bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensory Components of Behavioral Isolation Between Zimbabwe and Cosmopolitan Drosophila Melanogaster
Authors: Ma Daina , Smith Dean P. , Zheng Zhichao , Michalak Pawel
Published: October 2011

Successful reproduction requires males and females from the same species to recognize and prefer each other over individuals of other species. Mate recognition is mediated through the sensory systems, and one way speciation can occur is through behavioral isolation via sensory cues.Drosophila melanogasterfemales from central Africa (the "Zimbabwe" morph) prefer to mate with Zimbabwe males over males from otherDrosophilastrains ("Cosmopolitan" strains). Cosmopolitan females typically show little or no preference towards Cosmopolitan males. We hypothesize that alterations in one or more cues detected by the sensory system underlie the mating preferences of Zimbabwe females. Here, we investigate the relative contributions of three sensory factors (olfaction, vision, and hearing) to female mating preference using a number of Zimbabwe strains. Our findings suggest that auditory and visual cues are the most critical to this mate choice preference phenomenon. These results elucidate plausible mechanisms underlying incipient speciation inDrosophila.
Epidemia y perplejidades médicas: Uruguay, 1918-1919
Authors: Serrón Víctor
Published: November 2011

Se pretende establecer qué tipo de conexión tuvieron las respuestas que implementó el Estado uruguayo con el saber médico dominante, bajo la forma de políticas sanitarias, ante la epidemia de gripe de 1918-1919. El problema se puede desdoblar en dos aspectos: ¿Cuáles fueron las aristas más salientes del pensamiento médico al tener que enfrentar la epidemia de gripe durante los años 1918-1919? Y, ¿cómo se vinculó el saber médico con las acciones que llevó adelante el Estado uruguayo? Las respuestas intentarán ser dadas a través de una indagatoria indicial en virtud de dos razones: Primero, las fuentes consultadas presentan un grado muy alto de dispersión y heterogeneidad, segundo, quien redacta se encuentra en el contexto de la exploración del problema.
Los 'fueguinos', Robert Lehmann-Nitsche y el estudio de los onas en la Exposición Nacional de Buenos Aires (1898)
Authors: Ballestero Diego A.
Published: November 2011

Entre los primeros trabajos del antropólogo alemán Robert Lehmann-Nitsche como jefe del Departamento de Antropología del Museo de La Plata, Argentina, se cuentan las investigaciones sobre los habitantes de Tierra del Fuego, considerados como un 'relicto' evolutivo de la humanidad. Se repasa la importancia de las ferias y exposiciones como espacios de popularización científica y de 'trabajo de campo' para los estudiosos de fines del siglo XIX y principios del XX. Se examina la presentación de los 'fueguinos' en los espacios de las ferias y exposiciones europeas, los debates, los estudios realizados en Europa y el trabajo de Robert Lehmann-Nitsche en la Exposición Nacional de la Industria Argentina (Buenos Aires, 1898).
Representación matemática de una terapéutica: circulación de inscripciones tecnocientíficas en el tratamiento de la litotripsia extracorporal
Authors: Arellano Antonio
Published: November 2011

La noción estandarizada en las ciencias sociales en torno a la representación se refiere a los conocimientos expresados en el lenguaje provenientes de elaboraciones supraindividuales. Esta noción enfatiza el sustento social del conocimiento, pero minimiza los sustentos materiales y simbólicos que le son inherentes y sin los cuales no podría ser cabalmente comprendido. Sostengo que la circulación de inscripciones heterogéneas soporta la elaboración de las representaciones y para demostrarlo analizo las prácticas del mejoramiento de una terapéutica para cálculos renales, mostrando cómo los científicos ponen en circulación una serie de objetos, animales, modelos, textos, etc., hasta transformarlos en una representación matemática de una terapéutica.
Factors Related to Quality of Life and Satisfaction with Nasal Appearance in Patients Treated for Unilateral Cleft Lip and Palate
Authors: Mani Maria , Reiser Erika , Andlin-Sobocki Anna , Skoog Valdemer , Holmström Mats
Published: October 2011

Objective

To identify factors related to quality of life (QoL) and satisfaction with nasal appearance among patients treated for unilateral cleft lip and palate (UCLP).

Design

Cross-sectional population study with long-term follow-up.

Patients/Settings

All patients with UCLP born between 1960 and 1987, treated at Uppsala University Hospital, were invited (n = 109); 86 (79%) participated. Mean follow-up time was 35 years.

Main Outcome Measures

Quality of life was measured with Short Form–36 (SF-36) and analyzed using mental and physical cluster scores (MCS and PCS). Nasal appearance was self-assessed with the “Satisfaction With Appearance” questionnaire and by panel judgment. Multivariate regression analyses explored endogenous factors (age, gender, infancy cleft width, nasal function, nasolabial appearance) and exogenous factors (marital status, number of children, education level, operation method, number of rhinoplasties performed).

Results

A larger cleft width in infancy was associated with less satisfaction with nasal appearance as adults. A lower mental health QoL was associated with less satisfaction with nasal appearance. Despite female gender being linked to less satisfaction with nasal appearance, it was associated with higher mental health QoL. Higher resistance during nasal breathing was associated with lower physical health QoL.

Conclusions

Gender and infant cleft width may affect QoL and satisfaction with nasal appearance among adults. They are potential predictive factors for satisfaction with nasal appearance and QoL during adulthood. The correlation of nasal function impairment and decreased physical health QoL underlines the importance of treatment of nasal symptoms in these patients.
A Unique Case of Tessier 30 and Bilateral Cleft Lip and Palate: A New Clinical Syndrome?
Authors: Adetayo Oluwaseun A. , Martin Mark C.
Published: October 2011

Background

Tessier 30 cleft is rare and sparsely reported in the literature. A unique case of an infant with a Tessier 30 cleft, bilateral cleft lip and palate, and other anomalies is presented. In addition to craniofacial anomalies, he had cardiac, gastrointestinal, and genitourinal defects. The constellation of these findings suggests the possibility of a new clinical syndrome. We present these findings and postoperative results following surgical treatment.

Patient and Methods

A 37-week gestational male infant with multiple congenital anomalies is presented. Findings on clinical exam were notable for Tessier 30 median mandibular cleft, bilateral cleft of the lip and palate, and bifid tongue. Further workup revealed levocardia, perimembranous moderate-to-large ventricular septal defect, patent foramen ovale, double outlet right ventricle, intestinal malrotation, and bilateral undescended testicles. There were no extremity anomalies, and cytogenetic studies for 22q deletion were negative.

Results

The preoperative, intraoperative, and postoperative findings and images are discussed.

Conclusion

We present a unique case of a child with a Tessier 30 cleft associated with bilateral cleft lip and palate in the absence of intraoral masses or limb anomalies. Previous reports of median facial clefts have occurred either in the presence of intraoral hamartomas, suggesting the palatal defects are a result of sequence abnormalities, or in association with extremity findings consistent with the spectrum of orofaciodigital syndrome. The case we present is distinct and may represent a new clinical syndrome.
Hot Flashes: A Review of Pathophysiology and Treatment Modalities
Authors: Morrow Phuong Khanh H. , Mattair Danielle N. , Hortobagyi Gabriel N.
Published: November 2011

Many therapies are being studied for the treatment of hot flashes for individuals with cancer, yet few studies have demonstrated safe and effective clinical benefit for those who suffer from this distressing symptom. The purpose of this paper is to assess the current options for the management of hot flashes, examining key endpoints from recent clinical trials and reviewing future directions. Hot flashes are a common stressful symptom for individuals with cancer, particularly women with a history of breast cancer and men with prostate cancer. Lifestyle modifications are proposed as the first step in the management of less severe hot flashes. Several publications have addressed nonhormonal agents as a treatment option for hot flashes. Newer antidepressant and anticonvulsant agents have been studied and show potential in treating vasomotor symptoms. Although many complementary and alternative therapies, including herbal medications and phytoestrogens, have been studied for the treatment of hot flashes, none are clinically recommended at this time. Additionally, further evidence is needed for supportive exercise such as yoga and relaxation techniques. Acupuncture may warrant further investigation in the reduction and severity of hot flashes in both men and women. Hormonal therapies, including estrogens and progestogens, are the most well-known and efficient agents in alleviating hot flashes; however, the safety of these agents is disputable.
Second Malignancies Among Elderly Survivors of Cancer
Authors: VanderWalde Ari M. , Hurria Arti
Published: November 2011

The U.S. population is aging, life expectancy is increasing, and cancer is a disease associated with aging. Advances in screening and therapeutics have led to a growing number of cancer survivors who are at risk for the development of secondary malignancies. Although the risks for the development of second malignancies following a first diagnosis of cancer are well described for survivors of childhood malignancies, there are fewer data for malignancies common in older adults. With the aging of the U.S. population, and with improving survival statistics in many adult malignancies, there is an increasing need to identify those second malignancies that might develop in the older adult survivor of cancer. In this paper, we describe the types and rates of second malignancies following cancers commonly seen in older adults and review the literature on these malignancies. Comparisons are made between older and younger adults with regard to the risks for developing treatment-related cancers with different modalities. Recommendations for early detection of second malignancies are summarized, though there remains an unmet need for evidence-based guidelines for screening for second malignancies in the older adult in particular.
Sea pens (Octocorallia: Pennatulacea) from the Late Cretaceous of northern Germany
Authors: Reich Mike , Kutscher Manfred
Published: November 2011

The Late Cretaceous white chalk of the Isle of Rügen, northeastern Germany, yields a highly diverse marine floral and faunal assemblage with more than 1,400 described species, including pennatulacean corals. All the new collected material, composed of fragments of the axial rods, belongs to‘Graphularia’ quadrataVoigt, 1958, which was revised, and a new species, ‘Graphularia’ rugia.Analyses of the microstructure of axial rods of modern and fossil sea pens facilitate the discussion of the systematic relationships of the fossil material.‘Graphularia’ quadratashows an affinity to the Funiculinidae, whereas the new species‘Graphularia’ rugiaresembles the axial structure of the Pennatulidae.
Potential foraminiferal markers for the Visean–Serpukhovian and Serpukhovian–Bashkirian boundaries—a case-study from Central Morocco
Authors: Cózar Pedro , Said Ismail , Somerville Ian D. , Vachard Daniel , Medina-Varea Paula , Rodríguez Sergio , Berkhli Mostafa
Published: November 2011

The Carboniferous succession in Adarouch (Central Morocco, north of the Atlas Transform Fault) contains thick carbonate beds including upper Visean, Serpukhovian and basal Bashkirian rocks. Foraminifers enable precise recognition of the Visean/Serpukhovian (V/S), early/late Serpukhovian (eS/lS) and Serpukhovian/Bashkirian (S/B) boundaries.Insolentitheca horrida, Loeblichia ukrainica, “Millerella”spp. andEndostaffella? sp. 2 are regarded as regionally useful indices to the V/S boundary, whereasEostaffellinaspp.,Eostaffella pseudostruveiand some evolved species ofArchaediscusexhibit greater reliability for worldwide correlation of this level. Similarly, the eS/lS boundary is marked locally byBrenckleina rugosa, Eosigmoilinasp., andMonotaxinoidesspp. and globally byLoeblichia minima, Bradyina cribrostomata, Plectostaffellaspp.,Eostaffellina “protvae”and“Turrispiroides”, and the S/B boundary is marked locally byGlobivalulina bulloidesand globally bySeminovella elegantula, andNovella?. Occurrences of these taxa in Morocco allow correlations with the Moscow Basin, the Urals, the Donetz Basin and North America. The Moroccan assemblages share few taxa in common with Saharan basins south of the Atlas Transform Fault. Correlations with western European basins are difficult because of the paucity in the latter of foraminiferal-bearing carbonate strata.
Biodiversity and ecosystems – a guide for civil engineers
Authors: Cameron Andrew
Published: November 2011

Plant and animal species are dying out faster than ever before. Andrew Cameron of built-environment consultancy Crex says civil engineers and other construction professionals need to make saving biodiversity an even greater priority than tackling climate change.
Embodied carbon dioxide as a design tool – a case study
Authors: Knight David , Addis Bill
Published: November 2011

Embodied carbon dioxide is increasingly being used to measure the sustainability of a building’s structure. With reference to the West Kowloon terminus in Hong Kong, this paper outlines how estimates of embodied carbon dioxide were used as a design tool to develop structural options, and how embodied carbon dioxide data were incorporated within building information modelling processes. It proposes that embodied-carbon accounting be used alongside quantity surveying to determine the out-turn cost of a building, and recommends clients estimate embodied carbon dioxide on recently completed projects to help establish benchmarks.
ITZ volume fraction in concrete with spheroidal aggregate particles and application: Part II. Prediction of the chloride diffusivity of concrete
Authors: Zheng Jianjun J. , Guo Zhanqi Q. , Huang Xiaofeng F. , Stroeven Piet , Sluys Lambertus J.
Published: November 2011

Owing to its importance in the durability assessment of reinforced concrete structures located in a marine or de-icing salt environment, it is essential to determine the chloride diffusivity of concrete. The intention of the present paper is to present an analytical solution for the chloride diffusivity of concrete with aggregate shape effect. A three-phase composite spheroid model for the concrete matrix is proposed to represent the heterogeneous nature of concrete and to take into account the aggregate shape effect. By reducing the three-phase composite spheroid to two two-phase composite spheroids, an analytical solution for the chloride diffusivity of concrete is derived. After the validity of the derived analytical solution is verified with two sets of experimental results, the effects of main factors that affect the chloride diffusivity of concrete are evaluated in a quantitative manner. It is found that the chloride diffusivity of concrete increases with the increase of the thickness and chloride diffusivity of the interfacial transition zone (ITZ), but decreases with the increase of the aspect ratio of spheroidal particles and the maximum aggregate diameter. It is also found that the aggregate gradation has a significant influence on the chloride diffusivity of concrete. The paper concludes that the analytical solution derived here can predict the chloride diffusivity of concrete with reasonable accuracy.
A Case of Squamous Cell Carcinoma Presenting as Localized Severe Periodontitis in the Maxillary Gingiva
Authors: Kim Ok‐Su , Uhm So‐Won , Kim Sang‐Chul , Lee Bo‐Ah , Kim Ok‐Joon , Kim Young‐Joon , Chung Hyun‐Ju
Published: November 2011

Background: Squamous cell carcinoma (SCC) is the most common malignant neoplasm of the oral cavity. The clinical features of gingival SCC include alveolar bone loss and erythematous lesion. Therefore, gingival SCC sometimes presents as advanced periodontitis. This case report describes a patient diagnosed with gingival SCC after the extraction of molars presenting as being affected by localized severe periodontitis.

Methods: The patient was a 61‐year‐old man whose chief complaint was pain in the left maxillary area. Clinical and radiographic examinations revealed common findings of a periodontal abscess on the left maxillary first and second molars. These teeth were extracted based on a diagnosis of a periodontal abscess. Three months later, a rapidly growing exophytic soft tissue mass was observed, and a biopsy of the mass was performed.

Results: According to the biopsy, the final diagnosis was a well‐differentiated SCC. The patient was treated with a partial maxillectomy of the left maxilla and split‐thickness skin graft. Two years after treatment, the patient remained free of recurrence.

Conclusions: Gingival SCC is quite different from other forms of SCC, mimicking localized periodontal disease. Therefore, it can be misdiagnosed as localized periodontal disease and is generally discovered after extracting teeth. Therefore, clinicians must diagnose these lesions carefully and follow up with the patient after tooth extraction.
Acid Diversion using Viscoelastic Surfactants: The Effects of Flow Rate and Initial Permeability Contrast
Authors: Al-Ghamdi Abdulwahab H. , Hill A. D. , Nasr-El-Din Hisham A. , Mahmoud Mohamed A.
Published: October 2011

The purpose of matrix stimulation in carbonate reservoirs is to bypass damaged areas and increase the effective wellbore area. This can be achieved by creating highly conductive flow channels known as wormholes. A further injection of acid will follow a wormhole path where the permeability has increased significantly, leaving substantial intervals untreated. This problem can be more significant as the contrast in permeability increases within the target zones. Diverting materials, such as surfactant based-acids, plays an important role in mitigating this problem.

Acid injection rate was found to be a critical parameter to maximize the efficiency of using surfactant-based acids as a diverting chemical in addition to creating wormholes. We found that the maximum apparent viscosity, which developed during viscoelastic surfactant acid injection, occurred over a narrow window of acid injection rates. Higher injection rates were not effective in enhancing the acidizing process, and the use of diverting material became similar to that of regular acids. The use of surfactant-based acid was also found to be constrained by the scale of the initial permeability ratio. For permeability ratios greater than about 10, diversion was insufficient.

The results were obtained by conducting a large set of acidizing experiments using 20" long cores. Both single and parallel coreflood experiments were performed in this study. Carbonate cores were used with initial permeability of 4 md to 150 md, and the flow rate was varied from 1.5 cm3/min to 50 cm3/min. The initial ratio of permeabilities between the two cores ranged from 2 to 15. To characterize the wormholes, computerized tomography was used to generate a 3D view of the wormholes in each core.
Use of the Near-Balance Drilling Technology Enables an Operator to Drill Successfully the Deepest Exploratory Well in Pakistan: Case History
Authors: Crea Francesco , Mehmood Asad , Moyse Keith , saber Sherif , Torres Fabian , Arnone Maurizio
Published: October 2011

The correct selection and application of the innovative near balance drilling (e-nbd) technology combining the automatic surface backpressure control of Managed Pressure Drilling (MPD) with continuous fluid circulation method (e-cd) has demonstrated a key impact during the first application in country.

In 1998 an operator company drilled a well targeted to the Lower Cretaceous Goru and Sembar Sands as a primary objectives but it encountered a high pressured sequence (continuous increase in the background gas/formation pressure) and was not possible to continue drilling because of well construction limitations (at 3500m MD all available casing strings were consumed and in 6" hole was not possible to manage the coexistence of high background gas and losses). The objective formations in this field were considered not reachable with conventional drilling practices and even with technologies available at that time. Eleven years after this first attempt, another operator decided to target the Lower Goru (3500m MD) and Chiltan Formations (4900m MD), never explored in the Kirthar Fold Belt using the near balance drilling technique (e-nbd) technology combining the automatic control of surface backpressure of managed pressure drilling (MPD) together with the proprietary technology of the continuous circulating valves (e-cd) achieving to drill through the intervals in the Lower Goru formation, pushing the technical limit of drilling to the deeper horizon of the carbonates sequence of the Chiltan formation by first time ever.

Throughout the targeted two last hole sections for the MPD technology, Constant Annular Pressure technique was successfully applied drilling 45% more hole length than the previous reference well reaching the planned target with a bigger hole size than the offset, by precisely monitoring micro influxes and pressure losses in the annulus. The returns from annulus were taken through the MPD full automatic system in order to control the ECD and the flow from the well flow once drilling into expected high pressure gas formations.
Gauge Extension Optimizes Conventional Drill Bits for Superior Performance with Rotary Steerable Systems
Authors: Stroud Daryl , Lines Liam , Barton Steve , Sanchez Hector
Published: October 2011

Bit gauge length has been a hot topic for several years, particularly when assessing optimal length for rotary steerable systems (RSS). Discussion has not just been about the length; aspects such as geometry, tapering, width, cutting elements, have all complicated the matter further, as well as the fact that different RSS tools require different configurations for optimal balance between steerability, stability, durability, and drillability.

This paper describes a joint engineering approach in identifying gauge configurations for the latest generation of RSS that utilizes point-the-bit technology. The project included systematic testing at a purpose-built, full-size drilling test facility. This has enabled a direct comparison of the directional response, hole quality and drill string vibration to be made for the various gauge configurations tested.

The testing included use of a novel gauge extension stabilizer. This unique stabilizer provides a method of extending the gauge length of the bit on the rig floor, giving a wider variety of bit selection choices for specific applications. The gauge geometry of the stabilizer provides a 360 ° continuous circumferential contact with the borehole, thus providing improved borehole quality and reducing vibration.

Field trials proved that the addition of a gauge extender to a short gauge bit can dramatically improve hole quality when used with point-the-bit RSS. The closer gauge hole significantly reduced the severity of downhole vibration and backward whirl. Concerns over lack of steerability, in conjunction with high levels of stick slip and torque, proved unfounded.

This study proves that a short gauge, short length bit, when combined with a gauge extender, can be a suitable replacement for a long gauge bit; affording the improved lateral stability required by the RSS whilst allowing operators the freedom to select a widely available short gauge bit with the correct cutting structure.
Novel Approach of Gas Lift Valve Change out Which Eliminating Production Deferment for Multiple Oil Producer String
Authors: Ooi Zhon Wei , M Shahrizal B Hashim
Published: October 2011

Gas lifting is the most selected method for production enhancement purpose in Peninsular Malaysia Operations due to huge amount of gas source is available for utilization. However, production deferment due to gas lift valve change out (GLVC) is difficult to be eliminated especially for multiple oil producer wells due to the requirement to bleed off production casing pressure during the job.

Due to that constraint, further analysis was carried out to eliminate production deferment during GLVC and at the same time ensuring the planned job can be done without any safety issues. Two main parameters were deeply considered during job execution namely the pressure management and wellbore fluid volume calculation.

In the early analysis process, spreadsheet mathematical model was developed to reflect the requirement for continuous pressure monitoring during the job execution. Then, other associated factor such as hardware requirements, e.g. pumping unit, pumping tee and other accessories are captured into consideration. The success execution of this project is expected to eliminate any unnecessary production deferment during GLVC.

This paper will explain detail analysis of GLVC job without having to bleed off the casing pressure and spreadsheet model developed for easy continuous pressure calculation during the job execution.
Reserves Follow-up Using an Integrated Deterministic-Probabilistic Approach
Authors: Araujo Hugo , Rattia Aquiles
Published: October 2011

Currently, the deterministic methods for reserves estimation are the preferred method for both, companies and the U.S. Securities and Exchange Commission SEC. Last year, the SEC published the modernization rules for reporting oil and gas reserves where both, the deterministic and probabilistic methods, were accepted as valid methods for reserves estimation. In addition to the compulsory reporting of the oil and gas proved reserves, the probable and possible reserves were recognized to be disclosed in SEC filings for the first time, although it is optional for these two categories. In this paper the integrated deterministic-probabilistic approach is briefly reviewed, the cumulative probabilistic lognormal plots are used instead of a full Monte_Carlo simulation, and a procedure is proposed using these plots to follow up the reserves evolution in time. Plotting the deterministic reserves using probabilistic scale often reveals deviations with regards to the expected lognormal cumulative probability distribution behaviour, shown by real case examples. The corrections to obtain a better fit for the probabilistic distribution suggest to either changing the probable or the possible reserves or both. Furthermore, the slope of the probabilistic plots appears to be related to the uncertainty level of the probable and possible reserves. This property was used to follow up the reserves behaviour in time, finding consistency with the idea that as the fields are developed the level of uncertainty should be progressively reduced. Examples of the reserves follow up are also presented. The contribution of this paper is oriented to a practical use of an integrated deterministic-probabilistic approach as a complementary tool for reserves estimation for consistency with the probabilistic behaviour. The follow-up procedure of the reserves resulted to be quick and simple but powerful as indicator of the reserves evolution.
General Isothermal Enhanced Oil Recovery and Waterflood Forecasting Model
Authors: Mollaei Alireza , Delshad Mojdeh
Published: October 2011

Forecasting the performance of enhanced oil recovery (EOR) processes plays an important role in EOR study, design and selection of the best enhanced oil recovery method for a particular reservoir. However, lack of a general purpose EOR forecasting model is unsatisfactory. We address this deficiency by presenting a novel analytical-base general EOR forecasting model that does not rely on conventional numerical simulation.

Using the concepts of segregated flow, material balance and fractional flux (F-C or F-Phi) arrive at a general approach for modeling different isothermal EOR processes including chemical EOR (polymer, surfactant-polymer and alkaline surfactant polymer flooding), solvent flooding (miscible/immiscible, continuous gas flood and WAG) and also waterflooding. We used a Koval flow-storage capacity (F-C) model in the current research because of its strength and wide applicability for both homogenous and heterogeneous permeable media. The validity of the forecasting model was investigated by matching numerous secondary and tertiary field, pilot and simulation results.

History matching showed good agreement between field data and forecasting results. The forecasting model demonstrates a strong ability to forecast the oil saturation, recovery efficiency, cumulative oil recovery, oil cut and oil rate changes with time for secondary and tertiary recovery methods. In addition, predicting the recovery efficiency enables us to generate the volumetric efficiency change with time which is of great importance for studying the EOR processes. These valuable results are produced using a few input variables.
Application Specific Steel Body PDC Bit Technology Reduces Drilling Costs in Unconventional North America Shale Plays
Authors: Hanna Chase , Douglas Charles , Asr Hany , Durairajan Bala , Gerlero Martin , Mueller Levi , Pendse Bhushan , Travers Chris , Bits Smith
Published: October 2011

As drilling activity in conventional land-based plays continue to decline, technology focus is shifting to the unconventional shale gas prospects (Haynesville, Marcellus, Eagle Ford). Efficient and repeatable drilling practices, along with cost effective technologies, are paramount to economically exploit the known hydrocarbon reserves because of the large number of horizontal wells required to develop the vast acreage plays. The drilling challenges include high bottom hole temperatures, high mud weights and hole/bit cleaning issues. The key to reducing field development costs and improving project economics is increasing rate of penetration (ROP) in the lateral interval that typically extends 3000 to 6000ft after completing the build section.

To solve the penetration rate and hole cleaning challenges, an engineering team analyzed the latest polycrystalline diamond compact (PDC) technologies and best drilling practices to achieve the operator's ROP optimization goals. An FEA-based engineering software system was utilized to predict the dynamic behavior of the bit and BHA components in lithologies comparable to the specific field application. To ensure proper utilization of the available hydraulic energy, engineers used computational fluids dynamics (CFD) to ensure appropriate nozzle placement and orientation to effectively clean the bit face and hole bottom. Conclusions from the dual analysis were instrumental in developing new steel body PDC bit designs specifically engineered for emerging North American shale plays.

The new steel body PDC design and the associated bit technologies and updated operating practices have been run in the Bossier City, Louisiana and Tyler, Texas areas with outstanding results. The new PDC technology has increased lateral interval ROP by as much as 80%-100% compared to conventional matrix bodied PDC bits. The authors will present several case studies that document the significant cost savings.
Experimental Results and Analytical Modeling of Solvent-Leaching Gravity Drainage Phenomenon in Heavy Oil Reservoirs
Authors: Ahmadloo F. , Asghari K. , Henni A. , Freitag N. P.
Published: October 2011

Solvent-leaching gravity drainage based processes have gained increasing interest for improving recovery from low-pressure heavy oil and bitumen reservoirs around the world. In these processes, injected solvent in the vapor phase diffuses and dissolves into the oil, hence mobilizing it by viscosity reduction. The mobilized oil drains into a production well under the influence of gravity and capillary forces. In this study, a comprehensive experimental program was conducted to systematically investigate the effects of capillarity and drainage height on stabilized drainage rates in a permeability range of 5.1-6.5D, which is similar to that of western Canadian heavy oil reservoirs. In addition to these experiments, separate investigations were undertaken to measure the capillary pressure of sand packs, as well as phase behavior properties of the oil-solvent system used in this study. The novel design of the experimental setup made it possible to eliminate the effect of pressure disturbances and forced displacement for the duration of the experiments (20-45 days), and investigate the interplay between capillarity and drainage height in the gravity-dominant system. It was found that the observed stabilized drainage rates per unit length of porous media (9.85×10−7-3.44×10−5 cm3/s/cm) are function of drainage height, specific pore surface area of porous media, and concentration of diffused solvent into the oil phase. A one-dimensional analytical model was adapted to calculate the diffusion coefficients for these experiments and develop a new correlation for the prediction of the effective diffusion coefficient in this process. Experimental results and modeling showed that molecular diffusion was the major drive for the mass transfer phenomena in higher capillarities. According to the developed correlation in this study, drainage height, capillarity, and solvent concentration in the oil phase play more important roles in mass transfer phenomenon than those observed in experiments conducted at high permeabilities (>200D).
Evaluation of Fugitive Methane Emission Factor for Oil and Gas in India
Authors: Agarwal Ankit , Singh Ajay K
Published: October 2011

Methane Emissions from the Oil and Gas Industry has been a major Environmental concern for over a long period of time. This work estimates the Methane emissions from the Oil and Gas industry in India. The work has used the guidelines of IPCC (Intergovernmental Panel for Climate Change) which has been a pioneer in bringing regulations relating to environmental concerns. The IPCC guidelines define a two level hierarchical structure for source categories related to the oil and gas industries.

This project aims at estimating the Emissions of Methane from the Industry. For this proper activity data and methodology is required. National activity data in respect of oil and natural gas systems for the years 1990 to 2009 was collected. Methane emissions have been calculated for all the activities listed above. The methane emission factor used for calculating the emissions from the various activities are either used directly from the IPCC or they have been particularly calculated. For activities including oil refining, transportation and storage of oil, gas production, processing, transmission and other leakages default emission factors of Tier 1 Approach of IPCC have been considered.India specific methane emission factors have been evaluated for oil production and venting and flaring activities. This method is clearly defined in the IPCC under Tier 2 approach. The future scope of this work is also to formulate emission factor using Tier 2 Approach of IPCC guidelines for the country. For other ctivities for which some study has already been done and Tier 2 factors have already been calculated in this work, the next work is to implement Tier 3 approach of the IPCC guidelines for continuous monitoring of the emission of methane to the atmosphere.

Keywords: Greenhouse Gas Emission Inventory, Oil and Natural Gas, Fugitive Methane Emission, Activity Data, Emission Factor
History Matching and Production Forecast with Logs, as Effective Completion and Reservoir Managing Tools in Horizontal and Vertical Wells
Authors: Haro Carlos F.
Published: October 2011

Simulation history matching is a daunting, time-consuming task with numerous unknowns and several plausible answers. Scale differences in the data frequently obscure results, precluding its effective application in completion strategies. Good history matching does not guarantee accurate production forecasts. Reliable predictions, required for well planning, depend on our ability to reduce the uncertainties to find consistent and timely solutions. Logs can provide appropriate conditioning data for history matching and to manage the reservoir. We prove it with field data.

Electrofacies, absolute, relative permeability and capillary pressure, imprinted on logs, can be mathematically linked with irreducible water saturation. Logs are at the right scale for completion designs. They facilitate upscaling, honoring rock and fluid properties, and the physics of flow. Logs are snapshot measurements, amenable for conversion into dynamic forecasting tools employing flow and pressure equations. This concept permits creation of synthetic production logs over time, to calculate production decline.

We introduce the integrated utilization of material balance, flow-pressure algorithms, fluid data, cores and logs. We represent every well as a finite, gridded tank, capable of producing measurable volume of fluids, limited by its petrophysical constrains. Superposition, in terms of pressure and flow, combines the various components, within and amongst wells. Quality of the results is ensured, since material balance must withstand at every depth at all times, under different production scenarios and the prevailing driving mechanism.

With this log handling, we help to take strategic economic decisions to maximize reserves and optimize the reservoir development plan. We obtain oil in place, drainage radii, lateral connectivity, fluid bank arrival times, productivity indices, inflow performance, production allocation and recovery per zone, per well, parameters generally not provided by other methods. We streamline completion designs and conformance, the day to day managing of the reservoir, with this refined use of logs.
Production Forecasting with Logistic Growth Models
Authors: Clark A. J. , Lake L. W. , Patzek T. W.
Published: October 2011

With the commercial development of extremely low permeability oil and gas reservoirs, new challenges have arisen both from operational and reservoir standpoints. Reservoir models, which previously yielded reasonable results for reserves estimates and production forecasts, no longer do so. Various new models and techniques have been proposed to improve the accuracy and reliability of reserves estimates; however, none have gained widespread industry acceptance. This paper will propose a new empirical model for production forecasting in extremely low permeability oil and gas reservoirs based on logistic growth models. The new model incorporates known physical volumetric quantities of oil and gas into the forecast to constrain the reserve estimate to a reasonable quantity. The new model is easy to use, and it is very capable of trending existing production data and providing reasonable forecasts of future production. The logistic growth model does not extrapolate to non-physical values.
A Strategic Method To Accelerate Individual's Learning And Enhance Subsurface Team Performance Within Multidisciplinary And Multigenerational Environments
Authors: Dashti Qassem , Gunawan Christine
Published: October 2011

The development of young geoscientists and engineers to be independent contributors is paramount for Kuwait Oil Company's long-term success in optimizing their production and improving field development efficiency. In our fields, the main challenges are characterized by the deep and tight naturally fractured carbonate reservoirs, volatile fluids, high-pressure-high-temperature conditions and the presence of CO2 and sour gas.

Production enhancement activities play a significant role in maintaining production capacity. Therefore, rapid and integrated decisions from multidisciplinary teams are necessary to select potential solutions and to accelerate the required remedial work. Yet the largely junior population of the asset teams creates an immense challenge in getting the work completed.

Overcoming this challenge begins by developing individual staff learning programs that are aligned with competency gaps, business needs and personal development plans. The program lists the competencies required, which are then achieved through blended learning. The learning program emphasizes transferring knowledge and skills on the job, and holds the learner accountable for achieving results. Therefore, linking training with relevant and appropriate task assignments is essential to accelerate and reinforce competency development. One task which has proven key in the blended learning methodology is conducting formal and detailed well reviews, in which all pertinent data is presented on a specific well, and a multi-disciplinary team brainstorms and recommends an action plan and the additional. Staff assigned to conduct well reviews must develop knowledge outside their domain in order to facilitate team collaboration among the different disciplines, allowing the sharing of best practices and optimum decision making.

This accelerated staff development method has been applied for two years in North Kuwait and has resulted in meeting our production goals, better field management and improved team performance. Some examples of activities enabled by this methodology are defining perforation intervals, developing sector reservoir models to determine shut-in periods required for buildup testing, and formulating workover program design. In these two years 12 workover programs have been completed successfully - is an outcome of 66 well reviews. Just as importantly, junior staff competency grew 48%, an achievement which is mainly the result of their being assigned and performing jobs such as well data analysis and well reviews with minimum supervision.

This paper details the method and progress of what has proven to be the best approach to accelerating staff learning curves, reducing competency gaps and enhancing professional development that delivers. Also summarized is the value of team collaboration, interaction between engineers and geosciences for successful reservoir management, and lessons learned.
New Locking Clutch Turbine Technology Successfully Frees Stuck Bit/BHA in Deep Gas Wells, Oman
Authors: Kapoh Oddy , Van De Velden Mark , Al-Hajji Mohammed , Houqani Said , Cook Perry , van den Bos Maarten , Hanna Joseph , Al-Salti Mohammed , Arnott Steven
Published: October 2011

Drilling hard-rock sequences in northern Oman can present a number of distinct challenges. Operations are frequently hindered by formation breakout in rocks with high confined compressive strengths (15,000-50,000 psi). The problem is exacerbated by highly abrasive formations, extreme bottom hole temperatures (160-175C) and the subsequent deterioration of mud properties at vertical depths of approximately 4500-5500m.

The main challenge is bit/bottom hole assembly (BHA) sticking while drilling a tectonically stressed sandstone formation. Formation breakouts that occur at or just above the bit can go unnoticed as drilling progresses and are the main sticking mechanisms responsible for turbine stall. The use of durable impregnated bits and motor/turbine BHA can increase drilling performance. However they bring an increased risk of leaving tools in hole (LIH) because the bit and driveshaft are able to rotate independently of the drillstring in a stuck bit event. A conventional motor/turbine has no reliable mechanism to transfer the available high torque from the drillstring to the bit, leaving axial force (pushing/pulling) as the only means to free a stuck bit/BHA.

For this reason, the operator is exploring new technological solutions to reduce non productive time (NPT) associated with stuck events. A recent research and development effort has resulted in a new-style turbine, which in the event of stalling or bit sticking, locks the bit to the body of the drive-system so that drillstring torque can be applied to the bit. Transmission of drillstring torque to the bit significantly increases the chance of freeing a stuck bit/BHA. And instantaneous locking while rotary drilling can reduce the risk of becoming stuck by keeping the bit in motion should the turbine stall.

During technology trials in 2010 BHAs in nine deep wells were successfully freed after several stuck events. The authors will provide a BHA schematic and the procedural details that contributed to the successful operations.
Integration of Formation Pressure Data to Improve Reservoir Characterization and Reservoir Management in PL19-3 Oil Field, Bohai Bay
Authors: Yu H. , Hallenbeck L. , Hofer R. , Summers L. , Wu C. , Zhang J.
Published: October 2011

The Peng Lai (PL) 19-3 Oil Field, located in the ConocoPhillips operated Bozhong 11/05 Block in the central southern Bohai Sea, offshore China, is currently the largest offshore oil field in China. The trap is a complex wrench anticline developed along the Tanchen-Lujiang fault system. The main oil accumulation is in the Neogene Lower Minghuazhen and Guantao Formations with a vertical relief from the top reservoir to the deepest oil bearing rock of approximately 500 meters. The PL 19-3 Oil Field, deposited in a fluvial environment, is a complex stacking of unconsolidated sandstone reservoirs, with moderate porosity and permeability and low net gross ratio. The trap has been divided recently into numerous fault blocks which have unique contacts and variable oil properties both vertically and laterally, with oil gravities ranging from 12 to 22 API.

This paper reviews the pressure acquisition history and analysis from the 160 well formation test database, which includes both wireline formation test (WFT) and formation test while drilling (FTWD). Formation testing in the Neogene formation of Bohai Bay is challenging since the reservoir is unconsolidated and the oil is heavy. Common problems that affect pressure testing are described, efforts to enhance test efficiency are stated and key learnings and best practices to secure high quality pressure data are summarized.

Conventional pressure interpretation to derive fluid gradient and oil water contacts, identify reservoir compartmentalization and flow barrier is challenged due to small density contrast between the heavy oil and water in the field. The excess pressure method, which is attributed to formation water properties and consistent hydrostatic pressure gradient in the field, has been an effective way to analyze pressure data. In this paper, the historical application of excess pressure in the industry is reviewed, examples of the excess pressure interpretation in PL 19-3 Oil Field are given and integrated interpretation practices are emphasized.

Pressure data have wide application in the PL 19-3 oil field. This paper summarizes and demonstrates how original excess pressure and dynamic logging while drilling (LWD) pressure data have been used successfully to predict oil water contacts, to analyze fault transmissibility, to monitor water flooding efficiency, to identify fluid properties, to interpret fault cuts in wells, to optimize mud weights while drilling and to mitigate risk and well bore damage during completion operations