Not applicable.
1. Field of the Invention
The present invention relates to oil and natural gas production. More specifically, the invention is a system and method for fracturing within a limited range or within a specifically-desired direction within a hydrocarbon production zone.
2. Description of the Related Art
In hydrocarbon wells, fracturing (or “fracing”) is a technique used by well operators to create and extend fractures from the wellbore into the surrounding formation, thus increasing the surface area for formation fluids to flow into the well. Fracing is typically accomplished by either injecting fluids into the formation at high pressure (hydraulic fracturing) or injecting fluids laced with round granular material (proppant fracturing) into the formation. In either case, the fluids are pumped into the tubing string and into the formation through ports disposed in downhole tools, such as fracing valves.
Some productions zones present particular difficulties due to their thinness. For example, a particular zone may be only ten, fifty or one-hundred feet thick, presenting only a thin layer of formation in which to drill a lateral wellbore. Moreover, fracing vertically past (i.e., either above or below) the production zone can allow the introduction of production impediments into the production zone, such as if, for example, a volume of water is positioned above and within the fracing range of the tool. Fracing past the production zone vertically downward presents the possibility of providing an egress path out of the production zone.
The present invention addresses these and other problems associated with the fracing in relatively thin production zones. The system comprises a swivel sub having a connection radially rotatable relative to the tubing string portion located upwell; at least one ported sleeve positionable downwell of said swivel sub, said at least one ported sleeve defining a flowpath and comprising a ported housing having an outer surface with at least one planar engagement surface and at least one port providing a communication path to the interior of said housing; and an insert moveable within said ported housing between a first position and a second position, wherein in said first position said insert is positioned radially between said at least one port and said flowpath. The system further comprises a centralizer having a outer surface with at least one flute formed therein, said centralizer positionable downwell of said swivel sub.
When used with reference to the figures, unless otherwise specified, the terms “upwell,” “above,” “top,” “upper,” “downwell,” “below,” “bottom,” “lower,” and like terms are used relative to the direction of normal production through the tool and wellbore. Thus, normal production of hydrocarbons results in migration 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. Similarly, during the fracing process, fracing fluids move from the surface in the downwell direction to the portion of the tubing string within the formation.
A lower connection 40 comprises an upper portion 42 and a lower portion 44. The upper portion 42 partially encompasses the lower portion 24 of the top connection 22 and has a plurality of bearing grooves 46 formed in the inner surface 48 thereof. An annular upper end 50 of the lower connection 40 is adjacent to the lower end of the split ring retainer 36. The lower portion 44 extends through a housing sub 52. A housing 54 is positioned around a portion of the top connection 22 and an upper portion of the housing sub 52. Annular bearings 58 are positioned in bearing grooves 60 formed in the interior surface 62 of the housing sub 52.
The interiors of the top connection 22 and lower connection 40 form a longitudinal flowpath through the swivel sub 20. The flowpath is substantially sealed from the surrounding formation by annular seal stack 64 bounded by annular seal spacers 66.
A plurality of balls 56 is positioned in the annular bearing channels formed by placement of the lower connection 40 around the top connection 22, with bearing grooves 30, 46 aligned. As shown in
In the first position, the insert 106 is positioned between the ports 98, 100 to at least substantially prevent fluid flow between the flowpath and the exterior of the ported sleeve 90. Shear screws 108 are positioned through the ported housing 96 and engaged with the insert 106 in a groove 110 formed in the exterior surface 112 of the insert 106.
A middle section 94 of the ported housing 96 has an asymmetrical profile around the longitudinal axis 114 of the flowpath. A ratchet ring 116 is positioned in a ratchet ring groove 118 proximate to the lower end 120 of the insert 106. The exterior surface of the middle portion 94 has opposing engagement surfaces 119.
To shift the insert 106, a shifting device (not shown) is inserted through the string and engages the inside surface 107 of the insert 106. The shifting device is caused to exert force in the downwell direction sufficient to fracture the shear screws 108 and allow the insert 106 to be moved downwell to the second position, in which locking surface 122 of the insert engages with a locking surface 124 in upper end the bottom connection 104 to prevent rotation of the insert 106. In this position, the ratchet ring 116 engages a ratchet section 126 formed in the inner surface 128 of the ported housing 96.
As shown in
As the tubing string 200 is tools are run into the lateral portion of the wellbore, gravity causes the tubing string 200, centralizer 70, and ported sleeve 90 to contact the low side 202 (i.e., bottom) of the wellbore 204. When the centralizer 70 engages with the ground surface, fluted middle section 76 engages the low side of the wellbore and urges rotation of the centralizer 70 and attached tubing, including the ported sleeve 90, in the direction of flutes 78. The swivel sub 20 allows such rotation due to the rotatability of the lower connection 40 relative to the top connection 22, as described with reference to
If an engagement surface 119 is not already positioned against the low side 202 of the wellbore 204, rotation of the ported sleeve 90 will continue until such positioning occurs—that is, the ported sleeve 90 will be rotated along with the centralizer 70 until one of the engagement surfaces 119 substantially contacts the low side of the lateral wellbore 204. The eccentric shaping of the middle section 94 facilitates rotation by causing the center of mass to be misaligned with the flowpath's longitudinal axis.
When an engagement surface 119 of the low-side sleeve 90 contacts the low side 202 of the wellbore 204, frictional engagement of the engagement surface 119 is sufficient to resist the rotational urging caused by the fluted centralizer 70, after which the sleeve 90 and centralizer 70 drag straight within the wellbore as the tubing string 200 is moved further into the lateral 204. In this orientation, which is shown in
Because of the eccentricity, the low-side sleeve 90 may be run with measuring devices on the outside to make it effectively centric so that the eccentricity will not cause the tool to hang up in the well bore.
The present invention is described in terms of preferred embodiment in which a specific system and method are described. Those skilled in the art will recognize that alternative embodiments of such system, and alternative applications of the method, can be used in carrying out the present invention. Other aspects and advantages of the present invention may be obtained from a study of this disclosure and the drawings, along with the appended claims. Moreover, the recited order of the steps of the method described herein is not meant to limit the order in which those steps may be performed.
This original non-provisional application claims benefit of and priority to U.S. Provisional Application Ser. No. 61/381,376, filed Sep. 9, 2010 and entitled “Self-Orienting Fracturing Sleeve and System,” which is incorporated by reference herein.
Number | Date | Country | |
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61381376 | Sep 2010 | US |