenge to drill oil wells on the periphery of the swamp. The results have been mixed forcing remapping the area and looking at going deeper into the sedimentary formation.