Not applicable.
1. Field of the Invention
The present invention relates to a well stimulation tool for oil and/or gas production. More specifically, the invention is a hydraulically-actuated propellant stimulation downhole tool for use in a hydrocarbon well.
2. Description of the Related Art
In hydrocarbon wells, fracturing (or “fracing”) is a technique used by well operators to create and/or extend a fracture from the wellbore deeper into the surrounding formation, thus increasing the surface area for formation fluids to flow into the well. Fracing may be done by either injecting fluids at high pressure (hydraulic fracturing), injecting fluids laced with round granular material (proppant fracturing), or using explosives to generate a high pressure and high speed gas flow (TNT or PETN up to 1,900,000 psi) and propellant stimulation.
Gas generating propellants have been utilized in lieu of hydraulic fracturing techniques as a more cost effective manner to create and propagate fractures in a subterranean formation. In accordance with conventional propellant stimulation techniques, a propellant is ignited to pressurize the perforated subterranean interval either simultaneous with or after the perforating step so as to propagate fractures therein.
For example, U.S. Pat. No. 5,775,426 (issued Jul. 7, 1998), which is incorporated by reference herein, describes a perforating apparatus wherein a shell of propellant material is positioned to substantially encircle a shaped charge. The propellant material is ignited due to shock, heat, and/or pressure generated from a detonated charge. Upon burning, the propellant material generates gases that clean perforations formed in the formation by detonation of the shaped charge and which extend fluid communication between the formation and the well bore.
A preferred embodiment of the invention having a flowpath therethrough includes a first section having an internal sidewall, an outer sidewall, and at least a portion of a propellant volume within the first section. At least one chamber is disposed in an annular portion between the outer surface of the tool and the flowpath, with a first end of each chamber positioned adjacent to the propellant volume. A detonator assembly is positioned in each chamber proximal to the propellant volume to, when actuated, cause ignition of the propellant. Actuation of the detonator assembly is caused by impact of a primer by a firing pin, which is caused to move by the pressure differential between the flowpath and a portion of the chamber. Ignition of the propellant causes pressure waves to be directed radially away from the tool and into the surrounding formation.
Also according to the preferred embodiment, a plurality of flow ports is disposed through the exterior surface to provide for fluid flow into and out of the flowpath. A moveable sleeve assembly operates to prevent and permit fluid flow through the flow ports, depending on its position. In a first position, an insert sleeve substantially prevents fluid flow through the flow ports, while in a second position fluid flow is substantially permitted. The moveable sleeve assembly also prevents or allows pressure communication between the flowpath and each chamber to cause application of a hydraulic force to the firing pin.
When used with reference to the figures, unless otherwise specified, the terms “upwell,” “above,” “top,” “downwell,” “below,” and “bottom,” and like terms are used relative to the direction of normal production through the tool and wellbore. Thus, normal production of hydrocarbons migrates through the wellbore and production string from the downwell to upwell direction without regard to whether the tubing string is disposed in a vertical wellbore, a horizontal wellbore, or some combination of both. In the figures, the arrow depicting flowpath 30 is pointing in the “downwell” direction (i.e., opposite the normal direction of fluid flow in the tool during production).
The ported sleeve 26 has a plurality of circular pressure ports 40 spaced equally radially around the outer sidewall 28, and is attached to the top connection 32 with a plurality of low head cap screws 42. The bottom end of the ported sleeve 26 is attached to the upper end of the middle sub 34 with a series of interlaced tabs 44 positioned in slots 45 disposed in the outer surface of the middle sub 34.
A second section 48 of the tool includes a plurality of oblong flow ports 50 that define a fluid communication path between the flowpath 30 and the exterior of the tool. The flow ports 50 are equally spaced around, and disposed through, the cylindrical ported housing 36, which has an upper end connected to the lower end of the middle sub 34 with a plurality of circumferentially-aligned grub screws 52, and a lower end threadedly attached to the bottom connection 38. Sealing rings 60 are positioned throughout the embodiment to prevent undesired fluid communication between the various elements, except through the flowpath 30 and through the plurality of flow ports 50.
A cylindrical pressure chamber 54 is disposed longitudinally through a annular portion 56 of the middle sub 34. A detonator assembly 58 and firing pin 90 are located within the pressure chamber 54, with the detonator assembly 58 located proximal to the upper end of the pressure chamber 54.
The middle sub 34 and ported housing 36 enclose a moveable sleeve assembly 62 having an attached ball seat 64 for selectively allowing communication through the flow ports 50 to the surrounding formation, as will be described infra. The sleeve assembly 62 is anchored in a first position by a plurality of circumferentially-aligned shear pins 66.
A lower section of the piston sleeve 68 has a larger interior diameter than an upper section. In the first position, the upper end of the insert sleeve 70 initially abuts the shoulder 78 defining the top end of the second portion, and is coupled thereto with a circumferentially-positioned expandable piston locking key 80. The insert sleeve 70 is initially secured to the ported housing 36 with shear screws 66. Upper and lower sealing rings 84, 86 are circumferentially disposed around the insert sleeve 70 to isolate the flow ports 50 from the flowpath 30, thus substantially preventing communication between the flowpath 30 and the exterior of the tool.
The detonator assembly includes a primer 92, primer case 94, shaped charge 96, and an isolation bulkhead 98. The primer 92 is spaced above the firing pin 90 within the primer case 94. The shaped charge 96 is positioned above and adjacent to the primer case 94. The isolation bulkhead 98 is positioned adjacent the shaped charge 94 and proximal to the propellant volume 46. In this position, detonation of the shaped charge will cause corresponding ignition of the propellant volume 46.
After shearing the pins 66, increased fluid pressure within the flowpath 30 causes the insert sleeve 70 and piston sleeve 68 to move downwell until the lower section of the piston sleeve 68 contacts an inner shoulder 82 of the piston housing 36. In this position, the piston locking key 80 expands into an adjacent flanged section 81 and decouples the insert sleeve 70 from the piston sleeve 68. The insert sleeve 70 is thereafter allowed to continue downwell under the flowpath pressure until it contacts the bottom connection 38 (see
Movement the sleeve assembly 62 to the second position causes hydraulic actuation of the firing pin 90 as follows. Engagement of the piston sleeve 68 with the interior shoulder 86 positions an outer groove 110 to allow the firing pin locking key 76 to radially contract thereinto. This contraction causes the firing pin locking key 76 to disengage from the firing pin 90.
As shown in
The present invention is described above in terms of a preferred illustrative embodiment of a specifically described team roping training apparatus. Those skilled in the art will recognize that alternative constructions of such an apparatus can be used in carrying out the present invention. Other aspects, features, and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims.
This application is a continuation application claiming the benefit of the priority date of U.S. application Ser. No. 12/637,255 (now U.S. Pat. No. 8,381,807), filed Dec. 14, 2009, which is incorporated by reference herein.
Number | Date | Country | |
---|---|---|---|
Parent | 12637225 | Dec 2009 | US |
Child | 13777134 | US |