Patent ID: 7954547
Filing Date: 2011-06-07
Classification: E21B

Abstract:
1. A method of dewatering a gas well while allowing for gas production, the gas well comprising: a casing in the well bore for allowing flow of the liquid and gas; a tubing string in the casing for allowing flow of the liquid and gas; measurement devices for determining a rate of liquid influx into the well bore and a tubing critical velocity; a casing control valve moveable between various positions ranging from fully open and fully closed for controlling flow through the casing; a tubing control valve moveable between various positions ranging from fully open and fully closed for controlling flow through the tubing; flow measurement devices for determining the rate of flow through the tubing and the total rate of flow; the method comprising the steps of: a) determining the rate of liquid influx into the well bore; b) determining the critical tubing velocity and comparing the rate of flow through the tubing with the critical tubing velocity; and c) switching a current production phase to an alternate production phase if when the rate of flow through the tubing is above or below a specified velocity range encompassing the critical tubing velocity, or the rate of liquid influx is resulting in liquid build-up in the well bore; wherein step c) further includes determining when slug flow is happening based on comparing an average of flow of a number of discrete times against an overall average of flow and when slug flow is happening: iia) comparing the gas flow rate against a predetermined value Y multiplied by the critical rate and selecting a switching valves phase as the alternate production phase when the comparison shows the gas flow rate to be greater than the predetermined value Y multiplied by the critical rate or selecting a slipstreaming phase as the alternate phase when the comparison shows the gas flow rate to be less than the predetermined value Y multiplied by the critical rate; or when slug flow is not happening: iib) comparing the gas flow rate against a predetermined value Z multiplied by the critical rate and selecting the slipstreaming phase or the casing flow phase as the alternate production phase when the comparison shows the gas flow rate to be greater than the predetermined value Z multiplied by the critical rate; or comparing the gas flow rate against the predetermined value Y multiplied by the critical rate and selecting the switching valves phase as the alternate production phase when the comparison shows the gas flow rate to be greater than the predetermined value Y multiplied by the critical rate or selecting the slipstreaming phase as the alternate production phase when the comparison shows the gas flow rate to be less than the predetermined value Y multiplied by the critical rate.