Patent Application
20190010771
The field of the invention is flexible supports from a mandrel for borehole use and more particularly packers or centralizers, for example, where the flexible support assembly conforms to irregular borehole shapes for direct or indirect contact with the borehole.
There are many applications where zones in a borehole need isolation from each other in an annular space between a tubular string and the borehole wall. The borehole wall can be the formation and is referred to as open hole or there can be one or more casing strings attached in series in the case of a cased hole. Apart from the structure and shape of the borehole wall there are a large number of designs for annular barriers that need to span the gap between a tubular string in the borehole and the borehole wall. There are also a broad range of operating conditions that dictate the use of some known designs as opposed to others. In some cases the controlling criteria is pressure differential or/and service temperature. In other cases the percent expansion from the run in to the set dimension for the sealing element is controlling. Some designs use an external sleeve on a mandrel and internally expand the mandrel for high pressure isolation where there may be high temperatures well over 400 F, as shown in US 2003/0042028. Many designs simply axially compress an annularly shaped sealing element and employ embedded stiff rings at the opposed ends to control seal element extrusion as in U.S. Pat. No. 6,102,117. Others specially design the slip assemblies to handle high pressure differentials such as barrel shaped slips shown in U.S. Pat. No. 5,944,102. Yet other designs push a sealing element up a ramp to axially compress it and to bring it to the surrounding borehole wall as in U.S. Pat. No. 8,109,340. Some high expansion designs are shown in U.S. Pat. Nos. 6,827,150 and 6,041,858. Another design provides an extrusion barrier for a sealing element in the form of a slotted ring as in U.S. Pat. No. 8,701,787.
As an alternative to these designs a high pressure and temperature annular barrier is presented with a host of unique features. While actuation starts with an axial force along a mandrel that force moves a plurality of rings closer together. In between the actuation rings are spring discs rotationally locked to a mandrel. The actuation rings have an exterior circumferential projection which catches a sloping segment of an adjacent spring disc to exert a pivoting motion on the sloping portion of the spring disc such that a curled outer segment that is registered with a depression in a surrounding corrugated member results in pushing a respective corrugation radially. Externally the corrugated member has a series of valleys spaced between peaks. Those skilled in the art will not that the internal valleys where curled segments engage also define the spaced external peaks. A sealing material is disposed in the external valleys between the external peaks. The tube shaped corrugated member is design to yield as the sealing material in its outer valleys is pushed to the borehole wall. Because the sloping segment of the spring discs essentially rotates about the outer surface of the mandrel, the exterior valleys of the corrugated member get axially squeezed as the external peaks approach the borehole wall. This effect pushes the sealing material in the external valleys of the corrugated member out toward the borehole wall for enhanced sealing contact. The external peaks of the corrugated member also serve to control seal material extrusion in the axial direction along the length of the seal material as opposed to prior designs that focused extrusion control at ends of sealing elements. The corrugated member can be formed with one or more continuous spirals so that the sealing elements in the external groove can be continuous. Alternatively, the corrugations can be an array of parallel peaks and valleys with each external valley having a discrete seal ring. Optionally a the corrugated member itself can be a sealing element by the manner in which it is built such as with an external resilient coating that can handle the operating temperatures as high as 600 F.
The spring disc can be used by itself or in a stack or an array of separated discs in other applications than a high pressure high temperature packer described herein. These discs with their finger structure and end reinforcing in the form of a loop can be supported on a mandrel alone or in stacks or arrays and when rotationally locked have finger structures extending radially to conform to a surrounding environment, which could be an open hole borehole wall, a cased hole or some intermediate barrier that interacts with an irregular surface such as the packer application described herein or an anchor. The flexible fingers allow for a smaller run in dimension where the sleeve can be retracted to release the fingers to the set position. Alternatively, the discs can be run in relaxed and then actuated with flexing about a rigid base ring to radially extend further for a support or a barrier function using direct or indirect contact with the surrounding borehole. The base ring can be rotationally locked to a common mandrel.
These and other features will be more readily appreciated 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 from the appended claims.
Spring discs are rotationally locked to the mandrel are between pairs of actuation rings that feature a circumferential protrusion. On application of axial force release of a stored force from flexing, the protrusion engages a sloping portion of the spring disc and moves the sloping portion toward a more vertical orientation. Alternatively, a release of a stored force from flexing accomplishes the same result. Slots in the spring disc allow irregular growth to conform to surface irregularities of a surrounding surface. The discs can serve as anchors, centralizers or supports for a sealing element in a packer. Ends of fingers feature stiffeners to enhance strength. The discs can be stacked apart or together and oriented in the same or opposed directions. The can deliver an axial force when stacked and pushed toward flat and released.
Referring to
A series of actuator rings 18 are shown in more detail in
Referring back to
The details of spring discs 34 are best seen in
Referring to
Getting back to the spring disc 34 the tapered segment 42 has spaced slots 62 starting near base ring 40 but on the tapered segment 42 and terminating at the end of loop 44 whether it is open as shown or closed. The slots 62 create a 360 degree array of flexible fingers 64 that have independent movement. This feature comes into play in making the assembly adaptable to respond to a range of borehole sizes due to casing weights, or to borehole wall out of round portions or partial collapse or any other condition that could cause out of roundness in the borehole wall. Of course, in open hole there is a potential for greater out of roundness occurring. However, the preferred use for the described design is in cased hole.
Getting back to
Referring back to the spring disc 34 it has independent use by itself singly or in spaced arrays or in nested stacks. The fact that fingers 64 flex independently allows the spring disc structure to act as an effective tubular centralizer in a borehole as some fingers will more than others to compensate for borehole irregularities. Loop end 44 lends structural rigidity because it forms a stiffer end structure. Loop ends 44 provide a net force on the surrounding structure that is resisted from said base ring 40. In this manner the tapered segment 42 bridges the gap between the mandrel and the surrounding structure to fixate or centralize the mandrel or to move the surrounding structure outwardly as in a packer application or to create an annular obstruction in yet other applications. Making the slots 62 stop short of base ring 40 provides rigidity at an opposite end from loop 44. The shape of spring disc 34 has similarities to Belleville washers and stacks of them can also serve to store and release potential energy. Using the peaks 36 and valleys 38 with a mandrel as described above can keep fingers in a stack of spring disc 34 in alignment so that all the fingers of adjacent spring disc maintain full overlap to avoid binding.
Other applications can be to encase the spring discs in a retractable sleeve for running in at a small dimension and then allowing the tapered segment 42 to flex to conform a surrounding space even if it is irregular due to the independent nature of the flexing fingers 64 when acting alone or if in an abutting stack. The uses can be for anchoring or centralizing involving direct borehole wall contact or indirect borehole wall contact when used in an application such as a packer described above. When used to deliver axial force such as when stacked and flattened and then released to flex to a relaxed position the potential energy that is released can be used to operate a borehole tool with axial movement. Rotational alignment in such an application can be optional as the entirety of the tapered segments 42 flex as a unit rather than individual fingers flexing different amounts to conform to irregular surrounding shapes. Ends 44 can be open loops as shown or closed loops or the material can simply be bent back on itself to constitute a stiffener at the peripheral free end of the tapered segment 42. While in the preferred design the mandrel and base ring 40 are not radially expanded, in some applications the outside diameter can be further extended with mandrel expansion in combination with flexing of the tapered segment 42. The dimensional change in the radial direction is accomplished with flexing of the fingers 64 rather than the circumferential spreading apart of the fingers 64 although slots 62 will get somewhat wider due to their circular array combined with flexing with respect to the base ring 40. A retaining sleeve 80 can pre-flex the fingers 64 for running in and be retracted at the desired location to allow the fingers 64 to flex out to the surrounding surface and take its shape while applying a residual force against the surrounding surface. Instead of loops 44 fingers 64 can simply have thicker ends as a means of end reinforcement. This can be done with folding over the finger ends or simply adding more metal strips to the finger end or just machining the entire assembly with thicker ends. The transition between the base 40 and the tapered segment 42 can be angular as shown or curved.
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 be 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:
