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Abstract. A study of paraffin wax transitions using X-ray diffraction, differential thermal analysis, and dilatometric techniques showed that waxes melting below about 60 o C exhibit two solid-solid phase transitions, whereas those melting between 60 o C and approximately 75 o C have only a single transition. The absence of transitions in waxes melting above 75 O C is well known. The different transitions are discussed and the transition temperatures correlated with blocking and penetration behavior. The nature of the crystallization process is independent of melting point and composition in the waxes studied. The kinetics are not limited by the number of primary nuclei and the growth is two-dimensional involving a secondary nucleation process. Quenched wax films on paper substrates exhibit metastable behavior. The changes profoundly affect the water vapor permeability, the waxes showing the greatest metastable platelet growth having high initial permeabilities, but the eventual platelet development effectively seals the paper surface. Polymer additives influenced neither the transition behavior nor the crystallization kinetics. Electron micrographs, however, revealed that the polymer prevented the formation of intercrystalline low angle grain boundaries with their associated dislocation sequences. It is presumed that these phenomena account for some of the improved properties characteristic of wax-polymer blends. Résumé. Une étude des transitions de la cire de paraffine faite au moyen de la diffraction aux rayons X, de l'analyse thermique différentielle et de techniques dilatométriques a montré que les cires fondant au dessous de 60 o C possèdent deux phases de transition solide-solide, tandis que celles qui fondent entre 60 o C et approximativement 75 o C n'ont qu'une seule transition. L'absence de transitions dans les cires fondant au dessus de 75 o C est bien connue. Les différentes transitions sont discutées et les températures de transition sont corrélées avec le comportement au bloquage et à la pénétration. La nature du processus de cristallisation est indépendante du point de fusion et de la composition des cires étudiées. La cinétique n'en est pas limitée par le nombre de noyaux primaires et la croissance est bi-dimensionale et comporte un processus de nucléation secondaire. Les films de cire déposés a chaud sur des substrats de papier ont un comportement métastable. Les changements influencent profondément la perméabilité à la vapeur d'eau, en ce sens que les cires qui possèdent la plus grande croissance à plaquette métastable ont de grandes perméabilités initiales, mais le développement final de la plaquette scelle la surface du papier efficacement. L'addition de polymères n'influence ni le co
Being a young professional working in the oil and gas industry right now means learning a lot of things the tough way. Our business is changing rapidly, working to reflect the changing realities of a cyclical commodity, changes to environmental legislation, and increased technical rigor required to explore for and produce oil and gas. This means that for many young professionals, the required skill sets are changing quickly as is the need for certain expertise. I suspect many people have gone through some major career transitions in the last year, or at minimum, have association with individuals that have gone through one. The simple truth is that we all go through major transitions during the course of our life, whether it is at work or in our personal lives.
This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 100615, "Prediction of Slug-to-Annular Flow-Pattern Transition (SAT) for Reducing the Risk of Gas Lift Instabilities and Effective Gas-Liquid Transport From Low-Pressure Reservoirs," by P. Toma, SPE, P.R. Toma Consulting Ltd., and E. Vargas and E. Kuru, SPE, U. of Alberta, prepared for the 2006 SPE Gas Technology Symposium, Calgary, 15–17 May. Slug-flow to annular-flow transition occurring during upward gas/liquid flow is a source of flow instabilities often experienced in conventional gas lift as well as in unloading water accumulated at the bottom of gas wells. In both situations, a significant decrease in tubing pressure from perforations to wellhead is associated with a significant increase in superficial gas velocity and may induce flow-pattern transitions. The full-length paper uses field data and laboratory measurements to suggest that flow-pattern transition can result in flow instabilities and should be avoided. Introduction Understanding and prediction of slug-flow to annular-flow transition are essential for designing effective gas lift or unloading strategies. Mechanistic modeling of gas/liquid-flow systems including descriptions of major flow patterns and transitions is essential to develop suitable production strategies in both depleted and large offshore gas/oil reservoirs. These include the ability to control the stability of a suitable gas/liquid-flow pattern from perforations to wellhead and achieve the designed production volumes. To minimize the pressure drop, large-liquid-volume gas lift primarily uses a slug flow pattern, while production of gas with relatively small amounts of condensate or water uses an annular flow pattern. Slug-to-annular flow-pattern transition including the intermediate churn condition is considered to be a potential source of instabilities. Fig. 1 shows flow patterns for upward vertical flow. Difficulties visually assessing the hydrodynamic evolution of this transition because of highly turbulent gas/liquid-flow reversals are a source of controversy, mainly related to the definition of churn as a standalone flow pattern or as a transition stage between slug and annular flow. Slug Flow Pattern. The slug flow pattern is characterized by a chain of bullet-shaped, rising Taylor bubbles. A relatively large amount of liquid and much smaller gas bubbles are contained in a slug found between two consecutive Taylor bubbles. The population of much smaller bubbles found in the slug subpattern is formed continuously through turbulent breaking of the trailing edge of large Taylor bubbles and disappears through coalescence (back into Taylor bubble). The slug-subpattern volume is essential to transport a large amount of liquid upward during conventional gas lift operations. A back-flowing liquid film (found between Taylor bubbles and the tubing) is an equally essential feature of any slug flow pattern and limits the depth from which liquid can be transported in a slug flow pattern from extremely low-pressure reservoirs.
What’s Ahead–From TWA’s Editor-in-Chief Being a young professional working in the oil and gas industry right now means learning a lot of things the tough way. Our business is changing rapidly, working to reflect the changing realities of a cyclical commodity, changes to environmental legislation, and increased technical rigor required to explore for and produce oil and gas. This means that for many young professionals, the required skill sets are changing quickly as is the need for certain expertise. I suspect many people have gone through some major career transitions in the last year, or at minimum, have association with individuals that have gone through one. The simple truth is that we all go through major transitions during the course of our life, whether it is at work or in our personal lives. Some transitions are memorable, others are noble, and some are regrettable, but all of them provide you with an opportunity to reflect, learn, and adapt. I can think of several major transitions that I have gone through in my life, and all of them have provided me with an opportunity to grow as a person. One of the more memorable ones was moving to Christina Lake, Alberta—located in the boreal forest of the Canadian North—where I lived for 18 months supporting the construction and commissioning of a major oil sands facility. The experience I gained on site was both rewarding and exhausting. We worked long hours, lived in an on-site camp (the baked goods always get you), and spent evenings catching up on current events. Fortunately, our camp had a great recreational center which allowed me to keep in shape and inhibit the weight gain that almost seems inevitable at such times. I made some great friends at the site and I would say that the experience was well worth it for my career development, helping me understand our business and later transfer to more subsurface-based roles. But there was also an impact on my personal life. I was separated from the ones I loved and lost touch with many people over the 18 months. In many respects, I put my life on hold during the time I was up there. Working in the field as a young engineer provides development opportunities that are hard to replicate elsewhere—seeing well and field operations in action, conducting inspections, troubleshooting on the fly, and most of all, working with field personnel who have a plethora of experiences and wisdom to share. I suspect that many readers have their own stories of career transitions in the field, office, or academia. I would encourage you to share stories of your career transitions on SPE platforms like SPEConnect or SPE social media sites for the benefit of other young professionals.
In addition to family and friends, it can be useful to find others in similar situations who can provide support, share leads, strategies for staying positive, help you hone your elevator pitch, and more. Virtual community for Members in Transition on SPE Connect [member login required] Find a job seekers group through your local section, faith-based groups, alumni groups, or others from your company who may also have been laid off. Regardless of where you are professionally, whether you are a senior executive, a technology expert, or a college graduate seeking your first professional job, being unemployed is stressful. Acknowledge that, and adopt sound strategies to overcome the challenges.
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
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