Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
1999-11-08
2002-09-03
Shah, Kamini (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S012000
Reexamination Certificate
active
06446014
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to systems and methods for measuring volume and rate of fluid extraction from coal-seam gas wells, and the trending of volume and rate of fluid extraction from coal-seam gas wells by electrical means using differential pressure and metering with time integration. More specifically it relates to a methodology for automatically controlling variable speed submersible pumps in a coal-seam gas well to optimize both the water removal process and gas production from the wells. In addition, it relates to methods of remote trending data acquisition and remote event logging of fluid level, submersible pump speed, and submersible pump torque in a coal-seam gas well, and using the data to control and optimize production from the coal-seam gas well from a remote location.
2. Description of the Related Art
Coal-seam gas wells produce both hydrocarbon gases, primarily methane, and liquids, primarily water, herein referred to in combination as “fluids.” Referring to fry previous invention and claims, as set forth in U.S. Pat. No. 5,983,164, the method and apparatus for measuring and controlling the flow of natural gas from gas wells is taught. However, it neither teaches nor suggests the use of V-cone meters in such systems. In the past, the V-cone meter has been thought to be more suitable for measuring low volume gas of the type found in most coal-seam gas wells.
A typical coal-seam gas well has a low volume of gas production, for example less than 200 MCFD thousand cubic feet of methane gas and 200 Barrels of water per day per gas well. Gas is produced when water is removed from the coal-seam gas well bore. Therefore, removing or pumping out the water from the coal-seam gas well is the key aspect for the production of gas. In deep coal-seam gas wells, say below 7,000 feet, conventional beam-pumps are used to remove water from the coal-seam gas well. In less deep wells, submersible pumps are more practical and economical to use to remove water from the coal-seam gas well.
Coal-seam gas well liquid volume measurement devices are normally comprised of pulse train signal generating components, such as turbine meters with magnetic pick up, or positive displacement systems with a reed switch. The frequencies generated by such liquid volume measurement devices are generally believed to be linearly proportional to the liquid flow rate and volume passing through the meter. Electronic systems are common features of such state of the art liquid measurement system Such electronic systems are capable of counting the frequency generated by such meters, and may include firmware to accumulate or to total the number of pulses, and also to display the current flow rate and/or volume in a specific time interval, say daily, weekly, monthly, lifetime and so on. The electronic systems are also capable of scaling and processing the accumulated pulse data into volume units such as barrels or gallons. It should be further noted that the water produced from a coal-seam bed gas well, after being charcoal filtered or otherwise processed naturally, is suitable for human consumption or for agricultural uses, and is therefore, a valuable marketable product.
However, the state of the art liquid measurement systems only accumulate or provide total liquid volume measurements for a particular flow period, which data is then extrapolated into hourly, daily, weekly or monthly volume. The trending profile of the amount of actual liquid pumped in a given time period is not currently available, nor do the state of the art liquid measurement systems provide either auditable data or analytical trending data for the liquid which is produced
While analytical quality data or characterization in the above measurement systers is not an issue for accounting purposes, analytical quality data and characterization are vital information for control and optimization of a submersible pump used to remove liquid from a coal-seam gas well. In addition, as the water produced from a coal-seam gas well is a marketable product, analytical quality data and characterization can also be used to provides both records and an audit-trail for water custody transfer measurement. The state of the art systems are also capable of remote data acquisition of the accumulated daily, weekly or monthly volume of the water pumped. Instantaneous flow rate information is also available. This is similar to the prior art data acquisition capabilities for gas from gas well measurement systems, in which the state-of-the-art systems provide accounting data only.
In most coal-seam gas wells, submersible pumps with variable speed controllers are used as liquid removal systems. Removal of the liquid from a coal-seam gas well is required for release and recovery of the hydrocarbon gases, such as methane, absorbed in the liquid. However, removing liquid from a coal-seam gas well also lowers the hydrostatic head pressure of the liquid in the well. The state of the art systems do not provide analytical quality data for use in effectively controlling and producing gas and liquid from a coal seam well. With out interface software and systems to communicate with the variable speed controller of the pump, the-state-of-the-art system is incapable of fully automated operation for producing gas and liquid from a coal seam well. Therefore, manual operation and routine site visitation are a current state of the art necessity, and a costly part of a gas and liquid coal seam well operation. In the current state of heart strategic control of the pump run-time, the pump speeds, and the discharged pressure, has not been used to optimize the amount of gas and liquid produced from a coal-seam gas well, or to extend the life of the pump.
It would therefore be desirable to provide a method and system which provides analytical trending data of the liquid production and liquid level trending profile from a coal seam gas well. It would also be desirable to provide such a method and system which provides analytical trending data of the gas from a coal seam gas well. It would be further desirable to provide such a method and system that provides analytical trending data of both the gas and the liquids, i.e. the fluids from a coal seam gas well.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and system which provides analytical trending data of the liquid production and liquid level trending profile of a coal seam gas well.
It is a further object of the present invention to provide such a method and system which also provides analytical trending data of gas from a coal seam gas well.
It is yet an additional object of the present invention to provide such a method and system that provides analytical trending data of both the gas and the liquid, i.e. the fluids, from a coal seam gas well.
Strategic control of submersible pump run-time, pump speeds, and the discharged pressure, will optimize the amount of gas and liquid produced from a coal seam gas well, and extends the life of the pump. To maintain and optimize gas production from a coal-seam gas well, the well must not be pumped dry or the liquid pump turned off when liquid is present in the well bore. Therefore, trending of the fluid level by means of reading the pressures at the bottom of the well and at the surface is critical information to control the pump. However, the pump must be shut-off if the liquid level falls-below a pre-set level and turned on when certain fluid level is allowed to build up. Therefore, the trending characterizations of the liquid and gas flow-rates as well as the fluctuation of the liquid levels with respect to time provide valuable diagnostic as well as auditable measurement data to optimize and control the operation of a coal seam well. The trending methodology creates high resolution trending profiles for liquid flow rates and liquid levels that represent the operating conditions of the submersible pump used as a prime liquid removal system for coal-seam gas wells. In the present invention
Magnolia Donald W.
Shah Kamini
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