Today, I will introduce a national invention authorized patent-a cumulative gas flow meter and collection method. The patent was applied for by China National Petroleum Corporation, PetroChina Coalbed Methane Co., Ltd., China National Petroleum Group Logging Co., Ltd., and China United Coalbed Methane National Engineering Research Center Co., Ltd., and was granted an authorization announcement on February 15, 2017.
Content descriptionThe invention relates to a cumulative gas flow meter and a collection method, belonging to the technical field of coalbed methane well logging and natural gas well logging.
Background of the inventionIn the production process of natural gas and coalbed methane wells, it is sometimes necessary to understand the gas production of each layer underground, that is, to measure the production profile of the gas production well. At present, for wells with large gas production, the gas production of each layer downhole can be calculated by measuring temperature, pressure, water cut, density and turbine flow rate. However, for coalbed methane and natural gas wells with small gas production, this method cannot meet the requirements.
Summary of the inventionIn order to overcome the shortcomings of the prior art, the present invention provides a cumulative gas flow meter and a collection method, which adopts the method of collecting gas to measure gas production, which can be adapted to the logging requirements of low gas production wells.
A cumulative gas flow meter consisting of a circuit board, a motor, a ball screw, a push-pull rod, a piston, a capacitance sensor, and a gas collection tube; the connector is connected with the pressure tube; the circuit board is fixed on the circuit board skeleton, and the circuit board The frame is connected to the joint; the motor is connected to the ball screw, and the ball screw is connected to the push-pull rod; the push-pull rod passes through the joint, and the joint is connected to the pressure cylinder; the push-pull rod is connected to the piston, and the piston is connected to the capacitance sensor; the gas collection cylinder Connect with the connector; the circuit board is fixed on the circuit board frame, the motor is connected with the ball screw, and the ball screw is connected with the piston and the capacitance sensor through the push-pull rod; the circuit board, the circuit board frame, the motor and the ball screw are all installed in the bearing In the cylinder; the motor drives the ball screw and push-pull rod to open or close the piston.
The first seal ring and the second seal ring are installed on the first joint, the third seal ring is installed on the second push-pull rod, the fourth seal ring and the fifth seal ring are installed on the second joint, and the sixth seal ring is installed on the On the push-pull rod, the seventh sealing ring is installed on the insulating seat, the eighth sealing ring is installed on the insulating sleeve, and the ninth sealing ring is installed on the electrode seat; the circuit board is fixed on the circuit board skeleton; the motor is connected with the reducer to reduce speed The lower end of the device is connected to the drive assembly, and the drive assembly is connected to the first joint; the pressure-bearing cylinder passes through the circuit board frame, the motor, the reducer and the drive assembly and is screwed on the first joint, and the upper end of the pressure-bearing cylinder is connected to the joint; A push-pull rod is connected to the second push-pull rod, the first push-pull rod is inserted into the first joint to connect with the drive assembly; the first joint is screwed on the connecting tube, and the second joint is screwed on the connecting tube; the electrode is inserted into the electrode holder, in the electrode Put the electrode locking sleeve, the insulating sleeve and the insulating sleeve into the seat in sequence; the push-pull rod is connected to the electrode seat, the push-pull rod is inserted into the second joint, and the push-pull rod is connected with the second push-pull rod; a centralizing bracket is installed at the lower end of the electrode, and the gas collection tube is screwed on the On the second joint.
The first terminal is connected to the plug on the instrument, that is, the bus, and the second terminal is connected to the instrument housing; the first diode, the tenth resistor, the eleventh resistor, the twelfth resistor, the thirteenth resistor, the fourteenth resistor, The fifteenth resistor, the first voltage stabilizer, the second voltage stabilizer, the eighth capacitor, the ninth capacitor, the first triode, and the second triode form a voltage stabilizer circuit; the seventeenth resistor and the third stabilizer The pressure tube generates a voltage of 5V, which is output from the fifth terminal for the communication board.
When power is supplied to the instrument, under the control of the circuit, the motor can rotate forward or reverse, and the piston can be closed or opened under the action of the ball screw; when the flowmeter is in a well producing gas and water at the same time and the piston is turned from open When closed, because the specific gravity of the gas is smaller than that of water, it will form a gas accumulation under the piston; as time increases, the gas-water interface will gradually move downwards, and finally the gas will fill the entire gas collection tube.
Therefore, the gas production of the entire wellbore can be calculated by recording the time from when the piston is closed until the gas fills the entire gas collection barrel and the length of the gas collection barrel. For wells with relatively small gas production, as long as the waiting time is extended, the gas production can also be accurately measured.
The sensor that measures the position of the gas-water interface in the gas collection tube is a capacitive sensor; when the sensor is in full water, the capacitance is the largest, when the sensor is in full gas, the capacitance is the smallest; when the gas-water interface in the gas collection tube moves from top to bottom , The sensor capacitance will change from large to small; the size of the sensor capacitance reflects the position of the gas-water interface in the gas collection tube; the measuring circuit converts the sensor capacitance into a frequency signal and sends it to the ground instrument; when the piston is turned on, the flowmeter is in the gas collection tube The fluid state of is the same as the fluid state in the wellbore.
The invention has the advantages that: it can accurately measure the gas production of low-yield gas wells; in addition to measuring the gas production, the instrument can also measure the gas holdup rate.
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