Well configuration and method of increasing production from a hydrocarbon well
A well configuration and method of increasing production from a hydrocarbon well having pre-existing production tube. A composite velocity string having an outer diameter smaller than the inner diameter of the production tube is installed in the production tube so that an annular gap is formed between the outer surface of the velocity string and the inner surface of the production tube. Production from the well is increased because the coefficient of fluid flow friction through the composite velocity string, and the amount of heat loss through the composite velocity string, are reduced compared to a steel velocity string. Installation efficiency is also increased because the composite velocity string is much lighter than a steel velocity string.
1. A method of increasing production from a hydrocarbon well having pre-existing production tube extending from the surface to the production zone, comprising the steps of:
a) installing a composite velocity string having an outer diameter smaller than the inner diameter of the production tube so that an annular gap is formed between the outer surface of the velocity string and the inner surface of the production tube;
b) reducing the coefficient of fluid flow friction through the composite velocity string compared to the coefficient of fluid flow friction of a steel velocity string;
c) reducing the amount of heat loss through the composite velocity string compared to the amount of heat loss through a steel velocity string; and
d) reducing radially-inward pressure on the velocity string.
2. The method recited in claim 1 , wherein the composite velocity string is installed by inserting the velocity string along the length of the production tube and hanging the velocity string from the well head using a hanger.
3. The method recited in claim 2 , wherein the velocity string is inserted using an injection tube unit.
4. The method recited in claim 1 , including the step of reducing the amount of rust and scale formation on the interior of the velocity string compared to the amount of rust and scale formation in a steel velocity string.
5. The method recited in claim 1 , including the step of reducing the amount of tar and asphalt that adheres to the interior of the composite velocity string compared to the amount of tar and asphalt that adheres to a steel velocity string.
6. The method recited in claim 1 , including the step of reducing the amount of condensation that forms in the interior of the composite velocity string compared to the amount of condensation that forms in a steel velocity string.
7. The method recited in claim 1 , wherein radially-inward pressure is reduced by isolating the annular gap from the production zone of the well.
8. The method recited in claim 7 , including the step of installing a packer at the bottom of the velocity string to isolate the annular gap.
9. The method recited in claim 1 , wherein said composite velocity string comprises:
a) a continuous, extruded, polymeric tube; and,
b) a layer of reinforcement fibers surrounding the tube including a first plurality of reinforcement fibers that extend both axially and radially, and a second plurality of the fibers that extends only axially.
10. The method recited in claim 9 , wherein said polymeric tube comprises
a multi-layer, extruded, tube, including an interior barrier layer comprising polyphenylene sulfide, an exterior support layer comprising polyamide, and an intermediate layer binding said interior layer and exterior layer to one another.
11. A method of increasing production from a hydrocarbon well having a pre-existing production tube extending from the surface to the production zone, comprising the steps of:
a) providing a composite velocity string having an outer diameter smaller than the inner diameter of the production tube, said velocity string including:
i) a continuous extruded, polymeric tube; and,
ii) a layer of reinforcement fibers surrounding said tube including a first plurality of reinforcement fibers that extend both axially and radially, and a second plurality of the fibers that extend only axially; and,
b) installing the velocity string in the production tube of the well.
12. The method recited in claim 11 , wherein the composite velocity string includes an outer jacket surrounding the reinforcement fibers.
13. The method recited in claim 11 , wherein the polymeric tube and said jacket are formed from a thermoplastic material.
14. The method recited in claim 13 , wherein the thermoplastic material is selected from the group consisting of a polyamide material and a polyphenylene sulfide material.
15. The method recited in claim 13 , wherein the polymeric tube and the jacket are formed from different thermoplastic materials selected from the group consisting of a polyamide material and a polyphenylene sulfide material.
16. The method recited in claim 11 , wherein the first plurality of fibers are cross-braided.
17. The method recited in claim 11 , wherein the tube comprises a multi-layer, extruded, composite tube, including an interior barrier layer comprising polyphenylene sulfide, an exterior support layer comprising polyamide, and an intermediate layer binding said interior layer and exterior layer to one another.
18. The method recited in claim 17 , wherein the interior barrier layer comprises polyphenylene sulfide compounded with an ethylene/glycidyl methacrylate copolymer, the intermediate binding layer comprises ethylene/glycidyl methacrylate copolymer, and the exterior support layer comprises polyamide compounded with an ethylene/glycidyl methacrylate copolymer.
19. The method recited in claim 18 , wherein the barrier layer comprises at least about 70 percent polyphenylene sulfide.
20. The method recited in claim 19 , wherein the barrier layer comprises polyphenylene sulfide compounded with about 10 to about 30 percent ethylene/glycidyl methacrylate copolymer.
21. The method recited in claim 18 , wherein the exterior supporting layer comprises at least about 70 percent polyamide.
22. The method recited in claim 21 , wherein said exterior supporting layer comprises polyamide compounded with about 10 to about 30 percent ethylene/glycidyl methacrylate copolymer.
23. The method recited in claim 11 , including the step of suspending the velocity string in the production tube using a hanger.
24. The method recited in claim 11 , including the step of installing a packer near the bottom of the velocity string.
25. A well configuration, comprising:
a) a subterranean well bore extending downwardly to a production zone of hydrocarbons;
b) a production tube lining the bore;
c) a composite velocity string installed along the length of the production tube down to the production zone, said velocity string comprising:
i) a continuous extruded, polymeric tube; and,
ii) a layer of reinforcement fibers surrounding said tube including a first plurality of reinforcement fibers that extend both axially and radially, and a second plurality of the fibers that extend only axially;
d) a hanger suspending the velocity string in the production tube; and,
e) an insulating annular gap intermediate the outer surface of the velocity string and the inner surface of the production tube.
26. The well configuration recited in claim 25 , including a packer installed near the bottom of the velocity string.
27. The well configuration recited in claim 25 , wherein the polymeric tube comprises
a multi-layer, extruded tube, including an interior barrier layer comprising polyphenylene sulfide, an exterior support layer comprising polyamide, and an intermediate layer binding said interior layer and exterior layer to one another.
28. The well configuration recited in claim 25 , wherein the polymeric tube comprises a single-layer, extruded tube formed from a thermoplastic material selected from the group consisting of a polyamide material and a polyphenylene sulfide material.