CA1106724A - Aqueous acid solution gelling agents - Google Patents
Aqueous acid solution gelling agentsInfo
- Publication number
- CA1106724A CA1106724A CA313,028A CA313028A CA1106724A CA 1106724 A CA1106724 A CA 1106724A CA 313028 A CA313028 A CA 313028A CA 1106724 A CA1106724 A CA 1106724A
- Authority
- CA
- Canada
- Prior art keywords
- range
- acid
- solution
- carbon atoms
- gelling agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/06—Solidifying liquids
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/72—Eroding chemicals, e.g. acids
- C09K8/74—Eroding chemicals, e.g. acids combined with additives added for specific purposes
-
- C—CHEMISTRY; METALLURGY
- C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
- C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
- C11D1/00—Detergent compositions based essentially on surface-active compounds; Use of these compounds as a detergent
- C11D1/38—Cationic compounds
- C11D1/42—Amino alcohols or amino ethers
- C11D1/44—Ethers of polyoxyalkylenes with amino alcohols; Condensation products of epoxyalkanes with amines
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Wood Science & Technology (AREA)
- Colloid Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
AQUEOUS ACID SOLUTION GELLING AGENTS
Abstract of the Disclosure Gelling agents for gelling aqueous inorganic acid solutions comprising solutions of a water soluble organic solvent and an ethoxylated fatty amine or mixtures of such amines.
Abstract of the Disclosure Gelling agents for gelling aqueous inorganic acid solutions comprising solutions of a water soluble organic solvent and an ethoxylated fatty amine or mixtures of such amines.
Description
~cidizing and fracturing procedures using aqueous acid solutions are commonly carried out ir subterranean well formations to accomplish a number of purposes, one o~ which is to facilitate the increase in the recovery of hydrocarbons therefrom. II1 acidizing procedures, aqueous acid solutions are introduced into well formations under pressure so that the acid solutions flow into the pore spaces of the formations and react with materials con-tained therein whereby the pore spaces are enlarged and the permeability o~ the formations increased. In fracture acidizing procedures, one or more fractures are produced in the formations and the acid solutions are introduced into the fract~res to etch flow channels therein and/or to enlarge the pore spaces in the fracture aces and in the formations.
Increasing the viscosity of an aqueous acid solution, hereinafter re~erred to as "gelling," by the inclusion of certain swellable materials or gelling agents therein has -been accomplished heretofore. In acidizing and/or frac-ture acidizing subterranean formations, gelled aqueous acid solutions are useful in preventing the acid from be-coming prematurely spent and inactive. In addition, gelling of the acid solutions enables the development of wider fractures so that live acid can be forced further into the formation ~rom the well bore. Furthermore, increasing the ' -2-~ 72i~
.
viscosities of the acid solutions also permits better fluid loss control.
Gelled aqueous acid solutions have utility in indus-trial applications other than in the treatment of subterran-ean well formations such as in the cleaning of industrial eq~ipment.
Gelling agents such as hydratable gums and cellulose ¦ derivatives have been utilized to increase the viscosity i of aqueous acid solutions. However, the gels produced ~ 10 using such gelling agents generally haYe limited stability ¦ at high temperatures in the presence of acid. Other gell-ing agents which increase the viscosity of aqueous acid ¦ solutions have been developed and used, but they are often difficult to disperse and usually require considerable mixing or agitation to develop full viscosity. Still other ` prior art gelling agents can form an undesirable precipitate during the dissolution of formation materials such as lime-stone or dolomite, which precipitate can remain in the formation to thereby damage it by decreasing the perme-ability thereof.
` 3y the present invention, a gelling agent for increas-ing the viscosity of aqueous acid solutions, the resulting gelled aqueous acid solutions and methods of using such ¦ gelled aqueous acid solutions are provided. The gelling agent of the present invention can be easily dispersed into ~ 2 ~
an aqueous acid solution and only a small quantity of it is required to rapidly increase the viscosity of the acid solution with a minimum of mixing and agitation. The resulting gelled aqueous acid solutions of the present invention have excellent stability over a broad tempera-ture range; they are relatively non-damaging to subter-ranean formations treated therewith; and, upon becoming spent in subterranean formations, and, without the inclusion of chemical breakers or special additives therein, they break to low viscosity liquids having excellent fines suspension properties.
The gelling agent of this invention is comprised of a water soluble organic solvent selected from the group consisting of alkanols having in the range of from about 1 to 5 carbon atoms per molecule, ketones having in the range of about 3 to 6 carbon atoms per molecule, poly-hydroxy compounds having in the range of about 2 to 6 carbon atoms per molecule, ethers having in the range of about 2 to 6 carbon atoms per molecule, compounds con-20 taining both ether and alcohol functions having in the j range of about 4 to 8 carbon atoms per molecule, esters having in the range of about 2 to 6 carbon atoms per molecule, lactones having in the range of about 3 to 5 carbon atoms per molecule and mixtures of two or more of the foregoing compounds, and a mixture of ethoxylated fatty amines dissolved in said water soluble organic solvent having the general formula:
(CH2CH20) xH
R - N
(CH2CH20)yH (1) wherein:
Increasing the viscosity of an aqueous acid solution, hereinafter re~erred to as "gelling," by the inclusion of certain swellable materials or gelling agents therein has -been accomplished heretofore. In acidizing and/or frac-ture acidizing subterranean formations, gelled aqueous acid solutions are useful in preventing the acid from be-coming prematurely spent and inactive. In addition, gelling of the acid solutions enables the development of wider fractures so that live acid can be forced further into the formation ~rom the well bore. Furthermore, increasing the ' -2-~ 72i~
.
viscosities of the acid solutions also permits better fluid loss control.
Gelled aqueous acid solutions have utility in indus-trial applications other than in the treatment of subterran-ean well formations such as in the cleaning of industrial eq~ipment.
Gelling agents such as hydratable gums and cellulose ¦ derivatives have been utilized to increase the viscosity i of aqueous acid solutions. However, the gels produced ~ 10 using such gelling agents generally haYe limited stability ¦ at high temperatures in the presence of acid. Other gell-ing agents which increase the viscosity of aqueous acid ¦ solutions have been developed and used, but they are often difficult to disperse and usually require considerable mixing or agitation to develop full viscosity. Still other ` prior art gelling agents can form an undesirable precipitate during the dissolution of formation materials such as lime-stone or dolomite, which precipitate can remain in the formation to thereby damage it by decreasing the perme-ability thereof.
` 3y the present invention, a gelling agent for increas-ing the viscosity of aqueous acid solutions, the resulting gelled aqueous acid solutions and methods of using such ¦ gelled aqueous acid solutions are provided. The gelling agent of the present invention can be easily dispersed into ~ 2 ~
an aqueous acid solution and only a small quantity of it is required to rapidly increase the viscosity of the acid solution with a minimum of mixing and agitation. The resulting gelled aqueous acid solutions of the present invention have excellent stability over a broad tempera-ture range; they are relatively non-damaging to subter-ranean formations treated therewith; and, upon becoming spent in subterranean formations, and, without the inclusion of chemical breakers or special additives therein, they break to low viscosity liquids having excellent fines suspension properties.
The gelling agent of this invention is comprised of a water soluble organic solvent selected from the group consisting of alkanols having in the range of from about 1 to 5 carbon atoms per molecule, ketones having in the range of about 3 to 6 carbon atoms per molecule, poly-hydroxy compounds having in the range of about 2 to 6 carbon atoms per molecule, ethers having in the range of about 2 to 6 carbon atoms per molecule, compounds con-20 taining both ether and alcohol functions having in the j range of about 4 to 8 carbon atoms per molecule, esters having in the range of about 2 to 6 carbon atoms per molecule, lactones having in the range of about 3 to 5 carbon atoms per molecule and mixtures of two or more of the foregoing compounds, and a mixture of ethoxylated fatty amines dissolved in said water soluble organic solvent having the general formula:
(CH2CH20) xH
R - N
(CH2CH20)yH (1) wherein:
2~
- R is selected from saturated and unsaturated aliphatic groups having in the range of from about 8 to about 22 carbon atoms, and mixtures thereof, and x and y each have a value in the range of from about O to about 10. The preferred ethoxylated fatty amines and mixtures thereof useful herein are those wherein the average sum of the values of x and y in the amines used is in the range of from about 1.8 to about 2.2.
-4a-A
.6~
Mixtures of ethoxylated tertiary fatty amines derived fxom fats and oils such as coconut oil, soy bean oil, and tallow are particularly su~table for use in accordance with the present invention.
A ~referred mixture of ethoxylated fatty amines for ¦ use in this invention is a mixture of amines of the general¦ formula:
~C~2CH20 ) XH
}~
,~ 10 \~CH2cH~O)yH (2) I wherein:
R is selected from the group consisting of saturated and unsaturated aliphatic groups having in the range of from ¦ about 14 to about 18 carbon atoms and mixtures of such ¦ 15 groups; and wherein the average sum of the values of x and y in the I mixture of ethoxylated amines is equal to 2.
! In the most preferred embodiment, x and y each have ¦ a value of 1 ~one).
I 20 Examples of such amines are those derived from fatty ¦ acids of the type hexadecyl, tallow, soya and oleyl, either I saturated or unsaturated and either as pure components or ¦ mixtures.
! A variety of organic solvents can be utilized in mak-ing the gelling agents so long as such solvents are capable _5_ of dissolving the ethoxylat:ed fatty amines and are also water soluble. Examples of such water soluble organic solvents include alkanols having in the range of about 1 to 5 carbon atoms per molecule, such as methanol, ethanol, isopropanol and t-butanol; ketones having in the range of about 3 to 6 carbon atoms per molecule, such as acàtone . and methylethyl ketone; polyhydroxy compounds having in - the range of about 2 to 6 carbon atoms per molecule, such as ethylene glycol and glycerine; ethers having in the range of about 2 to 6 carbon atoms per molecule, such as dioxane and tetrahydrofuran; compounds containing both ether and alcohol functions having in the range of about 4 to 8 car-bon atoms per molecule, such as diethylene glycol and tri-ethylene glycol; organic acids having in the range of about 1 to 10 carbon atoms per molecule, such as ~ormic acid, malonic acid, acetic acid, gluconic acid, levulinic acid and propionic acid; esters having in the range of about 2 to 6 carbon atoms per molecule, such as methyl formate, dimethyl oxylate and dimethyl malonate; and lactones having in the range of about 3 to 5 carbon atoms per molecule, such ~ as beta-propyl lactone and gamma-butyl lactone. Due to the desirably low freezing point and/or high flash point (tag ~closed cup) of the resulting gelling agent the organic acids are prefexred with acetic acid being the most preferred. -The water soluble organic solvent useful herein is ~rrl~
preferably in liquid phase at the temperature at which it is mixed with the ethoxylated fatty amine. Furthermore, mixtures of the organic solvents can be used. An example is a mix~ure of methanol ancl gluconic acid.
Tha gelling agents useful herein can be prepared by mixing the water soluble organic solvènts with the ethoxy-lated fatty amines for a period of time sufficient to com-pletely dissolve the amines in the solvents. The quantity of ethoxylated amines dissolved in the organic solvent range i~ an amount of from about 10 to about 80, preferably from about 50 to about 60 percent amine by weight of the gelling agent.
~ As mentioned above, the organic solvents can be used ¦ singly, or in mixtures of solvents of the same chemical lS class (acids with acids, ketones with ketones and the like) or in mixtures of solvents of different chemical classes I (acids with alcohols, ethers with ketones and the like). A
! preferred organic solvent is a mixture of chemicals of dif-ferent chemical classes wherein at least one of the classes ¦ 2~ is an organic acid.
The ethoxylated fatty amines useful herein are very difficult to dissolve directly in aqueous inorganic acid solutions. However, the gelling agent of this invention, comprising a solution of the amines dissolved in a water soluble organic solvent, such as acetic acid, readily dis-solves in an aqueous inorganic acid solution and substan-tially immediately increases the viscosity of the acid solution.
The gelling agents of the present invention cause an ~6,'Z~
. ' ' ..
increase in the viscosity oi aqueous inorganic acid solu-tions having acid concentrations in the range from about 1 to about 25 percent active acid by weight of the solu-tions. `~owever, acid solutions having acid concentrations of greater than about 25 percent can be mixed with the gelling agents of this invention and such acid solutions, upon being reacted, will begin to exhibit a noticeable ! increase in viscosity when the acid concentration, due to the reaction, is diminished to a value of about 25 percent.
Such increase in~viscosity continues with continued decrease in acid concentration until the acid concentration reaches a value in the range of from about 10 percent to about 15 percent. To this exten~ then, this invention features a delayed gelling characteristic.
~ 15 The gelling agents of this invention will cause the i viscosity of aqueous inorganic acid solutions having acid ¦ concentrations in the range of frbm about l to about 10 I - percent, and more particularly in the range of from about ¦ 1 to about 5 percent, to rapidly increase providing that the I 2~ presence of dissolved salts in the acid solution is very low i and preferably absent. In this connection, the presence of dissolved salts in the gelled acids of this invention cause the gels to break when the acid concentration is less than about 10 percent and particularly when the acid concentration is less than about 5 percent. This breaking feature, as will . -8-}
be further explained below, can be of particular value when the acid gels of this invention are used to acid treat sub-terranean formations.
The gelling agents are particularly useful in increas-ing the viscosity of aqueous; inorganic acid solutions such as hydrochloric acid solutions, sulfu~ic acid solutions, phosphoric acid solutions, hydrofluoric acid solutions and ¦ solutions containing mixtures of such acids.
! In p~eparing a gelled aqueous acid solution of this invention, the acid or mixture o acids utilized can be, and is preferably, diluted with water to obtain an aqueous ! inorganic acid solution of desired acid concentration. A
I gelling agent of the present invention~ i.e., an ethoxylated ¦ fatty amine or mixture of such amines of the type described ¦ lS above dissolved in a water soluble organic solvent, is pre-/ ferably combined with the aqueous acid solution in an amount in the range of from about 0.1 to about 10, and more prefer-ably in the range of from about 2 to 6, percent gelling agent by weight of the aqueous acid solution. The acid solu-tion and gelling agent are agitated or mixed for a short period of time whereupon the viscosity of the aqueous acid solution is increased. More specifically, some increase in viscosity is obtained when as little as 0.1 percent gelling agent is combined with the aqueous acid solution, and greater amounts of the gelling agent bring about increased _9_ .1 , . ' .
~ 2 viscosity. When the gelling agent is combined with the aqueous acid solution in an ~nount of about 10 percent by weight of the solution, viscosities of about 150 centi-I poises càn be obtained.
¦ 5 Greater viscosity increase can be obtained through use of gelling agent amounts in excess of io percent. Thus, lO percent is not a limit on the capability of the gelling agent to increase the viscosity of acid, but is viewed as a working guide in view of current process economics and the practical capabilities of currently known liquid hand-ling and pumping e~uipment.
A gelled aqueous acid solution of this invention is comprised of water, a water soluble inorganic acid or,mix-ture o such acids, and a gelling agent comprised of a solution of a water soluble organic solvent and an ethoxy-lated fatty amine having the general formula:
~(CR2C~I20) XH
~ CX2CH2O)yH t3) wherein: 9 - R is selected from saturated and unsaturated aliphatic groups having in the range of from about 8 to about 22 car-bon atoms, and mixtures thereof, and x and y each have a - value in the range of from about 0 to about lO.
2S A pre:Eerred gelled aqueous acid solution'of this inven-tion is comprised of an inorganic aqueous acid solution comprising water and a water soluble inorgani~ acid or mixture of such acids, and a gelling agent comprised of a solution of a water solub].e organic solvent and a mix-ture of ethoxylated fatty amines having the general formula~
; : ~(CH2CH20) XH
R N ~
2CH2)y~ (4) wherein: .
R is selected from saturated and unsaturated aliphatic I groups having in the range of from about 14 to about 18 car-¦ bon atoms and mixtures of such groups; and x and y each have j a value in the range of from 0 to about 10 with the average ¦ .sum of the values of x and y in the mixture being in the ¦ 15 range of from about 1.8 to about 2.2.
I The most preferred gelled aqueous acid solution of this invention is comprised of an aqueous acid solution comprising water and an inorganic water soluble acid or a mixture of such acids, and a gelling agent present in the aqueous acid solution in an amount in the range of from about 1 to about 10 percent gelling agent by weight of the acid solution. The gelling agent is comprised of a solution of a water soluble organic solvent, ana a mixture of ethoxylated fatty amines present in the gelling agent in an amount of from about 10 to about 80 percent amines ..
by weight of the gelling agent. The ethoxylated fatty ami~es have the general formula:
, , . f CH2CH20) xH
; R - N~
5. ~ CH2CH20)yH (5) wherein: .
R is selected from the group consisting of saturated ¦ and unsaturated aliphatic groups having in the range of from about 16 to about 18 carbon atoms and mixtures of such I 10 groups; and ¦ the average sum of the values o x and y in said mix-¦ ture of ethoxylated amines is equal to 2.
In the most preferred embodiment, x and y in formula ~5) each have a value of one (1).
The gelled aqueous acid solutions of this invention are stable over a wide temperature range and therefore will not chemically degrade with time, even at a temperature as high as 250F. It must be understood, however, that the gelled acids of this invention, like other liguids, do experience viscosity change with temperature change. Thus, for example, with increasing temperature, the viscosity OL
these gels declines, but is regained upon decrease of tem-perature. Thus, gels made according to this invention have long storage life.
While~ the gelled aqueous acid solutions of this inven-tion have a variety of uses, they are particularly suitable , ' for carrying out acid treatments in subterranean welli formations for increasing the production of hydrocarbon ¦ fluids therefrom. When the gelled aqueous aaid solutions I are introduced into subterranean well formation, the acid 1 5 spends by reacting wlth materials in the formation, e.g., limestone and/or dolomite, whereby salts (e.g., chlorides I when HCl is used) are formed. The formation of salts in j the spe,nt acid solution causes the viscosity of the solu-tion to decrease. That is, as the acid'spends and salts form, the viscosity of the spent acid solution begins to decrease when acid concentration is in the range of about 10 to 15 percent. Thus, chemicals known in the art as , "breakers" are not required when the gelled acid solutions I of this in~ention are used to acid treat subterranean well j 15 formations. The spent acid solutions, after breakingj have viscosities in the range of from about 5 to about 15 centi-, poises and have excellent particle suspension properties I which facilitates the efficient clean-up of a treated forma-tion.
In using the gelled aqueous acid solutions for carrying j , out acidizing treatments in a subterranean well formation, ¦ an aqueous acid solution of desired acid strength is first - prepared. For example, in carrying out acidizing or acid fracturing treatments in limestone or dolomite formations, aqueous hydrochloric acid solutions in concentrations in .
~. .
the range of from about 3~ to about 28~ by weight are often utilized. After the particular aqueous acid solu-tion to be used has been prepared and diluted to the desired strength, the gelling agent of the present inven-tion is combined therewith, preferably in an amount in the range of from a~out 0.1 to about 10 percent by weight of the acid solution whereby the viscosity of the solution is increased. Other conventional well formation treating additives, such as corrosion inhibitors, non-emulsifying agents, fluid loss additives, etc., can also be combined with the solution. The resultant gelled aqueous acid solution is introduced into the formation to carry out an acidizing or acid fracturing treatment therein. After the aqueous acid solution has become spent by reaction with materials in the formation and thereby broken to a low viscosi y fluid, it is produced from the formation and the formation is cleaned up using conventional clean-up procedures followed by placing the formation on production.
Nhen a gelled aqueous hydrochloric acid solution of this invention having an initial acid concentration of below about 22 percent by weight of solution spends on limestone or dolomite to thus form calcium chloride and magnesium chloride and cools, some water and the gelling agent can separate out of the solution as a thick viscous phase.
Separation does not occur when the initial hydrochloric .
; -14-1~ ',, 2~
acid concentration is above about 22 percent by weight. In order to prevent separation in spent solutions when acid concentrations below about 2~ percent by weight are utilized, calcium chloride can be addel~ to the aqueous hydrochloric acid solution prior to gelling in an amount such that after reaction, the spent solution contains a calcium chloride concentration equivalent to a spent 22 percent by weight ! hydrochloric acid solu-tion. The amount of calcium chloride required generally falls within the range of from about 1 percent to about 10 percent by weight of the spent solution.
' That is, when a gelled aqueous hydrochloric acid solution I having an acid concentration of above about 22 percent by weight of the solution is utilized in the treatment of sub-terranean well formations containing calcium, no calcium chloride is added to the live solution. When a gelled aqueous hydrochloric acid solution at a co,ncentration of 20 percent by weight of solution is utilized, about 308 ~ pounds of calcium chloride per 1000 gallons of aqueous I acid solution are added thereto which prevents separation 1 20' at low temperatures (150F and below). When a gelled ¦ aqueous hydrochloric acid solution having a concen-trations of 15 percent by weight is utilized, about 1040 pounds of J calcium ch:Loride per 1000 gallons of acid solution are com-bined therewith to prevent such separation.
The following examples are given in order to further . illustrate the gelling agent and gelled aqueous acid solu-tions of the present invention.
' Example 1 Gelling agents of the present invention are prepared using various mixtures o~ ethoxylated fatty amines dissolved ¦ ~ in glacial acetic acid. The gelling agents are added to ¦ aqueous acid solutions containing 15 percent by weight hydro-I chloric-acid, and the viscosities of the resultant gels ! determined. The viscosities of the gels are apparent visco-i 10 sities measured on a Model 35 FANN viscometer, no. 1 spring, ¦ standard bob and sleeve, at room temperature (72 - 76F) and ¦ at 300 rpm. The results of these tests are given in Table I
! below.
i .
~ n.`6 ~
TABLE I - VISCOSITIES OF GELLED AQUEOUS
HYDROCHLORIC ACID SOLUTIONS USING VARIOUS GELLLN~ AGENTS
Ethoxylated Average Concentration concentratlon Vlscoslty Fatty Amine Moles of of Amines Con- of Gelling of Gelled Fatty Acid Ethylene tained in Gel- Agent in Aqueous Origin Oxide ling Agent, ~ Hydrochloric HCl Per Mole by Weight of Acid Solution, of Amine Acatic Acid- Solution, cp ;:-; Amine % by Weight Solution ... _ . . .. _ .. _ . . . _ ... _ Coconut (Mixture of . Chains Hav-ing 8, 10, 1~ 12, 14, 16 :; and 18 Car-bon Atoms) -2 33.3 9 3 Coconut (Mixture of .
Chains Hav-' ing 8, 10, s 12, 14, 16 and 18 Car-. bon Atoms) 5 33.3 9 3 ~ 25 Soya (Mix-~ ture of Chains Hav-ing 14, 16 and 18 Car-bon Atoms) 2 33.. 3 9 77 Soya (Mix-ture of Chains Hav-ing 14, 16 and 18 Carbon Atoms) 5 33.3 9 3 Tallow (Mixture of Chains Having 14, 16 and 18 . Carbon Atoms) 2 33.3 9 55 Oleyl (18 Carbon Atoms) 2 33.3 9 82 Palmityl (16 Car-bon Atoms) 2 50 6 52 i ~ ,r"'~
From Table I it can be seen that gelling agents con-taining etho~ylated fatty amines derived from coconut, soya, tallow, oleic, and palmitic fatty acids increase the viscosity of aqueous hydrochloric acid solutions.
S The results provided in Table I also màke it clear that ethoxylated fatty amines having an average of 2 moles of ethylene oxide per mole of amine and containing hydrocar-bon chain lengths of 14 to 18 carbon atoms significantly increase the viscosity of aqueous hydrochloric acid solutions.
¦ 10 ` Example 2 A gelling agent is prepared by dissolving 3 grams of l ethoxylated soya amines having an average of 2 moles of ! ethylene oxide per mole of amine in 6 mls. (about 7 grams) ¦ of glacial acetic acid. The approximate composition of a , 15 commercial mixture of fatty acids from which the soya amine is derived is as follows:
Acid % By Weight myristic (C14) 0 to 1%
palmitic (C16) 6 to 10%
steariC (C18) 2 to 4%
oleic (C18) 21 to 29~
linoleiC (C18) 50 to 59%
linoleniC (C18) 4 to 8%
The gelling agent is combined with 125 mls. (about 134 grams) of an aqueous hydrochloric acid solution containing 1~
15 percent by weight hydrochloric acid. After mixing, the aqueous hydrochloric acid solution has an apparent visco--- sity of 95 centipoises measured on a Model 35 FANN visco-meter, no. 1 spring, standatd bob and sleeve at room temperature (72 - 76F) and 300 rpm.
. ' Example 3 Gelling agents are prepared by dissolving 5 grams of ethoxylated tallow amines having an average ethylene oxide content of 2 moles per mole of amine with various organic solvents. The gelling agents are then each added in amounts of 10 mls. to 200 mls. of an aqueous acid solution prepared by combining 126.8 mls. of tap water with 73.2 mls. of a hydrochloric acid solution containing 37~5 percent by ¦ weight hydrochloric acid to thus produce 200 mls. of 15 - 15 percent HCl solution which weighed 215 grams. The solu-tion also contains 25 grams of calcium chloride and 0.4 ml. of a hydrochloric acid corrosion inhibitor. After mix-ing the gelling agents with the acid solutions, the apparent .
- R is selected from saturated and unsaturated aliphatic groups having in the range of from about 8 to about 22 carbon atoms, and mixtures thereof, and x and y each have a value in the range of from about O to about 10. The preferred ethoxylated fatty amines and mixtures thereof useful herein are those wherein the average sum of the values of x and y in the amines used is in the range of from about 1.8 to about 2.2.
-4a-A
.6~
Mixtures of ethoxylated tertiary fatty amines derived fxom fats and oils such as coconut oil, soy bean oil, and tallow are particularly su~table for use in accordance with the present invention.
A ~referred mixture of ethoxylated fatty amines for ¦ use in this invention is a mixture of amines of the general¦ formula:
~C~2CH20 ) XH
}~
,~ 10 \~CH2cH~O)yH (2) I wherein:
R is selected from the group consisting of saturated and unsaturated aliphatic groups having in the range of from ¦ about 14 to about 18 carbon atoms and mixtures of such ¦ 15 groups; and wherein the average sum of the values of x and y in the I mixture of ethoxylated amines is equal to 2.
! In the most preferred embodiment, x and y each have ¦ a value of 1 ~one).
I 20 Examples of such amines are those derived from fatty ¦ acids of the type hexadecyl, tallow, soya and oleyl, either I saturated or unsaturated and either as pure components or ¦ mixtures.
! A variety of organic solvents can be utilized in mak-ing the gelling agents so long as such solvents are capable _5_ of dissolving the ethoxylat:ed fatty amines and are also water soluble. Examples of such water soluble organic solvents include alkanols having in the range of about 1 to 5 carbon atoms per molecule, such as methanol, ethanol, isopropanol and t-butanol; ketones having in the range of about 3 to 6 carbon atoms per molecule, such as acàtone . and methylethyl ketone; polyhydroxy compounds having in - the range of about 2 to 6 carbon atoms per molecule, such as ethylene glycol and glycerine; ethers having in the range of about 2 to 6 carbon atoms per molecule, such as dioxane and tetrahydrofuran; compounds containing both ether and alcohol functions having in the range of about 4 to 8 car-bon atoms per molecule, such as diethylene glycol and tri-ethylene glycol; organic acids having in the range of about 1 to 10 carbon atoms per molecule, such as ~ormic acid, malonic acid, acetic acid, gluconic acid, levulinic acid and propionic acid; esters having in the range of about 2 to 6 carbon atoms per molecule, such as methyl formate, dimethyl oxylate and dimethyl malonate; and lactones having in the range of about 3 to 5 carbon atoms per molecule, such ~ as beta-propyl lactone and gamma-butyl lactone. Due to the desirably low freezing point and/or high flash point (tag ~closed cup) of the resulting gelling agent the organic acids are prefexred with acetic acid being the most preferred. -The water soluble organic solvent useful herein is ~rrl~
preferably in liquid phase at the temperature at which it is mixed with the ethoxylated fatty amine. Furthermore, mixtures of the organic solvents can be used. An example is a mix~ure of methanol ancl gluconic acid.
Tha gelling agents useful herein can be prepared by mixing the water soluble organic solvènts with the ethoxy-lated fatty amines for a period of time sufficient to com-pletely dissolve the amines in the solvents. The quantity of ethoxylated amines dissolved in the organic solvent range i~ an amount of from about 10 to about 80, preferably from about 50 to about 60 percent amine by weight of the gelling agent.
~ As mentioned above, the organic solvents can be used ¦ singly, or in mixtures of solvents of the same chemical lS class (acids with acids, ketones with ketones and the like) or in mixtures of solvents of different chemical classes I (acids with alcohols, ethers with ketones and the like). A
! preferred organic solvent is a mixture of chemicals of dif-ferent chemical classes wherein at least one of the classes ¦ 2~ is an organic acid.
The ethoxylated fatty amines useful herein are very difficult to dissolve directly in aqueous inorganic acid solutions. However, the gelling agent of this invention, comprising a solution of the amines dissolved in a water soluble organic solvent, such as acetic acid, readily dis-solves in an aqueous inorganic acid solution and substan-tially immediately increases the viscosity of the acid solution.
The gelling agents of the present invention cause an ~6,'Z~
. ' ' ..
increase in the viscosity oi aqueous inorganic acid solu-tions having acid concentrations in the range from about 1 to about 25 percent active acid by weight of the solu-tions. `~owever, acid solutions having acid concentrations of greater than about 25 percent can be mixed with the gelling agents of this invention and such acid solutions, upon being reacted, will begin to exhibit a noticeable ! increase in viscosity when the acid concentration, due to the reaction, is diminished to a value of about 25 percent.
Such increase in~viscosity continues with continued decrease in acid concentration until the acid concentration reaches a value in the range of from about 10 percent to about 15 percent. To this exten~ then, this invention features a delayed gelling characteristic.
~ 15 The gelling agents of this invention will cause the i viscosity of aqueous inorganic acid solutions having acid ¦ concentrations in the range of frbm about l to about 10 I - percent, and more particularly in the range of from about ¦ 1 to about 5 percent, to rapidly increase providing that the I 2~ presence of dissolved salts in the acid solution is very low i and preferably absent. In this connection, the presence of dissolved salts in the gelled acids of this invention cause the gels to break when the acid concentration is less than about 10 percent and particularly when the acid concentration is less than about 5 percent. This breaking feature, as will . -8-}
be further explained below, can be of particular value when the acid gels of this invention are used to acid treat sub-terranean formations.
The gelling agents are particularly useful in increas-ing the viscosity of aqueous; inorganic acid solutions such as hydrochloric acid solutions, sulfu~ic acid solutions, phosphoric acid solutions, hydrofluoric acid solutions and ¦ solutions containing mixtures of such acids.
! In p~eparing a gelled aqueous acid solution of this invention, the acid or mixture o acids utilized can be, and is preferably, diluted with water to obtain an aqueous ! inorganic acid solution of desired acid concentration. A
I gelling agent of the present invention~ i.e., an ethoxylated ¦ fatty amine or mixture of such amines of the type described ¦ lS above dissolved in a water soluble organic solvent, is pre-/ ferably combined with the aqueous acid solution in an amount in the range of from about 0.1 to about 10, and more prefer-ably in the range of from about 2 to 6, percent gelling agent by weight of the aqueous acid solution. The acid solu-tion and gelling agent are agitated or mixed for a short period of time whereupon the viscosity of the aqueous acid solution is increased. More specifically, some increase in viscosity is obtained when as little as 0.1 percent gelling agent is combined with the aqueous acid solution, and greater amounts of the gelling agent bring about increased _9_ .1 , . ' .
~ 2 viscosity. When the gelling agent is combined with the aqueous acid solution in an ~nount of about 10 percent by weight of the solution, viscosities of about 150 centi-I poises càn be obtained.
¦ 5 Greater viscosity increase can be obtained through use of gelling agent amounts in excess of io percent. Thus, lO percent is not a limit on the capability of the gelling agent to increase the viscosity of acid, but is viewed as a working guide in view of current process economics and the practical capabilities of currently known liquid hand-ling and pumping e~uipment.
A gelled aqueous acid solution of this invention is comprised of water, a water soluble inorganic acid or,mix-ture o such acids, and a gelling agent comprised of a solution of a water soluble organic solvent and an ethoxy-lated fatty amine having the general formula:
~(CR2C~I20) XH
~ CX2CH2O)yH t3) wherein: 9 - R is selected from saturated and unsaturated aliphatic groups having in the range of from about 8 to about 22 car-bon atoms, and mixtures thereof, and x and y each have a - value in the range of from about 0 to about lO.
2S A pre:Eerred gelled aqueous acid solution'of this inven-tion is comprised of an inorganic aqueous acid solution comprising water and a water soluble inorgani~ acid or mixture of such acids, and a gelling agent comprised of a solution of a water solub].e organic solvent and a mix-ture of ethoxylated fatty amines having the general formula~
; : ~(CH2CH20) XH
R N ~
2CH2)y~ (4) wherein: .
R is selected from saturated and unsaturated aliphatic I groups having in the range of from about 14 to about 18 car-¦ bon atoms and mixtures of such groups; and x and y each have j a value in the range of from 0 to about 10 with the average ¦ .sum of the values of x and y in the mixture being in the ¦ 15 range of from about 1.8 to about 2.2.
I The most preferred gelled aqueous acid solution of this invention is comprised of an aqueous acid solution comprising water and an inorganic water soluble acid or a mixture of such acids, and a gelling agent present in the aqueous acid solution in an amount in the range of from about 1 to about 10 percent gelling agent by weight of the acid solution. The gelling agent is comprised of a solution of a water soluble organic solvent, ana a mixture of ethoxylated fatty amines present in the gelling agent in an amount of from about 10 to about 80 percent amines ..
by weight of the gelling agent. The ethoxylated fatty ami~es have the general formula:
, , . f CH2CH20) xH
; R - N~
5. ~ CH2CH20)yH (5) wherein: .
R is selected from the group consisting of saturated ¦ and unsaturated aliphatic groups having in the range of from about 16 to about 18 carbon atoms and mixtures of such I 10 groups; and ¦ the average sum of the values o x and y in said mix-¦ ture of ethoxylated amines is equal to 2.
In the most preferred embodiment, x and y in formula ~5) each have a value of one (1).
The gelled aqueous acid solutions of this invention are stable over a wide temperature range and therefore will not chemically degrade with time, even at a temperature as high as 250F. It must be understood, however, that the gelled acids of this invention, like other liguids, do experience viscosity change with temperature change. Thus, for example, with increasing temperature, the viscosity OL
these gels declines, but is regained upon decrease of tem-perature. Thus, gels made according to this invention have long storage life.
While~ the gelled aqueous acid solutions of this inven-tion have a variety of uses, they are particularly suitable , ' for carrying out acid treatments in subterranean welli formations for increasing the production of hydrocarbon ¦ fluids therefrom. When the gelled aqueous aaid solutions I are introduced into subterranean well formation, the acid 1 5 spends by reacting wlth materials in the formation, e.g., limestone and/or dolomite, whereby salts (e.g., chlorides I when HCl is used) are formed. The formation of salts in j the spe,nt acid solution causes the viscosity of the solu-tion to decrease. That is, as the acid'spends and salts form, the viscosity of the spent acid solution begins to decrease when acid concentration is in the range of about 10 to 15 percent. Thus, chemicals known in the art as , "breakers" are not required when the gelled acid solutions I of this in~ention are used to acid treat subterranean well j 15 formations. The spent acid solutions, after breakingj have viscosities in the range of from about 5 to about 15 centi-, poises and have excellent particle suspension properties I which facilitates the efficient clean-up of a treated forma-tion.
In using the gelled aqueous acid solutions for carrying j , out acidizing treatments in a subterranean well formation, ¦ an aqueous acid solution of desired acid strength is first - prepared. For example, in carrying out acidizing or acid fracturing treatments in limestone or dolomite formations, aqueous hydrochloric acid solutions in concentrations in .
~. .
the range of from about 3~ to about 28~ by weight are often utilized. After the particular aqueous acid solu-tion to be used has been prepared and diluted to the desired strength, the gelling agent of the present inven-tion is combined therewith, preferably in an amount in the range of from a~out 0.1 to about 10 percent by weight of the acid solution whereby the viscosity of the solution is increased. Other conventional well formation treating additives, such as corrosion inhibitors, non-emulsifying agents, fluid loss additives, etc., can also be combined with the solution. The resultant gelled aqueous acid solution is introduced into the formation to carry out an acidizing or acid fracturing treatment therein. After the aqueous acid solution has become spent by reaction with materials in the formation and thereby broken to a low viscosi y fluid, it is produced from the formation and the formation is cleaned up using conventional clean-up procedures followed by placing the formation on production.
Nhen a gelled aqueous hydrochloric acid solution of this invention having an initial acid concentration of below about 22 percent by weight of solution spends on limestone or dolomite to thus form calcium chloride and magnesium chloride and cools, some water and the gelling agent can separate out of the solution as a thick viscous phase.
Separation does not occur when the initial hydrochloric .
; -14-1~ ',, 2~
acid concentration is above about 22 percent by weight. In order to prevent separation in spent solutions when acid concentrations below about 2~ percent by weight are utilized, calcium chloride can be addel~ to the aqueous hydrochloric acid solution prior to gelling in an amount such that after reaction, the spent solution contains a calcium chloride concentration equivalent to a spent 22 percent by weight ! hydrochloric acid solu-tion. The amount of calcium chloride required generally falls within the range of from about 1 percent to about 10 percent by weight of the spent solution.
' That is, when a gelled aqueous hydrochloric acid solution I having an acid concentration of above about 22 percent by weight of the solution is utilized in the treatment of sub-terranean well formations containing calcium, no calcium chloride is added to the live solution. When a gelled aqueous hydrochloric acid solution at a co,ncentration of 20 percent by weight of solution is utilized, about 308 ~ pounds of calcium chloride per 1000 gallons of aqueous I acid solution are added thereto which prevents separation 1 20' at low temperatures (150F and below). When a gelled ¦ aqueous hydrochloric acid solution having a concen-trations of 15 percent by weight is utilized, about 1040 pounds of J calcium ch:Loride per 1000 gallons of acid solution are com-bined therewith to prevent such separation.
The following examples are given in order to further . illustrate the gelling agent and gelled aqueous acid solu-tions of the present invention.
' Example 1 Gelling agents of the present invention are prepared using various mixtures o~ ethoxylated fatty amines dissolved ¦ ~ in glacial acetic acid. The gelling agents are added to ¦ aqueous acid solutions containing 15 percent by weight hydro-I chloric-acid, and the viscosities of the resultant gels ! determined. The viscosities of the gels are apparent visco-i 10 sities measured on a Model 35 FANN viscometer, no. 1 spring, ¦ standard bob and sleeve, at room temperature (72 - 76F) and ¦ at 300 rpm. The results of these tests are given in Table I
! below.
i .
~ n.`6 ~
TABLE I - VISCOSITIES OF GELLED AQUEOUS
HYDROCHLORIC ACID SOLUTIONS USING VARIOUS GELLLN~ AGENTS
Ethoxylated Average Concentration concentratlon Vlscoslty Fatty Amine Moles of of Amines Con- of Gelling of Gelled Fatty Acid Ethylene tained in Gel- Agent in Aqueous Origin Oxide ling Agent, ~ Hydrochloric HCl Per Mole by Weight of Acid Solution, of Amine Acatic Acid- Solution, cp ;:-; Amine % by Weight Solution ... _ . . .. _ .. _ . . . _ ... _ Coconut (Mixture of . Chains Hav-ing 8, 10, 1~ 12, 14, 16 :; and 18 Car-bon Atoms) -2 33.3 9 3 Coconut (Mixture of .
Chains Hav-' ing 8, 10, s 12, 14, 16 and 18 Car-. bon Atoms) 5 33.3 9 3 ~ 25 Soya (Mix-~ ture of Chains Hav-ing 14, 16 and 18 Car-bon Atoms) 2 33.. 3 9 77 Soya (Mix-ture of Chains Hav-ing 14, 16 and 18 Carbon Atoms) 5 33.3 9 3 Tallow (Mixture of Chains Having 14, 16 and 18 . Carbon Atoms) 2 33.3 9 55 Oleyl (18 Carbon Atoms) 2 33.3 9 82 Palmityl (16 Car-bon Atoms) 2 50 6 52 i ~ ,r"'~
From Table I it can be seen that gelling agents con-taining etho~ylated fatty amines derived from coconut, soya, tallow, oleic, and palmitic fatty acids increase the viscosity of aqueous hydrochloric acid solutions.
S The results provided in Table I also màke it clear that ethoxylated fatty amines having an average of 2 moles of ethylene oxide per mole of amine and containing hydrocar-bon chain lengths of 14 to 18 carbon atoms significantly increase the viscosity of aqueous hydrochloric acid solutions.
¦ 10 ` Example 2 A gelling agent is prepared by dissolving 3 grams of l ethoxylated soya amines having an average of 2 moles of ! ethylene oxide per mole of amine in 6 mls. (about 7 grams) ¦ of glacial acetic acid. The approximate composition of a , 15 commercial mixture of fatty acids from which the soya amine is derived is as follows:
Acid % By Weight myristic (C14) 0 to 1%
palmitic (C16) 6 to 10%
steariC (C18) 2 to 4%
oleic (C18) 21 to 29~
linoleiC (C18) 50 to 59%
linoleniC (C18) 4 to 8%
The gelling agent is combined with 125 mls. (about 134 grams) of an aqueous hydrochloric acid solution containing 1~
15 percent by weight hydrochloric acid. After mixing, the aqueous hydrochloric acid solution has an apparent visco--- sity of 95 centipoises measured on a Model 35 FANN visco-meter, no. 1 spring, standatd bob and sleeve at room temperature (72 - 76F) and 300 rpm.
. ' Example 3 Gelling agents are prepared by dissolving 5 grams of ethoxylated tallow amines having an average ethylene oxide content of 2 moles per mole of amine with various organic solvents. The gelling agents are then each added in amounts of 10 mls. to 200 mls. of an aqueous acid solution prepared by combining 126.8 mls. of tap water with 73.2 mls. of a hydrochloric acid solution containing 37~5 percent by ¦ weight hydrochloric acid to thus produce 200 mls. of 15 - 15 percent HCl solution which weighed 215 grams. The solu-tion also contains 25 grams of calcium chloride and 0.4 ml. of a hydrochloric acid corrosion inhibitor. After mix-ing the gelling agents with the acid solutions, the apparent .
3 viscosities of the resulting gelled aqueous hydrochloric acid 3 20 solutions are determined using a Model 35 FANN viscometer, no. 1 spr~ng, standard bob and sleeve at 80F and 300 rpm.
The results of these tests are shown in Table II below~
' .
' .
TABLE II - VISCOSITIES OF GELLED AQUEOUS HYDROCHLORIC ACID
SOLUTIO~S USING GELLING AGENTS CONTAINING VARIOUS ORGA~IC ACIDS
Quantity of Organic Quantity Degree of Viscosity I Ethoxylated Solvent of Difficulty of Gelled Tallow Organic in Dissolv- Aqueous Amines, ml 501vent, ing Amines Hydrochloric (grams-)~ ml in Solvent Acid (grams) Used solutions .
5 t 5 ) Propionic 5 (5.0) Easily 51 ~10 acid ` dissolved 5 ( 5 ) Acetic 5 (5.2) Very easily 70 acid dissolved 5 ( 5 ) Formic 5 (5.9) Difficult 88 Acid - 88%
5 ( 5 ) Acetone 5 (3.9) Easily 67 dissolved 5 ( 5 ) Ethylene 5 (5.5) Easily 75 Glycol dissolved Example 4 Gelling agents are prepared by dissolving ethoxylated tallow amines having an average of 2 moles of ethylene oxide per mole of amine in various organic acids in amounts of 50 percent by weight of amine-acid solution. Each of the gelling agents are combined with aqueous hydrochloric acid solutions in amounts of 5 percent gelling agent by weight of the acid solutions, and the viscosities of the resulting gelled aqueous acid solutions are determined at various tem-peratures. Each of the aqueous acid solutions contain 15 percent hydrochloric acid by weight, 12.5 grams of calcium chloride per 100 cc of acid solution, and 0.2 percent by weight o a hydrochloric acid corrosion inhibitor.
.
I TABLE III - VISCOSITIES OF GELLED HYDROCHLORIC ACID SOLUTIONS
. . AT VARIOUS TEMPERATUES USING GELLING AGENTS
-~ . CONTAINING VARIOUS ORGANIC ACIDS
¦ Organic Viscosities of Gelled Aqueous HC1 Solutions, cp1 5 Acid - - _ .
9~F.100F 110F 120F 130F 140F 150F 160F 170F 180F
Formic 70 66 61 55 48.5 40 30 ~3.5 19 16 I Acetic 67 61 ~4 46 35 29 23 19 14.5 10.5 ! Prop- 41.5 30 21.5 16 1310.5 8 6 4.5 3.5 l 10 ionic .' .
- As illustrated in Tables II and III above, gelling agents ! wherein formic acid is used as the amine solvent achieve the highest apparent viscosity in hydrochloric acid solutions. How-ever, because the dissolution of ethoxylated fatty amines in formic acid is difficult, acetic acid is praferred for use in aFcordance with this invention.
¦ Example 5 ! A gelling agent is prepared by dissolving ethoxylated ! tallow amines having an average ethylene oxide content of 2 ! 20 moles per mole of amine in acetic acid in an amount of 50 percent by weight of the amine-acid solution. Various amounts of the gelling agent are combined with aqueous hydrochloric ¦ acid solutions containing 15 percent by weight hydrochloric ' acid and 0.4 percent ~y weight hydrochloric acid corrosion 1 25 inhibitor. The apparent ~iscosities o the resulting gelled I aqueous hydrochloric acid solutions are determined at var-1 ious temperatures using a Model 35 FANN viscometer, no. 1 .i .
; -21--spring, standard bob ard sleeve at 300 rpm. The resultsof these tests are given in Table IV below.
TABLE IV - VISCOSITIES OF GELLED AQUEOUS HYDROCHLORIC ACID
. SOLU~IONS AT VARTOUS TEMPERATUES USING VARIOUS
. 5 ; QUANTITIES OF GELLING AGENT
~ .
Percent Viscosities of Gelled Aqueous HCl Solutions, cp ~elling Agent By Weight of Acid Solu- 90F 100F 110F120~F 130F 140F 150F 160F
tion 198.5 4 32.5 --~
3 37.5 35 31.5 27 21 15.5 6 2.5
The results of these tests are shown in Table II below~
' .
' .
TABLE II - VISCOSITIES OF GELLED AQUEOUS HYDROCHLORIC ACID
SOLUTIO~S USING GELLING AGENTS CONTAINING VARIOUS ORGA~IC ACIDS
Quantity of Organic Quantity Degree of Viscosity I Ethoxylated Solvent of Difficulty of Gelled Tallow Organic in Dissolv- Aqueous Amines, ml 501vent, ing Amines Hydrochloric (grams-)~ ml in Solvent Acid (grams) Used solutions .
5 t 5 ) Propionic 5 (5.0) Easily 51 ~10 acid ` dissolved 5 ( 5 ) Acetic 5 (5.2) Very easily 70 acid dissolved 5 ( 5 ) Formic 5 (5.9) Difficult 88 Acid - 88%
5 ( 5 ) Acetone 5 (3.9) Easily 67 dissolved 5 ( 5 ) Ethylene 5 (5.5) Easily 75 Glycol dissolved Example 4 Gelling agents are prepared by dissolving ethoxylated tallow amines having an average of 2 moles of ethylene oxide per mole of amine in various organic acids in amounts of 50 percent by weight of amine-acid solution. Each of the gelling agents are combined with aqueous hydrochloric acid solutions in amounts of 5 percent gelling agent by weight of the acid solutions, and the viscosities of the resulting gelled aqueous acid solutions are determined at various tem-peratures. Each of the aqueous acid solutions contain 15 percent hydrochloric acid by weight, 12.5 grams of calcium chloride per 100 cc of acid solution, and 0.2 percent by weight o a hydrochloric acid corrosion inhibitor.
.
I TABLE III - VISCOSITIES OF GELLED HYDROCHLORIC ACID SOLUTIONS
. . AT VARIOUS TEMPERATUES USING GELLING AGENTS
-~ . CONTAINING VARIOUS ORGANIC ACIDS
¦ Organic Viscosities of Gelled Aqueous HC1 Solutions, cp1 5 Acid - - _ .
9~F.100F 110F 120F 130F 140F 150F 160F 170F 180F
Formic 70 66 61 55 48.5 40 30 ~3.5 19 16 I Acetic 67 61 ~4 46 35 29 23 19 14.5 10.5 ! Prop- 41.5 30 21.5 16 1310.5 8 6 4.5 3.5 l 10 ionic .' .
- As illustrated in Tables II and III above, gelling agents ! wherein formic acid is used as the amine solvent achieve the highest apparent viscosity in hydrochloric acid solutions. How-ever, because the dissolution of ethoxylated fatty amines in formic acid is difficult, acetic acid is praferred for use in aFcordance with this invention.
¦ Example 5 ! A gelling agent is prepared by dissolving ethoxylated ! tallow amines having an average ethylene oxide content of 2 ! 20 moles per mole of amine in acetic acid in an amount of 50 percent by weight of the amine-acid solution. Various amounts of the gelling agent are combined with aqueous hydrochloric ¦ acid solutions containing 15 percent by weight hydrochloric ' acid and 0.4 percent ~y weight hydrochloric acid corrosion 1 25 inhibitor. The apparent ~iscosities o the resulting gelled I aqueous hydrochloric acid solutions are determined at var-1 ious temperatures using a Model 35 FANN viscometer, no. 1 .i .
; -21--spring, standard bob ard sleeve at 300 rpm. The resultsof these tests are given in Table IV below.
TABLE IV - VISCOSITIES OF GELLED AQUEOUS HYDROCHLORIC ACID
. SOLU~IONS AT VARTOUS TEMPERATUES USING VARIOUS
. 5 ; QUANTITIES OF GELLING AGENT
~ .
Percent Viscosities of Gelled Aqueous HCl Solutions, cp ~elling Agent By Weight of Acid Solu- 90F 100F 110F120~F 130F 140F 150F 160F
tion 198.5 4 32.5 --~
3 37.5 35 31.5 27 21 15.5 6 2.5
4 48.5 45 `. 40 31.5 24 18 14 10 68.5 65 5û 38 31 24 19 14 i From Table IV it can be seen that by increasing the ¦ amount of gelling agent combined with an aqueous soiution, I the viscosity of the resultant gelled solution is increased.
¦ . Example 6 ! 20 A gelling agent is prepared by dissolving ethoxylated tallow amines having an ethylene oxide content of 2 moles ! per mole of amine in glacial acetic acid in an amount of ¦ 50 percent by weight of the resulting solution. A portion ¦ of the gelling agent is combined with an aqueous hydrochloric l 25 acid solution in an amount of 5 percent by weight of the acid solution. The acid solution contains 15 percent by weight of hydrochloric acid, 12. 5 grams of calcium chloride , ,-per 100 cc of the solution and 0.2 percent by weight of a hydrochloric acid corrosion inhibitor. The resulting gelled aqueous hydrochloric acid solution is spent to 10.3 percent by weigh~ live hydrochloric acid by reacting the solution . . , with limestone. Viscosities of the spent solution are determined at various temperatures using a-Model 35 FANN
viscometer, no. 1 spring, standard bob and sleeve at 300 rpm. The results of these tests are given in Table V.
TABLE V - VISCOSITIES OF GELLED 15% BY WEIGHT
AQUEOUS HYDROCHLORIC ACID SOLUTION AT VARIOUS TEMPERATURES
AFTER BEING SPENT TO 10.3~ BY WEIGHT LI~E ACID
.. .. . ... _ . ..
Temperature, F Vlscosity, cp 84 ` 70 From Table V it can be seen that when a gelled 15 percent by weight hydrochloric acid solution is spent to a live acid concentration of 10.3 percent by weight, the acid solution is broken to a viscosity of less than about 10 cp at a temperature of 100F.
---~ 2fl~
Example 7 ¦ A gelling agent is prepared as described in Example 6and is combined with an aqueous hydrochloric acid solution in an amount of 5 percent by weight of acid solution. The hydroch ~ric acid solution contains 28 percent by weight hydrochloric acid and 0.5 percent by weight acid corrosion inhibitor. The resulting gelled aqueous hydrochloric acid solution is spent by reaction with limestone to various live ~ - acid concentrations, and the viscosities of such partially 3 10 spent solutions are determined at various temperatures using a Model 35 FANN viscometer, no. l spring, standard bob and sleeve at 300 rpm. The results of these tests are shown in Table VI below.
. TABLE VI - VISCOSITIES OF GELLED 28% BY WEIGHT AQUEOUS~YDROCHLORIC ACID SOLUTIONS AT VARIOUS TE~E~AT~RES
; AFTER BEING SPENT TO VARIOUS LIVE ACID CONCENTRATIONS
_ _ _ _ _ . r ~ . . . . . ~ .. _ _ I Spent Solution Viscosities of Spent Acid Solutions, cp Live Acid 20 - Concentra-~ tion, %
¦ - By Weight 90F 100F110F 120F 130F 140F150F 160F
19.9 19.5 20 20 19 18 16.515 13 j 1~5.9 70 66.5 60 51 40 30 5 3 10.3 45 8.5 6 5 4 3 2 1.5 ~.2 6 7 From Table VI it can be seen ~hat when a gelled aqueous 3 hydrochloric acid solution of this invention containing 28 I ~
i ~ 2~
. . , `
percent by weight hydrochloria acid is spent to a live acid concentration below about 16 percent by weight, such spent solution is broken to a viscosity below about 5 cp - at 150F.
Example 8 A gelling agent of the present invention is prepared by dissolving ethoxylated tallow amines having an ethylene ¦ oxide content of 2 moles per mole of amine in glacial ! acetic acid in an amount of 50 percent by weight of the solu-¦ 10 tion. Portions of the gelling agent are added to aqueous hydrochloric acid solutions, and the resulting gelled hydro-chloric acid solutions are spent by reaction with limes~one.
, The apparent viscosities of the spent solutions are measured I on a Model 35 FANN viscometer, no. 1 spring, standard bob and sleeve at 300 rpm. the particle or fines suspending properties of the spent acid solutions are determined by placing 2 grams of fines in 100 ml portions of the spent solutions, mixing the solutions and then allowing the ~ines to settle in the solutions for 6 hou,s. The fines remaining suspended in the solutions after the 6-hour periods are `¦ determined by collecting the fines by centriugation, wash-ing, drying and weighing. The results of ~hese tests are given in Table VII below.
1. .
~ .
~
T~BLE VII - FINE SIJSPENSION ABILITY OF
SPENT GELLED AQUEOUS ACID SOLUTIONS
. . -- . . ..
Gelled Aqueous Acid Solul:ion Solution ' Live
¦ . Example 6 ! 20 A gelling agent is prepared by dissolving ethoxylated tallow amines having an ethylene oxide content of 2 moles ! per mole of amine in glacial acetic acid in an amount of ¦ 50 percent by weight of the resulting solution. A portion ¦ of the gelling agent is combined with an aqueous hydrochloric l 25 acid solution in an amount of 5 percent by weight of the acid solution. The acid solution contains 15 percent by weight of hydrochloric acid, 12. 5 grams of calcium chloride , ,-per 100 cc of the solution and 0.2 percent by weight of a hydrochloric acid corrosion inhibitor. The resulting gelled aqueous hydrochloric acid solution is spent to 10.3 percent by weigh~ live hydrochloric acid by reacting the solution . . , with limestone. Viscosities of the spent solution are determined at various temperatures using a-Model 35 FANN
viscometer, no. 1 spring, standard bob and sleeve at 300 rpm. The results of these tests are given in Table V.
TABLE V - VISCOSITIES OF GELLED 15% BY WEIGHT
AQUEOUS HYDROCHLORIC ACID SOLUTION AT VARIOUS TEMPERATURES
AFTER BEING SPENT TO 10.3~ BY WEIGHT LI~E ACID
.. .. . ... _ . ..
Temperature, F Vlscosity, cp 84 ` 70 From Table V it can be seen that when a gelled 15 percent by weight hydrochloric acid solution is spent to a live acid concentration of 10.3 percent by weight, the acid solution is broken to a viscosity of less than about 10 cp at a temperature of 100F.
---~ 2fl~
Example 7 ¦ A gelling agent is prepared as described in Example 6and is combined with an aqueous hydrochloric acid solution in an amount of 5 percent by weight of acid solution. The hydroch ~ric acid solution contains 28 percent by weight hydrochloric acid and 0.5 percent by weight acid corrosion inhibitor. The resulting gelled aqueous hydrochloric acid solution is spent by reaction with limestone to various live ~ - acid concentrations, and the viscosities of such partially 3 10 spent solutions are determined at various temperatures using a Model 35 FANN viscometer, no. l spring, standard bob and sleeve at 300 rpm. The results of these tests are shown in Table VI below.
. TABLE VI - VISCOSITIES OF GELLED 28% BY WEIGHT AQUEOUS~YDROCHLORIC ACID SOLUTIONS AT VARIOUS TE~E~AT~RES
; AFTER BEING SPENT TO VARIOUS LIVE ACID CONCENTRATIONS
_ _ _ _ _ . r ~ . . . . . ~ .. _ _ I Spent Solution Viscosities of Spent Acid Solutions, cp Live Acid 20 - Concentra-~ tion, %
¦ - By Weight 90F 100F110F 120F 130F 140F150F 160F
19.9 19.5 20 20 19 18 16.515 13 j 1~5.9 70 66.5 60 51 40 30 5 3 10.3 45 8.5 6 5 4 3 2 1.5 ~.2 6 7 From Table VI it can be seen ~hat when a gelled aqueous 3 hydrochloric acid solution of this invention containing 28 I ~
i ~ 2~
. . , `
percent by weight hydrochloria acid is spent to a live acid concentration below about 16 percent by weight, such spent solution is broken to a viscosity below about 5 cp - at 150F.
Example 8 A gelling agent of the present invention is prepared by dissolving ethoxylated tallow amines having an ethylene ¦ oxide content of 2 moles per mole of amine in glacial ! acetic acid in an amount of 50 percent by weight of the solu-¦ 10 tion. Portions of the gelling agent are added to aqueous hydrochloric acid solutions, and the resulting gelled hydro-chloric acid solutions are spent by reaction with limes~one.
, The apparent viscosities of the spent solutions are measured I on a Model 35 FANN viscometer, no. 1 spring, standard bob and sleeve at 300 rpm. the particle or fines suspending properties of the spent acid solutions are determined by placing 2 grams of fines in 100 ml portions of the spent solutions, mixing the solutions and then allowing the ~ines to settle in the solutions for 6 hou,s. The fines remaining suspended in the solutions after the 6-hour periods are `¦ determined by collecting the fines by centriugation, wash-ing, drying and weighing. The results of ~hese tests are given in Table VII below.
1. .
~ .
~
T~BLE VII - FINE SIJSPENSION ABILITY OF
SPENT GELLED AQUEOUS ACID SOLUTIONS
. . -- . . ..
Gelled Aqueous Acid Solul:ion Solution ' Live
5. Acid Acid Suspended . -~aicium Corro- Concen- Viscosity Fines in , Chloride, sion tration .Of Spent Spent Acid Grams/ Inhi- Gelling After Acid Solution HCl, 100 cc bitor, Agent Spending, After After 6 l-Q by Acid ~ By % By % HC1 By Solution, Hours, mg/
Weight Solution Weight Weight Weight cp 100 cc 15 12.5 0.2 5 1.5 10 t74F)206 20 3~7 0.2 5 1.2 5 (80F)279 ~ 28 0 0.2 5 1.4 7.5 (64F) 330 ! 1S Deionized water only 5 .
~ From Table VI it can be seen that the spent gelled i aqueous acid solutions of this invention have excellent . fines suspension capability.
, ..
~ .
I ~ -26-;
Weight Solution Weight Weight Weight cp 100 cc 15 12.5 0.2 5 1.5 10 t74F)206 20 3~7 0.2 5 1.2 5 (80F)279 ~ 28 0 0.2 5 1.4 7.5 (64F) 330 ! 1S Deionized water only 5 .
~ From Table VI it can be seen that the spent gelled i aqueous acid solutions of this invention have excellent . fines suspension capability.
, ..
~ .
I ~ -26-;
Claims (7)
1. A gelling agent for gelling aqueous inorganic acid solutions comprising a water soluble organic solvent selected from the group consisting of alkanols having in the range of from about 1 to 5 carbon atoms per molecule, ketones having in the range of about 3 to 6 carbon atoms per molecule, polyhydroxy compounds having in the range of about 2 to 6 carbon atoms per molecule, ethers having in the range of about 2 to 6 carbon atoms per molecule, compounds containing both ether and alcohol functions having in the range of about 4 to 8 carbon atoms per molecule, esters having in the range of about 2 to 6 carbon atoms per molecule, lactones having in the range of about 3 to 5 carbon atoms per molecule and mixtures of two or more of the foregoing compounds, and a mixture of ethoxylated fatty amines dissolved in said water soluble organic solvent having the general formula:
wherein:
R is selected from saturated and unsaturated aliphatic groups having in the range of from about 8 to about 22 carbon atoms and mixtures thereof, and x and y each have a value in the range of from O to about 10.
wherein:
R is selected from saturated and unsaturated aliphatic groups having in the range of from about 8 to about 22 carbon atoms and mixtures thereof, and x and y each have a value in the range of from O to about 10.
2. The gelling agent of claim 1 wherein the average sum of the values of x and y in said mixture is in the range of from about 1.8 to about 2.2.
3. The gelling agent of claim 1 wherein R is selected from the group consisting of saturated and unsaturated aliphatic groups having in the range of from about 14 to about 18 carbon atoms and mixtures of such groups, and wherein the average sum of the values of x and y in said mixture of ethoyxlated amines is equal to 2.
4. The gelling agent of claim 1 wherein said mixture of ethoxylated fatty amines is present in said organic solvent-amine solution in an amount in the range of from about 10% to about 80% by weight of said solution.
5. The gelling agent of claim 3 wherein said water soluble organic solvent is an alkanol selected from the group consisting of methanol, ethanol, isopropanol, t-butanol and mixtures thereof and said mixtures of ethyloxylated fatty amines is present in said alkanol-amine solution in an amount of about 50% by weight of said solution.
6. A gelling agent for gelling aqueous inorganic acid solutions comprising a solution of methanol and an ethoxylated fatty amine having the general formula:
wherein:
R is selected from the group consisting of saturated and unsaturated aliphatic groups having in the range of from about 16 to about 18 carbon atoms and mixtures of such groups.
wherein:
R is selected from the group consisting of saturated and unsaturated aliphatic groups having in the range of from about 16 to about 18 carbon atoms and mixtures of such groups.
7. The gelling agent of claim 6 wherein said ethoxylated fatty amine is present in said solution in an amount of about 50% by weight of said solution.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US87173678A | 1978-01-23 | 1978-01-23 | |
| US871,736 | 1997-06-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1106724A true CA1106724A (en) | 1981-08-11 |
Family
ID=25358016
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA313,028A Expired CA1106724A (en) | 1978-01-23 | 1978-10-10 | Aqueous acid solution gelling agents |
Country Status (7)
| Country | Link |
|---|---|
| AU (1) | AU4068778A (en) |
| BR (1) | BR7807830A (en) |
| CA (1) | CA1106724A (en) |
| FR (1) | FR2415139A1 (en) |
| IT (1) | IT1110842B (en) |
| NO (1) | NO790211L (en) |
| PT (1) | PT68629A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NO170944C (en) * | 1987-01-24 | 1992-12-30 | Akzo Nv | THICKNESSED, MOISTURE PREPARATIONS, AND USE OF SUCH |
-
1978
- 1978-10-09 PT PT68629A patent/PT68629A/en unknown
- 1978-10-10 CA CA313,028A patent/CA1106724A/en not_active Expired
- 1978-10-13 AU AU40687/78A patent/AU4068778A/en active Pending
- 1978-11-02 FR FR7831061A patent/FR2415139A1/en not_active Withdrawn
- 1978-11-29 BR BR7807830A patent/BR7807830A/en unknown
-
1979
- 1979-01-22 NO NO790211A patent/NO790211L/en unknown
- 1979-01-23 IT IT19543/79A patent/IT1110842B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| BR7807830A (en) | 1979-07-31 |
| IT7919543A0 (en) | 1979-01-23 |
| PT68629A (en) | 1978-11-01 |
| FR2415139A1 (en) | 1979-08-17 |
| NO790211L (en) | 1979-07-24 |
| IT1110842B (en) | 1986-01-06 |
| AU4068778A (en) | 1980-04-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4324669A (en) | Foamed high viscosity aqueous inorganic acid solutions and methods of using the same | |
| US4324668A (en) | High viscosity acidic treating fluids and methods of forming and using the same | |
| US4313834A (en) | High viscosity acidic treating fluids and methods of forming and using the same | |
| US4215001A (en) | Methods of treating subterranean well formations | |
| AU2001260178B2 (en) | Viscosity reduction of viscoelastic surfactant based fluids | |
| EP1534926B1 (en) | Viscosity reduction of viscoelastic surfactant based fluids | |
| CA2384108C (en) | Quaternary ammonium salts as thickening agents for aqueous systems | |
| US7727936B2 (en) | Acidic treatment fluids comprising xanthan and associated methods | |
| US9725643B2 (en) | Foam or viscosified composition containing a chelating agent | |
| CA1109356A (en) | Gelled aqueous inorganic acid solutions and methods of using the same | |
| US5009799A (en) | Inorganic acid solution viscosifier and corrosion inhibitor and method | |
| US4167214A (en) | Process for stably sequestering iron while acidizing a reservoir | |
| US20070281868A1 (en) | Acidic treatment fluids comprising xanthan and associated methods | |
| CA1090549A (en) | Process and self-acidifying liquid system for dissolving a siliceous material in a remote location | |
| EA005909B1 (en) | Novel fluid system having controllable reversible viscosity | |
| US20080161207A1 (en) | Subterranean treatment fluids comprising viscoelastic surfactant gels | |
| CA2820920A1 (en) | Treatment of illitic formations using a chelating agent | |
| US4231882A (en) | Treating subterranean well formations | |
| US4487867A (en) | Water soluble anionic polymer composition and method for stimulating a subterranean formation | |
| CN108285784B (en) | Gelled emulsified acid and preparation method thereof | |
| CA2403079A1 (en) | Methods of drilling well bores using invertible oil external-water internal drilling fluids | |
| US4542790A (en) | Process for extracting extensively emulsion-free oil from a subterranean reservoir | |
| CA1244236A (en) | Liquid polymer containing compositions for thickening aqueous mediums | |
| CA1107947A (en) | Retarding acidizing fluids | |
| US4487866A (en) | Method of improving the dispersibility of water soluble anionic polymers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |