Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L59/00—Thermal insulation in general
  • F16L59/14—Arrangements for the insulation of pipes or pipe systems
  • F16L59/143—Pre-insulated pipes
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M173/00—Lubricating compositions containing more than 10% water
  • C10M173/02—Lubricating compositions containing more than 10% water not containing mineral or fatty oils
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B36/00—Heating, cooling or insulating arrangements for boreholes or wells, e.g. for use in permafrost zones
  • E21B36/003—Insulating arrangements
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/02—Hydroxy compounds
  • C10M2207/021—Hydroxy compounds having hydroxy groups bound to acyclic or cycloaliphatic carbon atoms
  • C10M2207/022—Hydroxy compounds having hydroxy groups bound to acyclic or cycloaliphatic carbon atoms containing at least two hydroxy groups
  • C10M2207/0225—Hydroxy compounds having hydroxy groups bound to acyclic or cycloaliphatic carbon atoms containing at least two hydroxy groups used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
  • C10M2207/04—Ethers; Acetals; Ortho-esters; Ortho-carbonates
  • C10M2207/0406—Ethers; Acetals; Ortho-esters; Ortho-carbonates used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
  • C10M2209/10—Macromolecular compoundss obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2209/103—Polyethers, i.e. containing di- or higher polyoxyalkylene groups
  • C10M2209/104—Polyethers, i.e. containing di- or higher polyoxyalkylene groups of alkylene oxides containing two carbon atoms only
  • C10M2209/1045—Polyethers, i.e. containing di- or higher polyoxyalkylene groups of alkylene oxides containing two carbon atoms only used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
  • C10M2209/10—Macromolecular compoundss obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2209/103—Polyethers, i.e. containing di- or higher polyoxyalkylene groups
  • C10M2209/105—Polyethers, i.e. containing di- or higher polyoxyalkylene groups of alkylene oxides containing three carbon atoms only
  • C10M2209/1055—Polyethers, i.e. containing di- or higher polyoxyalkylene groups of alkylene oxides containing three carbon atoms only used as base material
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
  • C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
  • C10M2209/10—Macromolecular compoundss obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • C10M2209/103—Polyethers, i.e. containing di- or higher polyoxyalkylene groups
  • C10M2209/108—Polyethers, i.e. containing di- or higher polyoxyalkylene groups etherified
  • C10M2209/1085—Polyethers, i.e. containing di- or higher polyoxyalkylene groups etherified used as base material

Definitions

• the present invention relates to insulating fluids, and more particularly, to aqueous-based insulating fluids that have greater stability at high temperatures with lower thermal conductivity that may be used, for example, in applications requiring an insulating fluid such as pipeline and subterranean applications (e.g., to insulate petroleum production conduits).
• Insulating fluids are often used in subterranean operations wherein the fluid is placed into an annulus between a first tubing and a second tubing or the walls of a well bore.
• the insulating fluid acts to insulate a first fluid (e.g., a hydrocarbon fluid) that may be located within the first tubing from the environment surrounding the first tubing or the second tubing to enable optimum recovery of the hydrocarbon fluid. For instance, if the surrounding environment is very cold, the insulating fluid is thought to protect the first fluid in the first tubing from the environment so that it can efficiently flow through the production tubing, e.g., the first tubing, to other facilities.
• a first fluid e.g., a hydrocarbon fluid
• Such fluids also may be used for similar applications involving pipelines for similar purposes, e.g., to protect a fluid located within the pipeline from the surrounding environmental conditions so that the fluid can efficiently flow through the pipeline.
• Insulating fluids can be used in other insulating applications as well wherein it is desirable to control heat transfer. These applications may or may not involve hydrocarbons.
• Beneficial insulating fluids preferably have a low inherent thermal conductivity, and also should remain gelled to prevent, inter alia, convection currents that could carry heat away. Additionally, preferred insulating fluids should be aqueous-based, and easy to handle and use. Moreover, preferred fluids should tolerate ultra high temperatures (e.g., temperatures of 400 0 F or above) for long periods of time for optimum performance.
• aqueous-based insulating fluids have been subject to many drawbacks.
• a second common limitation of many conventional aqueous-based insulating fluids is their density range. Typically, these fluids have an upper density limit of 12.5 ppg. Oftentimes, higher densities are desirable to maintain adequate pressure for the chosen application.
• aqueous-based insulating fluids have excessive thermal conductivities, which means that these fluids are not as efficient or effective at controlling conductive heat transfer.
• a viscosified fluid is required to eliminate convective currents, oftentimes to obtain the required viscosity in current aqueous-based fluids, the fluids may become too thick to be able to pump into place.
• Some aqueous-based fluids also can have different salt tolerances that may not be compatible with various brines used, which limits the operators' options as to what fluids to use in certain circumstances.
• insulating fluids may be oil-based. Certain oil- based fluids may offer an advantage because they may have lower thermal conductivity as compared to their aqueous counterparts. However, many disadvantages are associated with these fluids as well. First, oil-based insulating fluids can be hard to "weight up,” meaning that it may be hard to obtain the necessary density required for an application. Secondly, oil- based fluids may present toxicity and other environmental issues that must be managed, especially when such fluids are used in sub-sea applications. Additionally, there can be interface issues if aqueous completion fluids are used. Another complication presented when using oil-based insulating fluids is the concern about their compatibility with any elastomeric seals that may be present along the first tubing line.
• Another method that may be employed to insulate a first tubing involves using vacuum insulated tubing.
• this method also can present disadvantages.
• vacuum insulated tubing can be very costly and hard to place.
• heat transfer at the junctions or connective joints in the vacuum tubings can be problematic. These may lead to "hot spots" in the tubings.
• the present invention relates to insulating fluids, and more particularly, to aqueous-based insulating fluids that have greater stability at high temperatures with lower thermal conductivity that may be used, for example, in applications requiring an insulating fluid such as pipeline and subterranean applications (e.g., to insulate petroleum production conduits).
• the present invention provides a method comprising: providing an annulus between a first tubing and a second tubing; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides a method comprising: providing a tubing containing a first fluid located within a well bore such that an annulus is formed between the tubing and a surface of the well bore; providing an aqueous- based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides a method comprising: providing a first tubing that comprises at least a portion of a pipeline that contains a first fluid; providing a second tubing that substantially surrounds the first tubing thus creating an annulus between the first tubing and the second tubing; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides a method of forming an aqueous-based insulating fluid comprising: mixing an aqueous base fluid and a water-miscible organic liquid to form a mixture; adding at least one layered silicate to the mixture; allowing the silicate to hydrate; placing the mixture comprising the layered silicate in a chosen location; allowing the mixture comprising the layered silicate to activate to form a gel therein.
• a polymer may be added to the mixture and allowed to hydrate.
• a crosslinking agent may be added to the mixture comprising the polymer to crosslink the polymer.
• Figure 1 lists the materials used in the formulations and the amounts thereof as described in Example 1 in the Examples section.
• Figure 2 illustrates data from a fluid that was heated to about 190°F for 5000 minutes to activate the crosslinking agent and provide an increase in viscosity.
• Figure 3 lists the materials that may be used in the formulations and the approximate amounts thereof as described in Example 2 in the Examples section.
• Figure 4 illustrates data from a fluid that was heated from approximately 100°F to approximately 600°F for approximately 45,000 seconds at approximately 10,000 psi.
• the present invention relates to insulating fluids, and more particularly, to aqueous-based insulating fluids that have greater stability at high temperatures with lower thermal conductivity that may be used, for example, in applications requiring an insulating fluid such as pipeline and subterranean applications (e.g., to insulate petroleum production conduits).
• the aqueous-based insulating fluids of the present invention may be used in any application requiring an insulating fluid. Preferably, they may be used in pipeline and subterranean applications.
• the improved aqueous-based insulating fluids and methods of the present invention present many potential advantages, only some of which are alluded to herein.
• One of these many advantages is that the fluids may have enhanced thermal stability, which enables them to be beneficially used in many applications.
• the aqueous-based insulating fluids of the present invention may have higher densities than conventional aqueous-based insulating fluids, and therefore, present a distinct advantage in that respect.
• the aqueous-based insulating fluids of the present invention have relatively low thermal conductivity, which is thought to be especially beneficial in certain applications. In some embodiments, these fluids are believed to be very durable.
• the fluids of the present invention offer aqueous- based viscous insulating fluids with a broad fluid density range, decreased thermal conductivity, and stable gel properties at temperatures exceeding those of current industry standards (e.g., even at temperatures of about 600°F or more, depending on the organic liquid included).
• Another potential advantage is that these fluids may prevent the formation of hydrates within the insulating fluids themselves or the fluids being insulated.
• the aqueous-based insulating fluids of the present invention comprise an aqueous base fluid, a water-miscible organic liquid, and a layered silicate.
• the aqueous-based insulating fluids of the present invention comprise an aqueous base fluid, a water-miscible organic liquid, a layered silicate, and optionally a synthetic polymer.
• the polymer may be crosslinked by using or adding to the fluid an appropriate crosslinking agent.
• the term "polymer” as used herein refers to oligomers, copolymers, terpolymers and the like, which may or may not be crosslinked.
• the aqueous-based insulating fluids of the present invention may comprise other additives such as corrosion inhibitors, pH modifiers, biocides, glass beads, hollow spheres (e.g., hollow microspheres), rheology modifiers, buffers, hydrate inhibitors, breakers, tracers, additional weighting agents, viscosifiers, surfactants, and combinations of any of these.
• Other additives may be appropriate as well and beneficially used in conjunction with the aqueous-based insulating fluids of the present invention as may be recognized by one skilled in the art with the benefit of this disclosure.
• the aqueous base fluids that may be used in the aqueous-based insulating fluids of the present invention include any aqueous fluid suitable for use in insulating, subterranean, or pipeline applications.
• brines may be used, for example, when a relatively denser aqueous-based insulating fluid is desired (e.g., density of 10.5 ppg or greater); however, it may be observed that the fluids of the present invention may be less tolerant to higher concentrations of salts than other fluids, such as those that include a polymer as described herein but not a layered silicate as described herein.
• Suitable brines include, but are not limited to: NaCl, NaBr, KCl, CaCl 2 , CaBr 2 , ZrBr 2 , sodium carbonate, sodium formate, potassium formate, cesium formate, and combinations and derivatives of these brines. Others may be appropriate as well.
• the specific brine used may be dictated by the desired density of the resulting aqueous-based insulating fluid or for compatibility with other completion fluid brines that may be present. Denser brines may be useful in some instances. A density that is suitable for the application at issue should be used as recognized by one skilled in the art with the benefit of this disclosure.
• a general guideline to follow is that the aqueous fluid component should comprise the balance of a high temperature aqueous-based insulating fluid after considering the amount of the other components present therein.
• the water-miscible organic liquids that may be included in the aqueous-based insulating fluids of the present invention include water-miscible materials having relatively low thermal conductivity (e.g., about half as conductive as water or less).
• water-miscible it is meant that about 5 grams or more of the organic liquid will disperse in 100 grams of water.
• Suitable water-miscible organic liquids include, but are not limited to, esters, amines, alcohols, polyols, glycol ethers, or combinations and derivatives of these.
• suitable esters include low molecular weight esters; specific examples include, but are not limited to, methylformate, methyl acetate, and ethyl acetate.
• Combinations and derivatives are also suitable.
• suitable amines include low molecular weight amines; specific examples include, but are not limited to, diethyl amine, 2- aminoethanol, and 2-(dimethylamino)ethanol.
• suitable alcohols include methanol, ethanol, propanol, isopropanol, and the like.
• glycol ethers include ethylene glycol butyl ether, diethylene glycol methyl ether, dipropylene glycol methyl ether, tripropylene glycol methyl ether, and the like. Combinations and derivatives are also suitable.
• polyols are generally preferred in most cases over the other liquids since they generally are thought to exhibit greater thermal and chemical stability, higher flash point values, and are more benign with respect to elastomeric materials.
• Suitable polyols are those aliphatic alcohols containing two or more hydroxy groups. It is preferred that the polyol be at least partially water-miscible.
• suitable polyols that may be used in the aqueous-based insulating fluids of this invention include, but are not limited to, water-soluble diols such as ethylene glycols, propylene glycols, polyethylene glycols, polypropylene glycols, diethylene glycols, triethylene glycols, dipropylene glycols and tripropylene glycols, combinations of these glycols, their derivatives, and reaction products formed by reacting ethylene and propylene oxide or polyethylene glycols and polypropylene glycols with active hydrogen base compounds (e.g., polyalcohols, polycarboxylic acids, polyamines, or polyphenols).
• active hydrogen base compounds e.g., polyalcohols, polycarboxylic acids, polyamines, or polyphenols.
• the polyglycols of ethylene generally are thought to be water-miscible at molecular weights at least as high as 20,000.
• the polyglycols of propylene although giving slightly better grinding efficiency than the ethylene glycols, are thought to be water-miscible up to molecular weights of only about 1,000.
• Other glycols possibly contemplated include neopentyl glycol, pentanediols, butanediols, and such unsaturated diols as butyne diols and butene diols.
• the triol, glycerol, and such derivatives as ethylene or propylene oxide adducts may be used.
• Other higher polyols may include pentaerythritol.
• Another class of polyhydroxy alcohols contemplated is the sugar alcohols.
• the sugar alcohols are obtained by reduction of carbohydrates and differ greatly from the above-mentioned polyols. Combinations and derivatives of these are suitable as well.
• polyol to be used is largely dependent on the desired density of the fluid. Other factors to consider include thermal conductivity. For higher density fluids (e.g., 10.5 ppg or higher), a higher density polyol may be preferred, for instance, triethylene glycol or glycerol may be desirable in some instances. For lower density applications, ethylene or propylene glycol may be used. In some instances, more salt may be necessary to adequately weight the fluid to the desired density. In certain embodiments, the amount of polyol that should be used may be governed by the thermal conductivity ceiling of the fluid and the desired density of the fluid.
• the concentration of the polyol may be from about 40% to about 99% of a high temperature aqueous-based insulating fluid of the present invention. A more preferred range could be from about 70% to about 99%.
• Examples of layered silicates that may be suitable for use in the present invention include, but are not limited to, smectite, vermiculite, swellable fluoromica, montmorillonite, beidellite, hectorite, and saponite.
• a high-temperature, electrolyte stable synthetic hectorite may be particularly useful in some embodiments.
• An example of a synthetic hectorite clay for use in accordance with this invention is "LAPONITETM RD" commercially available from Laporte Absorbents Company of Cheshire, United Kingdom. Mixtures of any of these of silicates may be suitable as well.
• the silicate may be at least partially water soluble.
• the layered silicate may be a natural layered silicate or a synthetic layered silicate.
• the silicate should comprise from about 0.1% to about 15% weight by volume of the fluid, and more preferably, from about 0.5% to about 4% weight by volume of the fluid.
• Copolymers and terpolymers may be suitable as well. Mixtures of any of these of polymers may be suitable as well.
• the polymer should be at least partially water soluble. Suitable polymers can be cationic, anionic, nonionic, or zwitterionic. In certain embodiments, the polymer should comprise from about 0.1% to about 15% weight by volume of the fluid, and more preferably, from about 0.5% to about 4%.
• the polymer included in the fluid may be crosslinked by an appropriate crosslinking agent. In those embodiments of the present invention wherein it is desirable to crosslink the polymer, optionally and preferably, one or more crosslinking agents may be added to the fluid to crosslink the polymer.
• Suitable crosslinking agent is a combination of a phenolic component (or a phenolic precursor) and formaldehyde (or formaldehyde precursor).
• Suitable phenolic components or phenolic precursors include, but are not limited to, phenols, hydroquinone, salicylic acid, salicylamide, aspirin, methyl-p-hydroxybenzoate, phenyl acetate, phenyl salicylate, ⁇ -aminobenzoic acid, /?-aminobenzoic acid, /w-aminophenol, furfuryl alcohol, and benzoic acid.
• Suitable formaldehyde precursors may include, but are not limited to, hexamethylenetetramine, glyoxal, and 1,3,5-trioxane.
• This crosslinking agent system needs approximately 25O 0 F to thermally activate to crosslink the polymer.
• Another type of suitable crosslinking agent is polyalkylimine. This crosslinking agent needs approximately 9O 0 F to activate to crosslink the polymer. This crosslinking agent may be used alone or in conjunction with any of the other crosslinking agents discussed herein.
• crosslinking agent that may be used includes non-toxic organic crosslinking agents that are free from metal ions.
• organic cross- linking agents are polyalkyleneimines (e.g., polyethyleneimine), polyalkylenepolyamines and mixtures thereof.
• water-soluble polyfunctional aliphatic amines, arylalkylamines and heteroarylalkylamines may be utilized.
• suitable crosslinking agents may be present in the fluids of the present invention in an amount sufficient to provide, inter alia, the desired degree of crosslinking.
• the crosslinking agent or agents may be present in the fluids of the present invention in an amount in the range of from about 0.0005% to about 10% weight by volume of the fluid.
• the crosslinking agent may be present in the fluids of the present invention in an amount in the range of from about 0.001% to about 5% weight by volume of the fluid.
• crosslinking agent to include in a fluid of the present invention based on, among other things, the temperature conditions of a particular application, the type of polymer(s) used, the molecular weight of the polymer(s), the desired degree of viscosification, and/or the pH of the fluid.
• an aqueous-based insulating fluid of the present invention may be formulated at ambient temperature and pressure conditions by mixing water and a chosen water-miscible organic liquid.
• the water and water-miscible organic liquid preferably may be mixed so that the water-miscible organic liquid is miscible in the water.
• the chosen silicate may then be added and mixed into the water and water- miscible organic liquid mixture until the silicate is hydrated.
• Any chosen additives may be added at any, including a polymer.
• any additives are dispersed within the mixture.
• a crosslinking agent may be added.
• gel As used herein, and its derivatives refer to a semi-solid, jelly-like state assumed by some colloidal dispersions. Once activated, the gel should stay in place and be durable with negligible syneresis.
• the gels formed by hydrating the silicate may have a zero sheer viscosity of about 100,000 centipoise measured on an Anton Paar Controlled Stress Rheometer at standard conditions using standard operating procedure.
• one method of removing the gel may comprise diluting or breaking the crosslinks and/or the polymer structure within the gel using an appropriate method and/or composition to allow recovery or removal of the gel. Another method could involve physical removal of the gel by, for example, air or liquid.
• the aqueous-based insulating fluids of the present invention may be prepared on-the-fly at a well-site or pipeline location. In other embodiments, the aqueous-based insulating fluids of the present invention may be prepared off-site and transported to the site of use. In transporting the fluids, one should be mindful of the activation temperature of the fluid.
• the present invention provides a method comprising: providing a first tubing; providing a second tubing that substantially surrounds the first tubing thus creating an annulus between the first tubing and the second tubing; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a polyol, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the tubings may have any shape appropriate for a chosen application.
• the second tubing may not be the same length as the first tubing.
• the tubing may comprise a portion of a larger apparatus.
• the aqueous-based insulating fluid may be in contact with the entire first tubing from end to end, but in other situations, the aqueous-based insulating fluid may only be placed in a portion of the annulus and thus only contact a portion of the first tubing.
• the first tubing may be production tubing located within a well bore. In some instances, the tubings may be located in a geothermal well bore. The production tubing may be located in an off-shore location. In other instances, the production tubing may be located in a cold climate. In other instances, the first tubing may be a pipeline capable of transporting a fluid from one location to a second location.
• the present invention provides a method comprising: providing a first tubing; providing a second tubing that substantially surrounds the first tubing thus creating an annulus between the first tubing and the second tubing; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a water- miscible organic liquid, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides a method comprising: providing a tubing containing a first fluid located within a well bore such that an annulus is formed between the tubing and a surface of the well bore; providing an aqueous- based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides a method comprising: providing a first tubing that comprises at least a portion of a pipeline that contains a first fluid; providing a second tubing that substantially surrounds the first tubing thus creating an annulus between the first tubing and the second tubing; providing an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate; and placing the aqueous-based insulating fluid in the annulus.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides an aqueous-based insulating fluid that comprises an aqueous base fluid, a water-miscible organic liquid, and a layered silicate.
• the aqueous-based insulating fluid also includes a polymer.
• the present invention provides a method of forming an aqueous-based insulating fluid comprising: mixing an aqueous base fluid and a water-miscible organic liquid to form a mixture; adding at least one layered silicate to the mixture; allowing the layered silicate to hydrate; placing the mixture comprising the layered silicate in a chosen location; allowing the mixture comprising the layered silicate to activate to form a gel therein.
• a polymer may be added to the mixture and allowed to hydrate.
• a crosslinking agent may be added to the mixture comprising the polymer to crosslink the polymer.
• Thermal stability and static aging All formulations of fluids were statically aged at temperatures > about 280°F for two months. Formulations and properties for the tested fluids are shown in Tables 1 and 2 below. Most of the fluids appeared to remain intact, with the crosslinked systems showing an increase in viscosity and what appeared to be complete gelation behavior. We believe that these systems appeared to exhibit more desirable stability properties than other fluids, which included numerous biopolymers ⁇ e.g., xanthan, welan, and diutan gums) and inorganic clays and were generally destroyed after 3 days at 250 0 F. In addition, as to the thermal stability of these formulations tested, less than 1 % syneresis was observed for any of the samples.
• Sample 4 was evaluated using a high- temperature viscometer to examine the thermal activation of crosslinking agents (Figure 2).
• the fluid was subjected to a low shear rate at 190 0 F, with viscosity measurements showing an increase with time to reach the maximum recordable level around 5000 minutes.
• Thermal conductivity measurements The importance of a low thermal conductivity (K) is an important aspect of the success of insulating fluids.
• K thermal conductivity
• aqueous-based packer fluids in the density range of 8.5 to 12.3 ppg are expected to exhibit values for K of 0.3 to 0.2 BTU/hr ft °F, and preferably would have lower values. From the various formulations listed above, using these formulations fluid densities of 8.5 to 14.4 ppg were observed, all of which have a thermal conductivity of ⁇ 0.2 BTU/hr ft 0 F as shown in Tables 1 and 2.
• Thermal stability and static aging All formulations of fluids were statically aged at temperatures > about 400°F for 3 day intervals. Formulations and properties for the tested fluids are shown in Tables 3 and 4 below. Most of the fluids appeared to remain intact, with the crosslinked systems showing an increase in viscosity and what appeared to be complete gelation behavior. We believe that these systems appeared to exhibit more desirable stability properties than other fluids, which included numerous biopolymers ⁇ e.g., xanthan, welan, and diutan gums) and inorganic clays and were generally destroyed after 3 days at 250 °F. In addition, as to the thermal stability of these formulations tested, less than 1 % syneresis was observed for any of the samples.
• Thermal conductivity measurements The importance of a low thermal conductivity (K) is an important aspect of the success of insulating fluids.
• K thermal conductivity
• aqueous-based packer fluids in the density range of 8.5 to 10.5 ppg are expected to exhibit values for K of 0.3 to 0.2 BTU/hr ft °F, and preferably would have lower values. From the various formulations listed above, using these formulations fluid densities of 8.5 to 10.5 ppg were observed, all of which have a thermal conductivity of ⁇ 0.2 BTU/hr ft 0 F as shown in Tables 3 and 4.
• R RL+k* (RU-RL)
• k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent,..., 50 percent, 51 percent, 52 percent,..., 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent.
• any numerical range defined by two R numbers as defined in the above is also specifically disclosed.

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