Patent Application
20180363409
Downhole tools, more specifically, downhole tools that are dissolvable in a downhole fluid, and/or are shorter in overall length than typical, and/or may have only a single slip of novel construction and dimensions.
Downhole tools may be used in completion of oil and gas wells, in one example, for fracing operations by isolating the formations downhole to be treated as, for example, by fracing. These downhole tools may be interventionless, meaning they may be dissolvable in downhole fluids. Downhole fluids may be naturally occurring, or may be fluids added at the wellhead during completion, or fluids modified by adding chemicals at the wellhead to the natural downhole fluids or introduced fluids.
Dimensionally, most downhole tools have an overall length of about 13″ to 32″ long and weigh in the range of about 6 to 12 pounds. Reducing dimensions, such as weight and overall length, and mandrel wall thickness will create a lighter, easier handling, smaller tool. However, this is difficult, especially when balancing other goals, such as degradability strength). It is a challenge to make a tool which achieves degradability while also being light and compact. Nonetheless, disclosed herein are embodiments of tools that achieve, in an interventionless tool, useful size, weight, and other design parameters.
This application incorporates by reference the following: US Publication No. 2017/0067312, as well as US Publication No. 2017/0030161; U.S. patent application Ser. No. 13/969,066, filed Aug. 16, 2013, which is a continuation-in-part of U.S. patent application Ser. No. 13/895,707, filed May 23, 2013; U.S. patent application Ser. No. 13/894,649, filed May 15, 2013, which is a continuation of and claims priority to U.S. patent application Ser. No. 13/843,051, filed Mar. 15, 2013; and which claims the benefit of U.S. Provisional Application 61/648,749, filed May 18, 2012; U.S. Provisional Application 61/738,519, filed Dec. 18, 2012. All of the foregoing and US Patent Publication No. 2010/0155050, published Jun. 24, 2010, which is now U.S. patent application Ser. No. 12/317,497, filed Dec. 23, 2008, are incorporated herein by reference. U.S. Pat. No. 6,951,956 is also incorporated herein by reference. All of the foregoing patents, applications, and publications are incorporated herein by reference.
A downhole tool or plug is provided, in some embodiments, comprising: a mandrel, a bottom shoe engaging the mandrel, a single slip engaging the mandrel, a single wedge engaging the mandrel, an elastomer engaging the mandrel, a load ring engaging the mandrel; and a ratchet ring engaging the mandrel. One or more of the foregoing elements may be comprised of at least a first degradable material and, in some embodiments, a second degradable material. The first degradable material may be a metal, such as an aluminum, magnesium or zinc alloy. The second degradable material may be a polymer acid, such as polyglycolic or polylactic acid. A frac ball may be provided and either the removed end of the mandrel or the bottom shoe may be configured to receive the frac ball. The frac ball may be comprised of a degradable polymer acid or other degradable material such as a magnesium alloy. The slip may include multiple buttons. The multiple buttons may include a first set and a second set, the first set inclined in a first direction and a second set inclined in a second direction, thus holding the tool bi-directionally in the casing from moving either up or down. Bi-directional buttons may be in one or more slip elements. The elastomer may be degradable and comprised of a polyglycolic acid (“PGA”), a polylactic acid (“PLA”) or other degradable polymers or materials. The downhole tool may further include a tablet for Increasing the rate of dissolution of the one or more degradable elements.
In some embodiments, the plugs disclosed herein are “interventionless” if they do not have to be milled or drilled or retrieved from the well so completion can continue after their function is completed, but rather can be left in the well where they degrade, disintegrate or dissolve to the same effect. “Degrade” and “dissolve” are used interchangeably into the same effect herein. Interventionless downhole plugs may save time and expense in well completion and workover processes, including fracing and/or acid completions. In some embodiments, settable downhole tools combine one or more degradable polymeric or polymer acid elements with one or more degradable metallic elements to produce a tool which sets, and sufficiently degrades to no longer interfere with fluid flow through the casing without drilling out. In some embodiments, the degradable elements and the composition thereof are disclosed in U.S. patent applications: Ser. No. 13/893,160, filed May 13, 2013; Ser. No. 14/132,608, filed Dec. 18, 2013; and Ser. No. 14/677,242, filed Apr. 2, 2015, all incorporated herein by reference.
In one embodiment, the degradable polymer acid elements are non-composite elements and the degradable metallic elements are non-iron. Composite downhole tool elements tend to typically include a woven fabric and resin, such as a fiberglass. Unless otherwise indicated herein, “metal” includes in some embodiments pure metal and in other embodiments metal alloys. In some embodiments, the non-iron, degradable metallic elements may be aluminum (meaning pure aluminum or aluminum alloy) or magnesium (meaning pure magnesium or magnesium alloy) combined with the degradable non-metallic elements. In some embodiments, the degradable metallic elements include a bottom sub, a shear sub and/or slips and the non-metallic polymer acid degradable elements may include a mandrel. In some embodiments, the slip or slips include a body with cast iron buttons or other hard metal buttons, the body being comprised of a degradable, non-iron metallic.
The degradable, settable downhole tool is provided for engaging a casing at a rated setting strength, the casing containing a downhole fluid, typically an aqueous completion fluid, which may be freshwater or contain a salt of various concentrations, most typically about 2% NaCl or other chloride. In one embodiment, the tool has a degradable mandrel comprising at least in part, a degradable metal or solid high molecular weight acid polymer which is strong and hard enough to function as a mandrel and degradable enough in the downhole fluid to degrade enough so completion operations can continue without drilling out the mandrel and the degradation releases an acid into the downhole fluid, which changes the chemistry of the local downhole fluid to increase the rate of dissolution of at least some other parts of the tool.
For example, the polymer acid solid may be a pH neutral, high molecular weight PLA, PGA, PHA or any polymerized acid which, in some embodiments, is both (1) strong and hard enough to function as a downhole tool element, and (2) hydrolyzes in the aqueous drilling fluid to release enough acid with a low enough pH quickly enough into the local downhole fluid immediately adjacent the tool's metal elements to appreciably accelerate degradation of the tool's metal elements. For example, degradation of a solid high molecular weight polyglycolic acid in an aqueous downhole fluid solution may release glycolic acid and degradation of a solid high molecular weight polylactic acid polymer in an aqueous downhole fluid may release a lactic acid. Other polymers that degrade in an aqueous solution and release acid are found in U.S. Pat. No. 7,353,879, incorporated herein by reference. In some embodiments, the solid acid polymer elements of the tool react by hydrolysis in the aqueous downhole fluid, releasing acids into the downhole fluid as reaction products. The released acid in the local downhole fluid immediately adjacent to the tool's metallic elements speeds degradation of the nearby tool metallic elements, such as load rings and/or slips and/or cones, which may be made of ferric or non-ferric metals or any acid degradable material. In one embodiment some of the mandrel, slip, wedge, seal, load ring, ratchet ring, and bottom shoe are polymer acid elements comprised of one or more degradable polymer acids and some of the mandrel, slip, wedge, seal, load ring, ratchet ring and bottom shoe are metallic elements comprised of metals or metal alloys, the polymer acid elements being degradable in the well's downhole fluid to produce degradation products which will sufficiently reduce the pH of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the degradation rate of the metallic elements without the adjacent polymer acid elements degradation products so the plug releases from the casing in 80% of the time needed for a similar plug without such degradable polymer elements producing such degradation products to release from the casing
The degradable metal alloy, in one embodiment, is a degradable zinc alloy. The degradable metal alloy, in one embodiment, is a magnesium alloy as described in U.S. Patent Application No. 2016/0024619, incorporated herein by reference. The degradable metal alloy is degradable in the presence of water and chlorides with a pH of less than 7. The degradable metal alloy, in one embodiment, comprises one or more of the following: one slip, a bottom cone, a bottom shoe and a load ring. The polymer, in one embodiment, is degradable PGA or PLA and may comprise a cone and/or a bottom shoe or sub. The central elastomer may be degradable or dissolvable in aqueous downhole fluid. The slip, in one embodiment, may have heat treated ductile iron buttons or heat treated powder metal buttons.
In one embodiment, a bottom cone and a bottom shoe, all the foregoing elements and the mandrel may at least partly comprise a poly acid plastic. The central elastomer may be a dissolvable rubber or plastic. The degradable metal of any metal part may be as disclosed in US 2015/0240337; US 2015/0299838; or US 2015/0239795, all incorporated herein by reference.
Generally, the setting of tool 10 may be seen in
Turning now to the structure of bottom shoe 14, it is seen to have, in one embodiment, tapered walls 14c defining a nose thereof, to facilitate moving plug 10 downhole and grooves 14e, which may form an X-shape at the removed end of the tapered walls, so if a ball from below plug 10 comes up from below and strikes bottom shoe 14, fluid may still pass around the ball and through plug 10. Threaded walls 14b are designed to engage threaded walls on the lower end of the mandrel. O-ring 28 held in bottom shoe ring cutout 14a seals the bottom shoe 14/mandrel 12 interface. Any of the elements illustrated in
In the embodiment of
Embodiments of such a slip are shown in
In one embodiment, ball seat 42 may be on an upper shoulder of a lower portion of mandrel 12 which lower mandrel 43 is thicker than the upper mandrel 45 as shown in
In one embodiment, the mandrel overall length may usefully be in the range of about 15 to about 26 inches and the plug in the range of about 16 to about 27 inches. The mandrel wall thickness may be in the range of about 1.50 to about 0.75 inches, and preferably less than of about 1 inch. The O.A. length of the downhole tool in typical use may be between about 10 and 16 inches and the length of the plug in the range of about 11 to about 17 inches. A preferable mandrel length is less than about 12 inches, the length of the plug being less than about 13 inches. A most preferable mandrel length is less than about 11 inches, the plug being less than about 12 inches.
In one embodiment, the thickness of mandrel 12 of
Turning to
In one embodiment, an extra element is run into the well with the plug and is degradable in the downhole fluid to produce degradation products which will sufficiently reduce the pH of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the rate of degradation of the metallic elements without the polymer acid elements degradation products so the plug releases from the casing at least 20% faster than a similar plug without such extra degradable element producing such degradation products. In another embodiment, the extra element is or dissolvable in the downhole fluid to produce a salty solution which will sufficiently increase the salinity of the downhole fluid adjacent the metallic elements to appreciably accelerate the degradation rate of the metallic elements relative to the rate of degradation of the metallic elements without the salty elements salty dissolution products so the plug releases from the casing at least 20% faster than a similar plug without the extra element producing such salty dissolution products. In another embodiment, the extra elements produce both acid and saline solution as degradation and dissolution products. The number of extra elements used can be selected to control the degradation rate of the metallic elements and the speed of the plug releasing from the casing. In appropriate environments and with appropriate plugs, the use of such extra elements may decrease the time needed for the plug to release from the casing by 10% to 50%, a preferred range being from 20% to 30%.
Sealing or packing member 20 may be made from degradable materials such as are known in the art, including polyglycolic acid and polylactic acid which degrade to produce acid reaction products.
Load ring 22 has a general structure and function of load rings as known in the art and may be made from any degradable material and, in a preferred embodiment, a degradable polymer acid or a degradable metal. Ratchet ring 24 and washer 26, in one embodiment, may have, generally, the structure and function as set forth in the prior art. In one embodiment, they may be made from a degradable material, including a degradable acid or a degradable polymer acid.
Below is a table showing some ranges for use with Applicant's tool.
The present invention is adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. No limitations are intended to limit the details of construction or design shown, other than as described in the claims below. The illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present invention.
The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting. The singular form “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” and/or “comprising,” when used in the this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups therefore. Compositions and methods described in terms of “comprising,” “containing,” or “including” various components or steps, can also “consist essentially of or “consist of the various components and steps.
Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. Every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a to b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. The terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.
The corresponding structure, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description is presented for the purposes of illustration and description, but is not intended to be exhaustive or limited to the implementations in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The implementations were chosen and described in order to explain the principles of the disclosure and the practical application and to enable others or ordinary skill in the art to understand the disclosure for various implementations with various modifications as are suited to the particular use contemplated. Those skilled in the art will readily recognize that a variety of additions, deletions, modifications, and substitutions may be made to these implementations. Thus, the scope of the protected subject matter should be judged based on the following claims, which may capture one or more concepts of one or more implementations.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. On the contrary, various modifications of the disclosed embodiments will become apparent to those skilled in the art upon reference to the description of the invention. It is therefore contemplated that the appended claims will cover such modifications, alternatives, and equivalents that fall within the true spirit and scope of the invention.
This is a utility application that elms priority and the benefit of U.S. Provisional Application 62/519,350, filed Jun. 14, 2017.
| Number | Date | Country | |
|---|---|---|---|
| 62519350 | Jun 2017 | US |
