US 2004/0200615 A1 · Apparatus and method for enhancing productivity of natural gas wells

Abstract

A natural gas production system prevents liquid accumulation in the wellbore and minimizes friction loading in the wellbore by maintaining production gas velocity above a critical minimum velocity. A pressurized gas is injected into the well to supplement the flow of production gas such that the velocity of the total gas flow up the well exceeds the critical velocity. A choke is fitted to the gas injection line, and total gas flows are measured by a flow meter. A flow controller compares the measured total gas flow rate against the critical flow rate, and determines a minimum gas injection rate required to maintain the total gas flow rate at or above the critical flow rate. The flow controller then adjusts the choke to achieve the desired gas injection rate. The injection gas may be recirculated production gas from the well, or a gas from a separate source.

Claims45

Dependent claims

A method of producing natural gas from a well extending from ground surface into a subsurface production zone within a production formation, wherein:

(a) the wellbore is lined with a casing, said casing having perforations in the production zone;
(b) a tubing string extends through the casing and terminates adjacent to the production zone above the bottom of the wellbore;
and
(c) said casing defines an annulus between the tubing and the casing, the bottoms of said annulus and casing being in fluid communication with the well bore;
said method comprising the steps of:
(d) determining a minimum total gas flow rate for the well;
(e) injecting a pressurized injection gas into an injection chamber selected from the annulus and tubing, so as to induce flow of a gas stream up a production chamber selected from the annulus and the tubing, said production chamber not being the injection chamber, said gas stream comprising a mixture of the injection gas and production gas entering the wellbore from the formation through the casing perforations;
(f) measuring the actual total gas flow rate in the production chamber;
(g) comparing the measured total gas flow rate to the minimum total flow rate;
(h) determining the minimum gas injection rate required to maintain the total flow rate at or above the minimum total flow rate, according to whether and by how much the measured total flow rate exceeds the minimum total flow rate;
and
(i) adjusting the gas injection rate to a rate not less than the minimum gas injection rate.

9 more elements

An apparatus for producing natural gas from a well extending from ground surface into a subsurface production zone within a production formation, wherein:

(a) the wellbore is lined with a casing, said casing having perforations in the production zone;
(b) a tubing string extends through the casing and terminates adjacent to the production zone above the bottom of the wellbore;
(c) said casing defines an annulus between the tubing and the casing, the bottoms of said annulus and casing being in fluid communication with the well bore;
and
(d) a gas production pipeline is connected in fluid communication with the upper end of a production chamber selected from the tubing and the annulus;
said apparatus comprising:
(e) a gas injection pipeline having a first end connected in fluid communication with a source of pressurized injection gas, and a second end connected in fluid communication with an injection chamber selected from the tubing and the annulus, said injection chamber not being the production chamber;
and
(f) a choke associated with the injection pipeline, for regulating the flow of gas in the injection pipeline.

6 more elements

An apparatus for use in producing natural gas from a well extending from ground surface into a subsurface production zone within a production formation, wherein:

(a) the wellbore is lined with a casing, said casing having perforations in the production zone;
(b) a tubing string extends through the casing and terminates adjacent to the production zone above the bottom of the wellbore;
and
(c) said casing defines an annulus between the tubing and the casing, the bottoms of said annulus and casing being in fluid communication with the well bore;
said apparatus comprising:
(d) a gas compressor having a suction manifold and a discharge manifold;
(e) an upstream gas production pipeline having a first end connected in fluid communication with the upper end of a production chamber selected from the tubing and the annulus, and a second end connected in fluid communication with the suction manifold of the compressor;
(f) a downstream gas production pipeline having a first end connected in fluid communication with the discharge manifold;
(g) an auxiliary pipeline having a first end connected in fluid communication with the production pipeline at a point upstream of the compressor, and a second end connected in fluid communication with the production pipeline at a point downstream of the compressor;
(h) a gas injection pipeline having a first end connected in fluid communication with the auxiliary pipeline, and a second end connected in fluid communication with an injection chamber selected from the tubing and the annulus, said injection chamber not being the production chamber;
(i) a choke mounted in the injection pipeline, for regulating the flow of gas in the injection pipeline;
(j) a first flow valve mounted in the auxiliary pipeline between the point where the auxiliary pipeline connects with the production pipeline upstream of the compressor and the point where the injection pipeline connects with the auxiliary pipeline;
and
(k) a second flow valve mounted in the auxiliary pipeline between the point where the auxiliary pipeline connects with the production pipeline downstream of the compressor and the point where the injection pipeline connects with the auxiliary pipeline.

11 more elements

Dependencies are inferred from the claim text.

Apparatus and method for enhancing productivity of natural gas wells

Life of this patent

Apparatus and method for enhancing productivity of natural gas wells

Life of this patent

Abstract

Claims45