The field of the invention is packers and more particularly packers that are set with mechanical compression triggered by pressure applied to a landed plug on the setting mechanism with the plug advancing out of the packer after setting.
Packers are downhole barriers used in a number of applications to isolate portions of a borehole. They can be set with setting tools that create relative axial movement to axially compress a sealing element and associated slips such that those components extend radially to a sealing position with the slips anchoring the set position of the sealing element. The slips are frequently driven out radially on cones or ramps associated with the mandrel body of the packer. The extended or set position for the packer components can also be locked in with body lock rings or snap rings or dogs in grooves to name a few options. If the packer is to be retrieved, the locking mechanism can be defeated, generally with an upward pull on the packer mandrel through a connected tubular string or by way of a release tool run into the packer on a retrieval string. Some packers can also be released with cutting the mandrel to overcome the locking mechanism. The setting tools that create relative movement generally are of the type that hold a grip on the mandrel while pushing down a setting sleeve to ramp out the slips and axially compress the sealing element to increase its diameter so that a seal is obtained. These relative movement setting tools are driven by developed gas pressure such as by a chemical reaction and are released from the packer as part of the setting movement as a result of parting a retainer that allowed the setting tool to properly position the packer in the borehole.
Other packers can be set with tubing pressure acting on differential piston areas or one side of a piston to achieve axial compression of the assembly of slips, cones and sealing elements to obtain the set position. Another type of packer can hold a caged ball such that pressure from above seats the ball and drives a piston to compress the packer components for a set. The problem with these designs is that the bore through the packer is impeded for flow as the caged ball is displaced off its seat while retained in the cage as produced fluid has to flow around the caged ball. Other tools cannot pass the caged ball, precluding intervention beyond the packer. One example of this design is U.S. Pat. No. 6,394,180. Inflatable packers are set with tubing pressure going through a valving system and into an enclosed volume. Usually one end of the inflatable is free to move and rides up closer to the fixed end as the inflatable grows in radial dimension at a center location for the seal. Still other types of packer are set with reaction to well fluids or their temperature. The sealing element can be a swelling material or a shape memory foam for example.
What is needed and provided by the present invention is a way to set a packer quickly while still leaving the drift diameter of the bore through the packer intact. The setting mechanism is equipped to detain an object on which pressure can be developed to create the compressive force needed to set the packer. As the packer sets components of the setting system separate and retract from the mandrel passage allowing the object to pass leaving the drift dimension intact for operations through the packer. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined form the appended claims.
A packer setting mechanism has a series of fingers with tabs protruding into the mandrel bore. An object such as a plug is landed on the protruding tabs and pressure is applied. The fingers extend from a ring whose movement triggers the packer to set by driving out slips on cones and compressing a sealing element. When the packer set, tensile stress builds in the fingers and a reduced dimension location on the fingers just above the tabs parts in tension. The plug drives the fingers outwardly by pushing them along a ramp against an opposing spring force. The plug clears the tabs as the tabs are driven outwardly on respective ramps such that the tabs are precluded to enter the bore as the plug clears. The drift dimension in the mandrel is preserved when the plug clears.
The setting sleeve assembly 10 is slidably mounted over the mandrel 12 such that spaced fingers 14 each having tabs 16 that extend radially into bore 18 of mandrel 12. A pair of wings 20 and 22 straddle longitudinal openings 24 to allow the tabs 16 to extend into bore 18 to serve as support for a setting object such as a plug 26 as shown in
It should be noted that the plug 26 does not need to seal in bore 18 but simply to allow pressure to build behind it to move the assembly 10. The plug can be cylindrical or spherical or other shapes. Once the parted segments run past the ramp they are prevented from going in the reverse direction by the band spring 40 or equivalent designs such as a snap ring, a wedging action, a ratchet locking mechanism or the like. The tabs that supported the plug are retracted far enough to get out of the main mandrel bore so as not to reduce its drift diameter. Although four collet fingers are shown additional or fewer fingers can be used. While the wings 20 and 22 of adjacent fingers are shown spaced apart they can be adjacent to provide nearly continuous support for the band spring 40. The location for the break in the fingers in tension can be accomplished with a reduction in width or thickness or both or by drilling holes or providing a score that extends transversely.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below: