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US 7,401,655 B2Granted
Downhole gas compressor
AssigneeBaker Hughes Incorporated
InventorsJoseph E. Vandevier, John L. Bearden
Life of this patent
Estimating the term…
Abstract
A method for producing gas from a well with low pressure involves running a bottom hole pressure test to graph a P-Q curve. The operator computes a frictional pressure drop due to friction of the gas flowing through the production tubing to the surface. A packer is set above perforations in the well. A screw pump is selected that has a capacity equal to the sum of the frictional pressure drop plus a desired wellhead pressure. The screw pump has a flow rate capacity determined from the P-Q curve. The operator may vary the frequency of a downhole motor to achieve the desired wellhead pressure.
Claims17
A method for producing a gas well, comprising:
- (a) selecting a well having a production zone;
- (b) performing a bottom hole pressure versus flow rate test of the production zone while the well is free of a column of liquid above the production zone and graphing a pressure versus flow rate curve by varying a flow area of an orifice through which gas flows from the production zone, measuring a pressure and flow rate of the gas flowing from the production zone at the different flow areas of the orifice;
- (c) computing a frictional pressure drop due to friction of the well fluid flowing through a production tubing from the production zone to the surface;
- (d) selecting a compressor having at a selected speed a design pressure at least equal to a sum of the frictional pressure drop plus a desired wellhead pressure and a design flow rate based on the pressure versus flow rate curve;
- (e) operatively connecting a motor to the compressor, securing the compressor and motor to a string of production tubing, and lowering the motor and the compressor into the well after the pressure versus flow rate curve has been made;
- (f) supplying power to the motor and rotating the compressor at the selected speed, which creates a suction to draw gas from the production zone into the compressor;
- and
- (g) compressing the gas with the compressor and conveying the gas up the production tubing.
5 more elements
A method for producing gas, comprising:
- (a) selecting a well having a gas production zone;
- (b) performing a pressure versus flow rate test of the production zone while the well is free of a column of liquid above the gas production zone and graphing a pressure versus flow rate curve by causing the gas to flow from the production zone through a downhole orifice, varying a flow area of the orifice and recording the pressure and the flow rate of the gas as it flows through the orifice at the different flow areas;
- (c) computing a frictional pressure drop of the gas due to friction of the gas flowing through production tubing from the production zone to the surface;
- (d) selecting a screw pump having a design pressure capability equal to sum of the frictional pressure drop plus a desired wellhead pressure and a flow rate capacity at based on the pressure versus flow rate curve;
- (e) operatively connecting a motor to the screw pump, securing the screw pump and the motor to a string of production tubing, and lowering the motor and the screw pump into the well after the pressure versus flow rate curve has been made;
- (f) supplying power to the motor and rotating the screw pump, the screw pump drawing gas from the production zone, compressing the gas and conveying the gas up the production tubing;
- and
- (g) monitoring the wellhead pressure of the gas flowing up the production tubing and varying the speed of the motor to achieve the desired wellhead pressure.
5 more elements
A gas well, comprising:
- a casing in communication with a gas production zone;
- the well having a pressure versus flow rate curve characteristic based on a bottom hole pressure versus flow rate and made while the casing is free of a column of liquid above the gas production zone;
- a screw pump and downhole electrical motor suspended on a string of tubing in the casing;
- the string of tubing having a computed frictional pressure drop based on the characteristics of the tubing and the gas of the production zone;
- and
- the screw pump having at a selected speed a design pressure equal to a sum of the frictional pressure drop plus a desired wellhead pressure, and a design flow rate determined by the pressure versus flow rate curve characteristic of the well.
3 more elements
Dependencies are inferred from the claim text.