Patent Publication Number: US-11649391-B2

Title: High density brine internal phase

Description:
BACKGROUND 
     Brines may be used in subterranean operations for a number functions. By way of example, treatment fluids used in drilling, completion, or workover operations may include a brine. Examples of suitable treatment fluids may include, but are not limited to, drilling fluids, packer fluids, displacement fluids, completion fluids, gravel pack fluids, and work over fluids. In some instances, these treatment fluids may be an oil-based fluid in the form of an invert emulsion that includes an oil external phase and an aqueous internal phase. The aqueous internal phase may include a brine, for example, to provide a desired density for the treatment fluids. 
     In some instances, the use of brines with higher densities may be problematic. To provide a higher density to the treatment fluid, an aqueous internal phase of an appropriate density may be needed. Currently, calcium bromide can be used in the aqueous internal phase, but it can be challenging to achieve densities for the aqueous internal phase of greater than 14.2 lbs/gal (1,700 kg/m 3 ) without precipitation of the salt. The pressurized crystallization temperature (PCT) is the point where solids form in brine solutions under pressure. The effects of pressure can be significant in deep water applications and cold climates where the brines may crystallize at a temperature higher than the expected True Crystallization Temperature (TCT). Some negative effects due to crystallization may include, at very low temperatures, plugging of choke lines and kill lines. Additionally, at low temperatures, valves may seize. The removal of deposited crystals during pressure testing in locations of the wellbore where circulation may be poor may be extremely difficult and costly. Also, if crystals form at the surface, the density of the resulting brine may be lowered, this may present difficulties in controlling the pressure downhole. Accordingly, due to these crystallization concerns with calcium bromide, cesium formate is often used where high densities are needed. However, the high cost associated with cesium formate often precludes its use. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These drawings illustrate certain aspects of some examples of the present disclosure, and should not be used to limit or define the disclosure. 
         FIG.  1    illustrates placement of an oil-based treatment fluid into a wellbore in a subterranean operation, wherein the oil-based treatment fluid includes a true crystallization temperature reduction additive in the aqueous internal phase. 
         FIG.  2    illustrates a drilling system that may use an oil-based drilling fluid, wherein the oil-based drilling fluid includes a true crystallization temperature reduction additive in the aqueous internal phase. 
     
    
    
     DETAILED DESCRIPTION 
     Provided are compositions and methods for a well treatment and, more particularly, to oil-based treatment fluids that use a true crystallization temperature reduction additive in the aqueous internal phase. Advantageously, the true crystallization temperature reduction additive may reduce the true crystallization temperature of a bromide brine in the aqueous internal phase, thus enabling the use of higher density bromide brines than can be used without the true crystallization temperature reduction additive. Among other things, the high density brines that may be used are free or essentially free of zinc and cesium formate. The bromide brines may be considered essentially free of zinc and cesium formate if the brine includes zinc and cesium formate in an amount of about 1 wt. % based on the total weight of the brine or less. 
     Suitable oil-based treatment fluids may be in the form of an invert emulsion including an aqueous internal phase and an oil external phase. The treatment fluid may be any suitable treatment fluid for use in a variety of downhole applications. Suitable downhole applications may include, but are not limited to, drilling operations, lost circulation management operations, stimulation operations, sand control operations, perforating operations, completion operations, scale inhibiting operations, water-blocking operations, clay stabilizer operations, fracturing operations, frac-packing operations, gravel packing operations, wellbore strengthening operations, sag control operations, displacing solids laden drilling fluid, the like, and/or any combinations thereof. 
     Those of ordinary skill in the art will appreciate that the oil-based treatment fluid generally should have a density suitable for a particular application. By way of example, the oil-based treatment fluid may have a density in the range of from about 7 pounds per gallon (“lb/gal”) (840 kg/m 3 ) to about 20 lb/gal (2400 kg/m 3 ). In certain embodiments, the oil-based treatment fluids may have a density in the range of from about 8 lb/gal (960 kg/m 3 ) to about 12 lb/gal (1440 kg/m 3 ) or from about 12 lb/gal (1440 kg/m 3 ) to about 18 lb/gal 2160 kg/m 3 ) or from about 10 lb/gal (1200 kg/m 3 ) to about 14 lb/gal (1680 kg/m 3 ). Those of ordinary skill in the art, with the benefit of this disclosure, will recognize the appropriate density for a particular application. In some embodiments, the treatment fluid may be considered low solids or solids free. This may be particularly desirable, for example, where the oil-based treatment fluid may be used, for example, in completion applications or in a reservoir section of a wellbore (e.g., drill-in fluid). By using these low solids or solids free treatment fluids, formation damage may be minimized, in some instances. As used herein the term “solids free” means that a fluid (e.g., the oil-based treatment fluid) is free of intentionally added solids or, to the extent that intentionally added solids are present, the solids are present in an amount of less than 100 parts per million. It should be understood that minor amounts of solids may unintentionally be added to the fluid during use in a wellbore. 
     A suitable aqueous internal phase may include a bromide brine. Suitable bromide brines may be saturated or unsaturated as desired for a particular application. One or more salts may be added to water to provide a bromide brine that may include dissolved salt and water. Suitable dissolved salts may include any of a variety of bromide salts, including, but not limited to, lithium bromide, sodium bromide, potassium bromide, rubidium bromide, magnesium bromide, calcium bromide, strontium bromide, zinc bromide, manganese (II) bromide, or any combinations thereof. In a non-limiting example, one salt may be used to prepare the brine. In some embodiments, multiple bromide salts may be used to prepare the bromide brine such that the bromide brine may be considered a single bromide brine, for example, including no additional salt or, if present, no more than about 1 wt. % based on the total weight of the bromide brine. In some examples, the brine may be free or essentially free of zinc and cesium formate. 
     The bromide brine may be considered “high density.” As used herein, the term “high density” refers to a brine with a density of about 14.2 lbs/gal (1,700 kg/m 3 ) or greater. Suitable brines may have a density of about 14.2 lbs/gal (1,700 kg/m 3 ) to about 17 lbs/gal (2,040 kg/m 3 ), or a density of about 14.2 lbs/gal (1,700 kg/m 3 ) to about 16 lbs/gal (1,920 kg/m 3 ), or a density of about 15 lbs/gal (1,800 kg/m 3 ) to about 16 lbs/gal (1,920 kg/m 3 ). By way of example, the brine may have a density of about 14.2 lbs/gal, (1,700 kg/m 3 ), 14.5 lbs/gal (1,740 kg/m 3 ), 15 lbs/gal (1,800 kg/m 3 ), 16 lbs/gal (1,920 kg/m 3 ), 16.5 lbs/gal (1,980 kg/m 3 ), or 17 lbs/gal (2,040 kg/m 3 ). 
     The bromide brine may be considered “solids free.” As used herein the term “solids free” means that a fluid (e.g., the bromide brine) is free of intentionally added solids or, to the extent that intentionally added solids are present, the intentionally added solids are present in an amount of less than 100 parts per million. In some embodiments, an oil-based treatment fluid formulated with the bromide brine may be solids free. 
     Without limitation, the bromide brine may be present in the aqueous internal phase in any suitable amount, including but not limited to, 80 wt. % to 100 wt. % based on a total weight of the aqueous internal phase. One or ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate amount of the bromide brine for a particular application. 
     As previously described, a true crystallization temperature reduction additive may be included in the bromide brine. The true crystallization temperature reduction additive may disrupt the formation of a crystal structure in the bromide brines. Additionally, the true crystallization temperature reduction additive may be capable of enabling a bromide brine with a higher density in a liquid state than can be achieved for the same bromide brine without the true crystallization temperature reduction additive. Any suitable true crystallization temperature reduction additive capable of lowering the crystallization temperature of treatment fluid may be used. In a non-limiting example, suitable crystallization temperature reduction additives may include nitrates, such as magnesium nitrate, calcium nitrate, ammonium nitrate, glycols, polyols, sugar alcohols, sugar acids, aldoses, ketoses, malonamide, the like, and/or any combinations thereof. The true crystallization temperature reduction additive may be added to the bromide brine in any suitable amount. Suitable amounts may include, but are not limited to, an amount of about 1 wt. % to about 70 wt. % based on a total weight of the aqueous internal phase. Optionally, the crystallization temperature reduction additive may be added to the oil-based treatment fluid in an amount of about 5 wt. % to about 50 wt. % based on a total weight of the aqueous internal phase, or, alternatively, about 10 wt. % to about 40 wt. % based on a total weight of the aqueous internal phase, or alternatively, ranging about 1 wt. % to about 20 wt. % based on a total weight of the aqueous internal phase. For example, the true crystallization temperature reduction additive may be included in the bromide brine in an amount of about 1 wt. %, about 5 wt. %, about 10 wt. %, about 20 wt. %, about 30 wt. %, about 40 wt. %, about 50 wt. %, about 60 wt. %, or about 70 wt. % based on a total weight of the aqueous internal phase. 
     The bromide brine may have a true crystallization temperature. The crystallization temperature is the temperature at which crystallized solids begin to form in a fluid that includes dissolved salts. In particular, the true crystallization temperature refers to the temperature corresponding to the maximum temperature reached following the super-cooling minimum, as determined using the methods described in the 5 th  edition of the API Standards published in October 2014, under API RP 13J. 
     By inclusion of the true crystallization temperature additive in the bromide brine, the true crystallization temperature of the bromide brine may be reduced. An example method of preparing an oil-based treatment fluid may include providing a bromide brine. The bromide brine may be obtained or prepared by dissolution of a bromide salt in water. The bromide brine may have a first true crystallization temperature. The bromide brine may have a density of about 14.2 lbs/gal (1,700 kg/m 3 ) or greater. A true crystallization temperature reduction additive, as previously described, may then be added to the bromide brine to form an aqueous composition having a second true crystallization temperature. The true crystallization temperature reduction additive may be added to the bromide brine in any suitable manner, including but not limited to, adding the bromide brine and the true crystallization temperature reduction additive to a mixer. Any suitable mixer may be used. In some embodiments, the true crystallization temperature reduction additive may be added to a mixing tank by way of a mixing hopper. The true crystallization temperature reduction additive may be added in bulk and/or in small packages. By addition of the true crystallization temperature reduction additive, the second true crystallization temperature may be less than the first true crystallization temperature. By way of example, the second temperature true crystallization temperature may be less than the first temperature true crystallization temperature by about 5° F. (3° C.), about 10° F. (6° C.), or even more. In one example, the second temperature true crystallization temperature may be less than the first temperature true crystallization temperature by about 55° F. (30° C.). The reduction in the true crystallization temperature by addition of the crystallization temperature reduction additive may depend on a number of factors, including, but not limited to, the type of bromide brine and true crystallization temperature reduction additive, as well as concentration of the true crystallization temperature reduction additive. If desired, additional salt may be added to the aqueous composition, after addition of the true crystallization temperature additive, such that the aqueous composition has an increased density as compared to the bromide brine. For example, salt may be added to increase the density by 5%, 10%, 20%, or even more. In some embodiments, an invert emulsion may then be prepared by combining the aqueous composition with a base oil, thereby forming an oil-based treatment fluid including an aqueous internal phase and an oil external phase. 
     Increasing the density and lowering the true crystallization temperature of the bromide brine may provide many benefits for different applications downhole. For example, an oil-based treatment fluid may be prepared with a higher density, but the same ratio of oil external phase to aqueous internal phase as for the same oil-base treatment fluid without the true crystallization temperature reduction additive. By way of further example, an oil-based treatment fluid may be prepared with the same density, but less aqueous internal phase, thus reducing the amount of the bromide brine potentially improving the rheological profile of the resultant oil-based treatment fluid. 
     In some embodiments, the bromide brine may further include a glycol or a polyol. A glycol or a polyol may be added to the bromide brine to further reduce the true crystallization temperature of the bromide brine. Any suitable glycol and polyol may be added, including, but not limited to, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol, polyethylene-polypropylene glycol, glycerol, polyglycerol, trimethylolpropane, trimethylolethane, pentaerythritol, sugar alcohols, sugar acids, and combinations thereof. Glycol or polyol may be present in the oil-based treatment fluid in any suitable amount, including but not limited to, about 0.5 wt. % to about 50 wt. %, or about 1 wt. % to about 40 wt. %, or about 5 wt. % to about 30 wt. % based on a total weight of the oil-based treatment fluid. 
     The aqueous internal phase may be present in the oil-based fluid in any suitable amount, including but not limited to, an amount of about 1 wt. % to about 90 wt. %, about 1 wt. % to about 5 wt. %, about 5 wt. % to about 10 wt. %, about 10 wt. % to about 15 wt. %, about 15 wt. % to about 20 wt. %, about 20 wt. % to about 25 wt. %, about 25 wt. % to about 30 wt. %, about 3 wt. % to about 35 wt. %, about 35 wt. % to about 40 wt. %, about 40 wt. % to about 45 wt. %, about 45 wt. % to about 50 wt. %, about 10 wt. % to about 30 wt. %, or about 30 wt. % to about 80 wt. % based on a total weight of oil-based treatment fluid. With the benefit of this disclosure one of ordinary skill in the art should recognize the appropriate amount of the aqueous internal phase for a chosen application. 
     The oil-based treatment fluid may further include an oil external phase that includes a base oil Any suitable base oil may be used. It should be noted that the term “oil,” as used herein, is not limited to a viscous liquid derived from petroleum. The term “oil,” as used herein, may also refer to organic oils, synthetic oils, oils derived from petroleum products, mineral oils, the like, and/or any combination thereof. In an embodiment, suitable base oils may include, but are not limited to, light mineral oil, diesel oil, a glycol ether solvent, a hydrotreated light petroleum distillate having about 9 to 16 carbon atoms, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, an alkane, an aromatic organic compound, a cyclic alkane, a paraffin, desulfurized hydrogenated kerosene, a polyolefin, a polydiorganosiloxane, a siloxane, an ester, the like, and/or any combination thereof. In some embodiments, the base oil may be diesel oil. Base oil may be present in the oil external phase in any suitable amount, including an amount of about 80 wt. % to about 100 wt. % based on a total weight of the oil external phase. One or ordinary skill in the art, with the benefit of this disclose, should be able to select an appropriate base oil and amount thereof for a particular application. 
     The oil external phase may be present in the oil-based fluid treatment in any suitable amount, including but not limited to, an amount of about 10 wt. % to about 99 wt. %, about 1 wt. % to about 5 wt. %, about 5 wt. % to about 10 wt. %, about 10 wt. % to about 15 wt. %, about 15 wt. % to about 20 wt. %, about 20 wt. % to about 25 wt. %, about 25 wt. % to about 30 wt. %, about 3 wt. % to about 35 wt. %, about 35 wt. % to about 40 wt. %, about 40 wt. % to about 45 wt. %, about 45 wt. % to about 50 wt. %, about 10 wt. % to about 30 wt. %, about 10 wt. % to about 40 wt. %, or about 20 wt. % to about 70 wt. % based on a total weight of oil-based treatment fluid. One or ordinary skill in the art, with the benefit of this disclose, should be able to select an appropriate amount of the oil external phase for a particular application. 
     Embodiments of the oil-based treatments fluids may have any suitable oil external phase to aqueous internal phase ratio. In some embodiments, the oil-based treatments fluids may have an oil external phase to aqueous internal phase ratio of about 10:90 to about 99:1, or alternatively, about 40:60 to about 70:30, or alternatively, about 50:50 to about 60:40. For example, the oil-based treatments fluids may have an oil external phase to aqueous internal phase ratio of about 30:70, about 40:60, about 50:50, about 60:40, about 70:30, or about 80:20. Advantageously, by inclusion of true temperature reduction additive, oil-based treatment fluids may be prepared with increased density without changing the oil external phase to aqueous internal phase ratio. Additionally, oil-based treatments may be prepared of the same density with a reduction in the amount of water due to use of a bromide of increase density, which may provide improved rheological properties. 
     The oil-base treatment fluid may further include an emulsifying surfactant. Any suitable emulsifying surfactant for emulsifying an aqueous fluid into an oil external phase. The emulsifying surfactants may include nonionic, anionic, cationic, amphoteric, and zwitterionic surfactants. Suitable emulsifying surfactants may include but are not limited to, fatty amines, ethoxylated nonylphenols, fatty acids, fatty acid esters, tall oil, oxidized tall oil, modified tall oil, rosin acid, resin acid, and combinations thereof. In an embodiment, the emulsifying surfactant may be present in the oil-based drilling fluid in an amount of about 2 lb/bbl (6 kg/m 3 ) to about 24 lb/bbl (68 kg/m 3 ), or about 4 lb/bbl (11 kg/m 3 ) to about 20 lb/bbl (57 kg/m 3 ), or about 6 lb/bbl (17 kg/m 3 ) to about 16 lb/bbl (46 kg/m 3 ). In an embodiment, the emulsifying surfactant used may be determined based on the hydrophilic-lipophilic balance “HLB” value of the emulsifying surfactant. 
     The hydrophilic-lipophilic balance (“HLB”) of an emulsifying surfactant is a measure of the degree to which it is hydrophilic or lipophilic, determined by calculating a value based on the chemical groups of the molecule. This method is also referred to as the Davies HLB value. The advantage of this method is that it takes into account the effect of stronger and weaker hydrophilic groups. The method works as follows: HLB=7+m*Hh−n*H1 where m is the number of hydrophilic groups in the molecule, Hh is the respective group HLB value of the hydrophilic groups, n is the number of lipophilic groups in the molecule, and H1 is the respective HLB value of the lipophilic groups. 
     The HLB model can be used for applications including emulsification, detergency, solubilization, and other applications. Typically, a HLB value will indicate the emulsifying surfactant properties, where a value of 1 to 3 indicates anti-foaming of aqueous systems, a value of 3 to 7 indicates water in oil emulsification, a value of 7 to 9 indicates wetting, a value of 8 to 28 indicates oil in water emulsification, a value of 11 to 18 indicates solubilization, and a value of 12 to 15 indicates detergency and cleaning. In an embodiment, the emulsifying surfactant used may have an HLB value of about 8 to about 28. 
     Additionally, a wide variety of optional additives may be included in the oil-based treatment fluid as should be appreciated by those of ordinary skill in the art with the benefit of this disclosure. Suitable additives may include, but are not limited to, a surfactant (e.g., emulsifier, foamer, defoamer, wetting agent, detergent, lubricant, and corrosion inhibitor), a water softener (e.g., sodium carbonate), an oxygen scavenger, a biocide, pH adjusters, fluid loss control agents, viscosity increasing agents, weighting agents (other than salt), a corrosion inhibitor (other than surfactant), shale stabilizer, anti-scaling additives, hydrate inhibitors, the like, and/or any combination thereof. Optional additives may be added to the oil-based treatment fluid in any suitable amount as desired for a particular application. 
     As previously described, the disclosed oil-based treatment fluids may be used in any of a variety of suitable applications, including, but not limited to, drilling operations, lost circulation management operations, stimulation operations, sand control operations, perforating operations, completion operations, acidizing operations, scale inhibiting operations, water-blocking operations, clay stabilizer operations, fracturing operations, frac-packing operations, gravel packing operations, wellbore strengthening operations, sag control operations. Examples of suitable methods may include providing an oil-based treatment fluid including an aqueous internal phase and an oil external phase. The aqueous internal phase may include a bromide brine and a true crystallization temperature reduction additive. In some examples, the aqueous internal phase may include calcium bromide and calcium nitrate. The methods may further include introducing the oil-based treatment fluid into a wellbore. 
     In some examples, the oil-based treatment fluid may be used as a completion fluid. A completion fluid may be used, for example, to minimize damage to the hydrocarbon-containing reservoir when completing the well. In some embodiments, the completion fluid may be solids free. The completion fluid may be placed into the wellbore after drilling, for example, when transitioning to completion of the wellbore. By way of example, the completion fluid may displace the drilling fluid from the wellbore. In some embodiments, the completion fluid may be placed into the production tubing to displace drilling fluid from the production tubing such that the drilling fluid return to the surface through the annulus between the production tubing and casing. The completion fluid may be placed into the wellbore prior to initiation of production, for example, to minimize reservoir damage and control formation pressure. The completion fluid may be placed into the wellbore and allowed to remain in the wellbore during completion. For example, the completion fluid may be present in the wellbore when production equipment, such as production liners, downhole valves, and packers, placed into the wellbore in the completion fluid. 
       FIG.  1    illustrates an example of a downhole completion system  100  operating from a platform  102 . Platform  102  may be centered over a subterranean formation  104  located below the surface  106 . A conduit  108  may extend from deck  110  of platform  102  to wellhead installation  112  that includes blow-out preventers  114 . Platform  102  may have a hoisting apparatus  116  and a derrick  118  for raising and lowering pipe strings, such as, for example, work string  120  into and out of wellbore  122 . Wellbore  122  may extend through the various earth strata including subterranean formation  104 . Work string  120 , may be any suitable conveyance, including but not limited to, a tubing string, wireline, slick line, coil tubing, the like, and/or any combination thereof. A casing  124  may be cemented within wellbore  122  by cement  126 . At a desired time, oil-based treatment fluid  128  may be introduced in wellbore  122  and may aid in the completion of a well. In some embodiments, oil-based treatment fluid  128  may be introduced into wellbore  122  through work string  120 . Oil-based treatment fluid  128  may be any suitable treatment fluid disclosed herein. Any suitable well completion operation may be performed on wellbore  122 , including but not limited to, casing, cementing, perforating, gravel packing, packers, fracturing, the like, and/or any combination thereof. It should be noted that treatment fluid  128  may be used in any suitable well completion application and should not be limited to the applications herein. In a non-limiting embodiment, oil-based treatment fluid  128  may be disposed in well bore when one or more downhole tool (e.g., production equipment) are run into wellbore  122 . In some embodiments, work string  120  may be in the form a production tubing with oil-based treatment fluid  128  placed into work string  120  to replace a drilling fluid (or another fluid) previously disposed in production tubing. It should be noted that while  FIG.  1    generally depicts a subsea operation, those skilled in the art will readily recognize that the principles described herein are equally applicable to land-based systems, without departing from the scope of the disclosure. 
     Another example method may include a method of drilling a wellbore into a subterranean formation. A drilling method may include circulating an oil-based treatment fluid (e.g., a drilling fluid) in a wellbore. The circulating may include circulating the oil-based treatment fluid through a drill string and bottom hole assembly. The oil-based treatment fluid may include an aqueous internal phase and an oil external phase. The aqueous internal phase may include a brine and a crystallization temperature reduction additive. In some examples, the aqueous internal phase may include calcium bromide and calcium nitrate. The oil-based treatment fluid may transfer kinetic energy into a mud motor to drive a drill bit on the end of the bottom hole assembly thereby extending the wellbore. In some embodiments, the wellbore may be extended through a reservoir section of the subterranean formation, and the oil-based treatment fluid may be considered a drill-in fluid. 
       FIG.  2    illustrates a drilling assembly  200  in which a drilling fluid  122  as disclosed above may be used. It should be noted that while  FIG.  2    generally depicts a land-based drilling assembly, those skilled in the art will readily recognize that the principles described herein are equally applicable to subsea drilling operations that employ floating or sea-based platforms and rigs, without departing from the scope of the disclosure. 
     As illustrated, the drilling assembly  200  may include a drilling platform  202  that supports a derrick  204  having a traveling block  206  for raising and lowering a drill string  208 . The drill string  208  may include, but is not limited to, drill pipe and coiled tubing, as generally known to those skilled in the art. A kelly  210  may support the drill string  208  as it is lowered through a rotary table  212 . A drill bit  214  may be attached to the distal end of the drill string  208  and may be driven either by a downhole motor and/or via rotation of the drill string  208  from the well surface. The drill bit  214  may include, but is not limited to, roller cone bits, PDC bits, natural diamond bits, any hole openers, reamers, coring bits, etc. As the drill bit  214  rotates, it may create a wellbore  216  that penetrates various subterranean formations  218 . 
     Drilling fluid  222  including an aqueous internal phase, which may include a bromide brine and a true crystallization temperature reduction additive, and an oil external phase that includes a base oil, may be prepared. Additionally, drilling fluid  222  may further include additional additives, such as those described in the preceding sections. A pump  220  (e.g., a mud pump) may circulate drill-in fluid  222  through a feed pipe  224  and to the kelly  210 , which conveys the drilling fluid  222  downhole through the interior of the drill string  208  and through one or more orifices in the drill bit  214  and into subterranean formation  218 . The drilling fluid  222  then be circulated back to the surface via an annulus  226  defined between the drill string  208  and the walls of the wellbore  216 . At the surface, the recirculated or spent drilling fluid  222  may exit the annulus  226  and may be conveyed to one or more fluid processing unit(s)  228  via an interconnecting flow line  230 . The fluid processing unit(s)  228  may include, but is not limited to, one or more of a shaker (e.g., shale shaker), a centrifuge, a hydrocyclone, a separator (including magnetic and electrical separators), a desilter, a desander, a separator, a filter (e.g., diatomaceous earth filters), a heat exchanger, and/or any fluid reclamation equipment. The fluid processing unit(s)  228  may further include one or more sensors, gauges, pumps, compressors, and the like used store, monitor, regulate, and/or recondition the drilling fluid. 
     After passing through the fluid processing unit(s)  228 , a “cleaned” drilling fluid  222  may be deposited into a nearby retention pit  232  (i.e., a mud pit). While illustrated as being arranged at the outlet of the wellbore  216  via the annulus  226 , those skilled in the art will readily appreciate that the fluid processing unit(s)  228  may be arranged at any other location in the drilling assembly  100  to facilitate its proper function, without departing from the scope of the disclosure. One or more of the drilling fluid additives may be added to the drilling fluid  222  via a mixing hopper  234  communicably coupled to or otherwise in fluid communication with the retention pit  232 . The mixing hopper  234  may include, but is not limited to, mixers and related mixing equipment known to those skilled in the art. Alternatively, the drilling fluid additives may be added to the drilling fluid  222  at any other location in the drilling assembly  200 . While  FIG.  1    shows only a single retention pit  232 , there could be more than one retention pit  232 , such as multiple retention pits  232  in series. Moreover, the retention pit  232  may be representative of one or more fluid storage facilities and/or units where the drilling fluid additives may be stored, reconditioned, and/or regulated until added to the drilling fluid  222 . 
     Accordingly, this disclosure describes compositions and methods that may use the disclosed oil-based fluids having a true crystallization temperature reduction additive in the aqueous internal phase. The methods, systems, and apparatuses may include any of the following statements: 
     Statement 1. An example method may include providing an oil-based treatment fluid in the form of an invert emulsion including an aqueous internal phase and an oil external phase. The aqueous internal phase may include a bromide brine and a true crystallization temperature reduction additive, wherein the bromide brine has a density of about 14.2 lbs/gal or greater. The method may further include placing the oil-based treatment fluid into a wellbore. 
     Statement 2. The method of statement 1, further including circulating the oil-based treatment fluid in the wellbore while extending the wellbore into a subterranean formation with a drill bit. 
     Statement 3. The method of statement 1 or statement 2, further including running a downhole tool into the treatment fluid in the wellbore. 
     Statement 4. The method of any preceding statement, further including replacing a drilling fluid disposed in a production tubing disposed in the wellbore with the treatment fluid. 
     Statement 5. The method of any preceding statement, wherein the bromide brine includes at least one brine selected from the group consisting of a lithium bromide, sodium bromide, potassium bromide, rubidium bromide, magnesium bromide, calcium bromide, strontium bromide, zinc bromide, manganese (II) bromide, a manganese (II) brine, and any combination thereof. 
     Statement 6. The method of any preceding statement, wherein the oil external phase includes at least one base oil selected from the group consisting of a mineral oil, diesel oil, a glycol ether solvent, a hydrotreated light petroleum distillate having about 9 to 16 carbon atoms, an ethylene glycol monobutyl ether, an diethylene glycol monobutyl ether, an alkane, an aromatic organic compound, a cyclic alkane, a paraffin, desulfurized hydrogenated kerosene, a polyolefin, a polydiorganosiloxane, a siloxane, an ester, and combinations thereof. 
     Statement 7. The method of any preceding statement, wherein the invert emulsion has an oil external phase to aqueous internal phase ratio of about 10:90 to about 99:1. 
     Statement 8. The method of any preceding statement, wherein the true crystallization temperature reduction additive includes at least one additive selected from the group consisting of lithium nitrate, sodium nitrate, magnesium nitrate, calcium nitrate, ammonium nitrate, strontium nitrate, a glycol, a polyol, a sugar alcohol, a sugar acid, an aldoses, a ketose, malonamide and any combination thereof. 
     Statement 9. The method of any preceding statement, wherein the aqueous internal phase further includes a polyol. 
     Statement 10. The method of any preceding statement, wherein the oil-based treatment fluid is free or essentially free of zinc and cesium formate. 
     Statement 11. The method of any preceding statement, wherein true crystallization temperature reduction additive includes a nitrate in an amount of about 1 wt. % to about 70 wt. % based on a total weight of the oil-based treatment fluid. 
     Statement 12. The method of statement 1, wherein the bromide brine includes calcium bromide brine, wherein the true crystallization temperature reduction additive includes calcium nitrate, wherein the true crystallization temperature reduction additive is present in the aqueous internal phase in an amount of about 2 wt. % to about 40 wt. % based on a total weight of the aqueous internal phase, wherein the invert emulsion has an oil external phase to aqueous internal phase ratio of about 70:30 to about 20:40, wherein the bromide brine has a first true crystallization temperature without inclusion of the true crystallization temperature reduction additive, and wherein the bromide brine has a second true crystallization temperature with true crystallization temperature reduction additive that is lower than the first true crystallization temperature. 
     Statement 13. An oil-based treatment fluid for use in subterranean operations, the oil-based treatment fluid including an invert emulsion. The invert emulsion may include an aqueous internal phase and an oil external phase, wherein the aqueous internal phase includes a bromide brine and a true crystallization temperature reduction additive. The bromide brine may have a density of about 14.2 lbs/gal or greater. The bromide brine may have a first true crystallization temperature without inclusion of the true crystallization temperature reduction additive. The bromide brine may have a second true crystallization temperature with the true crystallization temperature reduction additive that is lower than the first true crystallization temperature reduction additive. 
     Statement 14. The oil-based treatment fluid of statement 13, wherein the second true crystallization temperature is less than the first true crystallization temperature by about 9° F. or more. 
     Statement 15. The oil-based treatment fluid of statement 13 or statement 14, wherein the bromide brine includes at least one brine selected from the group consisting of a lithium bromide, sodium bromide, potassium bromide, rubidium bromide, magnesium bromide, calcium bromide, strontium bromide, zinc bromide, manganese (II) bromide, a manganese (II) brine, and any combination thereof, and wherein the oil external phase includes at least one base oil selected from the group consisting of a mineral oil, diesel oil, a glycol ether solvent, a hydrotreated light petroleum distillate having about 9 to 16 carbon atoms, an ethylene glycol monobutyl ether, an diethylene glycol monobutyl ether, an alkane, an aromatic organic compound, a cyclic alkane, a paraffin, desulfurized hydrogenated kerosene, a polyolefin, a polydiorganosiloxane, a siloxane, an ester, and combinations thereof. 
     Statement 16. The oil-based treatment fluid of any one of statements 13 to 15, wherein the invert emulsion has an oil external phase to aqueous internal phase ratio of about 10:90 to about 99:1. 
     Statement 17. The oil-based treatment fluid of any one of statements 13 to 16, wherein the true crystallization temperature reduction additive includes at least one additive selected from the group consisting of lithium nitrate, sodium nitrate, magnesium nitrate, calcium nitrate, ammonium nitrate, strontium nitrate, a glycol, a polyol, a sugar alcohol, a sugar acid, an aldoses, a ketose, malonamide and any combination thereof. 
     Statement 18. The oil-based treatment fluid of any one of statements 13 to 17, wherein aqueous internal phase further includes a polyol. 
     Statement 19. The oil-based treatment fluid of any one of statements 13 to 18, wherein the oil-based treatment fluid is free or essentially free of zinc and cesium formate. 
     Statement 20. The oil-based treatment fluid of any one of statements 13 to 19, wherein true crystallization temperature reduction additive includes a nitrate in an amount of about 1 wt. % to about 70 wt. % based on a total weight of the oil-based treatment fluid. 
     To facilitate a better understanding of the present technique, the following examples of some specific embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the disclosure. 
     Examples 
     Oil-based treatment fluids were prepared that included a true crystallization temperature reduction additive in a high density brine. In particular, the oil-based treatment fluid included an aqueous internal phase. The aqueous internal phase included a high density brine having a density of 14.8 lbs/gal (1,770 kg/m3). The high density brine was a mixture of calcium bromide and a true crystallization temperature reduction additive. The true crystallization temperature reduction additive was calcium nitrate. The calcium nitrate was included in an amount of 15.7 wt. % based on a total weight of the high density brine. The oil external phase included a synthetic base fluid as the base oil. The oil-based treatment fluids further included two different invert emulsifiers, Emulsifier A (amidoamine) and Emulsifier B (alkoxylated alcohol). The oil-based treatment fluids also included lime, a fluid loss additive, a filtration control agent (acrylic co-polymer), an organophilic clay viscosifier, and a calcium carbonate bridging agent having a median particle size (d50) of 5 microns. 
     For this Example, four sample oil-based treatment fluids were prepared that are identified as Samples 1-4. The formulations for each Sample are provided in the table below. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Sample Number 
                 1 
                 2 
                 3 
                 4 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Flued Density 
                 12.1 
                 lb/gal 
                 12.1 
                 lb/gal 
                 12.5 
                 lb/gal 
                 12.5 
                 lb/gal 
               
               
                   
                 (1450 
                 kg/m 3 ) 
                 (1450 
                 kg/m 3 ) 
                 (1500 
                 kg/m 3 ) 
                 (1500 
                 kg/m 3 ) 
               
            
           
           
               
               
               
               
               
            
               
                 Oil-Water Ratio 
                 51/49 
                 50/50 
                 48/52 
                 45/55 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Synthetic Base Oil, bbl 
                 0.324 
                 (0.0515) 
                 0.322 
                 (0.0512) 
                 0.291 
                 (0.0463) 
                 0.275 
                 (0.0437) 
               
               
                 (m 3 ) 
               
               
                 Emulsifier A, lb(kg) 
                 6 
                 (2.72) 
                 6 
                 (2.72) 
                 6 
                 (2.72) 
                 6 
                 (2.72) 
               
               
                 Emulsifier B, lb (kg) 
                 14 
                 (6.35) 
                 14 
                 (6.35) 
                 14 
                 (6.35) 
                 14 
                 (6.35) 
               
               
                 Lime, lb (kg) 
                 2.8 
                 (1.27) 
                 2.8 
                 (1.27) 
                 2.8 
                 (1.27) 
                 2.8 
                 (1.27) 
               
               
                 High density brine 
                 0.556 
                 (0.0884) 
                 0.588 
                 (0.0935) 
                 0.586 
                 (0.0932) 
                 0.63 
                 (0.100) 
               
               
                 (14.8 lb/gal), bbl (m 3 ) 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Filtration Control 
                 2 
                 (0.907) 
                 — 
                 2 
                 (0.907) 
                 — 
               
               
                 Additive, lb (kg) 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Viscosifier, lb (kg) 
                 1 
                 (0.453) 
                 1 
                 (0.453) 
                 1 
                 (0.453) 
                 1 
                 (0.453) 
               
               
                 Bridging Agent, lb (kg) 
                 48 
                 (21.77) 
                 25 
                 (11.34) 
                 50 
                 (22.68) 
                 28 
                 (12.70) 
               
               
                   
               
            
           
         
       
     
     As illustrated in the table above, the oil-water ratio of each Sample was changed. After preparation, the Samples underwent rheological testing in accordance with “Recommended Practice for Field Testing of Oil-Based Drilling Fluids”, API Recommended Practice 13B-1, Fourth Edition, March 2005. The results of the rheological testing are provided in the following tables. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Sample 
                 #1 
                 #2 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Aging condition 
                 0 
                 HR- 
                 SA- 
                 0 
                 HR- 
                 SA- 
               
               
                 (248° F. (120° 
                   
                 4 hr 
                 16 hr 
                   
                 4 hr 
                 16 hr 
               
               
                 C.)) 
                   
                   
                   
                   
                   
                   
               
            
           
           
               
               
            
               
                 Testing 
                 120° F. (49° C.) 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 temperature 
                   
                   
                   
                   
                   
                   
               
               
                 600 rpm 
                 195 
                 207 
                 220 
                 147 
                 118 
                 122 
               
               
                 300 rpm 
                 112 
                 120 
                 129 
                 83 
                 67 
                 69 
               
               
                 200 rpm 
                 85 
                 87 
                 94 
                 60 
                 49 
                 50 
               
               
                 100 rpm 
                 47 
                 52 
                 56 
                 33 
                 27 
                 28 
               
               
                  6 rpm 
                 7 
                 10 
                 11 
                 5 
                 5 
                 5 
               
               
                  3 rpm 
                 5 
                 7 
                 8 
                 4 
                 3 
                 3 
               
               
                 Plastic viscosity, 
                 83 
                 87 
                 91 
                 64 
                 51 
                 53 
               
               
                 cP 
                   
                   
                   
                   
                   
                   
               
               
                 Yield point, 
                 29 
                 33 
                 38 
                 19 
                 16 
                 16 
               
               
                 lb/100 ft 2   
                 (139) 
                 (158 
                 (182) 
                 (91) 
                 (76) 
                 (76) 
               
               
                 (kPa) 
                   
                   
                   
                   
                   
                   
               
               
                 10 Sec gel, 
                 6 
                 8 
                 9 
                 4 
                 5 
                 5 
               
               
                 lb/100 ft 2   
                 (29) 
                 (38) 
                 (43) 
                 (19) 
                 (24) 
                 (24) 
               
               
                 (kPa) 
                   
                   
                   
                   
                   
                   
               
               
                 10 min gel, 
                 5 
                 7 
                 8 
                 4 
                 4 
                 4 
               
               
                 lb/100 ft 2   
                 (24) 
                 (34) 
                 (38* 
                 (19) 
                 (19) 
                 (19) 
               
               
                 (kPa) 
                   
                   
                   
                   
                   
                   
               
               
                 Electrical 
                 259 
                 525 
                 490 
                 228 
                 428 
                 348 
               
               
                 stability, V 
                   
                   
                   
                   
                   
                   
               
               
                 Top Oil, mL 
                 — 
                 — 
                 0 
                 — 
                 — 
                 0 
               
               
                 Bottom Mud 
                 — 
                 — 
                 12.1 
                 — 
                 — 
                 12.0 
               
               
                 Density, lb/gal 
                   
                   
                 (1450) 
                   
                   
                 (1438) 
               
               
                 (kg/m 3 ) 
                   
                   
                   
                   
                   
                   
               
               
                 Top Mud 
                 — 
                 — 
                 12.1 
                 — 
                 — 
                 12.0 
               
               
                 Density, lb/gal 
                   
                   
                 (1450) 
                   
                   
                 (1438) 
               
               
                 (kg/m 3 ) 
                   
                   
                   
                   
                   
                   
               
               
                 Sag Factor 
                 — 
                 — 
                 0.50 
                 — 
                 — 
                 0.50 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Sample 
                 #3 
                 #4 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Aging condition 
                 0 
                 HR- 
                 SA- 
                 0 
                 HR- 
                 SA- 
               
               
                 (248° F. (120° 
                   
                 4 hr 
                 16 hr 
                   
                 4 hr 
                 16 hr 
               
               
                 C.)) 
                   
                   
                   
                   
                   
                   
               
            
           
           
               
               
            
               
                 Testing 
                 120° F. (49° C.) 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 temperature 
                   
                   
                   
                   
                   
                   
               
               
                 600 rpm 
                 234 
                 265 
                 290 
                 190 
                 165 
                 180 
               
               
                 300 rpm 
                 139 
                 160 
                 174 
                 109 
                 98 
                 105 
               
               
                 200 rpm 
                 100 
                 118 
                 128 
                 77 
                 70 
                 76 
               
               
                 100 rpm 
                 600 
                 72 
                 81 
                 44 
                 42 
                 45 
               
               
                  6 rpm 
                 11 
                 15 
                 16 
                 8 
                 8 
                 9 
               
               
                  3 rpm 
                 7 
                 11 
                 11 
                 5 
                 6 
                 7 
               
               
                 Plastic viscosity, 
                 95 
                 105 
                 116 
                 81 
                 67 
                 75 
               
               
                 cP 
                   
                   
                   
                   
                   
                   
               
               
                 Yield point, 
                 44 
                 55 
                 58 
                 28 
                 31 
                 30 
               
               
                 lb/100 ft 2   
                 (211) 
                 (263) 
                 (278) 
                 (134) 
                 (148) 
                 (144) 
               
               
                 (kPa) 
                   
                   
                   
                   
                   
                   
               
               
                 10 Sec gel, 
                 8 
                 12 
                 12 
                 7 
                 7 
                 7 
               
               
                 lb/100 ft 2   
                 (38) 
                 (57) 
                 (57) 
                 (34) 
                 (34) 
                 (34) 
               
               
                 (kPa) 
                   
                   
                   
                   
                   
                   
               
               
                 10 min gel, 
                 5 
                 8 
                 1 
                 5 
                 6 
                 7 
               
               
                 lb/100 ft 2   
                 (24 
                 (38) 
                 (53)1 
                 (24 
                 (29) 
                 (34) 
               
               
                 (kPa) 
                   
                   
                   
                   
                   
                   
               
               
                 Electrical 
                 400 
                 569 
                 450 
                 257 
                 480 
                 414 
               
               
                 stability, V 
                   
                   
                   
                   
                   
                   
               
               
                 Top Oil, mL 
                 — 
                 — 
                 0 
                 — 
                 — 
                 0 
               
               
                 Bottom Mud 
                 — 
                 — 
                 12.3 
                 — 
                 — 
                 12.4 
               
               
                 Density, lb/gal 
                   
                   
                 (1474) 
                   
                   
                 (1486) 
               
               
                 (kg/m 3 ) 
                   
                   
                   
                   
                   
                   
               
               
                 Top Mud 
                 — 
                 — 
                 12.3 
                 — 
                 — 
                 12.4 
               
               
                 Density, lb/gal 
                   
                   
                 (1474) 
                   
                   
                 (1486) 
               
               
                 (kg/m 3 ) 
                   
                   
                   
                   
                   
                   
               
               
                 Sag Factor 
                 — 
                 — 
                 0.50 
                 — 
                 — 
                 0.50 
               
               
                   
               
            
           
         
       
     
     The preceding description provides various examples of the systems and methods of use disclosed herein which may contain different method steps and alternative combinations of components. It should be understood that, although individual examples may be discussed herein, the present disclosure covers all combinations of the disclosed examples, including, without limitation, the different component combinations, method step combinations, and properties of the system. It should be understood that the compositions and methods are described in terms of “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces. 
     For the sake of brevity, only certain ranges are explicitly disclosed herein. However, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values even if not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited. 
     Therefore, the present examples are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular examples disclosed above are illustrative only, and may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual examples are discussed, the disclosure covers all combinations of all of the examples. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. It is therefore evident that the particular illustrative examples disclosed above may be altered or modified and all such variations are considered within the scope and spirit of those examples. If there is any conflict in the usages of a word or term in this specification and one or more patent(s) or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted.