Extreme Temperature Retrievable Isolation Packer System

FIELD

The disclosure relates generally to downhole tools. The disclosure relates specifically to isolation packers rated to high temperature geothermal conditions.

BACKGROUND

Geothermal energy is one of the leading renewable sources of environmentally friendly power generation. It involves using the earth's stored thermal energy to super heat water, which can then be used to directly heat homes or generate electricity. Traditionally, geothermal electric plants have been built on the edges of tectonic plates where high temperature geothermal resources are available near the surface. Recent improvements in drilling and extraction technology have enabled the creation of geothermal power plants in areas where the thermal resources lie deep under the surface.

Geothermal projects pose challenges for safety and reliability because of the high pressure and high temperature of wells. These conditions have resulted in geothermal wells costing much more than oil and gas wells of comparable depths. The main challenge relating to geothermal wells is the temperature—which is often twice that of oil and gas wells—posing a serious challenge to the integrity of cement during setting, and therefore also the integrity of the well. Therefore, a zonal isolation and flow control system for an extremely high temperature (up to or even exceeding 400° C.), high differential pressure (up to or even exceeding 10,000 psi) geothermal well is needed. The system needs to be capable of maintaining a high-quality seal for long durations (estimated to be one year or longer), but also be easily retrievable, ideally without the need for additional milling or drilling.

Current packers either do not meet the extreme temperature requirement, cannot survive downhole for at least one year, and/or are not easily retrievable. Examples of the current commercially available packers include all-metal systems and elastomeric packer systems. All-metal systems are not easily deployable. They are either welded in place or covered with cement and are very difficult to retrieve/remove. Elastomeric packer systems can not be rated to high temperatures for the length of time required by geothermal wells.

Various prior art have suggested metal packer. For example, U.S. Pat. Pub. No. 2004/0256115, Vincent et al. Dec. 23, 2004, “Expansion Set Packer With Bias” discloses a packer element has a biasing member, The element is either fabricated with the biasing element in a relaxed condition and then the element is stretched prior to insertion downhole, the release of the element increases its diameter to allow the element to expand. U.S. patent application Ser. No. 17/662,229, filed on May 5, 2022, titled “Extreme Temperature Isolation Packer and Deployment System” by Downhole Emerging Technologies, disclose a metal packer, the contents of which are incorporated by reference in its entirety. The metal isolation packer comprises an inner mandrel, and an expandable sealing element. The expandable sealing element has an outer diameter, the outer diameter in a relaxed state is larger than the outer diameter in a stretched state. A key element of the isolation packer is to “pre-stretch” the isolation packer system. This reduces the outer diameter and allows it to safely fit into the casing and run in the hole. Then, once at depth, the system pre-stretch is released and further compressed to jam it into position and obtain a seal. The isolation packer needs an actuator to stretch the sealing element.

In the case of setting and retracting the above-mentioned isolation packer, a new setting tool with a much higher torque capability (approximately 10×) will be required since current explosive or hydraulic setting tools (e.g., “Baker 20”) are commonly limited to <70,000 pounds of linear force. The new setting tool for above mentioned isolation packer employs at least one gear reducer to trade speed for torque on the output shaft, which increases complexity and cost of the setting tool.

It would be advantageous to provide the industry with a new high-quality packer with low force to stretch, eliminating the need for a custom setting tool. This system will also need to survive the extreme temperatures and high pressure while providing a seal and being capable of being easily retrieved. This device could find expanded use beyond geothermal in other wellbore operations throughout the industry.

BRIEF SUMMARY OF THE INVENTION

In accordance with the teachings of the present invention, an isolation system and method for isolating a specific section of a wellbore are provided that maintain a high-quality seal in high pressure and high temperature of wells.

The main component of this system is an isolation packer comprising a sealing element, a base which the sealing element mounting on, a compress sleeve stretching and compressing the sealing element. It is all metal and is originally manufactured such that the sealing element, in one embodiment, has an outer diameter that is larger than the inner diameter of the wellbore casing that it will seal within. In other embodiments, the outer diameter is less than the inner diameter of the wellbore casing.

The sealing element is a ring-shaped component, the inner diameter of the sealing element slides onto a base of a mandrel, which is in conjunction with the compress sleeve to stretch and relax the sealing element in order to complete the barrier within the well bore and establish a seal. This mandrel also holds other components of the system and provides a surface for the ring to seal against. Additionally, there may be elastomeric seal components and metal rings to enhance the packer's sealing capabilities.

Multiple rings may be stacked to add additional redundant seal surfaces and for additional resistance force that prevents the isolation packer from sliding along the axis of the well bore.

Each of the multiple rings of the sealing element may be hollow and/or have a different wall thickness such that during compression, the multiple rings deform in sequence rather than all at once, which improves the likelihood of achieving a good quality seal and strong holding force.

Each of the multiple rings of the sealing element may have a limiter therein that prevents each ring from being over compressed, which could result in a failure of material integrity beyond elastic and plastic strain (e.g., tears, ruptures, material separation).

The isolation packer system further comprises a setting tool that is connected to the mandrel. This setting tool moves along a longitudinal axis of the mandrel and can both compress and stretch the ring-shaped sealing element through the compression sleeve.

In an embodiment, prior to running in hole, the setting tool is used to pre-stretch the ring-shaped sealing element such that the outer diameter is reduced enough to fit within the wellbore casing.

After running in hole, this pre-stretch is released, and the sealing element obtains an initial set. In an embodiment, the setting tool can be used to further compress the sealing element and additional force can be applied as needed to ensure a quality seal and necessary holding force to keep the packer system in position.

To retrieve this packer, the setting tool is reconnected, using wireline as a conveyance method, to the set packer system and the sealing element is stretched to break the seal and remove the locking forces that were keeping the packer system in position. Once the isolation packer has been returned to its approximate “pre-stretched” position, it is then safely pulled out of the hole.

In a preferred embodiment, deploying the isolation packer system into a wellbore includes the steps: Providing an isolation packer system with the sealing element in the relaxed state; coupling the setting tool with the sealing element and actuating the setting tool to stretch the expandable sealing element; hold in position using shear screws; moving the isolation system down to a desired depth of a casing, actuating the setting tool to relax the expandable sealing; continuing this actuation until the shear screws are sheared and full desired compression is achieve; and retrieving the setting tool from the casing.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other enhancements and objects of the disclosure are obtained, a more particular description of the disclosure briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the disclosure and are therefore not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is a schematic illustration of a typical tool string and surface system;

FIG. 2 is a perspective view of a prior art isolation packer utilizing a single large cylinder as a sealing element;

FIG. 3 is a perspective view of a sealing element;

FIG. 4 is a perspective view of a single ring of the sealing element in FIG. 3;

FIG. 5 is a cross section view of a single ring in FIG. 4;

FIG. 6 is a cross section view of a single ring with a limiter;

FIG. 7 is a schematic illustration of the sealings with different wall thicknesses;

FIG. 8 is a perspective view of a sealing element with addition of tabs;

FIG. 9 is a perspective view of an isolation packer;

FIG. 10 is a perspective view of an isolation packer adapted to a setting tool;

FIG. 11 is a cross section view of FIG. 10;

FIG. 12 is a schematic illustration of the sequence of force during the life cycle of the isolation packer system;

FIG. 13 a schematic illustration a setting tool re-connected to the isolation packer for retrieval.

DETAILED DESCRIPTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the disclosure. In this regard, no attempt is made to show structural details of the disclosure in more detail than is necessary for the fundamental understanding of the disclosure, the description taken with the drawings making apparent to those skilled in the art how the several forms of the disclosure may be embodied in practice.

The following definitions and explanations are meant and intended to be controlling in any future construction unless clearly and unambiguously modified in the following examples or when application of the meaning renders any construction meaningless or essentially meaningless. In cases where the construction of the term would render it meaningless or essentially meaningless, the definition should be taken from Webster's Dictionary 11th Edition.

In the following description of the embodiments of the disclosure, “above”, “upper”, “upward”, “top” and similar terms refer to a direction toward the earth's surface along a wellbore, and “below”, “lower”, “downward”, “bottom” and similar terms refer to a direction away from the earth's surface along the wellbore.

The present disclosure provides an isolation packer needed to be deployed into a wellbore during various operations throughout the life of the well.

In one embodiment, the packer includes an expandable sealing element coupled with an inner mandrel assembly. The expandable sealing element is made of metal and comprises a section that extends in a radially outward direction when the expandable sealing element is in a relaxed state. In the original relaxed state, the outer diameter of the expandable sealing element is machined to be close in size to the inner diameter of the wellbore casing, either slightly larger or slightly smaller, and the packer will not easily fit into the well and run without risk of getting stuck in this original relaxed machined state. To deploy the packer into the casing, the expandable sealing element can be elastically stretched such that the outer diameter of the expandable sealing element is reduced with enough clearance to safely run-in-hole without risk of getting stuck. Once at the desired depth, the tension on the expandable sealing element is released and the expandable sealing element returns to its original shape. With additional compression force from the setting tool, the expandable sealing element engages the casing wall and locks the expandable sealing element in place within the casing.

In a preferred embodiment, the setting tool and isolation packer systems are deployed using a conventional wireline configuration. Referring generally to FIG. 1, an isolation packer 100 can be deployed in a casing 500 utilizing a cable system 330 and acquisition system 340. The acquisition system 340 is a platform for raising and lowing a cable system in the casing 500 to locate the packer 100 in a desired position, and the cable system 330 can couple various other components, such as telemetry 320, electronics 310, power supplies 300, and a setting tool 200 which can help to arrange the packer in the casing.

FIG. 2 shows an extreme temperature isolation packer 100 in U.S. patent application Ser. No. 17/662,229, the packer 100 includes an expandable sealing element 150, a lower sleeve and an upper sleeve. the expandable sealing element 150 is formed of metal that can survive extreme temperatures and corrosive downhole conditions for long periods of time and has sufficient elasticity that does not exceed material stress/strain limits yet can obtain a sufficient sealing surface and holding (anti-slip) force for the specified casing. The lower sleeve and the upper sleeve can stretch the sealing element 150 to reduce outer diameter of the sealing element 150 such that the packer 100 fits into the casing and runs in the hole. Then, once at depth, the system pre-stretch is released and further compressed to jam it into position and obtain a seal. The packer 100 has essentially a large “diamond-like” shape, it needs high force to stretch.

Although using this same concept and diamond-shape, unlike the sealing system in in U.S. patent application Ser. No. 17/662,229, which utilizes a single cylinder with a “bulge” in the middle to be the element that is stretched (to fit) and compressed (to seal). as shown in FIG. 4, the present invention of the sealing element reduces the size and turns it into a ring, like a bracelet worn on a wrist (base).

As illustrated in FIGS. 3 and 4, the sealing element 150 of an embodiment of the present disclosure comprises at least one hollow annular ring 160. The sealing element 150 has a central axis 161. The hollow annular ring 160 has an outer diameter 162 and an inner diameter 163. Referring to FIG. 5, the hollow annular ring 160 is not solid, cross-section 170 of the hollow annular ring 160 comprises a hollow inner surface 172 encompassed by a wall 171 of the annular ring 160.

The hollow structure of the annular ring 160 make it easy to present elastic deformation under external force, for example, when stretched parallel to the central axis 161 of the sealing element 150, the annular ring will shrink in the direction perpendicular to the central axis 161, with the result that the ring has a smaller outer diameter 162 and a larger inner diameter 163. But, when compressed parallel to the axis direction of the annular, the ring will extend in the direction perpendicular to the central axis 161 of the sealing element 150, results in the outer diameter 162 increasing and the inner diameter 163 decreasing. The outer surface of the ring will press against the casing, the inner surface of the ring will press against a base (Depicted below), which both makes a seal in the well bore as well as locks into place (to prevent sliding along the axis of the well bore).

In an embodiment, the expandable sealing element is formed of metal that can survive extreme temperatures and corrosive downhole conditions for long periods of time and has sufficient elasticity that does not exceed material stress/strain limits yet can obtain a sufficient sealing surface and holding (anti-slip) force for the specified casing. In an embodiment, the metal can be stainless steel or similar materials such as non-stainless alloys, aluminum, titanium, nickel alloys, manganese alloy steel or other high strength metal. In an embodiment, small ceramic “teeth” can be added to increase the locking force of the isolation packer system.

Referring to FIG. 5, in a preferred embodiment, the cross-section 170 of the hollow annular ring 160 has “diamond-like” shape, that is, the shape of the cross-section 170 of the hollow annular ring 160 is a parallelogram. When two vertices 174, 175 of the parallelogram parallel to the axis direction of the sealing element 150 is stretched alone the central axis direction 161, the other two vertices 176, and 177 of the parallelogram perpendicular to the central axis direction of the annular ring will shrink, such that the ring has a smaller outer diameter 162 and a larger inner diameter 163. When two vertices 174 and 175 of the parallelogram parallel to the axis direction of the annular ring is compressed along the axis direction, the other two vertices 176, 177 of the parallelogram perpendicular to the central axis direction of the annular ring will shrink, such that the hollow annular ring 160 has a smaller outer diameter 162 and a larger inner diameter 163.

In a further preferred embodiment, the cross-section of the sealing element is a hollow diamond shape with two u-shaped edges 178 on both the vertices 176, and 177 of the parallelogram perpendicular to the central axis direction of the annular ring. These u-shaped edges reduce the force required to deform under both stretch and compress.

In a preferred embodiment, to prevent any individual diamond-shaped structure on the sealing element from “over-crushing”, or experiencing “extreme plastic deformation, which could lead to tearing, rupturing or other catastrophic material failure and loss of seal and restraining force, as shown in FIG. 6, a limiter 179 is added within the inside of the hollow ring 160. The limiter 179 comprises two plates coupled to vertices 174, 175 of the parallelogram respectively. In a relaxed state, there exists some distance between the two plates, when stretched, the distance between the two plates will decrease. In the case of over stretched, the distance will decrease to zero and the two plates will push against each other to avoid “over-crushing”.

Referring back to FIG. 3, the sealing element 150 is made of metal and comprises a plurality of hollow annular rings 160 stacked along the axis direction of the sealing element 150. The added additional sealing rings will increase likelihood of obtaining a good seal as well as additional force to resist any motion of the packer along the axis of the well after set. The greater number of rings stacked increases both parameters. It has been found that four diamond seals work well, though any number is possible. The sealing element 150 can be formed integrally through additive manufacturing process.

In the case that the sealing element 150 comprises a plurality of hollow annular rings 160, a testing revealed that as the sealing element was crushed, the topmost ring was forced to axially move/slide after it had fully expanded. This led to sealing issues and damage. To prevent this, as illustrated in FIG. 7, the sealing element 150 comprises four hollow annular rings 160, the hollow annular rings 160 have progressive wall thicknesses, for example, the lowest hollow annular rings 160 (the one against the non-moving base) has the thinnest wall 171, the thickness of the wall is X, above the lowest hollow annular rings 160, the thicknesses of the walls of other annular rings 160 are Y, Z, and A in sequence. Each structure above had progressively thicker walls, such that thickness A>Z>Y>X. Thus, the first structure to deform and lock against the ID of the casing is the lowest hollow annular ring. Then, as this ring locked in place, the hollow annular ring above the lowest hollow annular ring expanded and locked. Then the hollow annular ring element locked in place, and finally the fourth locked in place. This sequencing of ring expansion led to much better performance.

Referring to FIG. 8, the sealing element 150 has tabs 180, 181 on each end, each tab has a plurality of holes 182 for stainless steel pins that affix the ends to the tool. One end is locked to the base (typically, the low side) and the other end to the compression sleeve (typically, the uphole side) which is mechanically connected to the actuator of a setting tool.

In a preferred embodiment, the hollow annular rings 160 on the sealing element have holes 167 that connect fluid from the outside to the interior to equalize pressure and prevent collapse under high pressure. This is shown, as an example, in FIG. 8.

Referring to FIG. 9, an embodiment of isolation packer 100 of the present disclosure comprises a base 130 which the sealing element 150 can mount on, slide along and seal against. Also, in the preferred embodiment, the isolation packer 100 comprises a compress sleeve 140 which provides an interface between the sealing element 150 and an actuator system of a setting tool. Two ends of the sealing element 150 are coupled to the base 130 and a compress sleeve 140 respectively through stainless steel pins 183. The packer 100 also includes a mandrel to stretch or compress the compress sleeve 140.

Referring to FIGS. 10 and 11, prior to running in hole, the mandrel 132 of the isolation packer 100 is attached to a setting tool 110 through an adapter 133. The outer diameter 162 of the sealing element 150 is sized to be close to the ID of the wellbore casing (see state A of FIG. 12). In the original relaxed state, the isolation packer cannot be safely lowered into the wellbore. A typical setting tool such as a Baker-20 style setting tool, can stretch the isolation packer 100 by pulling the compress sleeve 140 through the mandrel 133, such that the annular rings 160 of the sealing element 150 are elastically stretched and the outer diameter being reduced with enough clearance to run in hole (see states B and C of FIG. 12).

The isolation packer 100 also has at least one shear bolt 136 (identical to those typically used on frac plugs). The shear bolt 136 releasably connects the base 130 to the mandrel 136, such that the isolation packer 100 releasably connects to the setting tool 110 and is maintained by the setting tool 110 during setting in hole.

During run in hole, the tension on the sealing element is maintained by the setting tool (see state C of FIG. 12).

Once at depth, the setting tool operates in a “forward” direction, which releases the tension in the sealing element and allows the sealing element to nearly return to its original “relaxed” shape. However, in the preferred embodiment, it interferes with the ID of the casing prior to full relaxation. This results with the isolation packer in obtaining an initial set and seal between the isolation packer and inner surface of the wellbore casing. (see state D of FIG. 12).

The setting tool then completes the actuation and reaches maximum setting force, which applies additional compressional forces on the sealing element. This results in a high setting pressure along the inner diameter of the wellbore casing as well as puts the inner mandrel in tension for the duration of the set (see state E of FIG. 12).

After the packer has been set in the casing, the setting tool 110 then pulls the mandrel 132 with sufficient force to cause the shear bolts 136 to shear. Once the shear bolts 136 are sheared, the setting tool & adapter assembly can be pulled out of the casing while leaving the isolation packer 100 in place.

To retrieve the isolation packer, the setting tool is run back in the hole and re-attached to the top of the isolation packer system. This can be done using a plurality of methods, one of which is illustrated in FIG. 13. The setting tool 110 uses spring-loaded buttons that deploy into a recess to capture the isolation packer 100. In order to reconnect to the setting tool, referring back to FIG. 11, the inner surface of the compression sleeve has a standard fishing profile just like a funnel. Other methods commonly used to “fish” or “retrieve” devices from wells are commercially available throughout the industry. Once re-attached, the setting tool is used to stretch the sealing element on the isolation packer, which releases the tension in the mandrel and reduces the OD of the sealing element until it is no longer is interfering with the inner diameter of the casing. This returns the isolation packer assembly approximately to the “pre-stretched” position as illustrated as state A in FIG. 12 and can be retrieved from the well.

Extreme Temperature Retrievable Isolation Packer System

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CROSS-REFERENCE TO RELATED APPLICATIONS

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