Patent Application
20190055808
The field of the invention is swelling packers for borehole use and more particularly where the sealing element is wedged on at least one end to radially compress the sealing element by advancing between a mandrel and the sealing element.
Borehole barriers are deployed for zone isolation for a variety of reasons. These barriers come on many configurations with some of the more popular styles being compression set and swell packers. Compression set packers employ tubing pressure to move a piston to axially compress a sealing element to a set position. There are other actuation modes by axial compression but in essence the sealing element that is an elastomer sleeve has its ends pushed together and the radius increases as a result until contact with a surrounding borehole is made for the set position.
Swell packers grow radially by exposure to well fluids already present, as in U.S. Pat. No. 9,587,459 FIGS. 4A-4B, or added to the borehole or by thermal loading from well temperatures. As a result of the swelling, the diameter of a sealing element grows into contact with the surrounding borehole wall for the set position. Sometimes the sealing element is covered with a sheath that goes away with exposure to well fluids in an effort to delay the onset of swelling until the desired depth is reached, as shown in US 2009/0178800. Typically the swelling element is boded to a supporting mandrel. One issue with such packers is that they take too long to fully set and even when fully swelled still have issues with holding the needed differential pressures.
Several attempts have been made to combine the swelling action with applied forces to ensure the desired performance of the swelling element in the set position. WO2017/058191 FIG. 4 illustrates the use of overlapping leaf structures on an end of a swelling element and an actuator that contacts the element during the set. The tool is in rotational registry with the end leaves on the sealing element. In essence the swelling element is end compressed and allowed to swell. A similar design that uses end compression of a swelling element 250 with a pressure actuated piston 242 powered by tubing pressure is EP 2407632, FIGS. 4A-4D. Another design combines a swell packer with a compression set packer where only the compression set packer is axially compressed, as in FIGS. 7 and 8 of U.S. Pat. No. 8,251,142 and a similar design in US 2012/0012342.
The present design addresses issues with prior designs with an end wedge that cooperates with an extrusion barrier where the wedge has a ramp surface pointing into the sealing element to separate the bond to the underlying mandrel and to add a radial force component to the end of the sealing element to allow the sealing element to come to design resistance to differential pressure sooner. The end wedge also interacts with the extrusion barrier to force the extrusion barrier out radially as the sealing element end is forced out radially making the swell packer almost immediately available for service upon wedge actuation even as the sealing element continues to swell to its final position against the surrounding borehole wall whether in open or cased hole.
A swell packer sealing element has a wedge on either or both ends that is driven axially when the packer is at the desired borehole location. The wedge releases an end bond of the sealing element and forces the end of the sealing element out radially against the surrounding borehole wall. The actuator for the wedge also forces out an extrusion barrier at the same time. The packer achieves the ability to handle the design differential pressure with aid of the end wedge even as portions of the packer sealing element beyond the end are still swelling into contact with the surrounding borehole wall whether in cased or open hole.
Referring to
Wedge 42 has a leading taper 46 which is preferably about 3 degrees but can be a greater or lesser angle that still ensures that end 48 slides between mandrel 12 and end 50 of the sealing element 14 as shown in
While the element 14 will swell when exposed to the swelling stimulus in the known way, the leading taper 46 will break the bond against the mandrel 12 and push end 50 radially outwardly against the borehole wall 44. What this does is provide immediate end isolation capability as end 50 is separated from the mandrel 12 and radially compressed against the borehole 44. This can happen as other parts of sealing element 14 have not fully swelled against the borehole wall 44. The packer is not only ready for the designed pressure differential that much sooner but the radial end force enhances the capability of the packer to resist pressure differential at an earlier time and does not create a leak path along the mandrel 12 if the radial boost force was to be applied along the full length of the sealing element 14. The illustrated arrangement can be present at the taphole end of the packer 10 only if the differential pressure is applied from above or on opposed ends if the differential can be in either of opposed directions.
The packer 10 can be used in well treatment into the formation. The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may he in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.
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:
