Patent Publication Number: US-9835016-B2

Title: Method and apparatus to deliver a reagent to a downhole device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is a Continuation-In-Part Application of U.S. Non-Provisional patent application Ser. No 14/561,523, filed Dec. 5, 2014 which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     Field of the Disclosure 
     This disclosure relates generally to degradable devices with reagents and systems that utilize the same for downhole applications. 
     Background of the Art 
     Wellbores are drilled in subsurface formations for the production of hydrocarbons (oil and gas). Hydrocarbons are trapped in various traps or zones in the subsurface formations at different depths. In many operations, such as fracturing, it is required to convey devices (such as packers, bridge plugs, etc.) in a downhole location to facilitate production of oil and gas. After such operations, conveyed devices must be removed or destroyed before following operations can begin. Such removal operations may be costly and/or time consuming. It is desired to provide a downhole device that can provide desired and predictable degradation characteristics without additional removal or treatment operations. 
     The disclosure herein provides degradable devices with reagents and systems using the same for downhole applications. 
     SUMMARY 
     In one aspect, a downhole device for use in a downhole environment is disclosed, including: a first material that degrades at a first rate when exposed to the downhole environment, and a second material protected from the downhole environment, wherein the second material when exposed to the downhole environment degrades the first material at a second rate greater than the first rate. 
     In another aspect, a method to degrade a downhole device in a downhole environment, is disclosed, including: providing a first material in the downhole environment; providing a second material protected from the downhole environment; degrading the first material at a first rate in response to exposure to the downhole environment; exposing the second material to the downhole environment and the first material; and degrading the first material at a second rate in response to exposure to the downhole environment and the second material, wherein the second rate is greater than the first rate. 
     In another aspect, a downhole system for use in a downhole environment, is disclosed, including a casing string; and a downhole device associated with the casing string, including a first material that degrades at a first rate when exposed to the downhole environment, and a second material protected from the downhole environment, wherein the second material when exposed to the downhole environment degrades the first material at a second rate greater than the first rate. 
     Examples of certain features of the apparatus and method disclosed herein are summarized rather broadly in order that the detailed description thereof that follows may be better understood. There are, of course, additional features of the apparatus and method disclosed hereinafter that will form the subject of the claims appended hereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure herein is best understood with reference to the accompanying figures, wherein like numerals have generally been assigned to like elements and in which: 
         FIG. 1  is a schematic diagram of an exemplary drilling system that includes downhole elements according to embodiments of the disclosure; 
         FIG. 2  is a schematic diagram of an exemplary downhole device for use in a downhole system, such as the one shown in  FIG. 1 , according to one embodiment of the disclosure; 
         FIG. 3  shows a partial view of an exemplary bottom sub for use with a downhole device, such as the downhole device shown in  FIG. 2  for use with a downhole system, according to one embodiment of the disclosure; and 
         FIG. 4  shows a partial view of an exemplary cone for use with a downhole device, such as the downhole device shown in  FIG. 2  for use with a downhole system, according to one embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  shows an exemplary embodiment of a downhole system to facilitate the production of oil and gas. In certain embodiments, system  100  allows for fracturing operations to facilitate production of oil and gas. System  100  includes a wellbore  106  formed in formation  104  with casing  108  disposed therein. 
     In an exemplary embodiment, a wellbore  106  is drilled from a surface  102  to a downhole location  110 . Casing  108  may be disposed within wellbore  106  to facilitate production. In an exemplary embodiment, casing  108  is disposed through multiple zones of production Z 1  . . . Zn in a downhole location  110 . Wellbore  106  may be a vertical wellbore, a horizontal wellbore, a deviated wellbore or any other suitable type of wellbore or any combination thereof. 
     To facilitate downhole operations, such as fracturing operations, bridge plugs  116   a,  packers  116   b,  or other suitable downhole devices are utilized within casing string  108 . In certain embodiments, such downhole devices  116   a,b  are anchored to casing string  108  via an anchor assembly  118 . In certain embodiments, bridge plugs  116   a  utilize an anchor assembly  118  and frac balls  120  to isolate zones Z 1  . . . Zn for fracturing operations. In certain embodiments, frac balls  120  are disposed at a downhole location  110  to obstruct and seal fluid flow in local zone  112  to facilitate flow to perforations  114  in conjunction with frac plugs  116   a.  In certain embodiments, packers  116   b  are utilized in conjunction with anchor assembly  118  to isolate zones Z 1  . . . Zn for fracturing operations. 
     In certain embodiments, frac fluid  124  is pumped from a frac fluid source  122  to a downhole location  110  to flow through perforations  114  in a zone  112  isolated by downhole device  116   a,b . Advantageously, fracturing operations allow for more oil and gas available for production. 
     After desired operations (such as fracturing operations) and before following operations, downhole devices  116   a,b  are often removed or otherwise destroyed to allow the flow of oil and gas through casing  108 . In an exemplary embodiment, downhole devices  116   a,b  are configured remain resident in casing  108  of local zone  112  until a predetermined time at which at least portions of downhole devices  116   a,b  dissolve or degrade to facilitate the production of oil and gas. Advantageously, in an exemplary embodiment, the downhole devices  116   a,b  herein utilize reagents conveyed with the downhole devices  116   a,b  to accelerate degradation of downhole devices  116   a,b  while allowing for suitable performance. 
       FIG. 2  shows a downhole device  216 , such as a bridge plug, packer, or any other suitable downhole device, for use downhole systems such as the system  100  shown in  FIG. 1 . In an exemplary embodiment, downhole system  200  includes downhole device  216  interfacing with casing  208  via anchor assembly  218  to anchor a downhole device  216 . In certain embodiments, a frac ball  220  is used with downhole device  216  to isolate frac fluid flow within the wellbore. 
     In an exemplary embodiment, anchor assembly  218  includes a wedge  224 , slip ring  228 , and bottom sub  230 . In certain embodiments, wedge  224  is forced downhole to force slip ring  228  outward against casing  208  to anchor against casing  208 . In certain embodiments, slip ring  228  can crack or otherwise separate as it is driven against casing  208 . In certain embodiments, wedge  224  is forced via a setting tool, explosives, or any other suitable means. In certain embodiments, downhole device  216  further utilizes a sealing member  226  to seal downhole device  216  against casing  208  and further resist movement. Sealing member  226  may similarly be driven toward casing  208  via wedge  224 . In certain embodiments, downhole device  216  can further utilize bottom sub  230  to interface against casing  208  and further resist movement. 
     In an exemplary embodiment, a substrate of one or more elements of downhole device  216  are formed of a degradable material to allow one or more elements of downhole device  216  to dissolve or degrade after a desired anchoring function is performed. In certain embodiments, the downhole temperature exposure to downhole device  216  varies from 100 to 350 degrees Fahrenheit at a particular downhole location for a given area. Advantageously, one or more elements of downhole device  216  as described herein may contain reagents conveyed with one or more elements of downhole device  216  to allow for rapid degradation of one or more elements of downhole device  216  after a desired time in certain downhole environments, while allowing suitable anchoring performance. 
       FIG. 3  shows an exemplary embodiment of bottom sub  330 . While an illustrated embodiment depicts a bottom sub  330 , the features described herein are suitable for any element of downhole device  216 . In an exemplary embodiment, bottom sub  330  is formed of a substrate  331  and includes cavities  332 . In certain embodiments, bottom sub  330  is used with downhole devices as shown in  FIG. 2 . Advantageously, bottom sub  330  is a degradable device and includes a reagent  333  to be conveyed with bottom sub  330  to expedite degradation of bottom sub  330 , other elements of downhole device  216 , or any other suitable element formed of degradable materials. In an exemplary embodiment, any suitable elements of downhole device  216  can be utilized as described to convey reagent  333  and release reagent  333 . 
     In an exemplary embodiment, bottom sub  330  includes an upper face  334 , a lower face  336 , and one or more cavities  332 . Bottom sub  330  can be utilized with elements of one or more elements of downhole device  216  to provide reagent  333  to one or more elements of downhole device  216 . In an exemplary embodiment, the features of bottom sub  330 , including upper face  334  and lower face  336  can be configured to interface with one or more elements of downhole device  216 . 
     In an exemplary embodiment, bottom sub is generally formed from substrate  331 . In an exemplary embodiment, substrate  331  is a degradable material. Advantageously, by forming one or more elements of downhole device  216  from a degradable material, a downhole device  216  may be remain resident downhole for a desired period of time, and then may be disintegrated to allow further operations without any obstructions. In an exemplary embodiment, substrate  331  and consequently bottom sub  330  can degrade at a first rate in response to conditions found in a downhole environment. 
     In certain embodiments, substrate  331  is formed from a corrodible metal such as a controlled electrolytic metallic, including but not limited to Intallic. Substrate  331  materials may include: a magnesium alloy, a magnesium silicon alloy, a magnesium aluminum alloy, a magnesium zinc alloy, a magnesium manganese alloy, a magnesium aluminum zinc alloy, a magnesium aluminum manganese alloy, a magnesium zinc zirconium alloy, and a magnesium rare earth element alloy. Rare earth elements may include, but is not limited to scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, and erbium. In certain embodiments, substrate materials  331  are further coated with aluminum, nickel, iron, tungsten, copper, cobalt. In certain embodiments, substrate  331  materials are consolidated and forged. In certain embodiments, the elements can be formed into a powder and a substrate can be formed from pressed powder. In an exemplary embodiment, the material of substrate  331  is selected based on desired degradation characteristics of one or more elements of downhole device  216 . 
     In an exemplary embodiment, bottom sub  330  includes at least one cavity  332 . Cavities  332 , also referred to as pockets, can be of any shape, any number and disposed anywhere along elements of downhole device  216 . In an exemplary embodiment, cavities  332  can be disposed in non-integral portions of bottom sub  330 , such as non-load bearing portions. In certain embodiments, cavities  332  are not utilized in high stress areas to avoid unintentional or uncontrolled release of reagent  333 . In an exemplary embodiment, cavities  332  are sealed to control the release and interaction of reagent  333  with the downhole environment and substrate  331 . 
     In an exemplary embodiment, cavities  332  contain reagent  333 . Advantageously, reagent  333  is conveyed with one or more elements of downhole device  216  to allow reagent  333  to be released without additional operations. In an exemplary embodiment, reagents  333  include, but are not limited to acidic oxides, acidic salts, neutral salts, and basic salts. Acidic oxides can include, but are not limited to sulfur dioxide, sulfur trioxide, chromium trioxide, phosphorus pentoxide, etc. Acidic salts can include, but are not limited to ammonium chloride, monosodium phosphate, sodium bisulfate, etc. Neutral salts can include, but are not limited to sodium chloride, sodium bromide, potassium chloride, potassium bromide, calcium chloride, calcium bromide, etc. Basic salts can include, but are not limited to sodium carbonate, sodium bicarbonate, etc. Any suitable reagent  333  can be selected in response to substrate  331  material, downhole environment conditions, and desired degradation rate. 
     In an exemplary embodiment, reagent  333  is stored as a solid. Advantageously, stored solid reagent  333  allows for high concentration levels of reagent  333  without unintentionally degrading substrate  331 . In certain embodiments, reagent  333  can be a gel substance, including, but not limited to a gelled acid. In other embodiments, reagent  333  can be a liquid. 
     In an exemplary embodiment, after a desired time in a downhole environment, substrate  331  of bottom sub  330  degrades at a first rate. As substrate  331  degrades, cavities  332  formed therein are exposed to the downhole environment. Accordingly, reagent  333  resident in cavities  332  are exposed to the fluids and conditions of the downhole environment. In an exemplary embodiment, reagent  333  mixes with fluids within the downhole environment to form an electrolytic fluid. In an exemplary embodiment, the resulting electrolytic fluid degrades substrate  331  at a second rate. In certain embodiments, the substrate  331  exposed to the electrolytic fluid formed from reagent  333  can degrade at a second rate 2 to 1000 times faster than substrate  331  degrading exposed to a downhole environment alone. 
     In certain embodiments, cavities  332  can include a protective material  338 . Protective material  338  can be a degradable material that degrades at a different rate than substrate  331  to control the mixing and release of reagent  333  and further prevent undesired release of reagent  333 . In certain embodiments, protective material  338  can cover portions of cavity  332 , all of cavity  332 , or portions or all of reagent  333 . Protective material  338  can include, but is not limited to polyurethane, Teflon, etc. In certain embodiments, protective material  338  can include a gel with a controlled or otherwise predetermined degradation. In certain embodiments, protective material  338  can include enteric coatings that are stable at low pH levels but can quickly degrade in neutral or alkaline environments. 
       FIG. 4  shows an exemplary embodiment of wedge  424 . Similarly, wedge  424  can include cavities  432  with reagent  433 . Similarly, cavities  432  can be disposed in non-integral portions of wedge  424  such as non-load bearing portions. In certain embodiments, the cavities  432  are lined with protective lining  438 . In an exemplary embodiment, wedge  424  is formed of degradable substrate  431 , having an upper face  440  and a lower face  442 . 
     Therefore, in one aspect, a downhole device for use in a downhole environment is disclosed, including: a first material that degrades at a first rate when exposed to the downhole environment, and a second material protected from the downhole environment, wherein the second material when exposed to the downhole environment degrades the first material at a second rate greater than the first rate. In certain embodiments, a cavity is formed in the first material, wherein the cavity contains the second material. In certain embodiments, the second material is a solid second material. In certain embodiments, the second material is a gel second material. In certain embodiments the downhole device further includes a protective material to control exposure of the second material to the downhole environment. In certain embodiments, the protective material is formed of at least one of a group consisting of: Teflon and polyurethane. In certain embodiments, the second material is formed of at least one of a group consisting of: acidic oxides, acidic salts, neutral salts, and basic salts. In certain embodiments, the at least one cavity is disposed in a non-load bearing portion of the first material. In certain embodiments, the at least one cavity is disposed in a non-integral portion of the first material. In certain embodiments, the downhole device is a bottom sub. In certain embodiments, the downhole device is a cone. 
     In another aspect, a method to degrade a downhole device in a downhole environment, is disclosed, including: providing a first material in the downhole environment; providing a second material protected from the downhole environment; degrading the first material at a first rate in response to exposure to the downhole environment; exposing the second material to the downhole environment and the first material; and degrading the first material at a second rate in response to exposure to the downhole environment and the second material, wherein the second rate is greater than the first rate. In certain embodiments, the method further includes forming a cavity in the first material; and providing the second material within the cavity. In certain embodiments, the second material is a solid second material. In certain embodiments, the second material is a gel second material. In certain embodiments, the method further includes controlling exposure of the second material to the downhole environment via a protective material. In certain embodiments, the downhole device is a bottom sub. In certain embodiments, the downhole device is a cone. 
     In another aspect, a downhole system for use in a downhole environment, is disclosed, including a casing string; and a downhole device associated with the casing string, including a first material that degrades at a first rate when exposed to the downhole environment, and a second material protected from the downhole environment, wherein the second material when exposed to the downhole environment degrades the first material at a second rate greater than the first rate. In certain embodiments, a cavity is formed in the first material, wherein the cavity contains the second material. 
     The foregoing disclosure is directed to certain specific embodiments for ease of explanation. Various changes and modifications to such embodiments, however, will be apparent to those skilled in the art. It is intended that all such changes and modifications within the scope and spirit of the appended claims be embraced by the disclosure herein.