CA1204586A - Low fluid loss heavy brines containing hydroxyethyl cellulose - Google Patents
Low fluid loss heavy brines containing hydroxyethyl celluloseInfo
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- CA1204586A CA1204586A CA000477862A CA477862A CA1204586A CA 1204586 A CA1204586 A CA 1204586A CA 000477862 A CA000477862 A CA 000477862A CA 477862 A CA477862 A CA 477862A CA 1204586 A CA1204586 A CA 1204586A
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- brine
- hydroxyethyl cellulose
- zinc bromide
- bromide
- weight
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Abstract
Abstract of the Disclosure Disclosed are heavy brine compositions containing zinc bromide, calcium chloride and calcium bromide, and a fluid loss reducing amount of hydroxyethyl cellulose. The brine contains more than about 20% by weight zinc bromide and a concentration of calcium chloride of at least (2X-33)% by weight where X is the % of the weight of zinc bromide in the brine. The brine is used in the oil and gas industry.
Description
8~
Back~ro_nd of the Invention_________________ The present invention relates to heavy brine solutions con-taining zinc bromide and at least one soluble salt selected froJn the group consisting of calcium chloride and calcium bromide, and, in particular, to such brines llaving a flow fluid loss con-taining hydroxyethyl cellulose. This is a divisional of Canadian application Serial No. 422,031, wiled February 21, 1983.
In recent years, the practical operating range of clear brines for use in the oil and gas industry has been signi-ficantly extended by utilizing soluble zinc salts, particu-larly zinc bromide, so that the advantages of clear brines can now be obtained with fluids having densities as high as l9.2 pounds per gallon at ambient temperatures and pressures.
The high density clear brines are used extensively: as completion fluids to minimize plugging of perforation tunnels, to protect focmation permeability and to minimize mechanical problems; as workover fluids, for the same reasons; as packer fluids, to allow easy movement and retrieval of the packer; for underreaming, gravel-pack and sand consolidation applications;
as kill fluid or ballast fluid; or wire-line work; and as drilling fluids.
Clear brines having a density of 14.2 pounds per gallon (ppg) or lower are generally formulated to contain sodium chloride, sodium bromide, potassium chloride, calcium chlor-ide, calcium bromide, or mixtures of these salts. Clear brineshaving a density up to about 15.1 ppg can be formulated with calcium chloride and calcium bromide; however, if the brine must have a low crystallization temperature, then clear brines in this density range are generally formulated to contain a soluble zinc salt. Zinc brsmide is preferred because urines containing it are less corrosive than brines containing zinc chloride. Clear brines having a density greater than aboutl5.1 ppg are formulated to contain zinc bromide.
Generally, hydroxyethyl cellulose (HEC) and xanthan gum polymers are compatible with the fluids which do not contain zinc saltsO however, at the higher densities, the hydration of the viscosifiers is significantly slower HEC is generally considered as unsatisfactory for use in fluids containing zinc salts.
lZ~45;~36 Summary of the Invention we have now found that HO will junction as a fluid loss additive in certain heavy brines in which HO does not function efficiently as a viscosifier. These heavy brines contain either:
1) from about 16~ to about 20% by weight zinc bromide; or
Back~ro_nd of the Invention_________________ The present invention relates to heavy brine solutions con-taining zinc bromide and at least one soluble salt selected froJn the group consisting of calcium chloride and calcium bromide, and, in particular, to such brines llaving a flow fluid loss con-taining hydroxyethyl cellulose. This is a divisional of Canadian application Serial No. 422,031, wiled February 21, 1983.
In recent years, the practical operating range of clear brines for use in the oil and gas industry has been signi-ficantly extended by utilizing soluble zinc salts, particu-larly zinc bromide, so that the advantages of clear brines can now be obtained with fluids having densities as high as l9.2 pounds per gallon at ambient temperatures and pressures.
The high density clear brines are used extensively: as completion fluids to minimize plugging of perforation tunnels, to protect focmation permeability and to minimize mechanical problems; as workover fluids, for the same reasons; as packer fluids, to allow easy movement and retrieval of the packer; for underreaming, gravel-pack and sand consolidation applications;
as kill fluid or ballast fluid; or wire-line work; and as drilling fluids.
Clear brines having a density of 14.2 pounds per gallon (ppg) or lower are generally formulated to contain sodium chloride, sodium bromide, potassium chloride, calcium chlor-ide, calcium bromide, or mixtures of these salts. Clear brineshaving a density up to about 15.1 ppg can be formulated with calcium chloride and calcium bromide; however, if the brine must have a low crystallization temperature, then clear brines in this density range are generally formulated to contain a soluble zinc salt. Zinc brsmide is preferred because urines containing it are less corrosive than brines containing zinc chloride. Clear brines having a density greater than aboutl5.1 ppg are formulated to contain zinc bromide.
Generally, hydroxyethyl cellulose (HEC) and xanthan gum polymers are compatible with the fluids which do not contain zinc saltsO however, at the higher densities, the hydration of the viscosifiers is significantly slower HEC is generally considered as unsatisfactory for use in fluids containing zinc salts.
lZ~45;~36 Summary of the Invention we have now found that HO will junction as a fluid loss additive in certain heavy brines in which HO does not function efficiently as a viscosifier. These heavy brines contain either:
1) from about 16~ to about 20% by weight zinc bromide; or
2) greater than 20% zinc bromide and a concentration of calcium chloride of at least (2X--33)% by weight, were X = zinc bromide.
It is, therefore, an object of this invention to provide certain heavy brinë solutions containing zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide, and a fluid loss reducing amount of hydroxyethyl cellulose.
Another object of this invention is to provide heavy brine solutions having a density in the range from about 14.2 to about 16.0 ppg containing zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide, and a fluid loss reducing amount of hydroxy-ethyl cellulose till another object of this invention is to provide a method of decreasing the fluid loss of heavy brines having a density in the range from about 14.2 to about 16.0 ppg con-tainir.g zinc bromide and at least one soluble salt selected from the group consistiny of calcium chloride and calcium bromide.
~20~6 Description of the Preferred Emb d_ ent The heavy brines for use in the present invention contain zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide.
In one embodiment of the invention, the concentration of zinc bromide must be in the range from about 16% to about 20%
by weight. Preferably the concentration of zinc brornide is <18~ and the concentration of calcium chloride is <5(X-17)%
where X is the % of zinc bromide.
In another embodiment of the invention, the brine must contain greater than 20% by weight zinc bromide and a con-centration of calcium chloride of at least (2X-33)% by weight, where X is the % of zinc bromide.
The preferred brines have a density in the range from about 14.2 to about 16.0 ppg.
Generally, heavy brines are prepared by mixing together various standard commercially available brines, as follows:
calcium chloride brines having a density in the range from about 11.0 to about 11.6 ppg; calcium bromide brine having a density of 14.2 ppg; and a calcium bromide/zinc bromide solution having a density of 19.2 ppg containing about 20% calcium bromide and about 57% zinc bromide. Solid calcium chloride and solid calcium bromide are also used in conjunction with these brines to Drepare the heavy brines for use in this invention. However, it is preferred to utilize only liquid solutions to formulate the brines in the practice of this invention. Standard brine mixing/preparation tables are available from the various manu-facturers and suppliers of these commercially available brines.
The HEC polymers which are useful as fluid loss control agents in the present invention are solid, particulate ma-terials which are water soluble or water dispersible gums and which upon solution or dispersion in an aqueous medium increase the viscosity of the system. HEC polymers are generally high yield, water soluble, non-ionic materials produced by treating cellulose wlth sodium hydroxide followed by reaction with ethylene oxide. Each anhydroglucose unit in the cellulose molecule has three reactive hydroxy groups. The average number 5~3~
of moles of the ethylene oxide that becomes attached to each anhydroglucose unit in cellulose is called moles of substituent combined. The average number of hydroxyls of each anhydroglucose unit which is reacted with ethylene oxide is called the degree of substitution. In general, it is preferable to use HEC polymers having a mole substitution greater than 1.
Usually, upon the addition of dry, powdered hydrophilic polymers, such as HO to waxer, the polymer particles undergo hydration preventing the interior of the particle f rom readily hydrating, solvating or otherwise dispersing in the aqueous medium. Accordingly, high shear, long mixing times and/or elevated temperatures must be applied in order to obtain a homogeneous system.
We have found that HEC and other hydrophilic polymers can be activated such that the polymers will viscosify heavy brines at ambient temperatures. Activated HEC com-positions/ and methods for activating HEC, are disclosed in co-pending Canadian patent applications 369,357, filed February 27, 1981 and 374,309 filed March 31, 1981.
Methods of activating other hydrophilic polymers are disclosed in co-pending Canadian patent application SN
378,082 filed May 22, 1981.
Activated HEC compositions comprise:
1) HEC, a solvating agent comprising a water miscible, polar organic liquid which when uniformly mixed with HEC
in a weight ratio of ~IEC to solvating agent of 1:2 produces a mixture with substantially no free liquid solvating agent present after remaining quiescent for one week at ambient temperature in a sealed container, and a diluting agent comprising an organic liquid which is not a solvating agent; and 2) HEC, an aqueous liquid, and a water soluble polar organic liquid which when uniformly mixed with HEC in a weight ratio of HEC to polar organic liquid of 1: 2 pro-duces a mixture with free liquid present after remaining quiescent for one week 8~
at ambient temperature in a sealed container. Preferably the aqueous liquid has a pH greater than 7Ø
Generally speaking, it has been found that virtually any organic compound which passes the solvation test described above, will function, to a usable degree, as a solvation agent.
Non-limiting but preferred solvating agents include: ali-phatic glycols containing from.2 to 5 carbon atoms such as ethylene glycol, 1,2-propanediol, 1,4-b~tanediol, 1,3-pent-anediol and the like; alkylene triols containing from 2 to 6 carbon atoms such as glycerol, 1,2,3~butane-triol, 1,2,3-pentanetriol, and the like; amides containing from 1 to 4 carbon atoms such as formamide, acetamide, dimethyl formamide, and the like; and the mixtures of the various above compounds.
The diluting agent, in general, will be any liquid organic compound or material which is not a solvating agent. In general, the diluting agents are liquids which do not appre-ciably swell the HEC polymers, i.e. they do not produce semi-solid or viscous mixtures which have no free liquid present after the one week solvation period described in the above test for determining solvating agents. Non-limiting examples of diluting agents include liquid aliphatic and aromatic hydro-carbons containing from 5 to 10 carbon atoms; kerosene, diesel oil, isopropanol, alkylene glycol ethers, vegetable oils, etc.
Particularly preferred are organic liquids which are water soluble or miscible most preferably alkanols having at least 3 carbon atoms, ethylene glycol monoalkyl ethers, dlalkylene glycol monoalkyl ethers, and the likeO The diluting agent will maintain the polymeric composition in a liquid, pourable state at a temperature of about 20~C. It will be understood, however, that lesser amounts of diluting agent can be used if desired and that the ultimate amount of diluting agent employed Jill depend upon the type of shear which is available to disperse the thickener. In general it has been found that desirable thick-eners, which are pourable liquids, can be produced from compo-sitions containing from about 10 Jo about 25% by weight HECpolymer, from about 2 to about 70~ by weight dilu~in~ agent, and from about 5 to about 88% solvating agent.
HEC has been added to heavy brines to increase the vis-so cosity of the brine such that the rate of loss of the brineto the formation contacted by the brine is reduced. Normally, in the absence of bridging particles, hydroxyethyl cellulose provides poor fluid loss control in those brines in which the HEC is fully hydrated. See for example co-pending Canadian patent application SN 380,104 filed June 18, 1981.
We have found, as disclosed in co-pending patent applica-tion SN 380,104 filed June 18, 1981, that if the concentration of zinc bromide is less than about 20% by weight, the HEC will not efficiently gel or viscosify the brine. Indeed, we have found that while it is possible to viscosify a brine contain-ing no zinc bromide or a brine solution containing a high concentration of zinc bromide, with HO if the two thickened solutions are admixed to produce a solution containing zinc bromide in less than about a 20% by weight concentration, the viscosity of the mixed brine will be essentially the same as if no HEC is present.
As indicated herein, it is a feature of this invention that HEC functions as an excellent fluid loss control additive in certain heavy brines in which the HO is a very inefficient viscosifier. The HEC containing brines of this invention are cloudy or opaque as compared to the clear brines obtained when the ~IEC is completely, or nearly completely, hydrated Apparently the HEC is not completely solubilized in these brinès and thus at least a portion of the HEC is available to act as a bridging agent to decrease the fluid loss of these brines.
It is preferred in the practice of this invention that the HEC be activated such that the HEC will hydrate in these heavy brines at ambient temperature.
The concentration of HEC need only be sufficient to reduce the fluid loss of the brine. Preferably, the concentration of HEC will be from about 0.25 to about 5.0 ppb, more preferably, prom about 0.25 to akout 3.0 ppb.
It is another embodiment of this invention to provide a method of decreasing the fluid loss of heavy brines containing zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide, which comprises formulating the brine to contain from about 16%
to about 20% by weight zinc bromide, and mixing with the brine a fluid loss reducing amount of HEC, as disclosed hereinbefore.
Still another embodiment of this invention provides a method 5 of decreasing the fluid loss of heavy brines containing zinc bromide, calcium chloride, and calcium brine, which comprises formulating the brine to contain greater than 20% zinc bromide and a concentration of calcium chloride of at least (2X-33)%
by weight, where X is the % of zinc bromide, and mixing with the brine a fluid loss reducing amount of HO as disclosed hereinbefore.
To more fully illustrate the invention, the following non-limiting examples are presented.
Examples of the Invention Heavy brines having the compositions listed in Table 1 were prepared by mixing together the indicated amounts of the follow-ing materials: a 19.2 ppg calcium bromide/zinc bromide solution containing 20% calcium bromide and 57% zinc bromide; a 14.2 ppg calcium bromide solution containing 53~ calcium bromide; an 11.6 ppg calcium chloride solution containing 37.6% calcium chloride; and calcium chloride pellets containing 95% calcium chloride. After cooling to room temperature, there were added either: 3 ppb of N~TROSOL~ 250 ~HR hydroxyethyl cellulose; or
It is, therefore, an object of this invention to provide certain heavy brinë solutions containing zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide, and a fluid loss reducing amount of hydroxyethyl cellulose.
Another object of this invention is to provide heavy brine solutions having a density in the range from about 14.2 to about 16.0 ppg containing zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide, and a fluid loss reducing amount of hydroxy-ethyl cellulose till another object of this invention is to provide a method of decreasing the fluid loss of heavy brines having a density in the range from about 14.2 to about 16.0 ppg con-tainir.g zinc bromide and at least one soluble salt selected from the group consistiny of calcium chloride and calcium bromide.
~20~6 Description of the Preferred Emb d_ ent The heavy brines for use in the present invention contain zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide.
In one embodiment of the invention, the concentration of zinc bromide must be in the range from about 16% to about 20%
by weight. Preferably the concentration of zinc brornide is <18~ and the concentration of calcium chloride is <5(X-17)%
where X is the % of zinc bromide.
In another embodiment of the invention, the brine must contain greater than 20% by weight zinc bromide and a con-centration of calcium chloride of at least (2X-33)% by weight, where X is the % of zinc bromide.
The preferred brines have a density in the range from about 14.2 to about 16.0 ppg.
Generally, heavy brines are prepared by mixing together various standard commercially available brines, as follows:
calcium chloride brines having a density in the range from about 11.0 to about 11.6 ppg; calcium bromide brine having a density of 14.2 ppg; and a calcium bromide/zinc bromide solution having a density of 19.2 ppg containing about 20% calcium bromide and about 57% zinc bromide. Solid calcium chloride and solid calcium bromide are also used in conjunction with these brines to Drepare the heavy brines for use in this invention. However, it is preferred to utilize only liquid solutions to formulate the brines in the practice of this invention. Standard brine mixing/preparation tables are available from the various manu-facturers and suppliers of these commercially available brines.
The HEC polymers which are useful as fluid loss control agents in the present invention are solid, particulate ma-terials which are water soluble or water dispersible gums and which upon solution or dispersion in an aqueous medium increase the viscosity of the system. HEC polymers are generally high yield, water soluble, non-ionic materials produced by treating cellulose wlth sodium hydroxide followed by reaction with ethylene oxide. Each anhydroglucose unit in the cellulose molecule has three reactive hydroxy groups. The average number 5~3~
of moles of the ethylene oxide that becomes attached to each anhydroglucose unit in cellulose is called moles of substituent combined. The average number of hydroxyls of each anhydroglucose unit which is reacted with ethylene oxide is called the degree of substitution. In general, it is preferable to use HEC polymers having a mole substitution greater than 1.
Usually, upon the addition of dry, powdered hydrophilic polymers, such as HO to waxer, the polymer particles undergo hydration preventing the interior of the particle f rom readily hydrating, solvating or otherwise dispersing in the aqueous medium. Accordingly, high shear, long mixing times and/or elevated temperatures must be applied in order to obtain a homogeneous system.
We have found that HEC and other hydrophilic polymers can be activated such that the polymers will viscosify heavy brines at ambient temperatures. Activated HEC com-positions/ and methods for activating HEC, are disclosed in co-pending Canadian patent applications 369,357, filed February 27, 1981 and 374,309 filed March 31, 1981.
Methods of activating other hydrophilic polymers are disclosed in co-pending Canadian patent application SN
378,082 filed May 22, 1981.
Activated HEC compositions comprise:
1) HEC, a solvating agent comprising a water miscible, polar organic liquid which when uniformly mixed with HEC
in a weight ratio of ~IEC to solvating agent of 1:2 produces a mixture with substantially no free liquid solvating agent present after remaining quiescent for one week at ambient temperature in a sealed container, and a diluting agent comprising an organic liquid which is not a solvating agent; and 2) HEC, an aqueous liquid, and a water soluble polar organic liquid which when uniformly mixed with HEC in a weight ratio of HEC to polar organic liquid of 1: 2 pro-duces a mixture with free liquid present after remaining quiescent for one week 8~
at ambient temperature in a sealed container. Preferably the aqueous liquid has a pH greater than 7Ø
Generally speaking, it has been found that virtually any organic compound which passes the solvation test described above, will function, to a usable degree, as a solvation agent.
Non-limiting but preferred solvating agents include: ali-phatic glycols containing from.2 to 5 carbon atoms such as ethylene glycol, 1,2-propanediol, 1,4-b~tanediol, 1,3-pent-anediol and the like; alkylene triols containing from 2 to 6 carbon atoms such as glycerol, 1,2,3~butane-triol, 1,2,3-pentanetriol, and the like; amides containing from 1 to 4 carbon atoms such as formamide, acetamide, dimethyl formamide, and the like; and the mixtures of the various above compounds.
The diluting agent, in general, will be any liquid organic compound or material which is not a solvating agent. In general, the diluting agents are liquids which do not appre-ciably swell the HEC polymers, i.e. they do not produce semi-solid or viscous mixtures which have no free liquid present after the one week solvation period described in the above test for determining solvating agents. Non-limiting examples of diluting agents include liquid aliphatic and aromatic hydro-carbons containing from 5 to 10 carbon atoms; kerosene, diesel oil, isopropanol, alkylene glycol ethers, vegetable oils, etc.
Particularly preferred are organic liquids which are water soluble or miscible most preferably alkanols having at least 3 carbon atoms, ethylene glycol monoalkyl ethers, dlalkylene glycol monoalkyl ethers, and the likeO The diluting agent will maintain the polymeric composition in a liquid, pourable state at a temperature of about 20~C. It will be understood, however, that lesser amounts of diluting agent can be used if desired and that the ultimate amount of diluting agent employed Jill depend upon the type of shear which is available to disperse the thickener. In general it has been found that desirable thick-eners, which are pourable liquids, can be produced from compo-sitions containing from about 10 Jo about 25% by weight HECpolymer, from about 2 to about 70~ by weight dilu~in~ agent, and from about 5 to about 88% solvating agent.
HEC has been added to heavy brines to increase the vis-so cosity of the brine such that the rate of loss of the brineto the formation contacted by the brine is reduced. Normally, in the absence of bridging particles, hydroxyethyl cellulose provides poor fluid loss control in those brines in which the HEC is fully hydrated. See for example co-pending Canadian patent application SN 380,104 filed June 18, 1981.
We have found, as disclosed in co-pending patent applica-tion SN 380,104 filed June 18, 1981, that if the concentration of zinc bromide is less than about 20% by weight, the HEC will not efficiently gel or viscosify the brine. Indeed, we have found that while it is possible to viscosify a brine contain-ing no zinc bromide or a brine solution containing a high concentration of zinc bromide, with HO if the two thickened solutions are admixed to produce a solution containing zinc bromide in less than about a 20% by weight concentration, the viscosity of the mixed brine will be essentially the same as if no HEC is present.
As indicated herein, it is a feature of this invention that HEC functions as an excellent fluid loss control additive in certain heavy brines in which the HO is a very inefficient viscosifier. The HEC containing brines of this invention are cloudy or opaque as compared to the clear brines obtained when the ~IEC is completely, or nearly completely, hydrated Apparently the HEC is not completely solubilized in these brinès and thus at least a portion of the HEC is available to act as a bridging agent to decrease the fluid loss of these brines.
It is preferred in the practice of this invention that the HEC be activated such that the HEC will hydrate in these heavy brines at ambient temperature.
The concentration of HEC need only be sufficient to reduce the fluid loss of the brine. Preferably, the concentration of HEC will be from about 0.25 to about 5.0 ppb, more preferably, prom about 0.25 to akout 3.0 ppb.
It is another embodiment of this invention to provide a method of decreasing the fluid loss of heavy brines containing zinc bromide and at least one soluble salt selected from the group consisting of calcium chloride and calcium bromide, which comprises formulating the brine to contain from about 16%
to about 20% by weight zinc bromide, and mixing with the brine a fluid loss reducing amount of HEC, as disclosed hereinbefore.
Still another embodiment of this invention provides a method 5 of decreasing the fluid loss of heavy brines containing zinc bromide, calcium chloride, and calcium brine, which comprises formulating the brine to contain greater than 20% zinc bromide and a concentration of calcium chloride of at least (2X-33)%
by weight, where X is the % of zinc bromide, and mixing with the brine a fluid loss reducing amount of HO as disclosed hereinbefore.
To more fully illustrate the invention, the following non-limiting examples are presented.
Examples of the Invention Heavy brines having the compositions listed in Table 1 were prepared by mixing together the indicated amounts of the follow-ing materials: a 19.2 ppg calcium bromide/zinc bromide solution containing 20% calcium bromide and 57% zinc bromide; a 14.2 ppg calcium bromide solution containing 53~ calcium bromide; an 11.6 ppg calcium chloride solution containing 37.6% calcium chloride; and calcium chloride pellets containing 95% calcium chloride. After cooling to room temperature, there were added either: 3 ppb of N~TROSOL~ 250 ~HR hydroxyethyl cellulose; or
3 ppb of activated NATROSOL 250 HHR (i.e., 15 ppb o a compos-ition containing 20% HEC, 25% glycerin, 54.6% isopropanol, and 0.4% CAB-O-SIL~ M5). Thereafter, the heavy brines were rolled 16 hours at room temperature and the PI RP 13B rheology and fluid loss obtainedO The heavy brines were then rolled 16 hours at 150F, cooled at room temperature, and the API RP 13B data again obtained. The data obtained are given in Table 2.
The data indicate that heavy brines containing HEC can be formulated to exhibit a very low API fluid loss provided the %
zinc bromide in the brine is in the range from about 16% to about 20% by weight, or the % zinc bromide is greater than 20%
and the % calcium chloride is greater than (2X-33)% where X is the of zinc bromide in the brine. Preferably, the % zinc bromide is in the range from about 18% to about 20% and the calcium chloride is less than about 5(X-17)%. In this preferred range the HEC solublizes to such an extent that appreciable viscosity is imparted to the heavy brine. The data also indicate that it is preferable to omit any solid calcium chloride from the heavy brine.
~2~5fi~i Brine Compositions 19.2 11.6 14.2 95%
~rineDensi ty % pp9. Pp3- PP9 CaC12 Numberppg. ZnBr2 CaC12 CaBr2 bbl . bbl .bbl . 1 b .
15.0 0 16.3 43.3 0 O.Q2850.8637 103 2 15.0 0 16.3 43.3 ' 0 0.02850.8637 103 3 15.~ 5.1 14.9 41.2 0.0714 0.02710.801495.7
The data indicate that heavy brines containing HEC can be formulated to exhibit a very low API fluid loss provided the %
zinc bromide in the brine is in the range from about 16% to about 20% by weight, or the % zinc bromide is greater than 20%
and the % calcium chloride is greater than (2X-33)% where X is the of zinc bromide in the brine. Preferably, the % zinc bromide is in the range from about 18% to about 20% and the calcium chloride is less than about 5(X-17)%. In this preferred range the HEC solublizes to such an extent that appreciable viscosity is imparted to the heavy brine. The data also indicate that it is preferable to omit any solid calcium chloride from the heavy brine.
~2~5fi~i Brine Compositions 19.2 11.6 14.2 95%
~rineDensi ty % pp9. Pp3- PP9 CaC12 Numberppg. ZnBr2 CaC12 CaBr2 bbl . bbl .bbl . 1 b .
15.0 0 16.3 43.3 0 O.Q2850.8637 103 2 15.0 0 16.3 43.3 ' 0 0.02850.8637 103 3 15.~ 5.1 14.9 41.2 0.0714 0.02710.801495.7
4 15.3 5.1 14.9 41.2 0.0714 0.02710.801495.7 15.0 11.7 0 46.2 0.160 0 0.840 0 6 15.0 11.7 0 46.2 0.160 0 0.840 0 7 1~.8 13.2 12.5 38.0 0.1~0 0.02290.700 83.4 8 15.8 13.2 12.5 38.0 O.lgO 0.02290.700 83.4 9 15.3 15.7 0 43.9 0.220 0 0.780 0 15.3 15.7 0 43.9 0.220 0 0.780 0 11 15.3 16.0 0 43.7 0.224 0 0.776 0 12 14.8 16.0 5.0 36.8 0.217 0.1700.613 0 13 14.4 16.0 10.0 29.6 0.2105 0.3300.4595 0 14 16.0 16.3 11.6 36.7 0.238 0.02140.658 78.5 1~5.0 16.3 11.6 36.7 0.238 0.02140.658 78.5 16 15.4 17.0 0 43.1 0.239 0 0.761 0 17 14.9 17.0 5.0 36.1 0.2317 0.171û.5973 0 18 15.5 18.0 0 42.5 0.255 0 0.745 0 19 15.0 18.0 5.0 35.5 0.2465 0.1720.5815 0 1 .75 1 8.0 7.5 32.0 0.2427 0.25370.5036 0 21 14.5 18.0 10.0 28.5 0.239 0.3340.427 0 22 15.5 18.4 0 42.4 0.260 0 0.740 0 23 15.5 18.4 0 42.4 0.260 0 0.740 0 24 15.5 19.0 0 42.1 0.270 0 0.730 0 15.1 19.0 5.0 34.~ 0.2615 0.17350.565 0 26 14.6 19.0 10.0 28.0 0.2535 0.33350.413 0 27 14.25 19.0 14.0 22.3 0.2474 0.45730.2953 0 28 15.6 20.0 0 41.5 0.2855 0 0.7145 0 29 14.8 20.0 8.0 30.2 0.2714 0.27290.4557 0 14.8 20.0 8.0 30.2 0.2714 0.27290.4557 0 31 14.3 20.0 14.0 2].7 0.2614 0.4600.2-786 0 32 14.3 20.0 14.0 21.7 0.2614 0.4600.2786 0 33 16.0 22.0 11.7 31.0 0.3214 0.1200.4957 59.3 34 ~6.0 22.0 11.7 31.0 0.3214 0.120n.4957 59.3 1~.6 22.0 12.0 23.4 0.2943 0.40280.302g 0 ~6 14.6 22.0 12.0 23.4 0.2943 0.40280.302g 0 37 14.4' 22.0 14.0 20.7 0.2gO 0.46280.2472 0 38 14.4 ~2.0 14.0 20.7 0.290 0.~6280.~472 0 ~4 ~2~ 86 Brine Evaluations 3 ppb. NATROSOL 250 HHR(l) 16 Hours @ 74F 16 Hours @ 150F
API API
Brine _API RheoloqY Fluid API Rheology Fluid Number 60b 300 3 Loss(2)~600 300 3 Loss _ 1 >300 ~300 130 23 ~300 >300 149 60 2 (68) ~35) (O) (20) (~300) (?300) (69) (80) 4 (62) (31) (O) (NC) (60) (30) (1) (187) 6 (14) (7) (O) (NC) (16) (8) () (~8) 8 (49) (25) (O) (NC) (51) (26) (O) (150) (15) (7) (O) (NC) (40! (24) (2) (4) 13 21 11 0 NC 44 17 0 9.5 (52) (~61 (o) (NC) (49) (25) (Q) (120) ~0 31 il5 0 50 47 25 3 22 205 158 33 1 ~300 184 44 23 (15) (8) (1) .(NC) (50) (25) (1) (2) 24 222 196 52 1 >300 227 59 26 158 104 . 12 1 187 120 10 28 202 218 57 1 ~300 249 :. 76 (14) (8) (O) (NC) (63) (33) (1) (1) 31 152 1 al 9 1 >300 233 57 5 32 (14) (7) (O) (NC) (48) (24) (1) (2) 33 46 .23 1 29 172 101 5 3~ (37) (19) (O) (NC) (47) (24) () (2) 36 l (8) (O) (NC) (103) (59) (1) (0-5) 37 229 170 39 2 213 .140 11 5 38 (16~ (8) (O) (NC) (77; (41) (1) (0.2) (l)Data ;n parentheses:obtained using dry, powdered NATROSOL 250 HHR
( 2 ) NC = No Co n trol
API API
Brine _API RheoloqY Fluid API Rheology Fluid Number 60b 300 3 Loss(2)~600 300 3 Loss _ 1 >300 ~300 130 23 ~300 >300 149 60 2 (68) ~35) (O) (20) (~300) (?300) (69) (80) 4 (62) (31) (O) (NC) (60) (30) (1) (187) 6 (14) (7) (O) (NC) (16) (8) () (~8) 8 (49) (25) (O) (NC) (51) (26) (O) (150) (15) (7) (O) (NC) (40! (24) (2) (4) 13 21 11 0 NC 44 17 0 9.5 (52) (~61 (o) (NC) (49) (25) (Q) (120) ~0 31 il5 0 50 47 25 3 22 205 158 33 1 ~300 184 44 23 (15) (8) (1) .(NC) (50) (25) (1) (2) 24 222 196 52 1 >300 227 59 26 158 104 . 12 1 187 120 10 28 202 218 57 1 ~300 249 :. 76 (14) (8) (O) (NC) (63) (33) (1) (1) 31 152 1 al 9 1 >300 233 57 5 32 (14) (7) (O) (NC) (48) (24) (1) (2) 33 46 .23 1 29 172 101 5 3~ (37) (19) (O) (NC) (47) (24) () (2) 36 l (8) (O) (NC) (103) (59) (1) (0-5) 37 229 170 39 2 213 .140 11 5 38 (16~ (8) (O) (NC) (77; (41) (1) (0.2) (l)Data ;n parentheses:obtained using dry, powdered NATROSOL 250 HHR
( 2 ) NC = No Co n trol
5~
The invention may be embodied in other specific forms without departing from the spirit or essential character-istics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foreyoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.
This invention is closely related to Canadian patent 1,169,641 and pending Canadian application Serial No 369,357.
The invention may be embodied in other specific forms without departing from the spirit or essential character-istics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foreyoing description, and all changes which come within the meaning and range of equivalence of the claims are therefore intended to be embraced therein.
This invention is closely related to Canadian patent 1,169,641 and pending Canadian application Serial No 369,357.
Claims (10)
1. A heavy brine solution containing zinc bromide, calcium chloride, and calcium bromide, and a fluid loss reducing amount of hydroxyethyl cellulose, wherein said brine contains greater than about 20% by weight zinc bromide and a concentration of calcium chloride of at least (2X-33)% by weight where X is the % by weight of zinc bromide in said brine.
2. The brine of Claim 1 having a density in the range from about 14.2 to about 16.0 pounds per gallon.
3. The brine of Claim 2 wherein the concentration of hydroxyethyl cellulose is from about 0.25 to about 5.0 pounds per 42 gallon barrel.
4. The brine of Claim 2 wherein the concentration of hydroxyethyl cellulose is from about 0.25 to about 3.0 pounds per 42 gallon barrel.
5. The brine of Claim 1, 2 or 3, wherein said hydroxy-ethyl cellulose has been activated such that said hydroxy-ethyl cellulose will hydrate in said brine at ambient temperatures.
6. A method of decreasing the fluid loss of heavy brines containing zinc bromide, calcium chloride, and calcium bromide, which comprises adjusting the concentration of zinc bromide in said brine to greater than 20% by weight, adjusting the concentration of calcium chloride in said brine to at least (2X-33)% by weight, where X is the % by weight of zinc bromide, and mixing with said brine a fluid loss reducing amount of hydroxyethyl cellulose.
7. The method of Claim 6 wherein said brine has a density in the range from about 14.2 to about 16.0 pounds per gallon.
8. The method of Claim 7 wherein the concentration of hydroxyethyl cellulose is from about 0.25 to about 5.0 pounds per 42 gallon barrel.
9. The method of Claim 7 wherein the concentration of hydroxyethyl cellulose is from about 0.25 to about 3.0 pounds per 42 gallon barrel.
10. The method of Claim 6, 7 or 8, wherein said hydroxyethyl cellulose has been activated such that said hydroxyethyl cellulose will hydrate in said brine at ambient temperatures.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000477862A CA1204586A (en) | 1982-03-11 | 1985-03-28 | Low fluid loss heavy brines containing hydroxyethyl cellulose |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US35730882A | 1982-03-11 | 1982-03-11 | |
| US357,308 | 1982-03-11 | ||
| CA000422031A CA1202477A (en) | 1982-03-11 | 1983-02-21 | Low fluid loss heavy brines containing hydroxyethyl cellulose |
| CA000477862A CA1204586A (en) | 1982-03-11 | 1985-03-28 | Low fluid loss heavy brines containing hydroxyethyl cellulose |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000422031A Division CA1202477A (en) | 1982-03-11 | 1983-02-21 | Low fluid loss heavy brines containing hydroxyethyl cellulose |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1204586A true CA1204586A (en) | 1986-05-20 |
Family
ID=25669945
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000477862A Expired CA1204586A (en) | 1982-03-11 | 1985-03-28 | Low fluid loss heavy brines containing hydroxyethyl cellulose |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1204586A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004038164A3 (en) * | 2002-09-12 | 2004-07-08 | Mi Llc | Remediation treatment of sustained casing pressures (scp) in wells with top down surface injection of fluids and additives |
-
1985
- 1985-03-28 CA CA000477862A patent/CA1204586A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004038164A3 (en) * | 2002-09-12 | 2004-07-08 | Mi Llc | Remediation treatment of sustained casing pressures (scp) in wells with top down surface injection of fluids and additives |
| GB2408536A (en) * | 2002-09-12 | 2005-06-01 | Mi Llc | Remediation treatment of sustained casing pressures (scp) in wells with top down surface injection of fluids and additives |
| GB2408536B (en) * | 2002-09-12 | 2006-02-22 | Mi Llc | Remediation treatment of sustained casing pressures (scp) in wells with top down surface injection of fluids and additives |
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