Method for producing hydrocarbon gas from a wellbore and valve assembly

摘要

The present invention provides a method for producing hydrocarbon gas from a wellbore and a control valve assembly for said wellbore. The wellbore comprises a wellhead, a production zone, a production tubing, and a velocity string installed inside the production tubing. The method comprises allowing gas to flow from the production zone through the velocity string, said gas forming a primary gas stream, and controlling the flow of gas from the annulus between the outer wall of the velocity string and the inner wall of the production tubing to the primary gas stream by means of the control valve wherein a controlled mass flow of said gas is combined with the primary gas stream.

主权项

1. A method for producing hydrocarbon gas from a wellbore, the wellbore comprising:
a wellhead, a production zone, a production tubing having an inner diameter, the production tubing extending inside the wellbore from the wellhead to the production zone, a velocity string having an outer diameter smaller than the inner diameter of the production tubing, the velocity string being installed inside the production tubing so that an annulus is formed between the outer wall of the velocity string and the inner wall of the production tubing, said annulus being in fluid communication with the production zone, the velocity string extending at least along a part of the production tubing,the method comprising:
allowing gas to flow from the production zone through the velocity string, said gas forming a primary gas stream, controlling the flow of gas from the annulus between the outer wall of the velocity string and the inner wall of the production tubing to the primary gas stream by means of a control valve wherein a controlled mass flow of said gas is combined with the primary gas stream, wherein a control line comprises a first branch and a second branch wherein said first branch is connected to a downhole safety valve which can be controlled between a closed position and an open position, wherein the downhole safety valve is biased to the closed position by means of a spring member, and wherein the second branch is connected to the control valve, wherein the downhole safety valve is urged to the open position, against the bias of the spring member, when the fluid pressure in the first branch is greater than an operating fluid pressure, and wherein the control valve is configured to be controlled between a closed position and an open position by varying the fluid pressure in the second branch within a range between a lower fluid pressure and a higher fluid pressure, wherein the lower fluid pressure of said range is greater than the operating fluid pressure.