PLUNGER LIFT SYSTEMS AND METHODS

摘要

Methods and systems for increasing the length of time of effectiveness for the plunger lifting liquid load from a gas well, by allowing the plunger to stay ahead of the liquid inflow into the wellbore. The methods and systems involve a plunger control logic which uses measurements of the liquid load pressure, the casing pressure, the line pressure, and the tubing pressure to time the opening and closing of various valves, in order to optimize the lifting of the liquid load to surface.

主权项

1. A method of producing liquid load from a horizontal section of a well having a casing in its vertical section, the horizontal section and the vertical section being connected by a heel, and the well having a plunger lift system installed therein, the plunger lift system comprising:
a tubing string with an upper end and a lower end, and having a plunger slidably movable therebetween, the tubing string and the casing defining a casing string therebetween, the tubing string being in fluid communication with a line via a tubing valve, the tubing string disposed in the vertical section, with its lower end at or near the heel and having an inlet, the tubing string having a tubing pressure and the line having a line pressure, and the casing string being in fluid communication with the line via a casing valve, the casing string having a casing pressure, the method comprising: (a) keeping the tubing valve and the casing valve closed for an initial off time; (b) determining a potential energy pressure at the expiry of the initial off time; (c) opening tubing valve for a pre-set time; (d) comparing a plunger arrival time with a preselected range and: (i) keeping the tubing valve open if the plunger arrival time is within the preselected range; (ii) reducing an after-flow time if the plunger arrival time is above the preselected range; or (iii) increasing the after-flow time if the plunger arrival time is below the preselected range; (e) closing the tubing valve at the expiry of the after-flow time; (f) determining a liquid load pressure; (g) keeping the tubing valve and the casing valve closed for the initial off time; (h) opening the tubing valve partially when the difference between the casing pressure and the line pressure is substantially equal to the potential energy pressure, and keeping the tubing valve open for a pre-set burping time; (i) closing the tubing valve at the expiry of the pre-set burping time; (j) opening the tubing valve when the difference between the casing pressure and the line pressure is substantially equal to the potential energy pressure; and (k) comparing the plunger arrival time with the preselected range and: (i) reducing the pre-set burping time and/or increasing a potential energy pressure time, if the plunger arrival time is above the preselected range; (ii) increasing the liquid load pressure and/or pre-set burping time, if the plunger arrival time is below the preselected range; or (iii) comparing the casing pressure with a flowing clean casing pressure or a lowest recorded casing pressure, if the plunger arrival time is within the preselected range.