CA2051081C - Method of inhibiting corrosion in acidizing wells - Google Patents
Method of inhibiting corrosion in acidizing wellsInfo
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- CA2051081C CA2051081C CA 2051081 CA2051081A CA2051081C CA 2051081 C CA2051081 C CA 2051081C CA 2051081 CA2051081 CA 2051081 CA 2051081 A CA2051081 A CA 2051081A CA 2051081 C CA2051081 C CA 2051081C
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- acid solution
- aqueous acid
- metal
- antimony
- corrosion inhibitor
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Abstract
Corrosion inhibitor additives are added directly to an aqueous acid solution used in acidizing subterranean formations.
The additives consist essentially of a metal selected from antimony and antimony mixtures, a quaternary compound, and a surfactant. The corrosion inhibitor is free of toxic acetylenic compounds.
The additives consist essentially of a metal selected from antimony and antimony mixtures, a quaternary compound, and a surfactant. The corrosion inhibitor is free of toxic acetylenic compounds.
Description
! (EXX0N 13) METHOD OF INHlBlTING CORROSI~N IN ACI~I~ING WELL~
1 BACKGR0UND OF THE INVENTIO~
This invention relates generally to corrosion inhibitors and more specifically to the use of corrosion inhibitors contain-in~ quaterndry/anti~ony complex in acid solutions used in acid treatment of subterranean formations without acetylenic alcohols.
In one aspect, the invention relates to the direct addition of the ~ corrosion inhibitor additives directly to the aqueous acid solution used in well acidizina.
DESC~IPTION OF THE PRIOR ART
Acids and acid solùtions have long been used in the stimulation of oil wells, gas wells, ~ater wells, and similar boreholes. ~cid stimulation is performed in wells completed in subterranean formations. Acidi2ing is used in conjunction with hydraulic fracturing techniques and matrix acidizing techniques.
In both acid fracturing and matrix acidizing, the well treating acid solutions, usually HCl, HF, or mixtures thereof, are pumped through the well tubular goods and injected into the formation where the acid attacks formation materials increasing its permeability to oil and/or gas.
In order to protect the equipment and tubular goods from the corrosive effects of the acid, the well treating acid almost always includes a corrosion inhibitor.
Corrosion inhibitors of diverse description and composition have been proposed over the years for use with well treating acids. Corrosion inhibitors that have received wide spread use are those containing metalJquaternary ammonium complexes. Some of these are described in the following U.S.
Patents: 3,773,465 (cuprous iodide); 4,498,997; 4,522,658;
and 4,552,672 (antimony compounds).
In the past, the metal/quaternary complexes, havé been used with an acetylenic compound which apparently contributes to the effectiveness of the complex, particularly at high tempera-tures and high concentrations. Corrosion inhibitors containing acetylenic compounds are toxic. Therefore, it is desirable to avoid the use of the acetylenics where possible.
f - 2 ~ 2 0 5 1 0 8 1 ~ 1 SUMMARY OF THE INVENTION
The method o~ the present invention comprises the steps of adding directly to a well treating aqueous acidizing solution corrosion inhibitor additives consisting essentially of:
(a) a surfactant;
(b) an antimony compound or antimony metal mixture; and (c) an ammonium quaternary compound capable of~
forming a complex with the antimony and other metals in the mixture.
, Surprisingly, it has been found that the nonacetylenic corrosion inhibitor additives described above, when added directly to the aqueous acid solution, exhibits excellent dispersion and provides improved corrosion protection for the well equipment at relatively low concentrations in comparison to corrosion inhibitors with acetylenics and aromatic hydrocarbons.
Although the reasons for the improved performance are not fully understood, it is believed that the acetylenic compound and/or the aromatic hydrocarbon solvent interfere with deposition of the antimony on the well tubulars.
The concentrations of the three essential additives in the acid solution are as follows:
MOST
BROAD PREFERRED PREFERRED
RANGE RANGE RANGE
25 Component (wt%) (wtX) (wt%) Metal/
Metal Mixture .04 to 2.0 .05 to 1.0 .07 to .80 Quaternary 30Compound 0.2 to 10 0.4 to 5.0 0.4 to 2.2 Surfactant 0.1 to 25 0.1 to 5.0 0.1 to 1.5 Generally, the component ranges are interchangeable. For example, the most preferred range of a metal component may be used with both the broad and preferred ranges of the other components.
? 205 ~ 08 1 1 The metal colnpound will always include antilnony, either alone or as one compounn of a binary or ternary blend. At least 0.04 wt~
of antimony should be present in the acid.
The corrosion inhibitor components are separately introduced into the well treating acid at a concentration suffi-cient to coat the well tubulars and equipment. The concentration of each component in the acid solution should generally be suffi-cient to provide the acid solution with from 0.04 wt% to 0.80 wt%
of Sb.
The method of the present invention provides effective corrosion high temperature protection associated with metal salt complexes and employs low toxicity additives which are separately dispersible in the aqueous acid solution. The method of the present invention offers the operational advantage of direct addition and dispersion in the acidizing solution without preformulation. The corrosion inhibitors with acetylenic compounds of the prior art generally required solvents and premixture of at least so~e of the components.
DESCRIPTION OF PREFERRED EMBODIMENTS
As indicated above the method of the present invention employs only three essential additives which combine in situ when added to a well treating acid solution to provide effective cor-rosion inhibition. Each of these compounds as well as the acid solution in which they are used are described below.
Aqueous Acid Solutions: Any of the known oil field acids may be used. These are referred to herein as "well treating acids" and include aqueous solutions of hydrochloric acid (HCl), hydrofluoric acid (HF), mixtures of HCl and HF (i.e. mud acid), acetic acid, formic acid, and other organic acids and anhydrides.
The most common acids are 3X H~l, 7 1/2X HCl, 15X HCl, 28X HCl and blends of HCl and HF (mud acid). Mud acid is normally a blend of 6 to 12X of HCl and 1 1/2 to 6X HF.
Antimony Compounds and Mixtures: The function of the antimony and/or the meta1 mixed therewith is to complex with the quaternary ammonium compound and form a protective deposit on the metal tubulars and equipment.
q - 2~5 1 081 1 Tests have shown that salts of the following metals and mixtures thereof exhibit corrosion protection when co;nplexed with a quaternary ammonium compound or conpounds: Sb, Sb/Al. Sb/~l/Cu+, Sh/Cu~, Sb/Ca/Cu~, and Ca/Sb. The preferred metals are Sb alone and Sb, Cu+, and Ca binary alld ternary ~l~ixtures.
The metal salts or mixtures must be readily dispersible in the aqueous acid solution and form a complex with the quaternary ammonium compound. The term ~complexU as used herein means a coordination or association of the metal compound with the quaternary compound.
The preferred antimony salts and salts of the mixture are halides, specifically metal chlorides. Some of the salts n,ay be formed in situ, in acid solution. For example, antimony chloride is produced from Sb203 in aqueous acid such as HCl. The insoluble Sb203 is converted to soluble salt.
The antimony compound may comprise, for example, antimony trichloride, antimony pentachloride, antimony trifluoride, alkali metal salts of antimony tartrate, antimony adducts of ethylene glycol, and antimony trioxide or any other trivalent or pentavalent antimony compound and the like. As men-tioned above, the antimony oxides may be converted to halide salts in the presence of ~queous acid.
The cuprous compound may be cuprous iodide as described in U.S. patent 3,773,465.
The binary and ternary metal mixtures are preferred for particularly severe corrosive environments since they appear to combine synergistically to provide protection. The binary and fernary metals may be mixed in any ratio, provided Sb constitutes at least 20 wt%, preferably 30 wtX, of the metal mixture.
Quaternary Compounds: The quaternary ammonium compounds (referred to as ~uaternary~ herein) employed in the present in-vention must be capable of complexing with the antimony and other metals of the metal mixture (if employed). The preferred quater-nary comprise aromatic nitrogen compounds which may be illustrated ' 205 1 08 1 _ 1 by alkyl pyridine-N-methyl chloride quaternary, alkyl pyridine-N-benzyl chloride quaternary, quinoline -N-methyl chloride quaternary, quinoline-N-benzyl chloride quaternary, quinoline-N-(chloro-benzyl chloride) quaternary, isoquinoline quaternaries, benzoquinoline quaternaries, chloromethyl napthalene quaternaries and admixtures of such compounds, and the like. The quaternary compoun~ and Sb and Sb mixtures may be used in molar ratios of 1:1 to 5:1.
Generally, the quaternary compound, because of its higher molecular weight, will be present in the acid solution at a higher concer,-tration than the metal compound. The weight ratios of the quater-nary compound and the Sb and Sb mixtures thereof preferably range from 1:1 to 4:1.
The Surfactant: The surfactant serves to wet the tubu-lar goods to permit deposition of the quaternary/metal complex.
The preferred surfactants are the nonionics having hydrophilic -lipophilic balance (HLB~ numbers of 8 to 18, preferably 9 to 16, such as laurates, stearates, and oleates. Nonionic surfactants include the polyoxyethylene surfactants (such as ethoxylated alkyl phenols, ethoxylated aliphatic alcohols) polyethylene glycol esters of fatty, resin, and tall oil acids. Examples of such surfactants are polyoxyethylene alkyl phenol wherein the alkyl group is linear or branched C8 - C12 and contains above about 60 wt% polyoxyethylene. Octyl and nonyl phenols containing 9 to 15 moles ethylene oxide per mole hydrophobe are the prefer-red ethoxylated alkyl phenol surfactants.
The polyoxyethylene ester of fatty acids include themono and dioleates and sesquioleates wherein the molecular weight of the esterified polyethylene glycol is between about 200 and 1000.
Polyoxyethylene sorbitan oleates are also useable.
In practice, the nonionics may be blended to provide the desired properties. A particularly useful surfactant is a blend of polyethylene glycol esters of fatty acids and ethoxylated alkylphenols.
Operation: In operation, the three essential additives are added to the aqueous acid solution at the well site. The - 6 ~ 205 1 0~ 1 1 additives may be added in any order but prefera~ly are in the ~ following order: (1) surfactant; (2) quaternary compound; (3) and metal compound. The concentration of quaternary/metdl complex in the acid solution should preferably provide a metal ~including Sb) concentration of at 0.050 wtX.
The procedure for preparing the inhibited acid for pumping down the well is preferably by a batch process. In this process, the additives are blended into the aqueous acid solution in a large tank and then pumped into the well.
It has been found that the direct addition of the additives requires only a few minutes for dispersion and complex-ina to occur, so that any pumping process including the continuous process may be employed. The batch process, however, is preferred 7 because it assures adequate conditioning of tne corrosion inhibitor in the acid prior to pumping.
The method of the present invention can be used in wells to protect tubular goods made of typical oil field tubular steels such as J-55, N-80, P:105, and the like; or made of high alloy chrome steels such as Cr-9, Cr-13, Cr-2205, Cr-2250, and the like.
EXPERIMENTS
In order to demonstrate the effectiveness of the non-acetylenic corrosion inhibitor additiYes added directly to the acid solution, several samples with and without acetylenics were tested using various components. The additives used in the tests were as follows.
The quaternary a~monium compounds used in the experi-ments was a quinoline-N-benzyl chloride quaternary (quaternary X).
The surfactant was nonylphenol (10 mols E0).
The HCl acid was 15X-HCl.
The HF was 12X HCl and 3X HF.
The acetylenic compounds were a ble~d of ethyl octynol and propar~yl in wt ratios of 1 to 1 or 2 to 3.
The Sb compounds were Sb203.
The procedure for preparing the aqueous acid solution _ 1 wit~ inhibitor and the test procedure was as follows (all X are Wtb unless otherwise indicated) 1. The additives were added to the aqueous acid sol~tion C(15~ HCl or mud acid, (12X HCl/3X
HF)] in the following order (a) surfactant (b) acetylenic alcohol (c~ aromatic hydrocar~on solvent (if used) (d) quaternary compound (e)Sb2o3 2. The c~upouns (N-80 steel or Cr-2205) were then put in the acid solution with the additives and heated to 350-F under 3,000 psi for four hours.
1 BACKGR0UND OF THE INVENTIO~
This invention relates generally to corrosion inhibitors and more specifically to the use of corrosion inhibitors contain-in~ quaterndry/anti~ony complex in acid solutions used in acid treatment of subterranean formations without acetylenic alcohols.
In one aspect, the invention relates to the direct addition of the ~ corrosion inhibitor additives directly to the aqueous acid solution used in well acidizina.
DESC~IPTION OF THE PRIOR ART
Acids and acid solùtions have long been used in the stimulation of oil wells, gas wells, ~ater wells, and similar boreholes. ~cid stimulation is performed in wells completed in subterranean formations. Acidi2ing is used in conjunction with hydraulic fracturing techniques and matrix acidizing techniques.
In both acid fracturing and matrix acidizing, the well treating acid solutions, usually HCl, HF, or mixtures thereof, are pumped through the well tubular goods and injected into the formation where the acid attacks formation materials increasing its permeability to oil and/or gas.
In order to protect the equipment and tubular goods from the corrosive effects of the acid, the well treating acid almost always includes a corrosion inhibitor.
Corrosion inhibitors of diverse description and composition have been proposed over the years for use with well treating acids. Corrosion inhibitors that have received wide spread use are those containing metalJquaternary ammonium complexes. Some of these are described in the following U.S.
Patents: 3,773,465 (cuprous iodide); 4,498,997; 4,522,658;
and 4,552,672 (antimony compounds).
In the past, the metal/quaternary complexes, havé been used with an acetylenic compound which apparently contributes to the effectiveness of the complex, particularly at high tempera-tures and high concentrations. Corrosion inhibitors containing acetylenic compounds are toxic. Therefore, it is desirable to avoid the use of the acetylenics where possible.
f - 2 ~ 2 0 5 1 0 8 1 ~ 1 SUMMARY OF THE INVENTION
The method o~ the present invention comprises the steps of adding directly to a well treating aqueous acidizing solution corrosion inhibitor additives consisting essentially of:
(a) a surfactant;
(b) an antimony compound or antimony metal mixture; and (c) an ammonium quaternary compound capable of~
forming a complex with the antimony and other metals in the mixture.
, Surprisingly, it has been found that the nonacetylenic corrosion inhibitor additives described above, when added directly to the aqueous acid solution, exhibits excellent dispersion and provides improved corrosion protection for the well equipment at relatively low concentrations in comparison to corrosion inhibitors with acetylenics and aromatic hydrocarbons.
Although the reasons for the improved performance are not fully understood, it is believed that the acetylenic compound and/or the aromatic hydrocarbon solvent interfere with deposition of the antimony on the well tubulars.
The concentrations of the three essential additives in the acid solution are as follows:
MOST
BROAD PREFERRED PREFERRED
RANGE RANGE RANGE
25 Component (wt%) (wtX) (wt%) Metal/
Metal Mixture .04 to 2.0 .05 to 1.0 .07 to .80 Quaternary 30Compound 0.2 to 10 0.4 to 5.0 0.4 to 2.2 Surfactant 0.1 to 25 0.1 to 5.0 0.1 to 1.5 Generally, the component ranges are interchangeable. For example, the most preferred range of a metal component may be used with both the broad and preferred ranges of the other components.
? 205 ~ 08 1 1 The metal colnpound will always include antilnony, either alone or as one compounn of a binary or ternary blend. At least 0.04 wt~
of antimony should be present in the acid.
The corrosion inhibitor components are separately introduced into the well treating acid at a concentration suffi-cient to coat the well tubulars and equipment. The concentration of each component in the acid solution should generally be suffi-cient to provide the acid solution with from 0.04 wt% to 0.80 wt%
of Sb.
The method of the present invention provides effective corrosion high temperature protection associated with metal salt complexes and employs low toxicity additives which are separately dispersible in the aqueous acid solution. The method of the present invention offers the operational advantage of direct addition and dispersion in the acidizing solution without preformulation. The corrosion inhibitors with acetylenic compounds of the prior art generally required solvents and premixture of at least so~e of the components.
DESCRIPTION OF PREFERRED EMBODIMENTS
As indicated above the method of the present invention employs only three essential additives which combine in situ when added to a well treating acid solution to provide effective cor-rosion inhibition. Each of these compounds as well as the acid solution in which they are used are described below.
Aqueous Acid Solutions: Any of the known oil field acids may be used. These are referred to herein as "well treating acids" and include aqueous solutions of hydrochloric acid (HCl), hydrofluoric acid (HF), mixtures of HCl and HF (i.e. mud acid), acetic acid, formic acid, and other organic acids and anhydrides.
The most common acids are 3X H~l, 7 1/2X HCl, 15X HCl, 28X HCl and blends of HCl and HF (mud acid). Mud acid is normally a blend of 6 to 12X of HCl and 1 1/2 to 6X HF.
Antimony Compounds and Mixtures: The function of the antimony and/or the meta1 mixed therewith is to complex with the quaternary ammonium compound and form a protective deposit on the metal tubulars and equipment.
q - 2~5 1 081 1 Tests have shown that salts of the following metals and mixtures thereof exhibit corrosion protection when co;nplexed with a quaternary ammonium compound or conpounds: Sb, Sb/Al. Sb/~l/Cu+, Sh/Cu~, Sb/Ca/Cu~, and Ca/Sb. The preferred metals are Sb alone and Sb, Cu+, and Ca binary alld ternary ~l~ixtures.
The metal salts or mixtures must be readily dispersible in the aqueous acid solution and form a complex with the quaternary ammonium compound. The term ~complexU as used herein means a coordination or association of the metal compound with the quaternary compound.
The preferred antimony salts and salts of the mixture are halides, specifically metal chlorides. Some of the salts n,ay be formed in situ, in acid solution. For example, antimony chloride is produced from Sb203 in aqueous acid such as HCl. The insoluble Sb203 is converted to soluble salt.
The antimony compound may comprise, for example, antimony trichloride, antimony pentachloride, antimony trifluoride, alkali metal salts of antimony tartrate, antimony adducts of ethylene glycol, and antimony trioxide or any other trivalent or pentavalent antimony compound and the like. As men-tioned above, the antimony oxides may be converted to halide salts in the presence of ~queous acid.
The cuprous compound may be cuprous iodide as described in U.S. patent 3,773,465.
The binary and ternary metal mixtures are preferred for particularly severe corrosive environments since they appear to combine synergistically to provide protection. The binary and fernary metals may be mixed in any ratio, provided Sb constitutes at least 20 wt%, preferably 30 wtX, of the metal mixture.
Quaternary Compounds: The quaternary ammonium compounds (referred to as ~uaternary~ herein) employed in the present in-vention must be capable of complexing with the antimony and other metals of the metal mixture (if employed). The preferred quater-nary comprise aromatic nitrogen compounds which may be illustrated ' 205 1 08 1 _ 1 by alkyl pyridine-N-methyl chloride quaternary, alkyl pyridine-N-benzyl chloride quaternary, quinoline -N-methyl chloride quaternary, quinoline-N-benzyl chloride quaternary, quinoline-N-(chloro-benzyl chloride) quaternary, isoquinoline quaternaries, benzoquinoline quaternaries, chloromethyl napthalene quaternaries and admixtures of such compounds, and the like. The quaternary compoun~ and Sb and Sb mixtures may be used in molar ratios of 1:1 to 5:1.
Generally, the quaternary compound, because of its higher molecular weight, will be present in the acid solution at a higher concer,-tration than the metal compound. The weight ratios of the quater-nary compound and the Sb and Sb mixtures thereof preferably range from 1:1 to 4:1.
The Surfactant: The surfactant serves to wet the tubu-lar goods to permit deposition of the quaternary/metal complex.
The preferred surfactants are the nonionics having hydrophilic -lipophilic balance (HLB~ numbers of 8 to 18, preferably 9 to 16, such as laurates, stearates, and oleates. Nonionic surfactants include the polyoxyethylene surfactants (such as ethoxylated alkyl phenols, ethoxylated aliphatic alcohols) polyethylene glycol esters of fatty, resin, and tall oil acids. Examples of such surfactants are polyoxyethylene alkyl phenol wherein the alkyl group is linear or branched C8 - C12 and contains above about 60 wt% polyoxyethylene. Octyl and nonyl phenols containing 9 to 15 moles ethylene oxide per mole hydrophobe are the prefer-red ethoxylated alkyl phenol surfactants.
The polyoxyethylene ester of fatty acids include themono and dioleates and sesquioleates wherein the molecular weight of the esterified polyethylene glycol is between about 200 and 1000.
Polyoxyethylene sorbitan oleates are also useable.
In practice, the nonionics may be blended to provide the desired properties. A particularly useful surfactant is a blend of polyethylene glycol esters of fatty acids and ethoxylated alkylphenols.
Operation: In operation, the three essential additives are added to the aqueous acid solution at the well site. The - 6 ~ 205 1 0~ 1 1 additives may be added in any order but prefera~ly are in the ~ following order: (1) surfactant; (2) quaternary compound; (3) and metal compound. The concentration of quaternary/metdl complex in the acid solution should preferably provide a metal ~including Sb) concentration of at 0.050 wtX.
The procedure for preparing the inhibited acid for pumping down the well is preferably by a batch process. In this process, the additives are blended into the aqueous acid solution in a large tank and then pumped into the well.
It has been found that the direct addition of the additives requires only a few minutes for dispersion and complex-ina to occur, so that any pumping process including the continuous process may be employed. The batch process, however, is preferred 7 because it assures adequate conditioning of tne corrosion inhibitor in the acid prior to pumping.
The method of the present invention can be used in wells to protect tubular goods made of typical oil field tubular steels such as J-55, N-80, P:105, and the like; or made of high alloy chrome steels such as Cr-9, Cr-13, Cr-2205, Cr-2250, and the like.
EXPERIMENTS
In order to demonstrate the effectiveness of the non-acetylenic corrosion inhibitor additiYes added directly to the acid solution, several samples with and without acetylenics were tested using various components. The additives used in the tests were as follows.
The quaternary a~monium compounds used in the experi-ments was a quinoline-N-benzyl chloride quaternary (quaternary X).
The surfactant was nonylphenol (10 mols E0).
The HCl acid was 15X-HCl.
The HF was 12X HCl and 3X HF.
The acetylenic compounds were a ble~d of ethyl octynol and propar~yl in wt ratios of 1 to 1 or 2 to 3.
The Sb compounds were Sb203.
The procedure for preparing the aqueous acid solution _ 1 wit~ inhibitor and the test procedure was as follows (all X are Wtb unless otherwise indicated) 1. The additives were added to the aqueous acid sol~tion C(15~ HCl or mud acid, (12X HCl/3X
HF)] in the following order (a) surfactant (b) acetylenic alcohol (c~ aromatic hydrocar~on solvent (if used) (d) quaternary compound (e)Sb2o3 2. The c~upouns (N-80 steel or Cr-2205) were then put in the acid solution with the additives and heated to 350-F under 3,000 psi for four hours.
3. The coupouns were then removed and cleaned, the weight loss ~easured, and the corrosion rate calculated.
T~e composition of the samples tested are shown in Tables I and II.
TABLE I - ACETYLENIC SAMPLES
Additives (wt%) Sample Surfactant Acet. Solvent Quat. Sb Acid A-1 0.37 0.35-~.40 0.37-0.40 1.12 0.075 HCl A-2 0.37 0.35-0.40 0.37-0.40 1.12 0.15 Mud A-3 0.37 0.35-0.40 0.37-0.40 0.60 0.75 HCl A-4 0.37 0.35-0.40 0.37-0.40 0.6~ 0.75 hud TABLE II - NONACETYLENIC SAMPLES
Additives (wt%) Sample Surfactant ~uat. Sb Acid NA-1 0.37 1.12 0.075 HCl NA-2 0.37 1.12 0.15 Mud NA-3 0.37 0~6 0.75 HCl NA-4 0.37 0.6 0.75 Mud The corrosion rates, expressed as pound/ft2, using the above samples are presented in Table III.
- B -1 ~ABLE III
HCl Corrosion Rate In Mud Acid Corrosion Rate In Sample N-80 Cr-2205Salnple N-80 Cr-2205 A-10.0156 0.0262 A-2 0.0302 0.0182 NA-10.009~ 0.0158 NA-2 0.0245 0.~107 A-30.0095 0.0089 A-4 0.0078 0.0109 NA-30.0056 0.006p NA-4 0.0052 0.0072 From the Table III data,it can be seen that the non-acetylenic samples (NA) gave improved results in all tests.
Additional samples were prepared and tests were carried out using binary and ternary mixtures of Sb. ~hese samples had the compositions shown in Table IV.
TABLE IV
Additive (wtX~
Sample Surfactant Quat. Sb Mixture1 Acid NA-5 0.37 1.12 SbtAl HCl NA-6 0.37 1.12 Sb/Al Mud 20 NA-7 0-37 1.12 Sb/Al/Cu+ HCl NA-8 0.37 1.12 Sb/Al/Cu+ Mud NA-9 0.37 1.12 Sb/Ca HCl NA-10 0.37 1.12 Sb/Ca Mud NA-11 0.37 1.12 Sb/Cu+ HCl 25NA-12 0.37 1.12 Sb/Cu+ Mvd NA-13 0.37 1.12 Sb/Ca/Cu+ ~Cl NA-14 0.37 1.12 Sb/Ca/Cu+ Mud 1The Sb mixtures were dS follows (all wtt):
Sb/Al: Mixture of Sb203 and AlCl3 (Sb 0.38%; Al 0.101 %) Sb/Al/Cu+: Mixture of Sb203, AlCl3, and CuI (Sb 0.25X;
Al 0.067%; and Cu+ 0.109X) Sb/Ca: Mixture of Sb203 and CaC12 (Sb 0.38X; Ca 0.136%) Sb/Cu~: Mixture of Sb203 and CuI (Sb 0.38X; Cu+ 0.164%) Sb/Ca/Cu+: Mixture of Sb203, CaCl2, and CuI (Sb 0.25X;
Cu 0.091%; and Cu+ ~.109X) _ 1 The corrosion rates (lb/ft2) using the binary and ternary mixtures of Sb are shown in rable V.
~ABLE V
HCl Corrosion Rate Mud Acid Corrosion Rate Sample MetalN-80 Cr-2205Sample N-80 Cr-2205 A-3 Sb 0.0095 0.0~8~ A-4 0.007~ 0.010~
NA-5 Sb/Al0.0~95 0.0070 NA-6 0.0143 0.0125 NA-7 Sb/Al/Cu+0.0115 ~.0111 NA-8 0.0078 0.0131 10NA-9 Sb/Ca0.0~66 0.0060 NA-10 0.0086 0.0030 NA-11 Sb/Cu+ 0.0064 0.0086 NA-12 0.0070 U.0041 NA-13 Sb/Ca/Cu+ 0.0069 0.0069 NA-14 0.0042 0.0047 .
A comparison of tne ~able V data reveals that the nonacetylenic samples (NA) performed generally as good as, an~
frequently better, than the acetylenic samples (A-3 and A-4).
Samples NA-9 throuqh NA-14, containing the binary and ternary mixtures of Sb, Ca and Cu+, gave exceptional results vis-a-vis Samples A-3 and A-4. Although the nonacetylenic Sb and Al mixtures (Samples NA-S though NA-~) performed generally the same as Samples A-3 and A-4, it is noted that the total metal content of the acetylenic samples was almost 50% higher than the metal content of the nonacetylenic samples. Moreover, the Sb content of the nonacetylenic samples was one-half or less than the Sb content of Samples A-3 and A-4 with the balance being Al or Al/Cu~. It was surprising that substitutin~ the less expensive Al and Al/Cu+ blend in the nonacetylenic samples gave comparable protection as the acetylenic samples, even at the lower total metal content.
T~e composition of the samples tested are shown in Tables I and II.
TABLE I - ACETYLENIC SAMPLES
Additives (wt%) Sample Surfactant Acet. Solvent Quat. Sb Acid A-1 0.37 0.35-~.40 0.37-0.40 1.12 0.075 HCl A-2 0.37 0.35-0.40 0.37-0.40 1.12 0.15 Mud A-3 0.37 0.35-0.40 0.37-0.40 0.60 0.75 HCl A-4 0.37 0.35-0.40 0.37-0.40 0.6~ 0.75 hud TABLE II - NONACETYLENIC SAMPLES
Additives (wt%) Sample Surfactant ~uat. Sb Acid NA-1 0.37 1.12 0.075 HCl NA-2 0.37 1.12 0.15 Mud NA-3 0.37 0~6 0.75 HCl NA-4 0.37 0.6 0.75 Mud The corrosion rates, expressed as pound/ft2, using the above samples are presented in Table III.
- B -1 ~ABLE III
HCl Corrosion Rate In Mud Acid Corrosion Rate In Sample N-80 Cr-2205Salnple N-80 Cr-2205 A-10.0156 0.0262 A-2 0.0302 0.0182 NA-10.009~ 0.0158 NA-2 0.0245 0.~107 A-30.0095 0.0089 A-4 0.0078 0.0109 NA-30.0056 0.006p NA-4 0.0052 0.0072 From the Table III data,it can be seen that the non-acetylenic samples (NA) gave improved results in all tests.
Additional samples were prepared and tests were carried out using binary and ternary mixtures of Sb. ~hese samples had the compositions shown in Table IV.
TABLE IV
Additive (wtX~
Sample Surfactant Quat. Sb Mixture1 Acid NA-5 0.37 1.12 SbtAl HCl NA-6 0.37 1.12 Sb/Al Mud 20 NA-7 0-37 1.12 Sb/Al/Cu+ HCl NA-8 0.37 1.12 Sb/Al/Cu+ Mud NA-9 0.37 1.12 Sb/Ca HCl NA-10 0.37 1.12 Sb/Ca Mud NA-11 0.37 1.12 Sb/Cu+ HCl 25NA-12 0.37 1.12 Sb/Cu+ Mvd NA-13 0.37 1.12 Sb/Ca/Cu+ ~Cl NA-14 0.37 1.12 Sb/Ca/Cu+ Mud 1The Sb mixtures were dS follows (all wtt):
Sb/Al: Mixture of Sb203 and AlCl3 (Sb 0.38%; Al 0.101 %) Sb/Al/Cu+: Mixture of Sb203, AlCl3, and CuI (Sb 0.25X;
Al 0.067%; and Cu+ 0.109X) Sb/Ca: Mixture of Sb203 and CaC12 (Sb 0.38X; Ca 0.136%) Sb/Cu~: Mixture of Sb203 and CuI (Sb 0.38X; Cu+ 0.164%) Sb/Ca/Cu+: Mixture of Sb203, CaCl2, and CuI (Sb 0.25X;
Cu 0.091%; and Cu+ ~.109X) _ 1 The corrosion rates (lb/ft2) using the binary and ternary mixtures of Sb are shown in rable V.
~ABLE V
HCl Corrosion Rate Mud Acid Corrosion Rate Sample MetalN-80 Cr-2205Sample N-80 Cr-2205 A-3 Sb 0.0095 0.0~8~ A-4 0.007~ 0.010~
NA-5 Sb/Al0.0~95 0.0070 NA-6 0.0143 0.0125 NA-7 Sb/Al/Cu+0.0115 ~.0111 NA-8 0.0078 0.0131 10NA-9 Sb/Ca0.0~66 0.0060 NA-10 0.0086 0.0030 NA-11 Sb/Cu+ 0.0064 0.0086 NA-12 0.0070 U.0041 NA-13 Sb/Ca/Cu+ 0.0069 0.0069 NA-14 0.0042 0.0047 .
A comparison of tne ~able V data reveals that the nonacetylenic samples (NA) performed generally as good as, an~
frequently better, than the acetylenic samples (A-3 and A-4).
Samples NA-9 throuqh NA-14, containing the binary and ternary mixtures of Sb, Ca and Cu+, gave exceptional results vis-a-vis Samples A-3 and A-4. Although the nonacetylenic Sb and Al mixtures (Samples NA-S though NA-~) performed generally the same as Samples A-3 and A-4, it is noted that the total metal content of the acetylenic samples was almost 50% higher than the metal content of the nonacetylenic samples. Moreover, the Sb content of the nonacetylenic samples was one-half or less than the Sb content of Samples A-3 and A-4 with the balance being Al or Al/Cu~. It was surprising that substitutin~ the less expensive Al and Al/Cu+ blend in the nonacetylenic samples gave comparable protection as the acetylenic samples, even at the lower total metal content.
Claims (12)
1. In a method of acidizing a subterranean formation penetrated by a borehole which has metal pipe positioned therein wherein an aqueous acid solution is pumped down said pipe and into the formation, the improvement comprising introducing corrosion inhibitor components of a non-acetylenic corrosion inhibitor directly into the aqueous acid solution to form the corrosion inhibitor in the acid solution at a concentration to inhibit corrosion of the metal, said components comprising:
(a) an antimony compound which provides from 0.04 to 2.0 wt% of antimony ions in the aqueous acid solution;
(b) from 0.2 to 10 wt% of a quaternary ammonium compound capable of forming a complex with the antimony ion; and (c) from 0.1 to 25 wt% of a surfactant capable of wetting the pipe.
(a) an antimony compound which provides from 0.04 to 2.0 wt% of antimony ions in the aqueous acid solution;
(b) from 0.2 to 10 wt% of a quaternary ammonium compound capable of forming a complex with the antimony ion; and (c) from 0.1 to 25 wt% of a surfactant capable of wetting the pipe.
2. The method of claim 1 wherein the aqueous acid solution is HCl and the antimony compound is [added in the form of] Sb2O3 and which reacts with the acid solution to form SbCI3
3. The method of claim 1 wherein the concentration of the antimony in the aqueous acid solution is between 0.070 wt% and 0.8 wt%.
4. The method of claim 1 wherein the aqueous acid solution is selected from HCl and HCl/HF blends.
5. The method of claim 1 wherein the pipe is made of high alloy chrome steel.
6. The method of claim 1 wherein the surfactant is nonionic having an HL8 no. between 8 and 18.
7. In a method of acidizing a subterranean formation penetrated by a borehole which has metal pipe positioned therein wherein an aqueous acid solution is pumped down said pipe and into the formation, tne improvement comprising introducing corrosion inhibitor additives directly into the aqueous acid solution at a concentration to inhibit corrosion of the metal, said additives consisting essentially of:
(a) from 0.04 to 2.0 wt% of a metal selected from binary and ternary mixtures containing antimony, and one or more metals selected from the group consisting of Al, Ca, and Cu+;
(b) from 0.2 to 10 wt% of a quaternary ammonium compound capable of forming a complex with said metals which are soluble in the aqueous acid solution; and (c) from 0.1 to 25 wt% of a surfactant capable of water wetting the pipe.
(a) from 0.04 to 2.0 wt% of a metal selected from binary and ternary mixtures containing antimony, and one or more metals selected from the group consisting of Al, Ca, and Cu+;
(b) from 0.2 to 10 wt% of a quaternary ammonium compound capable of forming a complex with said metals which are soluble in the aqueous acid solution; and (c) from 0.1 to 25 wt% of a surfactant capable of water wetting the pipe.
8. The method of claim 7 wherein the metal mixtures are selected from the group consisting of Sb/Al, Sb/Al/Cu+, Cu+/Sb, Cu+/Ca/Sb, and Ca/Sb.
9. The method of claim 7 wherein the mixture is selected from the group consisting of Sb/Ca, Sb/Cu+, and Sb/Ca/Cu+.
10. The method of claim 7 wherein Sb comprises at least 20 wt% of the metal mixture.
11. A method of acidizing a subterranean formation penetrated by a well having metal pipe disposed therein, which comprises (a) adding separately to the aqueous acid solution corrosion inhibitor additives consisting essentially of:
(i) from 0.05 to 1.0 of a Sb or metal mixture selected from the group consisting of Sb/Ca, Sb/Cu+, Sb/Ca/Cu+, wherein Sb constitutes at least 20 wt% of the mixture;
(ii) from 0.4 to 5.0 wt% of a quaternary ammonium, compound capable of for r forming a complex with the Sb or metal mixture; and (iii)from 0.1 to ?.0 wt% of a nonionic sur-factant having an HLB No. of 8 to 18;
and (b) pumping the aqueous acid solution containing the corrosion inhibitor additives down the pipe and into the formation .
(i) from 0.05 to 1.0 of a Sb or metal mixture selected from the group consisting of Sb/Ca, Sb/Cu+, Sb/Ca/Cu+, wherein Sb constitutes at least 20 wt% of the mixture;
(ii) from 0.4 to 5.0 wt% of a quaternary ammonium, compound capable of for r forming a complex with the Sb or metal mixture; and (iii)from 0.1 to ?.0 wt% of a nonionic sur-factant having an HLB No. of 8 to 18;
and (b) pumping the aqueous acid solution containing the corrosion inhibitor additives down the pipe and into the formation .
12. A liquid system for use in the treatment of a subterranean formation comprising (a) an aqueous acid solution; and (b) a nonactylenic corrosion inhibitor comprising (i) a complex formed by reacting from 0.04 to 2.0 wt% of an antimony compound with from 0.2 to 10 wt% of a quaternary ammonium compound, said complex being dispersed in the aqueous acid solution; and (ii) from 0.1 to 25 wt% of a surfactant dissolved in the aqueous solution, said surfactant being capable of water wetting metal, said wt%
being based on the weight of the aqueous acid solution.
being based on the weight of the aqueous acid solution.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2051081 CA2051081C (en) | 1991-09-10 | 1991-09-10 | Method of inhibiting corrosion in acidizing wells |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2051081 CA2051081C (en) | 1991-09-10 | 1991-09-10 | Method of inhibiting corrosion in acidizing wells |
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|---|---|
| CA2051081A1 CA2051081A1 (en) | 1993-03-11 |
| CA2051081C true CA2051081C (en) | 1996-01-09 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2051081 Expired - Fee Related CA2051081C (en) | 1991-09-10 | 1991-09-10 | Method of inhibiting corrosion in acidizing wells |
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| Country | Link |
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| CA (1) | CA2051081C (en) |
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1991
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| CA2051081A1 (en) | 1993-03-11 |
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