Device and method for light dissolvable encapsulation activation for downhole applications

A downhole device that drills a wellbore includes a stabilizer which has a body and blades. The blades are disposed on a surface of the body and each blade has a hollow space. The blades each include a dissolvable window that is disposed on a surface of each of the blades and a light source that emits light to the wellbore. The dissolvable window blocks light emitted from the light source thereby reducing or eliminating light from being transmitted to the wellbore. The dissolvable window dissolves upon exposure to a fluid containing a dissolving medium, thereby allowing the light source to transmit light to the wellbore. Methods of using the downhole device to activate downhole chemicals are also provided.

BACKGROUND

Wells are drilled into subsurface formations to produce valuable resources, such as oil and gas. A well is typically drilled by a downhole device to form a wellbore. A downhole device is inaccessible from a surface when lowered into a well and a downhole environment. It can be difficult to treat downhole issues such as lost circulation, shale stability, stuck pipe, and friction reduction that are caused downhole during drilling.

In order to deal with the aforementioned downhole issues, chemical treatments that respond to external stimuli (e.g., pH, temperature, pressure, light, electric field, and magnetic field) and drilling tools may be used. However, such external stimuli and drilling tools are not within the control of a downhole device from the surface. Therefore, development of new tools or modification of existing tools are needed to support chemical treatments in the downhole environment.

SUMMARY

In one aspect, embodiments disclosed herein relate to a downhole device that drills a wellbore including a stabilizer. The stabilizer may include a body and blades that are disposed on a surface of the body, and each blade may have a hollow space. The blades may further include a dissolvable window disposed on a surface of each of the blades and a light source that is configured to emit light to the wellbore. The dissolvable window may block light emitted from the light source thereby reducing or eliminating light from being transmitted to the wellbore. Furthermore, the dissolvable window may dissolve upon exposure to a fluid containing a dissolving medium, thereby allowing the light source to transmit light to the wellbore.

In another aspect, embodiments disclosed herein relate to a method for activating downhole chemicals, wherein the method may include providing a stabilizer that includes a body and blades disposed on a surface of the body, and each blade has a hollow space. Furthermore, the blades each include a dissolvable window disposed on a surface of each of the blades, and a light source that is configured to emit light to the wellbore. The method may further include introducing a fluid containing a dissolving medium and photosensitive capsules into the wellbore such that the dissolving medium contacts the dissolvable window, dissolving the dissolvable window thereby exposing the wellbore to the light source, exposing photosensitive capsules to light emitted from the light source, and degrading the photosensitive capsules by irradiation of the light.

DETAILED DESCRIPTION

Specific embodiments of the disclosure will now be described in detail with reference to the accompanying figures. Like elements in the various figures are denoted by like reference numerals for consistency.

“Uphole” may refer to objects, units, or processes that are positioned closer to the surface entry in a wellbore. “Downhole” may refer to objects, units, or processes that are positioned farther from the surface entry in a wellbore.

Embodiments disclosed herein generally relate to downhole devices and methods that activate downhole chemicals in accordance with one or more embodiments. In one or more embodiments, a fluid introduced into the wellbore contains a dissolving medium, at least one reactant, and photosensitive capsules that respond to light. Furthermore, the photosensitive capsules contain chemical substances useful for downhole applications such as super absorbent polymers or crosslinkers. Once the chemical substances inside the photosensitive capsules are released into the fluid by irradiation of light, the super absorbent polymers or crosslinkers undergo chemical reaction with the reactants in the fluid. The super absorbent polymers, crosslinkers and reactants in the fluid may be selected so that a variety of chemical reactions may be caused to address various downhole situations.

FIG.1illustrates a system1in accordance with one or more embodiments of the present disclosure. As shown inFIG.1, a system1may include a downhole device10, a rig20, a fluid tank30, and one or more pumps40. The rig20is the machine used to drill a borehole to form a wellbore50. The rig20may include drilling fluid tanks, drilling fluid pumps (e.g., rig mixing pumps), a derrick or mast, drawworks, a rotary table or top drive, drill string, power generation equipment and auxiliary equipment.

The downhole device10drills a borehole into the earth, such as drilling oil and natural gas wells. The borehole may be referred to as a downhole environment. The downhole device10may include a drill pipe100, a stabilizer101, and a drill bit103on a tip of the downhole device10to drill a borehole. The stabilizer101may include a blade102on a surface of the body of the stabilizer101. The downhole device10may further contain a rig20disposed above the opening of the borehole.

A drilling fluid may be pumped down a wellbore50from the rig20that may contain tanks with drilling fluid. The drilling fluid may be referred to as drilling mud or simply mud. The mud may be an oil-based mud or a water-based mud. A fluid301containing chemicals and a dissolving medium may be pumped from a fluid tank30using pumps40and flows through the drill pipe100to the drill bit103, flows out from the drill bit103and circulates back up in the wellbore50.

The blade102is disposed on the surface of the body of the stabilizer101and stabilizes the downhole device10in the borehole.

In a drilling operation, the fluid301may be pumped from a drilling tank30using one or more pumps40to send the fluid301to the downhole device10flowing through the drill pipe100into the borehole. The flow rate of the fluid301may be adjusted by setting a pumping rate of the pumps40per standard drilling protocols. In accordance with one or more embodiments of the present disclosure, the fluid may include a dissolving medium, at least one reactant, and photosensitive capsules.

FIGS.2A and2Bare schematic diagrams of a downhole device including a body1011of the stabilizer101and blades102disposed on a surface of the body1011. Each of the blades102contain a dissolvable window1021and a light source1022in accordance with one or more embodiments. The dissolvable window1021and the light source1022may be disposed at the same height along the axial direction of the stabilizer101. A blade102may be disposed on the surface of the body1011of the stabilizer101. In the embodiments shown inFIGS.2A and2B, the blade102is straight and positioned parallel to the drill pipe. However, as may be appreciated by those skilled in the art, the position and shape of the blade may vary. For example, the blade may be straight and positioned diagonally along the body of the stabilizer. The angle of the diagonal of the blade as compared to the body may also vary. For example, the angle of the blade as compared to the body may be around 30°, 45° or 60°. Some blades may be curved rather than straight.

FIG.2Ashows a dissolvable window1021blocking the light emitted from the light source1022from being transmitted to the wellbore50.FIG.2Bshows the light1025emitted from the light source1022being transmitted (as indicated by the horizontal arrows) via a dissolved window1024to the wellbore50when the dissolvable window1021is dissolved by a fluid301containing a dissolving medium. Such a fluid may be introduced into the drill pipe and circulates back up through the wellbore50towards the surface thereby contacting the dissolvable window as it travels uphole.

In one or more embodiments of the present disclosure, a blade102may include a dissolvable window1021and a light source1022. The light source1022may emit light1025to the outside of the stabilizer and into the wellbore (FIGS.2B and3B).

FIGS.3A and3Bare top-down views of a stabilizer101including a body1011and blades102disposed on a surface of the body1011. Each blades102contain a dissolvable window1021and a light source1022in accordance with one or more embodiments. As shown inFIG.3A, the dissolvable window1021may be disposed on the surface of the blade102and the light source1022is disposed in the hollow space of the blade102. As shown inFIG.3B, when the dissolvable window1021is dissolved by contacting the fluid301flowing in the wellbore, the light1025emitted from the light source1022is transmitted via dissolved window1024to the wellbore.

As shown inFIG.2A, the dissolvable window1021of one or more embodiments blocks the light emitted from the light source1022thereby reducing or eliminating light from being transmitted to the wellbore50at normal state. In the present disclosure, a “normal state” refers to a state with no dissolving medium introduced into the drill pipe. When a fluid301containing a dissolving medium is pumped through the drill pipe and flows out from drill bit103to the wellbore50, the dissolvable window1021is in contact with the fluid301and is dissolved by the dissolving medium thereby causing the light source1022to transmit light1025to the wellbore50(FIGS.2B and3B).

In one or more embodiments of the present disclosure, the dissolvable window1021may be made of a dissolvable metal or a dissolvable polymer. The dissolvable metal may be magnesium-based alloy or aluminum-based alloy. The dissolvable metal may be a commercially available product, such as those available from Terves Inc. (Euclid, Ohio). For example, the TervAlloy™ product line from Terves Inc. may include a number of suitable materials to be used as the dissolvable metal. The dissolvable metal may be selected based on its mechanical properties and its dissolution rate in different solutions. The dissolvable polymer of the dissolvable window1021may be a dissolvable polymer such as polyglycolic acid (PGA) or polylactic acid (PLA). In one or more embodiments of the present disclosure, the dissolvable window1021including dissolvable metal or dissolvable polymer may have thickness of from about 1 mm to about 50 mm.

In one or more embodiments of the present disclosure, the dissolving medium contained in the fluid301may be selected from the group consisting of brine, acid, water, and combinations thereof. The brine and acid composition may be selected based on the composition of the dissolvable window. For example, the brine may be potassium chloride in a suitable concentration range, such as from about 0.1 wt. % (weight percent) to about 25 wt. % in the dissolving medium. The acid may be any suitable acid known to a person of ordinary skill in the art, and its selection may be determined by the specific dissolvable window being used. In some embodiments, the acid may be one or more selected from the group consisting of hydrochloric acid, sulfuric acid, carboxylic acids such as acetic acid, and hydrofluoric acid. The acid may be included in the dissolving medium in an amount ranging from about 0.1 wt % to about 25 wt. %.

In one or more embodiments of the present disclosure, when the temperature and pressure of the downhole environment are fixed, the dissolving rate of the dissolvable window1021can be selected by changing fluid composition of the fluid301. The dissolving rate of the dissolvable window1021including dissolvable metal can be controlled by the concentration of brine or acid which are selected as dissolving mediums. When a brine having concentration in the range of 0.1% to 25% is used as a dissolving medium in conjunction with a dissolvable metal window, metal hydroxide powder is produced from a reaction between the dissolvable metal and the brine. The metal hydroxide powder may be flushed away by the dynamic flow of the fluid. In one or more embodiments, when an acid with a concentration in the range of 0.1% to 25% is used as a dissolving medium in conjunction with a dissolvable metal window, the product of a reaction between the dissolving medium and the acid may be ions that are soluble in the acid solution. As will be appreciated by those skilled in the art, as the wellbore is drilled deeper into the earth, the temperature and pressure within the wellbore may increase. Therefore, adjustments in the brine or acid concentration may be made to account for increased dissolution due to increased temperature and pressure.

In one or more embodiments, polymer-based dissolvable windows may be dissolved by water. The dissolving rate of the polymer-based window depends on the temperature and fluid composition. The dissolvable polymers may be degraded by hydrolysis, that is, degrading the dissolvable polymers into smaller polymers by exposing them to water such that chemical bonds are hydrolyzed resulting in the polymers losing their structural integrity and the mechanical properties.

In one or more embodiments, when a water-based mud is used as a drilling fluid, the polymer-based dissolvable window will begin to dissolve upon contact with the water of the water-based mud. Therefore, adjustments in the brine or acid concentration of the dissolving medium may be made to account for increased dissolution due to water of the water-based mud.

In one or more embodiments of the present disclosure, the light source1022disposed on the blade102may be an ultraviolet (UV) light source or a light emitting diode (LED). Furthermore, the light source1022may emit at least 2 different wavelengths of light. The wavelengths of the light source1022may be in a range of 10-800 nm depending on the photosensitive material used for encapsulation.

The present disclosure also relates to a method of activating downhole chemicals.FIG.4is a flowchart of a method400of activating downhole chemicals in accordance with one or more embodiments.

As shown inFIG.4and referring back toFIG.1, at step401, a fluid301containing a dissolving medium, at least one reactant, and photosensitive capsules is introduced from a fluid tank30located at the surface of the earth using one or more pumps40. The fluid flows down through the hollow space of the drill pipe and the stabilizer101with a blade102disposed on the surface.

In one or more embodiments, the fluid, dissolving medium, and photosensitive capsules may be introduced simultaneously or the dissolving medium may be introduced first and then the photosensitive capsules may be introduced after the windows have dissolved.

The blade102includes a light source1022that emits light to the wellbore50, and a dissolvable window1021disposed on the surface of the blade102between the light source1022and the wellbore50. As the fluid301flows through the wellbore50, the dissolving medium contained in the fluid301contacts the dissolvable window1021and dissolves the dissolvable window1021(step402). The rate at which the window dissolves varies based on the composition of the dissolvable window1021, the composition of the dissolving medium, and the temperature and pressure of the downhole environment. In one or more embodiments, about 100 mg per cm2of the surface area of the dissolvable window1021may be dissolved in about 1 hour. It may take from about 1 to 5 hours to break down the dissolvable window1021.

The light1025emitted from the light source1022is transmitted through the empty space where the dissolved window1024was located to the wellbore50. The photosensitive capsules in the fluid301are exposed to light1025emitted from the light source (step403). The photosensitive capsules degrade by irradiation of light1025(step404). Once the photosensitive capsules are degraded, chemicals such as super absorbent polymers, activators, crosslinkers, or triggers contained in the photosensitive capsules are released into the fluid.

In one or more embodiments, photosensitive capsules in the fluid301may be composed of photodegradable polymers. Photodegradable polymers may include photodegradable pendant groups, polymers that undergo chain scission reactions, polymers with photodegradable blocks, or polymers with photo-labile crosslinkers. In one or more embodiments, polymers that undergo chain scission reactions or polymers that undergo cleavage in cross-linkers are particularly useful for developing encapsulated capsules.

In one or more embodiments, photosensitive capsules in the fluid301may be polymers made of photo responsive monomers such as trans-azobenzene, cis-azobenzene, trans-stilbene, cis-stilbene, spiropyran or merocyanin. Polymers may be obtained by introducing such photo responsive monomers as photosensitive moieties in the polymeric backbone or in the sidechains.

In one or more embodiments, photosensitive capsules degrade by light-induced structural changes of the aforementioned monomers. The structural change of the photo responsive monomers may be cis-trans isomerization or ring-opening reaction. Isomerization may be accompanied by molecular changes in physical properties such as polarity, viscosity and absorbance. The change in such physical properties affect permeability of photosensitive capsules and leads to degradation of the shell of the capsules.

In one or more embodiments, the methods for encapsulation of super absorbent polymers, or crosslinkers inside photosensitive polymer capsules may include interfacial methods, templating methods, and self-assembly methods. Interfacial methods may be polycondensation or polyaddition of photo responsive monomers. Templating method may be layer-by-layer approach using polyelectrolytes or layer-by-layer approach using host-guest systems. Self-assembly is a spontaneous formation of non-covalent association of organic molecules in solution. Self-assembly method may be used to for micelles of block copolymers. Such techniques for encapsulation are understood by those skilled in the art and may be used as necessary to appropriately encapsulate the super absorbent polymers, or crosslinkers disclosed herein.

In one or more embodiments of the present disclosure, once the super absorbent polymers or crosslinkers are released from the capsules, they react with reactants in the fluid. Such reactants may include polymers, water, resins, or crosslinkers. For example, when sodium polyacrylate (a super absorbent polymer) is released from photosensitive capsules, it reacts with water in the fluid301and form a thick plug to cure loss of circulation.

In one or more embodiments, crosslinkers may be any material that initiates crosslinking of resins used in downhole applications. For example, the crosslinker may be used to crosslink resins used as loss circulation materials such that the resin hardens in particular locations to treat loss circulation.

Low molecular weight compounds having a secondary amino group include, but are not limited to, piperidine, pyrrolidine, diphenylamine, 2-methylimidazole, and 2-ethyl-4-methylimidazole.

Low molecular weight compounds having a tertiary amino group include, but are not limited to, imidazoles, such as 1-cyanoethyl-2-undecylimidazole-trimellitate, imidazolylsuccinic acid, 2-methylimidazole-succinic acid, 2-ethylimidazole-succinic acid, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, and 1-cyanoethyl-2-phenylimidazole.

Embodiments of the present disclosure may provide at least one of the following advantages. The disclosed downhole device may help address and control downhole issues that are difficult to deal with from the surface of the earth. In one or more embodiments, downhole issues may be addressed using the disclosed fluid containing downhole chemicals and the downhole device used to controllably release the downhole chemicals. Various downhole issues may be treated by selecting appropriate chemical substances in the fluid.

When the word “approximately” or “about” are used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.

Ranges may be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it is to be understood that another embodiment is from the one particular value to the other particular value, along with all particular values and combinations thereof within the range.

Thus, particular implementations of the subject matter have been described. Other implementations are within the scope of the following claims

It is noted that one or more of the following claims utilize the term “where” or “in which” as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.” For the purposes of defining the present technology, the transitional phrase “consisting of” may be introduced in the claims as a closed preamble term limiting the scope of the claims to the recited components or steps and any naturally occurring impurities. For the purposes of defining the present technology, the transitional phrase “consisting essentially of” may be introduced in the claims to limit the scope of one or more claims to the recited elements, components, materials, or method steps as well as any non-recited elements, components, materials, or method steps that do not materially affect the novel characteristics of the claimed subject matter. The transitional phrases “consisting of” and “consisting essentially of” may be interpreted to be subsets of the open-ended transitional phrases, such as “comprising” and “including,” such that any use of an open-ended phrase to introduce a recitation of a series of elements, components, materials, or steps should be interpreted to also disclose recitation of the series of elements, components, materials, or steps using the closed terms “consisting of” and “consisting essentially of” For example, the recitation of a composition “comprising” components A, B, and C should be interpreted as also disclosing a composition “consisting of” components A, B, and C as well as a composition “consisting essentially of” components A, B, and C. Any quantitative value expressed in the present application may be considered to include open-ended embodiments consistent with the transitional phrases “comprising” or “including” as well as closed or partially closed embodiments consistent with the transitional phrases “consisting of” and “consisting essentially of” The words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.