EXPANDABLE AND DEGRADABLE DOWNHOLE HYDRAULIC REGULATING ASSEMBLY
A hydraulic regulating mechanism for disposal in a well. The mechanism includes a degradable metal based element and a swellable component for hydraulic regulation. The mechanism is configured for ease of setting and removal by allowing degrading of the metal based element upon exposure of certain downhole conditions to trigger shrinking of the swellable component. Further, the swellable component may be initially set by exposure to downhole conditions as well. Ultimately, a mechanism is provided which may effectively regulate high pressure applications downhole and yet, as a practical matter, be removed via a displacement or drill out that may take less than 15 to 30 minutes to achieve.
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The present document is a Continuation in Part claiming priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 12/855,503 filed on Aug. 12, 2010, and entitled “Dissolvable Bridge Plug” which is in turn a Continuation in Part of U.S. patent application Ser. No. 11/427,233, filed on Jun. 28, 2006, and entitled, “Degradable Compositions, Apparatus Comprising Same, and Method of Use”. This '233 Application also in turn claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. Nos. 60/771,627 and 60/746,097, filed on Feb. 9, 2006, and May 1, 2006, respectively. The disclosures of each of these Applications are incorporated herein by reference in their entireties. Further, the present document is also a Continuation in Part claiming priority under 35 U.S.C. §120 to U.S. patent application Ser. No. 12/763,280, filed on Apr. 20, 2010, and entitled, “Swellable Downhole Device of Substantially Constant Profile”.
FIELDEmbodiments described relate to deliverable downhole device assemblies for affecting fluid flow in a well. More specifically, assemblies which are configured to swell in order to divert, restrict, or isolate are detailed. Further, these assemblies are also tailored to degrade in the well over a given period, upon exposure to certain downhole conditions, or both.
BACKGROUNDExploring, drilling and completing hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses, added emphasis has been placed on efficiencies associated with well completions and maintenance over the life of the well. Over the years, ever increasing well depths and sophisticated architecture have made reductions in time and effort spent in completions and maintenance operations of even greater focus.
Completions and maintenance operations often involve the utilization of isolation mechanisms such as packers, plugs, and other downhole devices. Such devices may be used to sealably isolate one downhole section of the well from another as an application is run in one of the sections. Indeed, a considerable amount of time and effort may be spent achieving such isolations in advance of running the application, as well as in removing the isolation mechanism following the application. For example, isolations for perforating and fracturing applications may involve a significant amount of time and effort, particularly as increases in well depths and sophisticated architecture are encountered. These applications involve the positioning of an isolation mechanism in the form of a bridge plug. More specifically, the bridge plug is located downhole of a well section to be perforated and fractured. Positioning of the bridge plug may be aided by pumping a driving fluid through the well. This may be particularly helpful where the plug is being advanced through a horizontal section of the well.
Once in place, equipment at the oilfield surface may communicate with the plug over conventional wireline so as to direct setting thereof. In the circumstance of a cased well, such setting may include expanding slips of the plug for interfacing a casing wall of the well and thereby anchoring of the plug in place. A seal of the plug may also be expanded into sealing engagement with the casing. Thus, structural and hydraulic isolation may be achieved.
Once anchored and hydraulically isolated, a perforation application may take place above the plug so as to provide perforations through the casing in the corresponding well section. Similarly, a fracturing application directing fracture fluid through the casing perforations and into the adjacent formation may follow. This process may be repeated, generally starting from the terminal end of the well and moving uphole section by section, until the casing and formation have been configured and treated as desired.
The presence of the set bridge plug as indicated above keeps the high pressure perforating and fracturing applications from affecting well sections below the plug. Indeed, even though the noted applications are likely to generate well over 5,000 psi, the well section below the plug is kept isolated from the section thereabove. This degree of isolation is achieved largely due to the use of durable metal features of the plug, including the above noted slips, as well as a central mandrel.
Unfortunately, unlike setting of the bridge plug, wireline communication is unavailable for releasing the plug. Rather, due to the high pressure nature of the applications and the degree of anchoring and sealing required of the plug, it is generally configured for near permanent placement once set. As a result, removal of a bridge plug may be quite challenging, particularly where the plug is set in a horizontal section of the well as detailed further below.
In many circumstances, a packer or seal such as that of the plug may be of a swellable configuration. That is, rather than employing a more challenging isolation technique, the seal may be of a material configured to swell upon exposure to certain downhole conditions. Generally, the material is configured to expand or ‘swell’ upon exposure to brine. As used herein, the term brine is meant to refer to any water-based fluid containing a measureable concentration of a salt such as sodium chloride. A brine swellable material may be well suited for construction of a seal that is to be exposed to a commonly encountered horizontal terminal end of a well. This is because such locations are often partially open-hole and prone to brine production. However, as alluded to above, due to the likely continued presence of brine in the horizontal section, the seal may be set for long term placement.
As also alluded to above, the slips of the plug may be anchored in a near permanent manner as well. Thus, ultimately a labor and time intensive drill-out of the plug may be required. Indeed, each drill-out of a plug in a horizontal well section may require hours of dedicated manpower and drilling equipment. All in all, this may add up to several days and several hundred thousand dollars in added manpower and equipment expenses, solely dedicated to bridge plug drill-out. Unfortunately, even with such expenses incurred, the most terminal or downhole horizontal plugs are often left in place, with the drill-out application unable to achieve complete plug removal, thus cutting off access to the last several hundred feet of the well. Furthermore, a host of other isolation mechanisms make use of metal based anchoring and support features as well as swellable elastomer based sealing elements, both of which display far greater setting than releasing characteristics.
SUMMARYA downhole isolation mechanism is disclosed for use in a well. The mechanism includes a metal based component configured for degrading in the well. A seal is also provided that is coupled to the metal based component and configured to swell upon exposure to a downhole condition. Further, the seal is also configured to shrink upon the degrading.
Referring now to
Embodiments are described with reference to certain downhole operations employing an expandable and degradable downhole hydraulic regulating assembly. For example, embodiments herein focus on such an assembly in the form of a bridge plug to aid in perforating and fracturing applications. However, a variety of alternate embodiments of expandable and degradable downhole hydraulic regulating assemblies are possible. For example, any number of devices for more temporary isolations, profilers, diverters, and/or constrictors, may take advantage of expandable and degradable characteristics of embodiments described below. Regardless, embodiments described herein include a downhole assembly of some type that is both expandable for hydraulic regulation and degradable to aid in removal or displacement.
Referring now to
In the embodiment of
In spite of the high strength and hardness characteristics of the slips 110 and mandrel 120, their degradable or dissolvable nature allows for subsequent displacement, drill-out or other plug removal techniques to be carried out in an efficient and time-saving manner (see
Continuing with reference to
In one embodiment the seal 150 is constructed of swellable elastomers that are less affected by fluctuations in brine concentration. Thus, its long-term effectiveness may be enhanced. More specifically, polymer particles may be drawn from a betaine group prepared by inverse emulsion polymerization. Additional fillers and vulcanizing agents and other substances may be incorporated into elastomer. Ultimately, the elastomer backbone of the brine swellable material may be tailored with particular concentrations of cations and/or anions grafted thereto so as to reduce the sensitivity thereof to brine concentration. As a result, the seal 150 may be constructed that is swellable in the presence of brine but with a resultant swell profile that is of a reduced sensitivity the actual concentration of brine in the well 180.
The elastomer base material for the seal 150 may also include non-elastomeric polymers and be constructed in a variety of configurations. For example, different non-elastomer and elastomer layers may be individually provided of varying thicknesses. Such layers may be stacked or of interpenetrating networks. Further, the elastomer composition itself may include fillers, plasticizers, accelerants and various fibers. Additionally, non-elastomeric polymer choices may include thermoplastic polymers, such as polyolefins, polyamides, polyesters, thermoplastic polyurethanes and polyurea urethanes, copolymers and blends thereof and/or thermoset polymers such as phenolic and epoxy resins.
Continuing with reference to
Referring now to
In the embodiment shown, a rig 210 is provided at the oilfield surface over a well head 220 with various lines 230, 240 coupled thereto for hydraulic access to the well 280. More specifically, a high pressure line 230 is depicted along with a production line 240. The production line 240 may be provided for recovery of hydrocarbons following completion of the well 280. However, more immediately, this line 240 may be utilized in recovering fracturing fluids. That is, the high pressure line 230 may be coupled to large scale surface equipment including fracturing pumps for generating at least about 5,000 psi for a fracturing application. Thus, fracturing fluid, primarily water, may be driven downhole for stimulation of a production region 260.
In the embodiment of
As to deployment and setting of the bridge plug 100, a variety of techniques may be utilized. For example, as noted above, wireline coupled to the head 175 may be used to drop the plug 100 down the vertical portion of the well 280 (see
Continuing with reference to
Referring now to
The seal 150 may be of conventional swellable materials. However, as indicated above, in one embodiment, variability in the degree of swell of the seal 150 may be reduced. That is, the seal 150 may be configured to remain of a substantially constant profile. More specifically, upon exposure to brine, the seal 150 may configured to swell to a given degree of between about 50% and 250% over and above its pre-swollen size, limited only by the surrounding structural restriction of the depicted casing 287. In this embodiment, the seal 150 is constructed of materials such that the achieved profile, or given degree to which the seal 150 is swollen, varies by no more than about 30% so long as the brine concentration remains less than about 10%.
In an alternate embodiment, where exposure to water or brine is less likely, the seal 150 may be configured to swell upon exposure to hydrocarbons. For example, in one embodiment, the seal 150 may be of a polyarylether ketone of tailored sulfonation to enhance swell upon hydrocarbon exposure. As such, sealing engagement of the seal 150 and casing 187 at the interface 376 may be adequately ensured. Nevertheless, as with brine swellable embodiments, the seal 150 may still be configured for dissolution upon degradation of other metal based components of the plug 100 as described further below.
Continuing with reference to
Referring now to
The degrade rate of the plug 100 may be tailored by the particular material choices selected for the reactive metals and alloying elements described above. That is, material choices selected in constructing the slips 110 and mandrel 120 of
Continuing with reference to
In circumstances where the well 280 is otherwise relatively water-free or not of particularly high temperature, the duration of the fracturing application may constitute the bulk of downhole conditions which trigger the degrade. Alternatively, the well 280 may already be significantly water producing or of relatively high temperature (e.g. exceeding about 75° C.). In total, the slips 110 and mandrel 120 are constructed of materials selected based on the desired degrade rate in light of downhole conditions whether inherent or induced as in the case of fracturing operations. Further, where the conditions are induced, the expected duration of the induced condition (e.g. fracturing application) may also be accounted for in tailoring the material choices for the slips 110 and mandrel 120.
While material choices may be selected based on induced downhole conditions such as fracturing operations, such operations may also be modulated based on the characteristics of the materials selected. So, for example, where the duration of the fracturing application is to be extended, effective isolation through the plug 100 may similarly be extended through the use of low temperature fracturing fluid (e.g. below about 25° C. upon entry into the well head 220 of
Compositions or material choices for the slips 110 and mandrel 120 are detailed at great length in the noted '233 Application. As described, these may include a reactive metal, which itself may be an alloy with structure of crystalline, amorphous or both. The metal may also be of powder-metallurgy like structure or even a hybrid structure of one or more reactive metals in a woven matrix. Generally, the reactive metal is selected from elements in columns I and II of the Periodic Table and combined with an alloying element. Thus, a high-strength structure may be formed that is nevertheless degradable.
In most cases, the reactive metal is one of calcium, magnesium and aluminum, preferably aluminum. Further, the alloying element is generally one of lithium, gallium, indium, zinc, or bismuth. Also, calcium, magnesium and/or aluminum may serve as the alloying element if not already selected as the reactive metal. For example, a reactive metal of aluminum may be effectively combined with an alloying element of magnesium in forming a slip 110 or mandrel 120.
In other embodiments, the materials selected for construction of the slips 110 and mandrel 120 may be reinforced with ceramic particulates or fibers which may have affect on the rate of degradation. Alternatively, the slips 110 and mandrel 120 may be coated with a variety of compositions which may be metallic, ceramic, or polymeric in nature. Such coatings may be selected so as to affect or delay the onset of degrade. For example, in one embodiment, a coating is selected that is itself configured to degrade only upon the introduction of a high temperature fracturing fluid. Thus, the degrade period for the underlying structure of the slips 110 and mandrel 120 is delayed until fracturing has actually begun.
The particular combinations of reactive metal and alloying elements which may be employed based on the desired degrade rate and downhole conditions are again detailed at great length in the noted '233 Application. Factors such as melting points of the materials, corrosion potential and/or the degradability in the presence of water, brine or hydrogen may all be accounted for in determining the makeup of the slips 110 and mandrel 120.
In one embodiment, the degrade apparent in
Continuing with reference to
Referring now to
In addition to exposure to the noted constituents 410 other readily available measures may utilized in shrinking/degrading the seal 150. For example, use of hotter fluids, above about 35° C. or so, during the perforating and/or fracturing applications, may increase the rate of dissolution of both the slip 110 and the seal 150. So to, would use of higher pH fluids, say above 7, during such applications. Of course, depending on the nature and duration of such applications, lower pH and temperature fluids may be employed where maintenance of the interfaces 375, 376 is sought for longer durations. In this manner, both the makeup of the seal 150 and slip 110 as well as the protocol of the applications may be tailored to support the duration of the interfaces 375, 376 sought.
Referring now to
As depicted in
Referring now to
Perhaps most notably, is the manner by which the mechanism may be dissolved or degraded for eventual displacement or removal. Namely, as indicated at 670 a metal-based component of the mechanism may be degraded. This may be upon exposure to the application noted at 660, positioning in the downhole environment as noted at 620, or both. Regardless, as indicated at 680, the swollen component may be shrunk by exposure to constituents of the degrading metal-based component.
Embodiments described hereinabove provide an expandable and degradable mechanism for downhole hydraulic regulation. The mechanism, may be used to manage hydraulic flow downhole, as in the case of a bridge plug. The mechanism may include swellable features such as that of a packer or seal as well as durable anchoring and structural features such as slips and mandrels. Nevertheless, long term placement of the mechanism may be avoided without requiring labor and time intensive drill-outs or other substantially expensive measures be taken.
The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. Furthermore, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.
Claims
1. A hydraulic regulating mechanism for disposal in a well, the mechanism comprising:
- a metal based element configured for degrading in the well; and
- a swellable component coupled to said element, said swellable component configured for swelling upon exposure to a downhole condition and for shrinking upon the degrading.
2. The hydraulic regulating mechanism of claim 1 wherein the metal based element is of constituents for releasing during the degrading to initiate the shrinking.
3. The hydraulic regulating mechanism of claim 1 wherein the metal based element is configured for degrading in the well upon exposure to a downhole condition.
4. The hydraulic regulating mechanism of claim 3 wherein the downhole condition for one of the degrading and the swelling is one of a water based condition, a hydrocarbon based condition and a temperature based condition.
5. The hydraulic regulating mechanism of claim 1 wherein the mechanism includes one of a bridge plug, temporary isolation device, profiler, diverter, and a constrictor.
6. The hydraulic regulating mechanism of claim 5 wherein the mechanism is the bridge plug, the metal based element comprising one of a slip and a mandrel thereof, and the swellable component a seal thereof.
7. The hydraulic regulating mechanism of claim 6 wherein the downhole condition is a presence of brine.
8. The hydraulic regulating mechanism of claim 7 wherein the seal is of a material selected from a group consisting of styrenic isoprene block copolymer, polyvinyl alcohol, polylactic acid, and sulfonated polyarylether ketone.
9. The hydraulic regulating mechanism of claim 4 wherein the downhole condition is the presence of hydrocarbons.
10. The hydraulic regulating mechanism of claim 9 wherein the seal is of a polyarylether ketone of tailored sulfonation for swelling in the presence of hydrocarbons.
11. The hydraulic regulating mechanism of claim 1 wherein the metal based element comprises:
- a reactive metal selected from a group consisting of aluminum, calcium, and magnesium; and
- an alloying element.
12. The hydraulic regulating mechanism of claim 11 wherein said alloying element is one of lithium, gallium, indium, zinc, bismuth, aluminum where aluminum is not said reactive metal, calcium where calcium is not said reactive metal, and magnesium where magnesium is not said reactive metal.
13. A hydraulic regulating assembly for disposal in a well, the assembly comprising:
- a component for exposure to a downhole condition arising from an open hole portion of a well, the exposure to induce swelling of the component; and
- a metal based element for exposure to a downhole condition to induce degrading thereof, the degrading to induce shrinking of said component.
14. The hydraulic regulating assembly of claim 13 wherein the assembly is a bridge plug for disposal uphole of a first production region to support one of perforating and fracturing of a second production region uphole of the assembly.
15. A method of hydraulic regulation in a well, the method comprising:
- positioning a hydraulic regulating mechanism in a well;
- swelling a swellable component of the mechanism into sealing engagement with a wall of the well;
- degrading a metal based element of the mechanism; and
- shrinking the swellable component by exposing to constituents of the degrading component.
16. The method of claim 15 wherein said swelling comprises exposing the swellable component to one of brine and hydrocarbons.
17. The method of claim 15 further comprising running an application in the well uphole of the mechanism after said swelling.
18. The method of claim 17 wherein the application is one of a perforating application and a fracturing application.
19. The method of claim 16 wherein said shrinking comprises driving up pH at a location of the mechanism in the well by the exposing.
20. The method of claim 19 wherein the driving up is to a pH of greater than about 9.
21. The method of claim 15 wherein said shrinking comprises driving up a temperature at a location of the mechanism in the well.
22. The method of claim 21 further comprising introducing heated fluid to the location to increase the temperature thereat.
23. The method of claim 15 further comprising removing the mechanism from productive portions of the well after said shrinking.
24. The method of claim 23 wherein said removing comprises one of displacing and drilling out of the mechanism.
25. The method of claim 23 wherein said removing is achieved over the course of less than about 15 minutes.
Type: Application
Filed: Oct 7, 2010
Publication Date: Mar 24, 2011
Applicant: SCHLUMBERGER TECHNOLOGY CORPORATION (SUGAR LAND, TX)
Inventors: Manuel Marya (Sugar Land, TX), Nitin Y. Vaidya (Missouri City, TX)
Application Number: 12/899,994
International Classification: E21B 33/12 (20060101);