The gas hydrate environments are hostile and pose a challenging condition when drilling through the formation bearing it. As a result of environmental concern and global warming, drilling companies preferably use water based mud in deepwater drilling of methane hydrate. The drilling mud being pumped through the drill string needs to be carefully weighed, balanced and monitored in order to prevent sudden upset of the hydrate stability. While drilling through the me- thane hydrate zone, the drilling tools could possibly upset the methane hydrate bearing formation which can lead to gases being released to the surface unex- pectedly which will pose greater danger. A prevailing hazard using this type of drilling mud is the formation of methane hydrate at the condition such as high pressure and low temperature. This can lead to a gas kick which can cause prob- lems associated with well control and safety. Gashydrates can form a blockage in the drilling conduit and cause flowassurance problems. Since gashydrates con- tain mostly water, the water based mud could lose its water to hydrate forma- tion. This increases the fluid weight and formation of slugs.
Gas hydrate has a practical problem of flowassurance which obstruct the transportation of methane gases in pipeline, forming whit- ish solids at a particular temperature and pressure. This problem is particularly serious because without proper management, trans- portation of this energy source will be made futile. The transportation methods have caused major concern for the usage of gas hy- drates as a result of its diminishing densities which arises from an increasing volume of methane in a little amount of gashydrates. The dissociation of gas hydrate at the sea floor releases some escape gases which affects sediment bodies and death to aquatic and marine lives. The impacts on gas hydrate commercial productions on our ecological system needs to be closely studied in order to come up with efficient and sustainable production processes before proceeding to exploit this energy source. Figure 6 shows various problem relating to gas hydrate recovery.
Flowassurance can be defined as an operation that provides a reliable and controlled flow of fluids from the reservoir to the sales point. Flowassurance operation deals with formation, depositions and blockages of gashydrates, paraffin, asphaltenes, and scales that can reduce flow efficiency of oil and gas pipelines. Due to significant technical difficulties and challenges, providing safe and efficient flowassurance needs interdisciplinary focus on the issue and joined efforts of scientists, engineers and operation engineers (Guo et al. , 2005).
Flowassurance studies play a significant role in the identification, quantification, prevention/mitigation of severe fluid flow issues in oil production/transportation systems in the offshore oil and gas industry. Flowassurance is a major technical challenge which results due to the appearance of wax and formation of hydrates at temperatures below the wax appearance temperature and hydrate formation temperature in flowlines, respectively. In some cases, asphaltene precipitate are formed in heavy crude oil and deposited on the pipe wall, thus restricting the flow. Flowassurance techniques are designed to optimize oil recovery and enhance oil production from wells over the full range of the oil field's life. It is a key factor in the developmental planning of any exploration site (Esaklul et al. 2003). Several techniques are available for flowassurance in the oil and gas industries which include chemical inhibitors, thermal management and thermo-chemical management. The chemical inhibitors may be in the form of hydrate inhibitors employed in the control of hydrate formation or pour-point-depressants used for wax deposition control. For long flowlines, the economics and viability of chemical inhibitors becomes questionable (Thant and Maung, 2012), (Thant et al. 2011). The use of chemical inhibitors alone has been reported by PETROBRAS to be of unfavorable in terms of cost-benefit (Rocha et al. 2009), (Cardoso et al. 2003), (Marques et al. 2003), (Minami et al. 1999), (Khalil et al. 1994). Thermal management is an alternative solution to chemical injection in the management of hydrate formation and wax appearance. Thermal management is a technique of heat containment in a flowline to control the temperature of the flowing hydrocarbons. Thermal management system comprises of thermal insulation and active heating. Thermal insulation uses materials with relatively low thermal conductivity to reduce heat loss from flowing hydrocarbon to the surrounding while active
Nowadays, the application of advanced technologies in modern production systems is the main trend of develop- ment and technological progress in many industrial sectors. It is due to the still growing trends of energy-saving and production quality enhancement. Wherever in the production process, the phase mixture is transported and it is not optimal or not economical, there is a need to develop a system which would be able to prevent any con- struction disaster, unexpected production line stopping or situation where for reasons of bad flow parameters, the final product is defective. This paper studies various sensors, measurement techniques and computer methods for signal processing and analysis to diagnose and control two-phase flows. Due to the possibility that the invasive measurement disturbs the process and changes it parameters and behaviour especially in the location just after the measurement point and simultaneously does not provide any information about these changes it is unreliable for the diagnosis or control. Therefore, the non-invasive techniques commonly used for measurement of flows parameters are described. Depending on the industrial demands, many applications examples for non-invasive two-phase flows measurement and monitoring are given. This description for identifying the flow parameters is divided into features categories of this phenomenon as void fraction distribution, velocity profile and flow regime. However, from these methods the high accuracy and short processing time are expected. The continued observa- tion and monitoring of the process deliver knowledge about the dynamic states of the flow to control it more effi- ciently. Therefore, the development of advanced process control is one of the most important challenges to keep the flow regime on the given level and for instant and long-term energy saving, quality improvement.
Transportation of petroleum products through pipeline presents considerable risks including wax formation and deposition as a result of heat loss of fluids, which is harmful to the flow due to the reduced inner diameter or totally blocked pipelines in extreme cases. The production interruption due to blocked pipelines can cause colossal financial loss. Therefore, in order to di- minish those adverse effects, it is critical that pipeline design for flow assur- ance should be considered. Flowassurance is a relatively new field in oil and gas industry, it means that the flow of hydrocarbon stream from one point to another must be ensured successfully and economically. Although flow as- surance is extremely diverse, encompassing many discrete and specialized subjects and bridging across the full gamut of engineering disciplines, our work concentrated principally on the study of wax deposit in the pipelines. The main purpose of this paper is to focus on the aspect of material in pipe- line design and the selection of thermal insulation coatings. Furthermore, op- erating parameters such as pressure, temperature and flowrate will be ex- amined to achieve optimum results. For the case study in this paper, the pipe- line connecting Ca NguVang Oilfield’s Wellhead Platform (WHP) to the Central Processing Platform of Bach Ho Oilfield (CPP-3) in Vietnam will be studied. Hence, this work covers several aspects, namely the theoretical study, the modeling using Excel as well as using specialized software OLGA, and fi- nally the application for a real case in the petroleum industry in Vietnam.
v ′ = − are the fluctuations of the streamwise and cross-stream velocities of the continuous phase. The turbulent intensity values in the two directions are not the same, meaning that the flow is not isotropic, although in some cases it is close to it. There is a tendency towards a higher degree of isotropicity at the higher void fraction and further downstream from the grid. This could be due to a more uniform cross-stream bubble distribution. The small bubbles in the flow system may have a role similar to that of the grid in creating uniform turbulence in the continuous phase, which is often associated with isotropicity. There is a stronger tendency towards non-isotropicity closer to the grid, which is more clearly seen for the low gas void fraction, which could be because of the unusual flow pattern occurring as the bubbles break through the second grid. The decay of turbulence with increasing distance from the grid (x/M) at the centre of the test section is shown in Figure 6 for both chosen void fractions. The turbulence in the direction of flow is slightly higher than that in the cross-stream direction. Before trying to explain these results it must be mentioned that all these data are based on 1000 images, and that they represent converged mean values according to the frame number graph given in Figure 9. In our previous paper (Moghaddas et al. ) it was suggested that a vortex be created behind the tracer injection nozzle, which had a frequency influenced by the interaction of the movements of the bubbles. The results presented above give some additional views on the flow characteristics. The observations
Previously, different studies had been carried out to study the multi-phase characteristics, including that of Descamps et al. (2007), where they performed a multi-phase flow (oil-water and air) experiment in a vertical pipe using optical fibre probes. The main aim of this study was to investigate the phase inversion phenomenon region. This phenomenon occurs when the continuous phase changes to a dispersed phase and vice versa. The authors mentioned that the pressure gradient and pressure increase when they reach the phase inversion region and observed that the dispersed phase (oil and water) had a major effect on bubble size. In addition, the authors reported that the gasflow rate has a significant effect on the distribution of oil and water phases in the cross-section of the vertical pipe. Despite the fact that this research demonstrated extensive understanding of the multi-phase flow behaviours, the study did not provide enough specific information about bubble shapes using these two-point probes and failed to discover the main cause of inversion phenomena. Their approach was not practically applicable to real oil fields, because putting any tool such as a ring inside the production tubing would create a restriction to the flow from the reservoir to the surface and for wireline unit operations. Therefore, another method should be developed for injecting the gas into the column without causing any restriction to the vertical column.
Measurements were taken on the precalciner in a 2500 t/d cement production line shown in Fig. 1. The experimental system and five monitoring positions are shown in Fig. 2. The solid line shows the gasflow direction while the dashed line shows the production material flow direction. The gases include the flue gas, tertiary gas and coal spreading air. The flue gas from the rotary kiln entered the precalciner bottom inlet, where it mixed with the preheated tertiary air from the grate cooler and the coal spreading air. Pulverized coal particles were sprayed with the coal spreading air into the precalciner. The coal particles were heated by the flue gas and tertiary air mixture before burning. The raw meal was brought into the precalciner on the other side after four preheating stages. The raw meal was further heated by the flue gas and coal combustion to accelerate decomposition before the gaseous and solid reaction products flowed into the fifth preheater. The gas stream then continued to flow into the earlier preheaters to heat the raw meal, while the solids entered the rotary kiln to be calcined to produce cement clinker.
the vehicle. In a naturally aspirated engine, the engine creates a low pressure during the intake stroke, causing the air from the atmosphere to enter the cylinders . The higher the rpm, the greater the pull, and the lower the pressure created inside the cylinder. According to the stoichiometric air-fuel ratio, to burn 1 gram of gasoline 14.7 grams of air is required. By reducing the diameter of the flow path from 50mm to 20mm, the flow cross-section area has reduced drastically . At low rpm’s of the engine when the engine requires less air, the reduction in area is compensated by the accelerated flow of air through the throat (20mm section). But since the car is designed to run at high rpm’s (6,000rpm to 10,000rpm with the restrictor attached), the flow at the throat reaches sonic velocities (also known as Critical Flow condition), and therein lays the problem. Critical Flow exists when the mass flow is the maximum possible for the existing upstream conditions, and the average velocity closely approximates the local sonic velocity (speed of sound in air ≈ 330m/s, or Mach 1) . Since the maximum mass flow rate is now a fixed parameter because of the restrictor, the aim is to allow the engine to achieve the maximum mass flow with minimal pull from the engine. In short, the pressure difference between atmosphere and the pressure created in the cylinder should be minimal, so that maximum airflow into the engine at all times.
The separation of Se in a simulated wastewater was first studied using strain NT-I. The Se in the wastewater was suc- cessfully reduced, and a precipitate containing 11–14 mass% Se(0) was obtained. This precipitate is referred to as biosele- nium and the bioselenium is composed of Se(0) and organic compounds originating from the microorganism along with inorganic components such as calcium (Ca), potassium (K), magnesium (Mg), sodium (Na), phosphorus (P) and sulfur (S). When the bioselenium is subjected to oxidizing roasting, it is predicted that the Se vaporizes, being separated as solid SeO 2 from the combustion gas at the low-temperature precip-
This work proposes the separation of Faults diagnosed from Hydrocarbon Gas Data Collected from Dissolved Gas Analysis of Power Transformers over a period of a Decade in the area of Tirunelveli District in South India. The condition of Power Transformers is diagnosed using Fuzzy Set Theory. (FST) Simulations are compared with conventional methods. The computational Efficiency ,Reliability and Success are evaluated and compared. FST is found to be more reliable ,efficient and its success rate is also high.
The long flexible pipe was also seen as a possible way for air to enter the system; it was now under more pressure (a few thousand Pascals) than under normal operation. It was not practical to attempt to seal it, and so a pressurisation test was carried out on it. The pipe was detached from the apparatus and sealed at its open end. A pressure tapping was inserted into the plug. The fan was used to create pressures and the rotameters displayed how much leakage was taking place. The statistics package SPSS fitted a cubic line to this data and this was used to correct the results from the original experiment, reducing the unaccounted for leaks by an average of 33%. When the experiment was repeated with the plastic sheet surrounding the aggregate the unaccounted-for-flow percentage fell to an average value of below 15%.
Para nitro toluene, nitric acid, and hydrogen peroxide has been procured from Sigma Aldrich of laboratory standards. The glass apparatus has been made of 5-liter assembly with the air flow meter column condenser, separate apparatus for making hydrogen peroxide solution, thermometer, and powder funnel is required. REMI RQG- 129/D stirrer has been used to dissolve the phosphorous into nitric acid solutions.
between the two orientations is that horizontal flow patterns are generally not axisymmetric. Because of this the measurement of gas/liquid multiphase flow in horizontal pipes is inherently more difficult than that in vertical pipes due to the flow regimes experienced in the former configuration. Therefore, this study focuses on horizontal gas-liquid flow in pipes. Typical flow regimes obtained in horizontal gas-liquid multiphase flows are stratified flow, wavy stratified flow, slug flow, plug flow, bubble flow and annular flow (Ma, Zheng, Xu, Liu, & Wu, 2001). In the bubble flow regime the bubbles are located near the top of the pipe due to buoyancy effects. Increasing the superficial velocity of the gas will promote the coalescence of the bubbles resulting in plug flow. A further increase in the superficial gas velocity will cause the gas plugs to form a continuous layer of gas above liquid resulting in a smooth interface between the gas and liquid which is termed stratified flow. In this flow regime the gas will move at a higher velocity than the liquid due to the lower viscosity and density of the gas phase. Once again increasing the superficial velocity of the gas will increase the interfacial stress and create wave flow. A further increase in the gasflow rate will result in waves that are able to bridge the top of the pipe and hence produce large slugs of air in the top section of the pipe and this is known as slug flow. At extremely high superficial gas velocities annular flow is achieved whereby a thin liquid film flows along the pipe wall surrounding a centralised core of gas. A further increase in the gasflow rate will result in the formation of spray flow where the liquid phase is distributed as small droplets within the gas phase (Holland & Bragg, 1995).
metal varies from 330 to 537 °C. This type of gas turbine with regeneration can achieve an effi ciency of 40 %, which is much more than the efficiencies of other modern gas turbines with no regeneration. This project was financially supported by RWE - Essen, knowhow about liquid metals was provided by Siemens - Bergisch Gladbach, European Gas Turbines - Essen supplied the modified gas turbine and the Faculty of Mechanical Engineering of Ljubljana performed the computer optimization of the modified compressor for the gas turbine. This package of papers, which had never been pre sented elsewhere, is certainly the most important achievement of the Symposium.