This article discusses modern methods of operational flow measurement in gas production wells. Analysis of domestic and foreign experience shows that recently there has been a tendency to solve the problem of information support for production based on the creation and implementation of special technical means of individual monitoring of well productivity.
Keywords: measuring system, multiphase flow meter, radioisotope densitometer, production well, flow measurement.
The bulk of oil and gas production in Russia falls on the fields of Western Siberia and the Far North. The effective operation of gas and oil condensate fields and the implementation of the planned volumes of gas, oil and gas condensate production under such conditions largely depend on the mode of the production well.
In the process of developing a field, the parameters of the well change over time, so decisions must be made about switching to other operating modes. Such decisions should be based on reliable, regularly received information on the operation of each well separately. The regularity of obtaining such information, its accumulation and analysis have a direct impact on decision-making on managing the development of deposits and the field as a whole.
Current disadvantages of traditional methods and means of measuring flow are the following:
– flowmeters of variable differential pressure turn out to be inoperative under conditions of multiphase flow of well production, taking into account difficult climatic and geological conditions;
– methods for measuring the productivity of wells used in the fields (in particular, using diaphragm meters for critical flows) are associated with the release of gas into the atmosphere, which worsens the environmental situation, and does not provide operational control of the parameters of the well;
– due to the lack of reliable information about the flow parameters and the failure to take timely measures to change the operating mode of the wells, the design processes for the development of a gas-oil-condensate deposit are violated, the wells are flooded and abrasive impurities are removed.
Therefore the issues associated with the creation of new information-measuring systems for monitoring the main technological parameters of the product flow, which determine the mode of operation of the wells, are very relevant. Information about the flow rate is particularly important.
A number of organizations are working on solving the problems of operational measurement of multiphase flow rates. Among the foreign companies producing multiphase flow meters, the prominent representatives are Agar, Framo Engineering AS, Kongsberg Offshore A.S, A.S Norske Shell and Shell Research. However the measuring systems they produce are focused on operating conditions that differ significantly from the operating conditions of gas condensate fields in the Far North of Russia. Potentially promising development of a gas-liquid flowmeter RGZh-001 NIIIS (N. Novgorod) can be distinguished from domestic ones. But to date, this work has not been brought to wide industrial use .
The company “G ANT-Neftegazavtomatika” (Moscow) produces measuring systems for controlling the parameters of the Potok series wells, which are based on the spectrometric method .
The method allows to obtain information about the composition of multiphase products directly from the characteristics of the flow — pressure fluctuations. Until recently, the Potok series systems were used in oil and low-water gas wells.
Of the domestic developments, the most striking representative is the gas-liquid flow meter RGZh-001, created at the Scientific Research Institute of Measuring Systems (Nizhny Novgorod) in collaboration with GAZPROM. This device is built directly into the pipeline where the medium is located. The following method of component-by-phase determination of phase flow is implemented: simultaneously, the flow rate of the product and the cross-sectional area occupied by various phases (in particular, the liquid phase) are determined.
Agar MPFM is a multi-phase flow meter that measures high gas flows at a range from 0 to 99.5 % of the gas in the stream. The 400 Series extends the dynamic range of Agar flowmeters with a dynamic separator designed to divert the bulk of the free gas to an additional gas bypass, where its flow rate is measured using a vortex flowmeter. This makes it possible to measure flows with a gas content of more than 99 %. The basis is the in-line separation of products using a mini-separator and component-wise determination of phase flow .
PieSha multiphase flow meters (Norway) are designed to measure the flow of oil, gas and water in a vertical section of the pipeline without preliminary preparation by mixing and physical separation into components.
The MPPM 1900 VI measuring system consists of a capacitive sensor, an inductive sensor, a radioisotope densitometer, a variable differential pressure meter such as a Venturi pipe and a computer system. The proportion of oil, gas and water in the stream is determined by measuring the average dielectric constant of a capacitive transducer and the average density of a radioisotope densitometer.
There is also a number of promising developments, such as multi-phase flowmeter FRAMO (Company Framo Engineering AS), measuring system KOS MCF 350 (Kongsberg Offshore AS, AS Norske Shell and Shell Research), which are based either on proprietary flow-forming devices and the original a technique for calculating phases or a flow separation device. However, all of the above systems have a number of significant drawbacks. The measuring systems MPFM 1900 VI (Fluenta), Framo (Framo Engineering AS) include radioisotope density transducers (gamma — density meters) which create maintenance problems and errors that occur when changing such properties of a liquid as sulfur content, etc. In addition importing gamma — density meters into the territory of the Russian Federation is problematic. Systems with no gamma emitters containing separators (in-line) are also unsuitable for use in most production gas wells Russia .
Installation of the systems under consideration, installation is laborious, usually requiring a significant change in the technological piping of the wells. In addition to the above disadvantages, measuring systems also have a high cost.
Thus the methods and means of monitoring the productivity of wells currently used in field conditions are ineffective. They do not meet the current needs of the industry in terms of efficiency and reliability of the information used to control the operation mode of the wells.
Considering the above, the problem of developing new methods for measuring the flow rate of multiphase production of wells and creating information-measuring systems of a new generation on their basis is very relevant for oil and gas industry.
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