Methods of adjusting the rate of galvanic corrosion of a wellbore isolation device.

(54) Title: METHODS TO ADJUST THE GALVANIC CORROSION SPEED OF A WELL ISOLATION DEVICE.

(54) Title: METHODS OF ADJUSTING THE RATE OF GALVANIC CORROSION OF A WELLBORE ISOLATION DEVICE.

(57) Summary

A well insulation device comprises a first material and pieces of a second material, where the first material: is a metal or metal alloy; it forms an array of the part of the well isolation device; and it partially or totally dissolves when there is a partially conductive path between the first material and the second material and at least a part of the first and second material are in contact with the electrolyte, where the pieces of the second material: are a metal or alloy metallic; and they are embedded within the matrix of the first material; where the first material and the second material form a galvanic pair and where the first material is the anode and the second material is the cathode of the pair. The well insulation device also includes a bonding agent to bond the pieces of the second material inside the matrix of the first material.

(57) Abstract

A wellbore isolation device comprises a first material and pieces of a second material, where the first material: is a metal or a metal alloy; forms a matrix of the portion of the wellbore isolation device; and partially or wholly dissolves when an electrically conductive path exists between the first material and the second material and at least a portion of the first and second materials are in contact with the electrolyte, where the pieces of the second material: are a metal or metal alloy; and are embedded within the matrix of the first material; where the first material and the second material form a galvanic couple and where the first material is the anode and the second material is the cathode of the couple. The isolation device can also inelude a bonding agent for bonding the pieces of the second material into the matrix of the first material.

METHODS TO ADJUST THE GALVANIC CORROSION SPEED OF A WELL ISOLATION DEVICE

FIELD OF THE INVENTION

An isolation device and methods of removing the isolation device are provided. The isolation device includes at least one first material that is capable of dissolving by galvanic corrosion when an electrically conductive path exists between the first material and a different metal or metal alloy in the presence of an electrolyte. According to one embodiment, the isolation device is used in an oil or gas well operation. Various factors can be adjusted to control the dissolution rate of the first material in a desired amount of time

BRIEF DESCRIPTION OF THE FIGURES

The characteristics and advantages of certain modalities will be more easily appreciated when considered together with the attached figures. Figures should not be construed as limiting preferred modalities.

Figure 1 illustrates a well system that contains more than one isolation device.

Figure 2 represents an isolation device, according to one embodiment.

Ref. 266108

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the words understand, have, include, and all grammatical variations thereof are intended to have an open, non-limiting meaning, which does not exclude additional elements or steps.

It will be understood that, as used herein, first, second, third, etc., are arbitrarily assigned and are merely intended to differentiate between two or more materials, insulation devices, well gaps, etc., as appropriate, and do not indicate any specific sequence or orientation. Likewise, it will be understood that the simple use of the first term does not require that there be a second and that the simple use of the second term does not require that there be a third, etc.

As used herein, a fluid is a substance that has a continuous phase that tends to flow and conform to the contour of its container when the substance is analyzed at a temperature of 71 ° F (22 ° C) and a pressure of one atmosphere or atm (0.1 megapascals, MPa). A fluid can be a liquid or a gas.

Oil and gas hydrocarbons are of natural origin in some underground formations. In the oil and gas industry, an underground formation containing oil or gas is called an oil field. A deposit can be located underground or in the sea. Typically, reservoirs are located from a few hundred feet (shallow reservoirs) to a few tens of thousands of feet (ultra-deep reservoirs). In order to produce oil or gas, a well is drilled in the field or in a position adjacent to the field. The oil, gas, or water produced from a reservoir is called the reservoir fluid.

A well may include, but is not limited to, an injection well, or an oil, gas, or water production well. As used herein, a well includes at least one hole. A well can include vertical, inclined and horizontal parts, and can be straight, curved or branched. As used herein, the term well includes coated, uncoated, and open parts of the well. A region near the well is the underground material and rock from the underground formation surrounding the well. As used herein, a well also includes the region near the hole. The region near the well is generally considered to be the region within a radius of approximately (30.48 m) 100 feet from the well. As used herein, in a well means and includes anywhere in the well, including the hole in the region near the well through the well.

A part of a well can be an open hole or a covered hole. In a part of an open hole well, a string of pipe can be placed inside the well. The pipe string allows fluids to be introduced or flowed from a remote part of the well. In a lined well part, a liner pipe is placed in the well that may also contain a string of pipe. A well can contain an annular space. Examples of annular spaces include, but are not limited to: the space between the well and the outside of the pipe string in an open well; the space between the well and the outside of the casing in a cased well; and the space between the inside of the casing and the outside of the pipe string in a casing.

It is not unusual for a well to span several hundred feet or several thousand feet in an underground formation. The underground formation can have different zones. A zone is a range of rock differentiated from the surrounding rocks based on their fossil content or other characteristics, such as faults or fractures. For example, one zone may have a higher permeability compared to another zone. It is often preferred to treat one or more locations in multiple areas of a formation. One or more zones of the formation can be isolated within the well by using an isolation device to create multiple well intervals. At least one well interval corresponds to one area of ​​the formation. The isolation device can be used for zonal isolation and works to block fluid flow within a tubular, for example, a string of pipe or within an annular space. Blocking fluid flow prevents fluid from flowing through the isolation device in any direction and isolates the area of ​​interest. In this way, treatment techniques can be practiced in the area of ​​interest.

Common isolation devices include, but are not limited to, a sphere and a seat, a bridge plug, a packer, a plug, and a cleaning plug. It will be understood that the reference to a sphere is not intended to limit the geometric shape to a spherical shape, but is intended to include any device that can be linked to a seat. A sphere can be spherical, but it can also be dart, bar, or any other shape. Zonal isolation can be achieved by means of a sphere and seat, by releasing or flowing the sphere from the well head to the seat located inside the well. The sphere meshes with the seat and the seal created by this union prevents fluid communication at other well intervals subsequent to the sphere and seat. As used herein, the term "relative back" means at a location remote from a wellhead. To treat more than one area with a sphere and seat, the well may contain more than one sphere seat. For example, a seat may be located within each well interval. Generally, the internal diameter (ID) of ball seats is different for each zone. For example, the ID of ball seats decreases sequentially in each zone, moving from the wellhead to the bottom of the wellbore. Thus, a smaller sphere is first dropped into a first wellbore which is the furthest posterior; the corresponding area is treated; then a slightly larger sphere is dropped into another hole interval that is a location prior to the first hole interval; then that corresponding area is treated; and the process continues in this way, moving backwards along the well, until all the desired areas are treated. As used herein, the above relative term means at a location closer to the wellhead.

A bridge plug consists primarily of jaws, a plug mandrel, and a rubber sealing element. It is possible to insert a bridge plug into a well and cause the closure element to block fluid flow at later intervals. A packer generally consists of a sealing device, a clamping or fixing device, and an internal fluid passage. A packer can be used to block fluid flow through the annular space located between the outside of a tubular structure and the wall of the well or the inside of a casing.

Isolation devices can be classified as permanent or recoverable. Although permanent isolation devices are generally designed to remain in the well after use, recoverable devices can be removed after use. It is often desirable to use a recoverable isolation device to restore fluid communication between one or more well intervals. Traditionally, isolation devices are recovered by inserting a recovery tool into the well that links to the isolation device, attaches to the isolation device, and then removes the isolation device from the well. Another way to remove an isolation device from the well is to grind at least part of the device or the entire device. However, another way to remove an isolation device is to bring the device into contact with a solvent, for example an acid, in order to dissolve all or part of the device.

However, some of the disadvantages of using traditional methods to remove a recoverable isolation device include: using a recovery tool can be difficult and time consuming, the grinding procedure can be time consuming and expensive, and the premature dissolution of the isolation device can take place. For example, premature dissolution may occur if acidic fluids are used in the well prior to the time the isolation device is to be dissolved.

A novel method of removing an isolation device includes the use of galvanic corrosion to dissolve at least part of the isolation device. The corrosion rate can be adjusted by selecting the materials used, the electrolyte used, the concentration of free ions available in the electrolyte, and the distance between the two materials in the galvanic system.

Galvanic corrosion occurs when two different metals or metal alloys are in electrical connectivity with each other and both are in contact with an electrolyte. As used herein, the term "electrical connectivity" means that two different metals or metal alloys are touching or close enough so that when the two different metals are in contact with an electrolyte, the electrolyte becomes conductive to the electricity and an ion migration occurs between one of the metals and the other metal, and is not intended to require a real physical connection between the two different metals, for example, using a metal cable. It will be understood that, as used herein, the term metal includes pure metals and also metal alloys, without the need to continually specify that the metal may also be a metal alloy. Furthermore, the use of the term metal or metal alloy in one sentence or paragraph does not mean that the mere use of the word metal in another sentence or paragraph excludes a metal alloy. As used herein, the term "metal alloy" means a mixture of two or more elements, where at least one of the elements is a metal. The other elements can be a nonmetal or a different metal. An example of a metal and a non-metallic alloy is steel, which comprises the metallic element iron and the non-metallic element carbon. An example of a metal and metal alloy is bronze, which includes the metallic elements copper and tin.

The less noble metal, compared to the other metal, will dissolve in the electrolyte. The less noble metal is often called the anode and the noblest metal is often called the cathode. Galvanic corrosion is an electrochemical process by which free ions in the electrolyte make the electrolyte electrically conductive, which provides a means for the migration of ions from the anode to the cathode, resulting in deposition formed at the cathode. The metals can be arranged in a galvanic series. The galvanic series lists the metals in order from the noblest to the least noble.

An anode index lists the electrochemical voltage (V) that develops between a metal and a standard reference electrode (gold (Au)) in a given electrolyte. The actual electrolyte used can affect where a specific metal or metal alloy appears in the galvanic series and can also affect the electrochemical voltage. For example, the dissolved oxygen content in the electrolyte can stipulate where the metal or metal alloy appears in the galvanic series and the electrochemical voltage of the metal. The anode index of gold is -0 V; while the anodic index of beryllium is -1.85 V. A metal that has a higher anodic index than another metal is nobler than the other metal and functions as the cathode. In contrast, metal that has a lower anode index than other metal is less noble and works as the anode. To determine the relative voltage between two different metals, the anode index of the least noble metal is subtracted from the anode index of the other metal, resulting in a positive value.

There are several factors that can affect the speed of galvanic corrosion. One of the factors is the distance that separates the metals in the galvanic series diagram or the difference between the anode indices of the metals. For example, beryllium is one of the last metals to appear at the least noble end of the galvanic series, and platinum is one of the first metals to appear at the most noble end of the series. In contrast, tin appears directly below lead in the galvanic series. Using the anode index of metals, the difference between the anode index of gold and beryllium is 1.85 V; while the difference between tin and lead is 0.05 V. This means that galvanic corrosion will occur at a much higher rate for magnesium or beryllium and gold compared to lead and tin.

The following is a partial galvanic series diagram that uses a deoxygenated sodium chloride water solution as the electrolyte. The metals are listed in descending order, from the noblest (cathodic) to the least noble (anodic). The following list is not exhaustive and one skilled in the art can find where a specific metal or metal alloy appears in a galvanic series in a given electrolyte.

PLATINUM

GOLD

ZIRCONIUM

GRAPHITE

SILVER

CHROME IRON

SILVER WELDING

COPPER - NICKEL ALLOY 80-20

COPPER - NICKEL ALLOY 90-10

MANGANESE BRONZE (CA 675), TIN BRONZE (CA903, 905)

COPPER (CA102)

BRASS

NICKEL (ACTIVE)

TIN

LEAD

ALUMINUM BRONZE

STAINLESS STEEL

CHROME IRON

SOFT STEEL (1018), WROUGHT IRON

ALUMINUM 2117, 2017, 2024

CADMIUM

ALUMINUM 5052, 3004, 3003, 1100, 6053

ZINC

MAGNESIUM BERYLIUM

The following is a partial anodic index that lists the voltage of a listed metal based on a standard reference electrode (gold) that uses a deoxygenated sodium chloride water solution as the electrode. The metals are listed in descending order, from the highest voltage (most cathodic) to the lowest voltage (most anode). The following list is not exhaustive, and the person skilled in the art can find the anode number of a specific metal or metal alloy in a given electrolyte.

<td colspan="2">anode index</td>

<td>Metal</td><td>index (V)</td>

<td>Gold, solid and plated, gold-platinum alloy</td><td> -0,00</td>

<td>Rhodium plated silver-plated copper</td><td> -0,05</td>

<td>Silver, solid or plated; monel metal. High nickel-copper alloys</td><td> -0,15</td>

<td>Nickel, solid or plated, titanium, s alloys, Monel</td><td> -0,30</td>

<td>Copper, solid or plated; lower brass or brass; silver solder; German silver plated high nickel copper alloys; nickel-chrome alloys</td><td> -0,35</td>

<td>Brass and bronzes</td><td> -0,40</td>

<td>Higher brass and brass</td><td> -0,45</td>

<td>18% chrome corrosion resistant steels</td><td> -0,50</td>

<td>Chrome plated; tin plated; 12% chrome corrosion resistant steels</td><td> -0,60</td>

<td>Tin-sheet metal; tin-lead solder</td><td> -0,65</td>

<td>Lead, solid or plated; high lead alloys</td><td> -0,70</td>

<td>2000 Series Forged Aluminum</td><td> -0,75</td>

<td>Iron, wrought, gray or malleable, plain carbon and low alloy steels</td><td> -0,85</td>

<td>Aluminum, forged alloys other than 2000 series aluminum, molten silicon-type alloys</td><td> -0,90</td>

<td>Aluminum, cast alloys other than silicon, cadmium, plating and chromate</td><td> -0,95</td>

<td>Hot-dip galvanized sheet metal; Galvanised steel</td><td> -1,20</td>

<td>Zinc, forged; zinc based die casting alloys; zinc plated</td><td> -1,25</td>

<td>Magnesium and magnesium base alloys, cast or forged</td><td> -1,75</td>

<td>Beryllium</td><td> -1,85</td>

Another factor that can affect the galvanic corrosion rate is the temperature and concentration of the electrolyte. The higher the temperature and concentration of the electrolyte, the higher the corrosion rate. Another factor that can affect the galvanic corrosion rate is the total amount of surface area of ​​the least noble metal (anodic metal). The larger the surface area of ​​the anode that comes in contact with the electrolyte, the higher the rate of corrosion. The cross sectional size of the anode metal chunks can be decreased to increase the total amount of surface area per total volume of the material. The anodic metal or metal alloy may also be a matrix in which pieces of the cathode material are embedded in the anode matrix. Another factor that can affect the galvanic corrosion rate is the ambient pressure. Depending on the chemistry of the electrolyte and the two metals, the corrosion rate may be higher at higher pressures than at lower pressures if gaseous components are generated. Another factor that can affect the galvanic corrosion rate is the physical distance between the two different metals and / or metal alloys of the galvanic system.

According to one embodiment, a method of removing a well isolation device comprises: contacting or allowing the well isolation device to contact an electrolyte, where at least a part of the well isolation device comprises a first material and pieces of a second material, where the first material: (A) is a metal or metal alloy; (B) forms an array of the well isolation device portion; and (C) partially or totally dissolves when there is a partially conductive path between the first material and the second material and at least a part of the first and second material are in contact with the electrolyte, where the pieces of the second material: (A ) are a metal or metal alloy; and (B) are embedded within the matrix of the first material; where the first material and the second material form a galvanic pair and where the first material is the anode and the second material is the cathode of the pair; and allowing at least a part of the first material to dissolve.

According to another embodiment, a method of removing a well isolation device comprises: contacting or allowing the well isolation device to come into contact with an electrolyte, where at least a part of the well isolation device comprises pieces of a first material, pieces of a second material and a third material, where the first material: (A) is a metal or metal alloy; and (B) partially or totally dissolves when there is a partially conductive path between the first material and the second material and at least a part of the first and second material are in contact with the electrolyte, where the second material is a metal or alloy. metallic, where the first material and the second material form a galvanic pair and where the first material is the anode and the second material is the cathode of the pair, and where the third material physically separates at least a part of a surface of one or more pieces of the first material from at least a part of a surface of one or more pieces of the second material; and allowing at least some chunks of the first material to dissolve.

Any discussion of the modalities regarding the isolation device or any component related to the isolation device (eg, electrolyte) is intended to apply to all modalities of the method.

Referring to the figures, Figure 1 depicts a well system 10. Well system 10 may include at least one well 11. Well 11 may penetrate an underground formation 20. Underground formation 20 may be a part of a reservoir or be adjacent to a reservoir. Well 11 may include casing pipe 12. Well 11 may include only a generally vertical well section or may include only a generally horizontal well section. A string of pipe 15 may be installed in well 11. Well system 10 may comprise at least a first well interval 13 and a second well interval 14. Well system 10 may also include more than two well intervals, for example well system 10 may further include a third well interval, a fourth well interval, and so on. At least one well interval may correspond to an area of ​​the underground formation 20. Likewise, the well system 10 may include one or more packers 18. Packers 18 can be used in addition to the isolation device to create the pit intervals and isolate each zone of the underground formation 20. Packers 18 can be the isolation device. Packers 18 can be used to prevent the flow of fluids between one or more well intervals (for example, between the first well interval 13 and the second well interval 14) through annular space 19. Pipe string 15 may also include one or more ports 17. There may be one or more ports 17 located in each well interval. Furthermore, it is not necessary that all well intervals include one or more ports 17. For example, the first well interval 13 may include one or more ports 17, while the second well interval 14 does not contain a port. In this way, the fluid flow in annular space 19 can be selected for a specific well interval based on the specific oil or gas operation.

It should be mentioned that the well system 10 is illustrated in the figures and is described herein merely as an example of a wide variety of well systems in which the principles of this description can be used. It should be clearly understood that the principles of this disclosure are not limited to any of the details of the well system 10, or the components therein, depicted in the figures or described herein. Furthermore, well system 10 may include other components not shown in the figure. For example, well system 10 may further include a well filter. By way of another example, cement can be used in place of packers 18 to assist the isolation device in providing zonal isolation. Cement can also be used in addition to packers 18.

According to one embodiment, the isolation device can restrict or prevent the flow of fluids between a first well interval 13 and a second well interval 14. The first well interval 13 may be located in a position before or after the second well interval 14. Thus, depending on oil or gas operation, fluids are restricted or prevented from flowing in either direction in the second well interval 14. Examples of isolation devices capable of limiting or preventing the flow of fluids between zones include, but are not limited to, a sphere and a seat, a plug, a bridge plug, a cleaning plug, a packer, and a plug in a base pipe. . A detailed discussion of the use of a plug in a base pipe can be found in US Patent 7,699,101 to Michael L. Fripp, Haoyue Zhang, Luke W. Holderman, Deborah Fripp, Ashok K. Santra, Anindya Ghosh on April 20, 2010, which is hereby incorporated in its entirety for all purposes. If there is any conflict in the use of a word or phrase herein and any document incorporated by reference, the definitions contained herein will be taken into account. The part of the isolation device that includes at least the first material and the second material can be the mandrel of a packer or plug, a spacer ring, a wedge, a retaining ring, an extrusion limiter or support shoe, a shoe mule, ball, check valve, ball seat, sleeve, or any other wellbore tool or wellbore tool component used for zonal isolation.

As illustrated in the figures, the isolation device can be a sphere 30 (for example, a first sphere 31 or a second sphere 32) and a seat 40 (for example, a first seat 41 or a second seat 42). The sphere 30 can be linked with the seat 40. The seat 40 can be located inside a string of pipe 15. The internal diameter (ID) of the first seat 41 may be less than the ID of the second seat 42. In this way, a first sphere 31 can be dropped or flowed into the well. The first sphere 31 may have a smaller outer diameter (OD) than the second sphere 32. The first sphere 31 may mesh with the first seat 41. Fluid flow is temporarily restricted or prevented in any well range located in a position after the first hole interval 13. In the event that it is desirable to temporarily restrict or prevent fluid flow in any well interval located posterior to the second well interval 14, the second sphere 32 may be dropped or flowed into the well and prevented from falling beyond the second seat 42 since the second sphere 32 has a larger DE than the ID of the second seat 42. The second sphere 32 can be linked with the second seat 42. The sphere (either a first sphere 31 or a second sphere 32) can engage with a sliding sleeve 16 during placement. This link with the sliding sleeve 16 can cause the sliding sleeve to move and therefore open a port 17 located adjacent to the seat. Port 17 can also be opened through a variety of mechanisms instead of a sphere. The use of other mechanisms can be beneficial when the isolation device is not a sphere. After placement of the isolation device, fluid can be flowed from or into the underground formation 20 by means of one or more open ports 17 located within a specific well range. As such, a fluid can be produced in the underground formation 20 or can be injected into the formation.

Referring to Figures 2-3, the isolation device comprises at least a first material 51, where the first material dissolves partially or completely when an electrically conductive path exists between the first material 51 and the second material 52. The First material 51 and second material 52 are metals or metal alloys. The metal or metal alloy can be selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, beryllium, calcium, strontium, barium, radium, aluminum, gallium, indium, tin, thallium, lead, bismuth, scandium, titanium , vanadium, chromium, manganese, thorium, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, praseodymium, silver, cadmium, lanthanum, tantalum, tungsten, terbium, rhenium , osmium, iridium, platinum, gold, neodymium, gadolinium, erbium, oxides of any of the above, graphite, carbon, silicon, boron nitride and any combination of these. Preferably, the metal or metal alloy is selected from the group consisting of magnesium, aluminum, zinc, beryllium, tin, iron, nickel, copper, oxides of any of the foregoing, and combinations thereof. According to one embodiment, the metal is neither radioactive nor unstable.

According to one embodiment, the first material 51 and the second material 52 are different metals or metal alloys. By way of example, the first material 51 may be magnesium and the second material 52 may be iron. Furthermore, the first material 51 can be a metal and the second material 52 can be a metal alloy. The first material 51 and the second material 52 can be a metal and the first material and the second material can be a metal alloy. The first material and the second material form a galvanic pair and where the first material is the anode and the second material is the cathode of the pair. Otherwise, the second material 52 is more noble than the first material 51. In this way, the first material 51 (which acts as the anode) partially or totally dissolves when it is in electrical connectivity with the second material 52 and when the first material and the second material are in contact with the electric.

Methods include allowing at least a portion of the first material or at least some pieces of the first material to dissolve. The permitting step may be carried out after the contacting step or allowing the first material to contact the electrolyte. . At least a part of the first material 51 can be dissolved in a desired amount of time. The desired amount of time can be pre-determined, based in part on the specific oil or gas well operation to be performed. The desired amount of time may be in the range of from about 1 hour to about 2 months, preferably from about 5 to about 10 days. There are several factors that can affect the dissolution rate of the first material 51. According to one embodiment, the first material 51 and the second material 52 are selected such that at least a part of the first material 51 dissolves in the desired amount of time. As an example, the greater the difference between the anode index of the second material and the anode index of the first material, the greater the dissolution rate. Conversely, the smaller the difference between the anode index of the second material and the anode index of the first material, the lower the dissolution rate. By way of another example, the further away the first material and the second material are from each other in a galvanic series, the higher the dissolution rate; and the closer the first material and the second material are to each other in the galvanic series, the lower the dissolution rate. By evaluating the difference in the anode index of the first material and the second material, or evaluating the order in a galvanic series, the person skilled in the art will be able to determine the dissolution rate of the first material in a certain electrolyte.

Another factor that can affect the dissolution rate of the first material 51 is the proximity between the first material 51 and the second material 52. A detailed discussion regarding the different modalities of the proximity of the first and second materials is presented below. In general, the closer you are to the first material 51 from the second material 52, the greater the dissolution rate of the first material

51.

In contrast, in general, the farther the first and second materials are from each other, the lower the dissolution rate.

It should be noted that the distance between the first material 51 and the second material 52 should not be so great as to cause an electrically conductive path to cease to exist between the first and second materials. According to one embodiment, any distance between the first and second material 51/52 is selected such that at least a part of the first material 51 dissolves in the desired amount of time.

Another factor that can affect the dissolution rate of the first material 51 is the concentration of the electrolyte and the temperature of the electrolyte. A more detailed discussion of the electrolyte is presented below. In general, the higher the electrolyte concentration, the higher the dissolution rate of the first material 51, and the lower the electrolyte concentration, the lower the dissolution rate. Furthermore, the higher the electrolyte temperature, the higher the dissolution rate of the first material 51, and the lower the electrolyte temperature, the lower the dissolution rate. A person skilled in the art can select: the exact metals and / or metal alloys, the proximity between the first and second material and the concentration of the electrolyte based on the anticipated temperature so that at least a part of the first material 51 dissolves in the amount desired time.

Figure 2 represents the isolation device 30, according to certain modalities. According to this embodiment, the first material 51 forms an array of the part of the well device containing the first material 51 and the second material 52. It will be understood that the complete isolation device, for example, when the isolation device is a sphere or a sphere seat, may be made of at least the first material and the second material. Furthermore, only one or more parts of the isolation device can be made of at least the first material and the second material. As can be seen in Figure 2, the second material 52 can be in the form of pieces, where the pieces of the second material are embedded within the matrix of the first material 51. The exact amount or concentration of the pieces of the second material 52 can be selected and adjusted to control the dissolution rate of the first material 51 so that at least the part of the first material 51 dissolves in the desired amount of time. For example, the higher the concentration of pieces of the second material 52 that are embedded within the matrix of the first material 51, in general, the higher the dissolution rate. Furthermore, the pieces of the second material 52 can be evenly distributed along the matrix of the first material 51. This embodiment can be useful when a constant dissolution rate of the first material is desired. The pieces of the second material may also be unevenly distributed throughout the matrix of the first material, such that different concentrations of the second material are located within different areas of the matrix. As an example, a higher concentration of the pieces of the second material can be distributed closer to the outside of the matrix to allow an initially higher dissolution rate; while a lower concentration of the pieces can be distributed in the center and inside of the matrix to allow a lower dissolution rate. On the contrary, a higher concentration of the pieces of the second material can be distributed in the center and / or the interior of the matrix to allow a higher dissolution rate at the end of the dissolution; while a lower concentration of the pieces can be distributed closer to the outside of the matrix to allow an initially lower dissolution rate. Of course, the concentration of the pieces of the second material can be distributed in various ways to allow different dissolution rates of the matrix of the first material.

According to one embodiment, a third material is included in the part of the isolation device (not shown in Figure 2). The third material may be a bonding agent for bonding the pieces of the second material inside the die of the first material 51. This embodiment may be useful during the manufacturing process to provide a proper bond between the matrix of the first material 51 and pieces of the second material 52. Preferred manufacturing processes may include casting, forging, hot and / or cold production, metal injection molding, but exclude sintering and powder compaction. Preferably, the part of the isolation device is made by casting. Preferably, the part of the isolation device is also modified with a heat treatment. In one embodiment, heat treatment involves precipitation heat treatment, where the alloy is heated to allow precipitation of the constituent ingredients that are held in a solid solution. The temperature of the precipitation heat treatment can be in the range of 300 ° F to 500 ° F (149 ° C to 260 ° C) for 1 to 16 hours. For example, a forged metal alloy can be heated for 24 hours at 350 ° F (177 ° C). In another example, parts made by casting are heated during

<img file="MX2016005704A_D0001.tif" />

2 hours from 400 ° F to 500 ° F (204 ° C to 260 ° C), followed by slow cooling. The precipitation heat treatment may follow a solution heat treatment. A technical solution treatment involves heating the metal alloy to a temperature at which certain ingredients in the alloy go into solution, and then inactivating it, in order to keep these ingredients in solution during cooling. The solution heat treatment temperature can be in the range of 650 ° F to 1050 ° F (343 ° C to 566 ° C) for 10 to 24 hours.

Some examples of materials suitable for use as a third bonding material include, but are not limited to, copper, platinum, gold, silver, nickel, iron, chromium, molybdenum, tungsten, stainless steel, zirconium, titanium, indium, or oxides of any of the above. Preferably, the third material includes a metal and / or a nonmetal that is different from the metals that make up the first and second materials 51/52. In one example, the first material is aluminum, the second material is iron, and the third material is iron oxide. In another example, the first material is magnesium, the second material is carbon, and the third material is iron oxide. It may be desirable to use metal oxide to create a better bond between the first and second materials 51/52. The third material can be used to coat pieces of the second material 52. A layer of the third material can be located between the surfaces of the pieces of the second material and the matrix of the first material, where the surfaces of the pieces of the second material are physically separated from the matrix of the first material by means of the layer of the third material. The third material coating may form a metallic or metal oxide contact surface with the surface of each of the pieces of the second material 52 with the matrix of the first material 51. Accordingly, after fabrication, there will be a layer of the third material 53 located between the surfaces of the pieces of the second material 52 and the matrix of the first material 51. The thickness of the third material layer can be selected to provide the desired bond strength between the pieces of the second material 52 and the die of the first material 51. For example, if the layer is very thin then there will be insufficient quantity of the third material to create a satisfactory bond, and if the layer is very thick then the layer may become mechanically weak and mechanical failure may occur on the surface of contact between the third material 53 and the first or second material, or failure could also occur within the third material layer. Preferably, the thickness of the third material layer is in the range of from about 10 nanometers to about 100 nanometers. In another embodiment, the thickness of the third material is less than nanometers. In another embodiment, the thickness of the third material is from 100 nanometers to 5,000 nanometers.

Figure 3 represents the isolation device, according to certain modalities. As shown in Figure 3, the isolation device may comprise pieces of the first material 51, pieces of the second material 52, and the third material 53. Although this embodiment shown in Figure 3 illustrates the isolation device as a sphere, it should be understood that this embodiment and discussion of it can be applied equally to an isolation device that is a bridge plug, packer, etc. For galvanic corrosion (and therefore dissolution of at least part of the first material 51) to occur, both the first material and the second material 51/52 need to be able to be in contact with the electrolyte. Preferably, at least a part of one or more pieces of the first material 51 and of the second material 52 forms the exterior of the isolation device, such as a sphere 30. In this way, at least a part of the first and second material 51/52 is capable of being in contact with the electrolyte.

According to another embodiment, the third material 53 physically separates at least a part of a surface of one or more pieces of the first material 51 from at least a part of a surface of one or more pieces of the second material

52. These modalities may be useful when it is desired to use the distance between the first and second materials 51/52 as a way to control the dissolution rate of the first material 51. The third material 53 may also limit the ionic conductivity or electrical conductivity between the first and second material 51/52. According to one embodiment, the third material 53 is in the form of pieces. The third material can be selected from the group consisting of metals, nonmetals, sand, plastics, ceramics, and polymers. Preferably, the third material includes a metal and / or a nonmetal that is different from the metals that make up the first and second materials 51/52. The pieces of the third material 53 may be located between one or more pieces of the first and second material 51/52. The size and shape of the pieces of the third material 53 can be selected to provide a desired distance of separation of the first and second materials 51/52. By way of example, the greater the thickness of the cross section of the third material piece 53, the greater the reduction in ionic and / or electrical conductivity between the pieces of the first material 51 and the pieces of the second material 52. On the contrary, the smaller the thickness of the third material, the less the reduction of the ionic and / or electrical conductivity between the pieces of the first and second material 51/52. The pieces of the third material 53 can also separate two or more pieces of the first material 51 and / or two or more pieces of the second material 52. The size of the pieces of the third material 53 can be the same or different. Pieces of the third material having different thicknesses can be distributed throughout the part of the isolation device in a variety of ways to provide different dissolution rates. For example, larger pieces may be located toward the outside of the part of the isolation device; while the smaller pieces can be located towards the center and / or the internal part. This modality could provide an initially lower dissolution rate, due to the distance initially between the first and second material 51/52 and a higher speed for subsequent dissolution, due to a decrease in the distance between the first and second material 51 / 52. Of course, the distribution of the different size pieces of the third material 53 can be varied and selected to provide the desired dissolution rates of at least some pieces of the first material 51.

The concentration and distribution patterns of the third material 53 can also be selected to provide the desired dissolution rate of at least some pieces of the first material 51, so that at least some of the pieces of the first material dissolve in the desired amount of time . For example, in general, the higher the concentration of the third material, the higher the dissolution rate, and the lower the concentration of the third material, the lower the dissolution rate. Furthermore, the pieces of the third material 53 can be evenly distributed along the part of the insulation device that contains the first, second and third materials. This embodiment (assuming a relatively uniform size of the third material pieces) can be useful in providing a relatively constant dissolution rate of the third material pieces 51. The third material pieces 53 may also be unevenly distributed to along the part of the isolation device. By way of example, a higher concentration of the third material chunks may be distributed closer to the outside of the insulation distribution part to allow for an initially lower dissolution rate; while a lower concentration of the pieces can be distributed in the center and inside to allow a higher dissolution rate. On the contrary, a higher concentration of the pieces of the third material can be distributed in the center and / or the interior of the matrix to allow a lower dissolution rate at the end of the dissolution; while a lower concentration of the pieces can be distributed closer to the outside to allow an initially higher dissolution rate.

The pieces of the first material 51 and the pieces of the second material 52 can be joined together by a third material, as previously described with reference to Figure 2. Thus, the pieces of the first material and the pieces of the second material are They can be joined together to form part of the isolation device. The device of Figure 3 can also be optionally manufactured and subjected to the heat treatments described above.

The size, shape and placement of the pieces of the first and second material 51/52 can also be adjusted to control the dissolution rate of the first material 51. By way of example, generally, the smaller the cross-sectional area of ​​each piece, the higher the dissolution rate. The smaller cross-sectional area increases the ratio of the surface area to the total volume of the material, allowing a larger amount of material to come in contact with the electrolyte. The cross sectional area of ​​each piece of the first material 51 can be the same or different, the cross sectional area of ​​each piece of the second material 52 can be the same or different, and the cross sectional area of ​​the pieces of the first material 51 and the pieces second material 52 can be the same or different. Additionally, the cross-sectional area of ​​the pieces that form the outer part of the isolation device and the pieces that form the inner part of the isolation device may be the same or different. As an example, if it is desired that the external part of the isolation device continue at a higher rate of galvanic corrosion in

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smaller compared to the cross-sectional area of ​​the pieces that comprise the internal part. The shape of the pieces of the first and second material 51/52 can also be adjusted to allow more or less cross-sectional area.

According to one embodiment, at least the first material 51 and the second material 52 are capable of withstanding a specific pressure differential for a desired amount of time. As used herein, the term resist means that the substance does not crack, break, or collapse. The pressure differential may be the pressure inside the underground formation well 20 through the device. As used herein, the term "borehole interior" means the location of the borehole where the portion of the isolation device is located. Formation pressures can range from about 1,000 to about 30,000 pounds of force per square inch (psi) (from about 6.9 to about 206.8 megapascals, MPa). The pressure differential can also be created during oil or gas operations. For example, a fluid, when introduced into the well 11 in a position before or after the substance, can create a higher pressure above or below, respectively, the isolation device. Pressure differentials can range from 100 to over 10,000 psi (between about 0.7 to over 68.9 MPa). According to another embodiment, the isolation device can withstand a specific pressure differential for the desired amount of time. The amount of time may be desired to be at least 30 minutes. The desired amount of time can also be in the range of between about 30 minutes and 14 days, preferably between 30 minutes and 2 days, more preferably between 4 hours and 24 hours.

As discussed above, the dissolution rate of the first material 51 can be controlled through the use of a variety of factors. According to one embodiment, at least the first material 51 includes one or more tracers (not shown). Tracers can be, without limitation, radioactive, chemical, electronic or acoustic. As shown in Figure 3, each piece of the first material 51 can include a tracer. A tracer can be useful for determining real-time information on the dissolution rate of the first material 51. For example, a first material 51 that contains a tracer, upon dissolving, can flow through well 11 and into the wellhead or into the wellhead. the interior of the underground formation 20. By being able to monitor the presence of the tracer, surface workers can make decisions on the fly that may affect the dissolution rate of the rest of the first material 51.

Decisions may include increasing or decreasing the electrolyte concentration. As used herein, an electrolyte is any substance that contains free ions (i.e., a positively or negatively electrically charged atom or group of atoms) that makes the substance electrically conductive. The electrolyte can be selected from the group consisting of solutions of an acid, a base, a salt and combinations of these. A salt can be dissolved in water, for example, to create a salt solution. Common free ions in an electrolyte include sodium (Na⁺), potassium (K⁺), calcium (Ca^{2 +} ), magnesium (Mg^{2 +} ), chloride (Cl '), hydrogen phosphate (HPO₄²') and hydrogen carbonate (HCO₃'). The concentration (ie, the total amount of free ions available in the electrolyte) of the electrolyte can be adjusted to control the dissolution rate of the first material 51. According to one embodiment, the concentration of the electrolyte is selected such that upon least a part of the first material 51 dissolves in the desired period of time. If more than one electrolyte is used, the concentration of the electrolytes is selected such that the first material 51 dissolves in a desired period of time. The concentration can be determined at least based on the specific metals or metal alloys selected for the first and second 51/52 material and the downhole temperature of the well. Furthermore, since free ions in the electrolyte allow the electrochemical reaction to occur between the first and second materials 51/52 by donating their free ions, the amount of free ions will decrease as the reaction occurs. At some point, the electrolyte may become devoid of free ions if there is any unreacted 51/52 first or second material left. If this occurs, the galvanic corrosion that causes the first material 51 to dissolve stops. In this example, it may be necessary to cause or allow the first and second materials to come in contact with a second, third, or fourth electrolyte, and so on.

It may be desirable to delay contact of the first and second materials 51/52 with the electrolyte.

The isolation device may further include a coating 60 on the outside of the device.

The coating can be a compound, such as a wax, thermoplastic, sugar, salt, or a conductive polymer can include chromates, phosphates, and polyanilines.

The coating can be selected so that the coating dissolves in the well fluids, melts at certain temperatures, or breaks and falls off.

After dissolution or fusion, at least the first material 51 of the isolation solution is available to contact the electrolyte. The coating 60 can also be porous to allow the electrolyte to contact a part of the surface of the first and second material 51/52.

It may also be desirable to selectively dissolve certain portions of the first material 51 at different times or at different rates. By way of example, it may be desirable to dissolve the top of the isolation device first and then to dissolve the bottom at a later time. This can be accomplished, for example, by introducing a first electrolyte into the wellbore to contact the first and second materials 51/52. There are many operations, such as stimulation operations involving fracturing or acidification techniques, or tertiary recovery operations involving injection techniques, in which this may be desirable. After carrying out the desired operation, the bottom of the isolation device may contact produced formation fluid. The formation fluids can contain a sufficient concentration of free ions to allow the rest of the first material 51 to dissolve.

The methods include the step of contacting or allowing the well isolation device to contact the electrolyte. The contacting step may include introducing the electrolyte into the well 11. The permitting step may include allowing the isolation device to come into contact with a fluid, such as a reservoir fluid. Methods may include contacting or allowing the device to come in contact with two or more electrolytes. If more than one electrolyte is used, the free ions in each electrolyte may be the same or different. A first electrolyte can be, for example, a stronger electrolyte compared to a second electrolyte. Furthermore, the concentration of each electrolyte can be the same or different. It will be understood that when analyzing the concentration of an electrolyte, reference is made to a concentration prior to contact with either the first or second material 51/52, since the concentration will decrease during the galvanic corrosion reaction.

Tracers can be used to help determine the necessary concentration of electrolyte to help control the rate and irreversibility of the dissolution of the first material.

51. For example, if you want the first material to dissolve until a point device is allowed to flow to

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the first and second well speed or you can 5 days and the electrolyte speed plus the dissolution speed is too high, you can discharge the first electrolyte from the well and then you can introduce a less concentrated electrolyte into the well.

The methods may further include the step of placing the isolation device in a part of the well 11, where the stage of placing is performed before

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isolation device in multiple parts of the well.

The methods may further include the step of removing all or part of the dissolved first material 51 and / or all or part of the second material 52 or substance 60, where the removal step is performed after the step of allowing at least a part of the first material dissolves. The removal step may include flowing the first material 51 and / or the second third material 52 or substance 60 from the well 11. According to one embodiment, a sufficient amount of the first material 51 is dissolved so that the isolation device is capable of flowing from well 11. According to this embodiment, the isolation device should be able to flow from the well by dissolving the first material 51, without the use of a milling apparatus, recovery apparatus, or other similar apparatus commonly used to remove isolation devices. According to one embodiment, after dissolution the first material 51, the second material 52 or the substance 60 has a cross-sectional area less than (0.32 cm²) 0.05 square inches, preferably less than (0.06 cm²)

0.01 square inches.

Therefore, the present invention is satisfactorily adapted to achieve the purposes and advantages mentioned, as well as those inherent therein. The particular embodiments described above are merely illustrative, as the present invention can be modified and can be practiced in various but equivalent ways that are obvious to one skilled in the art having the benefit of what is described herein. Furthermore, it is not intended to limit the construction or design details shown herein, except as described in the claims below. It is evident, therefore, that the particular illustrative embodiments described above may be altered or modified and that all variations are deemed to be within the scope and spirit of the present invention. While compositions and methods are described in terms of comprising, containing or including various components or steps, the compositions and methods may 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 described, any number and any range included within the range is specifically described. In particular, it is understood that each range of values ​​(in the form of from about a to about b, equivalently, from about a to b) described herein establishes every number and range of values. Unless claims are defined in a manner defined by the owner, which is understood by the interval in turn, the terms have their common and usual meaning, explicitly and clearly from another of the patent. In addition, one or one indefinite articles, as used in the claims, are defined herein as one or more than one of the elements presented. Should there be any conflict in the uses of a word or term in the present description and one or more patents or other documents that may be incorporated herein by reference, the definitions that are consistent with the present description should be adopted.

It is noted that in relation to this date, the best method known by the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.