New requirements have recently appeared for accurate and reliable flow rate measurements in various operational areas where viscous fluids are produced. Heavy oil as produced in Venezuela, Confederation of Independent States (CIS), Brazil, Angola and China and lighter oil emulsified with large water cuts (worldwide) present new challenges to multiphase metering. The compact, cost-effective multiphase meter described in this paper is intended to replace large, costly test separators designed for heavy oils. The meter is non-intrusive and combines a classical venturi to measure total mass flow rate and a dual energy gamma-ray composition meter to measure oil, water and gas fractions. A benefit of this compact design is that the meter can be switched from one well to another and provide robust, consistent flow rate measurements without any flow recalibration. According to published single-phase flow literature, liquid viscosity plays an important role in meter performance. Oil companies are becoming increasingly aware of these problems and want more evidence that a multiphase meter will perform regardless of fluid properties. To qualify the multiphase meter in high-viscosity flows, we conducted comprehensive flow loop tests in Venezuela. The challenge was to gain a solid understanding of viscosity effects even in the presence of large amounts of gas, and for the entire operating envelope of the meter. These test results have been used to refine the meter interpretation model to maintain the metering accuracy in these conditions. The interpretation includes a mixture viscosity model based on the dead-oil viscosity; for permanent monitoring and periodic testing, the effluent viscosity variations are updated when pressure, temperature or water cut is changing. To demonstrate that the specified measurement accuracy was achieved up to the highest viscosities tested (several thousand centipoise), the meter was field tested in comparison with a test separator. We present the results of 54 jobs. Until recently, the only multiphase meters available to measure viscous oil flowing with gas were intrusive. Positive displacement meters, such as oval gears, twin helical screws or vane types, were used to measure the total gas-liquid volume flow rate. These meters are very sensitive to severe slugging in the upstream pipeline and prone to mechanical damage from produced solid particles. The lightweight, small-footprint meter described here solves these problems. Consistent flow rate information can be obtained even when the meter is switched from well to well. Fluid property or flow regime changes do not affect the flow rate measurement. Introduction One of the main objectives of multiphase flow meter design is a low-cost system that will accurately measure the flow rates of oil, water and gas in difficult multiphase flow regimes. These include emulsions, high-viscosity oils and foaming conditions for which conventional metering systems based on phase separation have great difficulties or cannot successfully perform the tests. Even during efficient separation conditions in a conventional metering system, there is a significant advantage in continuously monitoring a well stream. Whereas a conventional testing system may take hours for stable measurements, a multiphase flow meter can yield good test results minutes after the well is opened. Elimination of a test separator, manifold and/or flow line is ordinarily the single most important reason for choosing to use a multiphase meter. Test separators and the associated metering equipment are expensive and require additional platform space on offshore topside installations. In satellite fields, a test line back to a test separator on a platform is a significant capital expense. For subsea applications the advantages are even greater as separate test lines and, in some cases, entire platforms, may be eliminated.
Dedicated wet-gas flowmeters are now commercially available for the measurement of gas and liquid flow rates. They offer a more compact measurement solution than the traditional separator approach. The interpretation models of traditional multiphase flowmeters emphasize the liquid rate measurements; they have been used to well test and meter mostly liquid-rich flow streams. These models were not developed for the measurement of gas flow rates, particularly those of wet gas. A new interpretation is described that allows a traditional multiphase flowmeter to operate in a dual mode either as a multiphase meter or as a wet-gas meter in 90% to 100% gas. The new interpretation model was developed for a commercially available multiphase flowmeter consisting of a venturi and a dual-energy composition meter. This combination results in excellent predictions of the gas flow rate, and in addition, liquid rate and water-cut predictions are made with an acceptable accuracy with no additional measurements. The wet-gas and low-liquid-volume-fraction interpretation model is described together with the multiphase flow meter. Examples are presented of applying this model to data collected on flow loops, with comparison to reference flow rates. The data from the Sintef and NEL flow loops show an error, better than ± 2% reading for the gas flow rate, at line conditions; the absolute error in the measured total liquid flow rate at line conditions of was better than ± 2 m3/h (< ± 300 bpd). This new interpretation model offers a significant advance in the metering of wet-gas multiphase flows and yields the possibility of high accuracies to meet the needs of gas-well testing and production allocation applications without the use of separators. Introduction There has been considerable focus in recent years on the development of new flow measurement techniques for application to surface well testing and flow measurement allocation in multiphase conditions without separating the phases. This has resulted in new technology from the industry for both gas and oil production. Today, there are wet-gas flow meters, dedicated to the metering of wet-gas flows, and multiphase meters, for the metering of multiphase liquid flows. The common approach to wet-gas measurement relates gas and liquid flows to a "pseudo-gas flow rate" calculated from the standard equations. This approach addresses the need for gas measurement in the presence of liquids and can be applied to a limit of liquid flow (or gas volume fraction, GVF), though the accuracy of this approach decreases with decreasing GVF. The accurate determination of liquid rates by wet-gas meters, however, is restricted in range. The application and performance of multiphase meters has been well documented through technical papers and industry forums, and after several years of development is maturing.1 Some multiphase measurement techniques can perform better, and the meters provide a more compact solution, than the traditional separation approach. It is not surprising that the use of multiphase flowmeters has grown significantly, the worldwide population doubling in little over a 2-year period.2 Multiphase flowmeter interpretation emphasizes the liquid rate measurement. The application of multiphase flowmeters has been predominantly for liquid-rich flow stream allocation and well testing. Of these two approaches, neither has been optimized for the measurement of gas and liquid flow rates across the range of GVF typical for wet-gas production, prompting the need for further development in wet-gas flow measurement. Furthermore, the benefits of multiphase flow measurement are now being sought for gas wells. To address the need for a broad solution to wet-gas flow measurement, a new interpretation model has been developed using the hardware platform of a commercially available dual-energy-venturi multiphase flowmeter. This model has been used for excellent predictions of the gas flow rate across the full range of GVF, from 90% to 100%. In addition, liquid rate and water-cut predictions are achieved to an acceptable accuracy with no additional measurements.
Intravenous regional anesthesia has gained increased popularity and considerable discussion has been provoked by differing methods of administration and various explanations of action. This is probably why a purely descriptive term like "intravenous regional", has found popular acceptance. Attempts to classify in the spaces provided on the usual anesthesia record are unrewarding since it may be considered a local, intravenous, or regional block technique.Discussion of the site of action is rendered more difficult because, in addition to multiple techniques in use, their exact method of employment and emphasis varies from author to author. Exsanguination, ischemia and venous perfusion with a local anaesthetic agent are invariably recommended to some extent. Lidocaine without epinephrine, the most widely used agent, is a local anesthetic of rapid onset. To a certain extent one may separate the effects of various factors on a temporal basis. Events observed early in the block will be mainly due to the local anesthetic agent, while as time passes effects of ischemia and acidosis will be superimposed. The phenomenon of intravenous regional anesthesia is immediate and, therefore, observations made early after exsanguination and the prompt administration of the local agent are apt to be more significant of the mode of action. The clinical technique we have most frequently used, however, is is that previously reported' and does not differ significantly from the modification of BIER^ described by HOLMES~.It would seem appropriate to discuss the distribution of drugs achieved by this route of adminiitration because this is intimately connected with any theory concerning the site of action. Curare is a suitable drug with which to examine distribution, since its action is localized to one site and its effects are easy to demonstrate. Accordingly, Dr. Jerome Modell, of the University of Miami, and I undertook experiments injecting dilute d-tuboctmarineinto the isolated limb. The dosage was of the order of 3 mgm in 4Occ of saline. Profound neuromuscular block developed rapidly and lasted until the tourniquet was released. With the injection of a sufficient volume, therefore, a small dose
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