Granted Patent B2

US 7,861,785 · App. 11/851,536 · Granted Jan 4, 2011

Abstract

Claims (39)

1. A downhole tool for subsurface fracturing, comprising:

two or more propellant assemblies connected in series, each assembly comprising:

a first tubular member having an annulus formed therethrough;

a second tubular member at least partially disposed within the annulus of the first tubular member;

one or more tubular propellants housed within the first tubular member, between an inner diameter of the first tubular member and an outer diameter of the second tubular member;

one or more detonating cords housed within the second tubular member, wherein the second tubular member has one or more portions thereof having a reduced wall thickness, wherein the first and second tubular members are substantially concentric to one another; and

a first end connector and a second end connector disposed at opposite ends of the first tubular member, wherein the second tubular member has threaded ends adapted to threadably engage the first and second end connectors;

a male coupler having a first side and a second side that is adapted to be received into the first end connector of one of the two or more propellant assemblies;

a female coupler having a first side and a second side that is adapted to receive the second end connector of one of the two or more propellant assemblies; and

a transfer sub housing disposed between the two or more propellant assemblies, the transfer sub housing having first and second ends, wherein the first sides of the male and female couplers are adapted to be received into either of the first and second ends of the transfer sub housing.

2. The tool of claim 1 , further comprising a perforating gun connected to the two or more propellant assemblies.

3. The tool of claim 1 , wherein the tool is adapted to be lowered into a wellbore on a wireline, production tubing, coiled tubing, or any combination thereof.

4. The tool of claim 1 , wherein the first end connector of a first propellant assembly is adapted to engage or connect to the second end connector of a second propellant assembly to stack the first and second propellant assemblies in series.

5. The tool of claim 1 , wherein the second tubular member has a reduced wall thickness along an entire length thereof.

6. The tool of claim 1 , wherein the portions having a reduced wall thickness are spaced longitudinally about the second tubular member.

7. The tool of claim 1 , wherein the portions having a reduced wall thickness are spaced radially about the second tubular member.

8. The tool of claim 1 , wherein the portions having a reduced wall thickness are spaced radially and longitudinally about the second tubular member.

9. The tool of claim 1 , wherein the one or more tubular propellants comprises bauxite.

10. The tool of claim 9 , wherein the propellant comprises from about 5 wt % to about 50 wt % of bauxite.

11. The tool of claim 1 , wherein at least one of the first and second end connectors of at least one of the first and second propellant assemblies defines a substantially unobstructed opening that is communicable between the second tubular member and a bore of the transfer sub housing.

12. The tool of claim 1 , further comprising a third tubular member disposed about the first tubular member, wherein the third tubular member comprises one or more openings formed therethrough.

13. A method for fracturing subsurface formations, comprising:

igniting a plurality of propellant assemblies of a downhole tool within a wellbore, each propellant assembly comprising:

a first tubular member having an annulus fanned therethrough;

a second tubular member at least partially disposed within the annulus of the first tubular member;

one or more tubular propellants housed within the first tubular member, between an inner diameter of the first tubular member and an outer diameter of the second tubular member;

one or more detonating cords housed within the second tubular member, wherein the second tubular member has one or more portions thereof having a reduced wall thickness, wherein the first and second tubular members are substantially concentric to one another;

a first end connector and a second end connector disposed at opposite ends of the first tubular member, wherein the second tubular member has threaded ends adapted to threadably engage the first and second end connectors;

wherein the downhole tool further comprises:

a male coupler having a first side and a second side that is adapted to be received into the first end connector of one of the two or more propellant assemblies;

a female coupler having a first side and a second side that is adapted to receive the second end connector of one of the two or more propellant assemblies; and

a transfer sub housing disposed between the two or more propellant assemblies, the transfer sub housing having first and second ends, wherein the first sides of the male and female couplers are adapted to be received into either of the first and second ends of the transfer sub housing,

wherein igniting each propellant assembly comprises:

igniting the one or more detonating cords;

separating the one or more portions of the second tubular member having a reduced wall thickness;

burning the one or more tubular propellants to produce high pressure gas pulses; and

fracturing the subsurface formations with the high pressure gas.

14. The method of claim 13 , wherein the one or more tubular propellants comprises bauxite.

15. The method of claim 13 , wherein each propellant assembly further comprises a third tubular member disposed about the first tubular member, wherein the third tubular member comprises one or more openings formed therethrough.

Assignments (10)