WO1998016592A1

WO1998016592A1 - Corrosion inhibitor for wellbore applications

Info

Publication number: WO1998016592A1
Application number: PCT/US1996/016352
Authority: WO
Inventors: Yulin Wu
Original assignee: Phillips Petroleum Co
Current assignee: Phillips Petroleum Co
Priority date: 1995-06-02
Filing date: 1996-10-15
Publication date: 1998-04-23
Anticipated expiration: 1999-04-15
Also published as: US5654260A

Abstract

This invention concerns a corrosion-inhibitor nominally comprised of a phenolic compound and a hydroxide-bearing compound capable of imparting a pH of 9 to water, the inclusion thereof in aerated water-based fluids and foams, and the use of these fluids in wellbore applications; particularly applications conducted at elevated temperatures.

Description

CORROSION INHIBITOR FOR WELLBORE APPLICATIONS

Background of the Invention

This invention relates to a corrosion inhibitor and the use thereof in wellbore

applications.

Aerated liquids and foams are frequently employed as wellbore fluids during

drilling, completion, workover and production operations. Aerated as used herein refers to the

existence of distinct gas and liquid phases. Aerated liquids are distinguishable from foams by

the absence or the presence in de minimis amounts of surface active agents which promote

gas-liquid interphase dispersibility.

Aerated liquids and foams are particularly useful when reduced hydrostatic

pressures in wellbores are desired. The reduced hydrostatic pressure or head is made possible

by the lower bulk densities of aerated liquids and foams when compared to their liquid

counterparts. Examples wherein reduced hydrostatic heads are favored include (1) situations

where the wellbore fluids are exposed to under-pressured geological strata and minimum

invasion of the strata by the wellbore fluid is desired and (2) during the perforation of a

geological strata at underbalanced conditions (i.e., wellbore pressure less than fluid pressure

in exposed strata)wherein the reduced head helps to minimize plugging of the perforation

caused by movement of fines into the perforation from the wellbore. Aerated liquids are nominally comprised of a gas and a liquid and may

additionally contain additives such as corrosion inhibitors and suspended solids such as mud

and sand. Aerated fluids useful in drilling, completion, workover and production operations

are typically prepared by the downhole combination of a gas and a liquid. In drilling, one

means of combining these components downhole is by the use of dual drill strings and dual

swivels. Another means frequently used in downhole applications is to employ parasitic

tubing for transporting the gas downhole to an injection point where it is combined with liquid

and returned to the surface. Injection of gas at any downhole location serves to reduce the

bottomhole hydrostatic head from that of a 100% liquid head. Downhole gas injection is also

practiced when gas lift is used to facilitate fluids production in a well. Foams are highly

dispersed gas in liquid two-phase systems. A foam is physically composed of gas bubbles

surrounded by a surfactant-bearing aqueous film and is nominally comprised of a gas, at least

one surfactant which functions as a foaming agent, and water. The quality of the foam or

foam quality is defined to be the volume percent of gas in the two-phase mixture. The water

used in foams may be chemically pure, fresh, or contain varying degrees of salinity and/or

hardness. The foam may additionally be comprised of other additives which alter the

properties of the foam. Such additives include selected polymers and/or bentonite which

increase film strength thereby forming stiff or gel foams and corrosion inhibitors which

function to decrease foam corrosivity in metal-bearing systems.

The rheological properties of foam are complex and provide a separate and

distinct basis for distinguishing foam from aerated and non-aerated liquids. The rheological

properties are dependent upon many parameters such as bubble size and distribution, fluid

viscosity, foam quality, and the concentration and type of foaming agent used. The use of foam in place of conventional fluids generally reduces the degree of fluid invasion from the

wellbore into the surrounding strata. Furthermore, the foam which does invade the strata

generally contains a high volume percentage of gas which upon pressurization possesses

significant energy. Upon depressurization, the stored energy which is released causes a

significant portion of this fluid to be returned to the wellbore. Compared to conventional

fluids, foam also possesses at low linear flow velocities excellent carrying capacities,

particularly for water and solids. These properties are particularly useful when conducting

drilling, completion and workover operations on vertical and horizontal wells and even more

so when low pressure, semi-depleted or water sensitive formations are encountered. The

unique properties of foam also enable the use of coiled tubing units during workover

operations. The use of such units results in significant savings of time and money because

downhole operations can be performed without removal of the wellbore tubing.

Historically, a major problem associated with the use of aerated liquids and foams

has been metal corrosion attributed to the presence of oxidizing agents such as oxygen,

hydrogen sulfide and carbon dioxide in the gas phase. Oxygen generally originates from air.

Carbon dioxide and hydrogen sulfide are generally produced from the geological strata of

interest. Corrosion problems generally become more severe as wellbore temperatures

increase. Because of cost and availability, air is the preferred gaseous species when downhole

corrosion is not a problem. However, because of the lack of suitable corrosion inhibitors

when downhole conditions become severe ((i.e., high temperatures and the presence of

significant quantities of oxidizing agents), inert gases which are expensive, most notably

nitrogen, are frequently used. Summary of the Invention

It is an object of this invention to develop a corrosion inhibitor suitable for use in

gas-liquid systems at oxidative conditions.

It is a further object of this invention to develop a corrosion-inhibited gas-liquid

mixture suitable for use under oxidative conditions.

It is a still further object of this invention to develop a corrosion-inhibited foam

suitable for use under oxidative conditions.

It is yet a still further object of this invention to develop a corrosion-inhibited

oxygen-bearing gas/liquid mixture suitable for use in wellbore applications including drilling,

workover, completion and production.

It is still yet a further object of this invention to develop a corrosion-inhibited

air/liquid mixture suitable for use at temperatures of at least about 200 °F.

Still a further object of this invention to develop a corrosion inhibited oxygen-

bearing gas/liquid mixture wherein the chemicals imparting the corrosion-inhibition

properties are relatively inexpensive commodity chemicals.

A yet still further object is to develop a process employing foam suitable for use

under highly oxidative conditions in the drilling, completion, workover and production of

wells.

In accordance with this invention, a formulation for a corrosion inhibitor

comprised of a phenolic compound and a hydroxide-bearing compound capable of imparting

basicity to water has been discovered.

In a second embodiment, a corrosion-inhibited gas-liquid mixture nominally

comprised of a gas, water, a phenolic compound and a hydroxide-bearing compound capable of imparting basicity to water has been discovered.

In a third embodiment, a novel corrosion-inhibited gas foam nominally

comprised of gas, water, foaming agent, and a corrosion inhibitor comprised of a phenolic

compound and a hydroxide-bearing compound capable of imparting basicity to water has been

discovered.

In a fourth embodiment, a process utilizing the inventive gas-liquid mixture under

oxidative conditions such as those existing in wellbore applications has been discovered.

And in a fifth embodiment, a process utilizing the inventive foam under oxidative

conditions such as those existing in wellbore applications has been discovered.

Description of the Invention

In its multiple embodiments, this invention concerns a unique formulation for a

corrosion inhibitor, a formulation for corrosion-inhibited aerated liquids, a formulation for

corrosion-inhibited foams, and the use thereof of the aerated liquids or foams in wellbore

applications which include drilling, workover, completion and production operations.

Corrosion Inhibitor

The inventive corrosion inhibitor is nominally comprised of at least one phenolic

compound including the salts thereof and at least one hydroxide-bearing compound capable of

imparting a pH of at least 9 to an aqueous phase. The hydroxy-bearing hydrocarbon

compound is preferably a phenolic compound of the formula

OH

wherein R_b R₂, R₃, R₄ and R₅ are independently selected from the group consisting of

hydroxyl groups, alkoxy groups containing from 1 to 6 carbon atoms; alkyl groups containing

from 1 to 6 carbon atoms, a phenyl group, NO₂, COOH, COH, sulfonic acids, ketones

containing from 1 to 6 carbon atoms, F, Cl, Br, I, hydrogen, or the salts of any of the

preceding acids or alcohols, wherein at least two of the above R groups are hydrogen; or

phenolic mixtures thereof, and the resulting compound is water dispersible or soluable.

Another group of compounds included within the term phenolic compound are

the flavotannins. Flavotannins are polyphenolic materials which are extracted from the bark

and wood of trees. Quebracho is an example of a suitable flavotannin.

Representative examples of suitable phenolic compounds are those selected from

the group consisting of monohydroxy phenols, polyhydroxy phenols, monohydroxy

naphthols, polyhydroxy naphthols, o-cresol, m-cresol, p-cresol, o-fluorophenol, m-

fluorophenol, p-fluorophenol, o-chlorophenol, m-chlorophenol, p-chlorophenol, o-

bromophenol, m-bromophenol, p-bromophenol, o-iodophenol, m-iodophenol, p-iodophenol,

o-nitrophenol, m-nitrophenol, p-nitrophenol, flavotannins, phenol, resorcinol, catechol,

hydroquinone, phloroglucinol, pyrogallol, 1,3-dihydroxynaphthalene, o-methoxyphenol, p-

methoxyphenol, m-methyoxyphenol, o-hydroxybenzoic acid, p-hydroxybenzoic acid, m-

hydroxybenzoic acid, o-phenolsulfonic acid, p-phenolsulfonic acid, m-phenolsulfonic acid,

dichlorophenols, 4,4-biphenol, salicylaldehyde, guaiacol and the salts of the preceding acids

and alcohols or mixtures thereof selected from the preceding group.

The phenolic compound is more preferably phenol, o-cresol, o-fluorophenol, o-

chlorophenol, o-bromophenol, o-iodophenol, o-nitrophenol, catechol, resorcinol, guaiacol,

hydroquinone, salicylaldehyde, phloroglucinol, pyrogallol, 4,4-biphenol, 1,3-dihydroxy naphthalene or o-allylphenol or any of the salts of the preceding or mixtures thereof of the

preceding. Still more preferred are those selected from the group consisting of phenol, o-

cresol, salicylaldehyde, o-nitrophenol and the ammonium, sodium and potassium salts thereof

or mixtures of the preceding. The most preferred phenolate salts are those of sodium and

potassium. Based on performance, cost, and commercial availability, the most preferred

phenolic compounds are phenol and the sodium and potassium salts thereof which are sodium

phenolate and potassium phenolate.

The hydroxide-bearing compound must be a compound capable of imparting a

pH of 9 to an aqueous phase. Preferred hydroxide-bearing compounds are the alkali metal

hydroxides, ammonium hydroxide or mixtures thereof. More preferred are those selected

from the group consisting of ammonium hydroxide, sodium hydroxide and potassium

hydroxide. Of these, sodium hydroxide and potassium hydroxide are still more preferred.

Most preferred is potassium hydroxide.

The hydroxide-bearing compound must be present in an amount effective to

insure appreciable dissociation of the hydrogen atoms associated with the hydroxyl group or

groups on the phenolic compound. On a molar basis, a mole ratio of hydroxide-bearing

compound to phenolic compound of 5 to 1000 is preferred. A mole ratio of about 10 to about

500 more preferred. A ratio of about 20 to about 350 is most preferred. When using the

preferred hydroxide-bearing compounds consisting of ammonium hydroxide, potassium

hydroxide or sodium hydroxide or mixtures thereof and the most preferred phenolic

compound, phenol, a hydroxide compound to phenol weight ratio of about 10 to about 70 is

preferred. When using the more preferred sodium hydroxide and potassium hydroxide

species, a weight ratio of about 10 to about 40 is preferred. The corrosion inhibitor may additionally be comprised of water in an amount

effective to function as a dispersing or carrying agent for the phenolic compound and the

hydroxide-bearing compound thereby simplifying the mixing of these components with other

components when preparing aerated liquids or foams. The water may be chemically pure,

fresh or contain appreciable salinity and/or hardness and may contain dissolved gases which

favor oxidation.

The inventive corrosion inhibitor is distinguished from many other inhibitors,

particularly scavengers, by its ability to effectively function when the molar ratio of a key

active component, the phenolic compound, to the oxidizing agent or agents in the system is

significantly less than 1. The corrosion inhibitor is effective at both ambient and elevated

temperatures. The inventive inhibitor is also distinguishable from many commercially

available inhibitors by its effectiveness at temperatures of at least about 200 °F and is further

distinguished by its superior corrosion inhibition properties at temperatures of at least about

350°F. The corrosion inhibitor is particularly effective when the oxidizing agent is oxygen or

the oxidation-related compounds thereof.

Corrosion-Inhibited Aerated Liquid

A corrosion-inhibited aerated liquid possessing various utilities as a wellbore

fluid has been discovered. The aerated liquid is nominally comprised of a gas which contains

an oxidizing agent, water, and the inventive corrosion inhibitor described in the previous

section. As previously noted, the corrosion inhibitor is particularly effective when the

oxidizing agents are hydrogen sulfide, carbon dioxide, and oxygen or oxidation-related

compounds to these agents. Treatment of aerated liquids containing oxygen as the oxidizing

agent is preferred. The water may be chemically pure, fresh, or contain appreciable salinitv and/or hardness and may contain dissolved gases, some of which may favor oxidation. The

aerated liquid may additionally be comprised of solids such as sand and dirt or a separate

organic phase.

Aerated liquids are particularly useful when a reduction in the bulk density of the

base liquid is desired. Such a need frequently occurs in wellbore applications when a

reduction in hydrostatic head is desired.

An aerated liquid is prepared by combining a gas containing at least one

oxidizing agent, a water-based liquid, and the corrosion inhibitor using ordinary skill in the

art. Preferably, the water-based liquid and corrosion inhibitor are first combined to form a

corrosion inhibited liquid. The gas is then added via contacting the liquid and gas phases. In

the drilling, completion, workover, or production of a well, the latter contacting step is usually

conducted downhole in a borehole using ordinary skill in the art.

The corrosion inhibitor may also be used in well production wherein gas lift

technology is used. In such an application, the corrosion inhibitor may be combined

downhole with the gas used for gas lift and the produced fluids which contain water. In such

an application, the reduced hydrostatic head allows the reservoir fluids, which may also

include a separate gas phase, to flow to the surface using the existing reservoir pressure as the

driving force thereby avoiding the use of more complicated and expensive means of

production such as pumpjacks, submersible pumps, etc. In such an operation, gaseous

oxidizing agents such as hydrogen sulfide, carbon dioxide, or oxygen and oxidation-related

compounds of these agents may be present in either the gas used for the gas lift or in the fluids

produced from the reservoir.

The required concentration of corrosion inhibitor in the aerated fluid is that amount effective to insure corrosion inhibition over the time frame of interest at the

conditions of interest. These concentrations may be readily ascertained by one skilled in the

art via routine test procedures. Generally, the preferred weight percent of hydroxide-bearing

compound and phenolic compound based on the combined weight of water and corrosion

inhibitor are about 0.1 to about 40 wt% and about 0.005 to about 4.0 wt%, respectively. More

preferred are respective weight percent ranges of about 1 to about 20 wt% and about 0.01 to

about 0.50 wt%, respectively. Still more preferred are respective weight percent ranges of

about 1 to about 10 and about 0.05 to about 0.30. The most preferred weight percent ranges

are about 5 to about 10 and about 0.10 to about 0.30, respectively.

One factor distinguishing the inventive corrosion inhibitor from other inhibitors,

particularly scavengers, when incorporated into aerated liquid, is the ability of the inhibitor to

effectively function when the molar ratio of a key active component, the phenolic compound,

to the oxidizing agent or agents in the system is significantly less that 1. The corrosion-

inhibited aerated liquid may be used in metal-bearing systems at both ambient and elevated

temperatures. An additional factor distinguishing the inventive inhibitor from the many

commercially available inhibitors is its effectiveness at temperatures of about or greater than

200 °F and even more so, its effectiveness at temperatures of about or greater than 350 °F. The

corrosion inhibitor when incorporated into an aerated liquid is particularly effective when the

oxidizing agent is oxygen or the oxidation-related compounds thereof.

Corrosion-Inhibited Foam

The inventive corrosion-inhibited foam is nominally comprised of a dispersed gas

phase wherein the gas contains an oxidizing agent and a continuous liquid phase nominally

comprised of a foaming agent, water in a major portion, and the inventive corrosion inhibitor. The water may be chemically pure, fresh, or contain appreciable salinity and/or hardness, and

may contain dissolved gases, some of which may favor oxidation. At the discretion of one

skilled in the art, the liquid phase may contain other additives which function to produce a

better performing foam at the conditions of use. Foam stabilizers are one such example. The

foam may additionally contain solids such as sand and dirt and/or a separate organic phase.

The volume percentage of the combined gaseous and liquid phase which is gas is defined

to be the foam quality. The quality of the foam is preferably about 60 to about 99.75% and

more preferably about 75 to about 99.5 volume percent at wellbore conditions. The properties

of the foam may be altered by the use of various additives known to those skilled in the art.

As an example, a stiffer foam may be prepared by adding guar gum or other organic polymers

and solids such as bentonite to the base components.

The gaseous phase may initially contain an oxidizing agent or the phase may be

inert and absorb oxidizing agents such as oxygen, hydrogen sulfide or carbon dioxide or

oxidation-related compounds during the course of process operation. Because of the

effectiveness of the inventive corrosion inhibitor, when oxygen is the oxidizing species,

inhibited foams containing oxygen are particularly favored. Because of cost and availability,

a gaseous phase comprised in major portion of air is preferred.

As previously discussed for the aerated liquid, corrosion inhibitor in an amount

effective to insure corrosion inhibition over the time frame of interest at the conditions of

interest is required. These concentrations may be readily ascertained by one skilled in the art

via routine test procedures. Specific ranges of preference based on the combined weight

percentage of water, corrosion inhibitor and foaming agent are identical to those reported for

the aerated liquid wherein said weight percentage was based on water and corrosion inhibitor. One factor distinguishing the inventive corrosion inhibitor from other inhibitors,

particularly scavengers, when incorporated into foam is the ability of the inhibitor to

to the oxidizing agent or agents in the system is significantly less than 1. The corrosion-

inhibited foam may be used in metal-bearing systems at both ambient and elevated

temperatures. An additional factor distinguishing the inventive corrosion-inhibited foam from

many foams using commercially available inhibitors are the corrosion inhibition properties

exhibited at temperatures of about and greater than 200 °F and more so, the superior corrosion

inhibition properties exhibited at temperatures of about and greater than 350 °F. The

corrosion inhibitor is particularly effective when the oxidizing agent is oxygen or oxidation-

related compounds thereof.

Foaming agent in an amount effective to obtain the desired foam quality is

required. The concentration will be dependent on water salinity and hardness, foaming agent,

and anticipated exposure conditions in the wellbore. The selection of an appropriate agent

and the concentration of said agent is readily within the capability of one possessing ordinary

skill in the art. Test methods routinely used by one skilled in the art include the Ross-Miles

foam analysis method discussed in Oil and Soap. Vol. 18, 1941, pages 99-102 and Synthetic

Detergent. J.W. McCutcheon-author, McNair-Dorland Co., New York, NY, 1950, specifically

page 435; both of which are hereby incorporated by reference in their entirety. One class of

preferred foaming agents are those possessing a Ross-Miles initial foam height of at least 10

cm and a cumulative foam height of at least 30 cm at test conditions where cumulative foam

height is the sum of foam heights at 0, 1, 2, 5 and 10 min obtained using the Ross-Miles

method. Typical foaming agent concentrations, based on active foaming agent concentration. are about 0.005 to about 4.0 wt% based upon the weight of water, corrosion inhibitor and

foaming agent in the liquid phase. More preferred foaming agent concentrations are about

0.01 to about 1.0 wτ% based on the liquid phase. Still more preferred foaming agent

concentrations are about 0.1 to about 0.3 wt% also based on the liquid phase.

A wide variety of compounds referred to as surfactants possess foam-forming

properties. The propensity of these compounds to function as foaming agents is discussed in

the section entitled "Surfactants and Distersive Systems", Kirk-Othmer Encyclopedia of

Chemical Technology, 3rd Edition, Volume 22, pages 332-387 which is hereby incorporated

by reference in its entirety.

Preferred foaming agents include one or more of the following:

(a) One or more N-acylsarcosinates, more preferably one or more possessing

the formula of:

CH₃

R-N-CH₂CO₂M

where R is cocoyl, lauryl, or oleoyl and M is H or Na;

(b) One or more sodium N-acyl-N-alkyltaurates, more preferably one or more

possessing the formula of

CH₃

R-N-CH₂CH₂SO₃Na

where R is cocoyl, palmitoyl, or tall oil;

(c) One or more alkyl sulfates, more preferably one or more possessing the

formula of

R-O-SO₃M where R is lauryl and M is an ammonium-containing or an alkali metal cation, more

preferably Na, Mg, K, NH₄, MEA (monoethanolammonium), DEA (diethanolammonium) or

TEA (triethanolammonium);

(d) One or more ethoxylated and sulfated alcohols, more preferably one or

more possessing the formula of

where n is 1-5, M is an ammonium-containing or alkali metal cation, more preferably NH₄ or

Na, and R is linear C₁₂.₁₄, linear C₁₂.₁₅, lauryl, tridecyl, myristyl, or capryl-capryl;

(e) One or more ethoxylated and sulfated phenols, more preferably one or

more possessing the formula of

R— τ;C₆H₄ ) OCH₂CH₂^^OSO₃M

where n is 1-5, M is an ammonium-containing or alkali metal cation, more preferably Na or

NH₄, and R is nonyl, octyl, or decyl;

(f) One or more alcohol ethoxylates, more preferably one or more of the

formula

where R is selected from the group consisting of the linear and branch alkyl groups of C₆, C₈,

Cα._n, C,₀, C,₀._I2, C,₂, C,₂.₁₄, C₁₄, C₁₂.i₅, C₁₆, and C₁₈ isosteryl, lauryl, cetyl, stearyl, oleyl,

tridecyl, tallow, trimethylnonyl, or isodecyl and n is 2 to 100;

(g) One or more amine oxides, more preferably amine oxides possessing the formula of

O

R— N— R

R where R is cetyl, lauryl, myristyl, stearyl, coco, hydrogenated tallow, hexadecyl, tallow,

octadecyl, decyl, C₈.₁₀, oxypropyl, Co.,, oxypropyl, or C,₂.,₅ oxypropyl and R' is CH₃ or

CH₂CH₂OH and may be the same or different;

(h) One or more alkyl betaines, more preferably possessing the formula of

where R is coco, decyl, cetyl, lauryl, or oleyl;

(i) One or more amido propylbetaines, more preferably amido propylbetaines possessing the formula of

H CH₃

R-N-CH₂CH₂CH₂-N⁺-CH₂CO₂ ^"

CH₃

where R is cocyl, lauroyl, isostearoyl, myristoyl, palmitoyl, and most preferably R is cocyl; or

(j) One or more fluorochemical surfactants, more preferably a fluoroprotein or a

fluoroaliphatic surfactant.

When the foam is to be exposed to a temperature greater than 200 °F and

particularly greater than 300 °F, the preferred foaming agent is comprised of one or more

amidopropylbetaines and more preferably comprised of one or more amidopropylbetaines and

one or more ethoxylated, sulfated alcohols or one or more aliphatic or alkyl aryl hydrocarbon

sulfonates of formula

R-SO₃M

wherein R is an oleophilic group having from 10 to 18 carbon atoms and M is an alkali metal or ammonium cation. The most preferred foaming agent is comprised of cocoamidopropyl

betaine and a sulfated ethylene glycol ether, the active ingredients in Homco SF-1009. The

preferred concentrations for the preceeding two component foaming agent systems are about

0.0025 to about 2.0 wt% for each component based upon the weight of water, corrosion

inhibitor and foaming agent in the liquid phase. More preferred are concentrations for each

component of about 0.01 to about 2.0 wt%. Still more preferred are concentrations for each

component of about 0.05 to about 0.15 wt%. Most preferred are concentrations for each

component of about 0.08 wt%.

Foam is generally prepared using surface facilities wherein the gas which will

become the dispersed phase and the liquid which will become the continuous phase are

combined in a turbulent manner. Generally, this step is conducted by combining the gas and

liquid components under turbulent conditions at a "mixing T". A second method of foam

generation is to separately flow the liquid and gas down the wellbore using separate confining

means and to then combine the gas and liquid downhole thereby creating foam in the

wellbore. The confining means are those readily available to one skilled in the art and include

wellbore tubing, drillsteam, the annular space between the tubing or drillstream and the wall

or well casing, and parasitic tubing. In a third method, the foam is generated in the wellbore

by the cocurrent flow of gas and liquid down and back up the wellbore. A good foam will

generally have the consistency of shaving cream.

In the preferred method, the foam is generated at the surface by intimately mixing

the gas and liquid thereby forming foam and injecting the foam into either the tubular or

annular space in the wellbore. The wellbore fluid is produced via the non-injected tubular or

annular space. Foam velocity is dependent upon the type of wellbore operation being performed and the designation of said operating conditions is readily within the capabilities of

one possessing ordinary skill in the art.

Examples

Control Test Series #1

These laboratory screening tests indicated that two commercially available

corrosion inhibitors identified for possible use in air/foam wellbore operations are ineffective

at the conditions herein studied. These tests employed air as the gas phase and a process

temperature of 120°F. Corrosivity was observed to increase as the concentration of inhibitor

or foamer (i.e., foaming agent) increased.

Unless otherwise noted, the tests were conducted using the Wheel Test Method as

detailed in NACE Publication 1D182. The test solutions were prepared from 2% potassium

chloride field brine, a designated foaming agent, air, and one of two designated and

commercially available corrosion inhibitors. The test vessels were constructed of Hastelloy C

Steel and each vessel contained two 2 1/2 inch x 1/2 inch carbon steel coupons. The coupons

were accurately weighed prior to the test. Each vessel possessing a volume of approximately

45 ml was charged with 30 ml of total fluid consisting of 2% KC1 brine and a designated

amount of chemical. The vapor space above the liquid in each vessel was purged with air and

the vessel subsequently pressurized with air to a pressure of 3 psig. The test vessels were then

attached to the wheel and rotated for a period of one day at a test temperature of 120°F.

Each test vessel was then cooled to ambient temperature, the pressure released,

and the vessel opened. The test coupons were retrieved and first cleaned using a corrosion-

inhibited acid wash. The coupons were further cleaned by contacting with a steel wool pad to

remove residual corrosion by-products. The coupons were then weighed and based on the difference between initial and final coupon weights, the corrosion rate was calculated. The

reported corrosion rate in mils per year is an averaged rate based on the two test coupons

used in each test.

As shown in Table I, Inhibitors A and B and the Foamer which are marketed

commercially as Homco MC-21, Homco MC-117 and Homco SF-1009 respectively, failed

to inhibit oxygen corrosion at the test conditions. The active components for some of these

inhibitors and their respective sources are identified in Table X. The former two chemicals

are routinely used in the field as corrosion inhibitors and the latter chemical is used in the

field as a foaming agent. For each of these chemicals, the corrosion rate was observed to

increase with increasing chemical composition and the corrosion rates were greater than the

observed rate without chemical. All test coupons showed some pitting.

TABLE I

Wheel Test Results at 120°F for Two Commercial Inhibitors

Inhibitor Inhibitor

Run A B Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) (wt %) (psig) (°F) (hrs.) (mph)

1 0 0 0 0 68 24 17.4

2 0 0 0 3 120 24 51.2

3 0.01 0 0 3 120 24 53.2 J 4 0.03 0 0 3 120 24 54.6

5 0.05 0 0 3 120 24 56.4

0 0.01 0 w 6 3 120 24 53.3 w 7 0 0.03 0 3 120 24 55.7^

H 8 0 0.05 0 3 120 24 58.6^b

9 0 0 0.01 3 120 24 55.2

10 0 0 0.03 3 120 24 53.0

11 0 0 0.05 3 120 24 70.7

30 ml of total fluid used in each test. System volume of approximately 45 ml. Fluid consisted of 2% KC1 brine plus additives. Vapor spaces purged with air and then pressurized to 3 psig, except for Test No. 1.

All coupons showed some pitting but pitting for these was quite severe. Homco MC-21

"Homco MC-1 17 'Homco SF-1009

Control Test Series #2

These control tests demonstrate the complexity of formulating a foam

which possesses corrosion inhibition properties. These control tests specifically examine the

unique interactions between Inhibitor A (Homco MC-21), Inhibitor C (Homco AC-105-C)

and Foamer (Homco SF-1009). The active components for some of these inhibitors and their

respective sources are identified in Table X.

The tests were conducted using the general procedure described for Control

Test Series #1. The observed corrosion rate for Run #4 which contained the two corrosion

inhibitors and the foamer at designated concentrations was 4.77 mpy. However, when the

concentrations of Inhibitors A and C and the foamer were increased 2 1/2-fold and 5-fold as in

Runs #5 and #6, the corrosion rates were respectively increased by at least 3 -fold and 7-fold.

When the respective chemical compositions were reduced by 50% from that of Run #4, the

corrosion rates increased by nearly 15-fold. This latter corrosion rate was similar to that

obtained during Runs #1 and #2 wherein the samples did not contain Inhibitor C but did

contain the other two chemicals. These results are presented in Table II.

TABLE II

Wheel Test Results at 120°F for Identified Commercial Inhibitors

2

Control Inhibitor Inhibitor

Test A C Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) (wt %) (psig) (°F) (his.) (mph)

1 0.10 0 0.25 2.5 120 24 65.l

2 0.10 0 0.25 2.5 120 24 67.9^b

3 0.01 0.01 0.025 2.5 120 24 67.0^b

4 0.02 0.02 0.050 2.5 120 24 4.77

5 0.05 0.05 0.125 2.5 120 24 15.68^c t

6 0.10 0.10 0.250 2.5 120 24 36.1^c

^a180 ml of total fluid used in each test consisting of 10 vol% kerosene and 90 vol% of 2%KC1 solution to π which was added the identified concentrations of chemicals. Total system volume was approximately

215 ml. ^bPitting

Slight pitting Borneo MC-21 ²Homco AC-105-C

³Homco SF-1009

Control Test Series #3

The test results for Control Test Series #3 were obtained using the Corrator

test method. The results are consistent with the observations reported for Control Test #2.

Below and above an apparently narrow concentration range, the inhibitors at 120°F were

found to be ineffective.

The tests were carried out in a 1 -liter Erlenmeyer flasks equipped with

magnetic stirring bars under laboratory conditions designed to simulate the corrosive oil-

water environment frequently encountered in field operation. The rate of corrosion and the

® relative effectiveness of the treatment process was determined using a Corrator

monitoring system (Rohrback Instruments). Each test consisted of fastening two one-inch

long carbon-steel electrodes to a probe and suspending the probe in a stirred

inhibitor/foamer bearing solutions of the composition provided in Table III. The process

temperature was 120°F.

Consistent with the observations for Control Test Series #2, Run #2 containing

0.02 wt% Inhibitor A (Homco MC-21), 0.02 wt% Inhibitor C (Homco AC-105-C) and 0.05

wt% Foamer (Homco SF-1009) produced the lowest observed corrosion rate. Test results

for Runs #1 presented in Table III for Control Test Series #3 are similar to the results for

Runs #1 and #2 and for Run #6 presented in Table II for Control Test Series #2. The active

components for some of the identified inhibitors and their respective sources are provided

in Table X. TABLE III

Results for Corrosion Test Series #3 Conducted at 120° F Using Corrator Test Method

Inhibitor Inhibitor Corrosion Rate

Run A C Foamer Temperature (mpy)

No. (wt %) (wt %) (wt %) (°F) Average Final

0.10 0 0.25 120 47.3 51.1

2 0.02 0.02 0.05 120 6.9 1.7 3 0.10 0.10 0.25 120 23.9 20.0 r πTest fluids were 900 ml 2%KC1 field brine, 100 ml Kerosene and the designated weight 3 percentage of additives. Fluids were air saturated at ambient pressure. Tests lasted 24 hours.

Homco MC-21

Ηomco AC-105-C

Ηomco SF-1009

Control Test Series #4

Run Numbers 1-24 in Control Test Series #4 established Inhibitor D (Amtech

MC-1) to be ineffective as a corrosion inhibitor at the conditions studied. Runs 25-42 wherein

Inhibitor E (Amtech B-1) was used demonstrated relatively low corrosion rates at the test

conditions. The inhibitors may be obtained from the source identified in Table X.

All tests were conducted at 120°F using the procedures previously presented in

Control Test Series #1. Test results for this test series are presented in Table IV.

TABLE IV - Part I

Wheel Test Results at 120" ^DF for Identified Commercial Inhibitors^a

Inhibitor Inhibitor

Run A E Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) (wt %) (psig) (°F) (hrs.) (mph)

1

2 0 0 0 2.4 120 24 76.8b

3 0 0 0 2.4 120 24 83.5b

4 0 0 0 2.4 120 24 75.3

5 0 0 0 2.4 120 24 78.3

6 0.10 0 0.25 2.4 120 24 74.4

w ^est liquid for each test was 135 ml of 2% KC1 brine and 15 ml kerosene to which was added the identified inhibitors and foamer. Total system volume was approximately 215 ml. c Severe pitting observed.

?T Borneo MC-21

O ² Amtech MC-1

³Homco SF-1009

TABLE IV - Part II

Wheel Test Results at 120 °F for Identified Commercial Inhibitors

Inhibitor Inhibitor

Run A D Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) (wt %) sig) (°F) (his.) (mph)

7 0 0.10 0.20 2.5 120 24 61.5

8 0.10 0.10 0.20 2.5 120 24 61.7

9 0.15 0.10 0.20 2.5 120 24 58.3

10 0 0.10 0.25 2.5 120 24 59.6

11 0.10 0.10 0.25 2.5 120 24 59.0

12 0.15 0.10 0.25 2.5 120 24 62.5

13 0 0.15 0.20 2.5 120 24 58.8

14 0.10 0.15 0.20 2.5 120 24 57.9

15 0.15 0.15 0.20 2.5 120 24 53.9

16 0 0.15 0.25 2.5 120 24 53.6 &

17 0.10 0.15 0.25 2.5 120 24 55.0

18 0.15 0.15 0.25 2.5 120 24 51.8

19 0 0.20 0.20 2.5 120 24 50.4

20 0.10 0.20 0.20 2.5 120 24 50.8

-n 21 0.15 0.20 0.20 2.5 120 24 50.2

22 0 0.20 0.25 2.5 120 24 52.2 > 23 0.10 0.20 0.25 2.5 120 24 50.8 σ 24 0.15 0.20 0.25 2.5 120 24 49.9

^est liquid was 135 ml of 2% KC1 brine and 15 ml kerosene to which was added the identified inhibitors and foamer. Total system volume was approximately 215 ml.

Borneo MC-21

TABLE IV - Part III

Wheel Test Results at 120 °F for Identified Commercial Inhibitors

Inhibitor Inhibitor

Run A E Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) (wt %) (psig) (°F) (hrs.) (mph)

25 0 0.10 0.20 2.5 120 24 4.99

26 0.10 0.10 0.20 2.5 120 24 5.36

27 0.15 0.10 0.20 2.5 120 24 5.06

28 0 0.10 0.25 2.5 120 24 4.95

29 0.10 0.10 0.25 2.5 120 24 5.88

30 0.15 0.10 0.25 2.5 120 24 4.82 -H

31 0 0.15 0.20 2.5 120 24 4.86

32 0.10 0.15 0.20 2.5 120 24 4.95

33 0.15 0.15 0.20 2.5 120 24 4.29 to /3 34 0 0.15 0.25 2.5 120 24 3.86

35 0.10 0.15 0.25 2.5 120 24 4.67

36 0.15 0.15 0.25 2.5 120 24 4.50 w

H 37 0 0.20 0.20 2.5 120 24 5.02

38 0.10 0.20 0.20 2.5 120 24 4.59

39 0.15 0.20 0.20 2.5 120 24 5.09 re^* 40 0 0.20 0.25 2.5 120 24 5.01

41 0.10 0.20 0.25 2.5 120 24 4.55

42 0.15 0.20 0.25 2.5 120 24 4.33

^est liquid was 135 ml of 2% KC1 field brine and 15 ml kerosene to which was added the identified inhibitors and foamer. Total system volume was approximately 215 ml. * Homco MC-1

Amtech MC-21

A Homco SF-1009

Amtech B-1

Control Test Series #5

Control Test Series #5 provides comparative data regarding the applicability of

Inhibitor D (Amtech MC-1), Inhibitor E (Amtech B-1) and Inhibitor F (Baker Cronox C-617)

as corrosion inhibitors at 120°F. The test results indicate Inhibitor F (Run 15) to be superior

to Inhibitor E (Runs 9-14) which is markedly superior to Inhibitor D (Runs 1-8). The results

for the latter comparison are consistent with those reported for Control Series #4. The active

components in some of these inhibitors and their respective souces are identified in Table X.

Test conditions and results are presented in Table V. All tests were conducted at

120°F using the Wheel Test procedures previously presented in Control Test Series #1.

Based on the corrosion inhibition results for Control Test Series #1 through #5

wherein 6 commercially available corrosion inhibitors were evaluated, the preferred corrosion

inhibitor among the six tested at these test conditions is Inhibitor F.

TABLE V - Part I

Wheel Test Results at 120' ^DF for Identified Commercial Inhibitors

2

Inhibitor Inhibitor ->

Test A D Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) (wt %) ( sig) (°F) (hrs.) (mph)

1 0 0 0 2.5 120 24 216.5

2 0.10 0 0.25 2.5 120 24 216.5

3 0 0.10 0.20 2.5 120 24 181.7^b

4 0.10 0.10 0.20 2.5 120 24 149.3?

5 0.15 0.10 0.20 2.5 120 24 125.3 I n 6 0 0.10 0.25 2.5 120 24 192.5^b

7 0.10 0.10 0.25 2.5 120 24 192.6 w 8 0.20 0.10 0.25 2.5 120 24 177.6

H d was 135 ml of 2% KC1 brine and 15 ml kerosene to which was added the identified and foamer. Total system volume was approximately 215 ml.

O Severe pitting Some pitting Homco MC-2. 1

² Amtech MC-1

³Homco SF-1009

TABLE V - Part II

Wheel Test Results at 120° F for Identified Commercial Inhibitors

Inhibitor Inhibitor

Test A E Foamer Air Temperature Time Corrosion Rate

No. (wt %) (wt %) ( t %) (psig) (°F) (his.) (mph)

Inhibitor F o

15 0.10 o.io- 0.25 2.5 120 24 5.49

^est liquid was 135 ml of 2% KC1 brine and 15 ml kerosene to which was added the identified inhibitors and foamer. Total system volume of approximately 215 ml. iT Severe pitting 'Some pitting

Homco MC-21 ^"Amtech MC-1 ⁵Homco SF-1009

Amtech B-1 (See Footnote 5) 'inhibitor F, Baker Cronox C-617

Test Series #1

This test series with the exception of one run was conducted at 200 °F and

conclusively establishes that potassium hydroxide and phenol in combination is superior to

the best corrosion inhibitor identified in Control Test Series #1 through #5, that corrosion

inhibitor being Inhibitor F (Baker Cronox C-617). The test series also establishes the

effectiveness of the potassium hydroxide/phenol corrosion inhibitor at phenol to oxygen

molar ratios in the test apparatus of significantly less than 1.0.

Test procedures were similar to those presented for Control Test Series #1.

Chemical concentrations, tests conditions and results are presented in Table VI for Inhibitor F

(Runs 4-6) and the inventive corrosion inhibitor (Runs 7-12). Whereas Inhibitor F

demonstrates unacceptable performance at 200 °F and 10 and 100 psig pressure (corrosion

rates of 23.0 and 43.4 mpy, respectively), the corrosion rates for the inventive formulation are

approximately an order of magnitude less (2.71 and 2.73 mpy, respectively). Whereas the

corrosion rates for Inhibitor F at concentrations similar to the inventive inhibitor were found

to be a function of air pressure, such a dependence was not observed for the inventive

inhibitor. As noted, the inventive inhibitor was effective at phenol to oxygen molar ratios in

the system of significantly less than 1.

TABLE VI

Wheel Test Results at 120° F and 200 °F for Inhibitor F and Inventive Corrosion Inhibitor Formulation

Test Inhibitor F T¹ KOH Phenol Foamer^{^} Air Pressure Temperature Test Time Corrosion Rate

No. (wt %) (wt %) (wt %) (wt %) (psig) (°F) (hrs.) (mpy)

4 0.1 0 0 0.25 2.5 120 24 5.49 5 0.15 0 0 0.20 10.0 200 48 23.0 6 0.15 0 0 0.20 100.0 200 48 43.4^

7 0 5 0.15 0 10 200 48 5.76 8 0 10 0.15 0 10 200 48 2.78 to

9 0 10 0.15 0.20 10 200 48 2.71

10 0 10 0.15 0.20 50 200 48 2.82

11 0 10 0.15 0.20 100 200 48 2.73

12^C 0 10 0.15 0.20 200 200 48 2.19

Hest liquid was 80 ml of 2% KC1 brine to which was added the above specified chemicals, inhibitors and ^* foamer. Total system volume was approximately 120 ml.

Pittings

'Mole ratio of phenol to oxygen in test apparatus was 0.148.

1 Baker Cronox C-617

'Homco SF-1009

Test Series #2

This test series further illustrates the outstanding corrosion inhibition

properties possessed by NaOH/phenol and KOH/phenol in highly oxidative environments (air,

water and carbon steel coupon at 350°F and 7 psig).

Test results and conditions are presented in Tables VII and VIII. Test

procedures were similar to those described for Control Test Series #1.

Test results for Inhibitor F which was shown in Control Test Series #5, Run

#15, to be the most promising of the commercial inhibitors tested are presented in Table VII.

The test results confirm at a higher temperature the results presented in Test Series #1. These

results indicated Inhibitor F to be ineffective as a corrosion inhibitor at elevated temperatures.

Results presented in Table VIII for Test #1 and #2 clearly demonstrate that

corrosion rates are unacceptable in the studied system in the absence of a corrosion inhibitor.

Test results for Test #3 and #4 show that the foaming agent used in these studies fails to

provide corrosion inhibition. The results obtained in Test #5 show that phenol by itself at

0.30 wt% provides little if any corrosion inhibition. Test Numbers 6-7 and 8-9 respectively

show that the addition of either NaOH or KOH to the studied systems results in significant

corrosion inhibition. Of the two, KOH appears to provide better corrosion inhibition

performance at a given weight percentage. The combination of either NaOH or KOH with

phenol unexpectedly enhanced corrosion inhibition as evidenced by the results for Test

Numbers 10-15 over that observed for the individual alkali metal hydroxides. The degree of

corrosion inhibition for the NaOH/phenol system (Run #10-11) and the KOH/phenol systems

(Run #12-14) were similar. Test results obtained for Runs #17-20 wherein KOH and phenol was used

for corrosion inhibition at 350°F further show the excellent inhibition properties of these

chemicals when used in combination at greater air pressures. The greater air pressure

correspond to greater partial pressures of the oxygen oxidizing agent.

TABLE VII

Wheel Test Results at 300 °F for Commercial Inhibitor F

Test^a Inhibitor F Foamer Air Temperature Time Corrosion Rate No. (wt %) (wt %) (psig) (°F) (hrs.) (mpy)

1 50 1 7 320 24 33.4^b

2 1 1 7 320 24 26.7^b

^est liquid was 80 ml of 2% KCI field brine containing above designated components at designated weight percentages. Total system volume was 120 ml. I ^bPirting LO LΛ

Baker Cronox C-617

'Homco SF-1009

TABLE VIII

Wheel Test Results at 300' and 350°F

ϋ

6 5 0 0 0.2 5 350 55 4.06 7 10 0 0 0.2 5 350 55 6.31 8 0 5 0 0.2 5 350 55 3.70 ϋ 9 0 10 0 0.2 5 350 55 3.98

10 5 0 0.15 0.2 5 350 55 3.11 LO 11 10 0 0.30 0.2 5 350 55 2.42 0\ 3 12 0 5 0.15 0.2 5 350 55 2.44 13 0 10 0.30 0.2 5 350 55 2.95 14 0 10 0.30 0.2 5 350 55 1.90

"1 15 0 1 0.30 0.2 5 350 55 3.42^b

16 0 1 0.05 0.2 10 350 55 4.27^b 17 0 5 0.05 0.2 10 350 55 3.13 18 0 10 0.05 0.2 10 350 55 3.32 19 0 1 0.10 0.2 10 350 55 3.06

20 0 10 0.10 0.2 10 350 55 3.43

^est liquid was 80 ml of 2% KCI to which the designated components were added in the designated weight percentages. b P_τ itting

Homco SF-1009

Test Series #3

This series of tests further illustrate the beneficial corrosion inhibition imparted

by a phenolic compound, phenol, when added to a brine solution containing a hydroxide-

bearing compound capable of imparting a pH of at least 9 to a base aqueous fluid, KOH, or

NH₄OH and/or a foaming agent. For every combination, the addition of phenol was found to

reduce the corrosion rate (i.e., improve corrosion inhibition).

Test results and conditions are presented in Table IX. Test procedures were

analogous to those reported for Control Test Series #1. The tests were conducted by exposing

the air/brine/coupon system to a temperature of 350°F for 42.5 hrs. Test Numbers 1-5

concern corrosion inhibition in an air/brine system containing KOH (Run #1), an air/brine

system containing KOH and Foamer (Run #2), an air/brine system containing KOH and

phenol (Run #3), an air/brine system containing KOH, foamer and phenol (Runs #4 and #5).

Test Numbers 6-10 similarly concern corrosion inhibition in an air/brine system containing

NH₄OH (Run #6), an air/brine system containing NH₄OH and foamer (Run #7), an air/brine

system containing NH₄OH and phenol (Run #8), an air/brine system containing NH₄OH,

foamer, and phenol (Runs #9 and #10). The results for Runs #4 and #5 and for Runs #9 and

#10 additionally and surprisingly show a reduction in corrosion rates when the phenol

concentration is reduced from 0.3 wt.% to 0.15 wt.%. As previously noted, the addition of

phenol to the fluid system in all tests resulted in a reduction in corrosion rate. The magnitude

of the reduction was generally greater for solutions containing KOH rather than NH₄OH. The

corrosion rates for comparable systems were generally lower for those systems containing

NH₄OH than for KOH. TABLE IX

Wheel Test Results at 350°F

KOH NH₄OH Phenol Foamer Corrosion Rate

Test No.^a'^b (wt %) (wt %) (wt %) (wt %) (mpy)

1 10 0 0 0 7.43

2 10 0 0 0.2 7.04

3 10 0 0.3 0 3.32

4 10 0 0.3 0.2 3.20

5 10 0 0.15 0.2 3.01

6 0 10 0 0 4.24

7 0 10 0 0.2 3.38

8 0 10 0.3 0 2.81

9 0 10 0.3 0.2 2.57

10 0 10 0.15 0.2 2.32

80 ml of total fluid used in each test. Fluids for Test Numbers 1-5 were prepared from 80 ml of 2% KCI brine to which KOH, phenol and foamer were added in the designated percentages. Fluids for Test Numbers 6-10 were prepared from 65 ml of 2% KCI brine and 15 ml of 60 wt% NH₄OH to which phenol and foamer were added in the designated percentages. Total system volume was 120 ml.

Test conditions were 350°F and 7.6 psig for 42.5 hrs. Overburden gas was air.

Foamer was Homco SF-1009

TABLE X

Commercial Inhibitors

Inhibitor Tradename Active Components'

A Homco MC-21 ^: Amine, methanol

B Homco MC-117² Ethylene glycol

C Homco AC- 105-C² Methanol

D Amtech MC-1³ Ethylene glycol, methanol

E Amtech B- 1³ Ethylene glycol

F Baker Cronox C-617⁴ Phosphonate, 2-butoxyethanol

'Components disclosed on Material Safety Data Sheet. Other active components may be present but were not disclosed.

²Homco International, Inc., P.O. Box 26292, 6021 Camille Avenue, Oklahoma City, OK, 72129

³Amtech Corp., 2221 S. Eastern, Oklahoma City, OK, 73129

⁴Baker Performance Chemicals, Inc., 3920 Esses Lane. Houston, TX

Claims

THAT WHICH IS CLAIMED IS:

1. A corrosion inhibitor comprising at least one hydroxide-bearing compound

capable of imparting a pH of at least 9 to water and at least one phenolic compound.

2. The composition of matter of claim 1 wherein said phenolic compound is of the formula

wherein R R₂, R₃, R, and R₅ are independently selected from the group consisting of

phenolic mixtures thereof, and the resulting compound is water soluable or dispersible.

3. The composition of matter according to claim 2 wherein said hydroxide-

bearing compound is an alkali metal hydroxide, ammonium hydroxide or a mixture thereof.

4. The composition of matter according to claim 3 wherein said alkali metal

hydroxide is sodium hydroxide or potassium hydroxide.

5. The composition of matter according to claim 4 wherein said phenolic

compound is phenol, o-cresol, o-fluorophenol, o-chlorophenol, o-bromophenol, o-iodophenol,

o-nitrophenol, catechol, resorcinol, guaiacol, hydroquinone, salicylaldehyde phloroglucinol,

pyrogallol, 4,4-biphenol, 1,3-dihydroxy naphthalene, or o-allylphenol or the salts thereof.

6. The composition of matter according to claim 5 wherein said phenolic compound is phenol, o-cresol, salicyaldehyde, or o-nitrophenol or the ammonium, potassium

or sodium salts thereof.

7. The composition of matter according to claim 6 wherein said phenolic

compound is phenol or a sodium or potassium salt thereof and said hydroxide-bearing

compound is sodium hydroxide or potassium hydroxide.

8. The composition of matter of claim 1 wherein said corrosion inhibitor is

additionally comprised of water.

9. The composition of matter of claim 7 wherein said corrosion inhibitor is

additionally comprised of water.

10. An aerated liquid comprising a gaseous phase dispersed in a continuous

liquid phase wherein said liquid phase is comprised of (a) water in a major portion, and a (b)

corrosion inhibitor wherein said corrosion inhibitor is comprised of at least one phenolic

compound in concentrations sufficient to impart a pH of at least 9 to said liquid phase and an

effective amount of at least one phenolic compound.

11. The composition of matter of claim 10 wherein said phenolic compound is of the formula

OH

wherein R_b R₂, R₃, R, and R₅ are independently selected from the group consisting of

containing from 1 to 6 carbon atoms, F, Cl, Br, I, hydrogen, or the salts of any of the preceding acids or alcohols, wherein at least two of the above R groups are hydrogen; or

12. The composition of matter according to claim 11 wherein said hydroxide-

13. The composition of matter according to claim 12 wherein said gaseous

phase is comprised of nitrogen and at least one component selected from oxygen, hydrogen

sulfide, or carbon dioxide.

14. The composition of matter according to claim 13 wherein said alkali metal

hydroxide is sodium hydroxide or potassium hydroxide.

15. The composition of matter according to claim 14 wherein said gaseous

phase is comprised in major portion of air.

16. The composition of matter according to claim 15 wherein said phenolic

pyrogallol, 4,4-biphenol, 1,3-dihydroxy naphthalene, or o-allylphenol or salts thereof.

17. The composition of matter according to claim 16 wherein said phenolic

compound is phenol, o-cresol, salicyaldehyde, or o-nitrophenol or the ammonium, potassium

or sodium salts thereof.

18. The composition of matter according to claim 17 wherein said phenolic

compound is sodium hydroxide or potassium hydroxide.

19. In a process for drilling a wellbore or conducting workover, completion or

production operations in a wellbore wherein aerated liquid comprised of a gas phase dispersed in a continuous water-based liquid phase is employed as the principle wellbore fluid, the

improvement comprises the inclusion in said liquid phase of a corrosion inhibitor comprising

at least one hydroxide-bearing compound in concentrations sufficient to impart a pH of at

least 9 to said liquid phase and an effective amount of at least one phenolic compound.

20. The process according to claim 19 wherein said phenolic compound is of the formula

wherein R,, R₂, R₃, R₄ and R₅ are independently selected from the group consisting of

preceding acids or alcohol, wherein at least two of the above R groups are hydrogen; or

21. A process according to claim 20 wherein said hydroxide-bearing compound

is an alkali metal hydroxide or ammonium hydroxide.

22. A process according to claim 21 wherein said alkali metal hydroxide is

sodium hydroxide or potassium hydroxide.

23. A process according to claim 22 wherein said phenolic compound is

phenol, o-cresol, o-fluorophenol, o-chlorophenol, o-bromophenol, o-iodophenol, o-

nitrophenol, catechol, resorcinol, guaiacol, hyroquinone, salicylaldehyde or o-allylphenol or

the salts thereof.

24. The process according to claim 22 wherein said phenolic compound is

phenol, cresol, salicylaldehyde, or o-nitrophenol or the ammonium, potassium or sodium salts

thereof.

25. A process according to claim 24 wherein said phenolic is phenol or sodium

or potassium salts thereof and said hydroxide-bearing compound is sodium hydroxide or

potassium hydroxide.

26. A drilling, completion, workover or production process comprising

mixing in the wellbore at a predetermined depth a gas and a liquid comprised of

(a) water in a major portion, and a (b) corrosion inhibitor wherein said corrosion inhibitor is

comprised of an effective amount of at least one hydroxide-bearing compound in

concentrations sufficient to impart and maintain a pH of at least 9 to said liquid and at least

one an effective amount of at least one phenolic compound thereby forming a corrosion-

inhibited aerated liquid.

27. A process according to claim 26 wherein said phenolic compound is of the formula

preceding acids or alcohols wherein at least two of the above R groups are hydrogen; or phenolic mixtures thereof, and the resulting compound is water soluable or dispersible.

28. The process according to claim 27 wherein said hydroxide-bearing

compound is an alkali metal hydroxide or ammonium hydroxide.

29. A process according to claim 28 wherein said alkali metal hydroxide is

sodium hydroxide or potassium hydroxide.

30. The process according to claim 29 wherein said phenolic compound is

phenol, cresol, o-fluorophenol, o-chlorophenol, o-bromophenol, o-iodophenol, o-nitrophenol,

catechol, resorcinol, guaiacol, hydroquinone, salicylaldehyde or o-allylphenol or the salts

thereof.

31. A process according to claim 29 wherein said phenolic compound is

phenol, cresol, salicylaldehyde or o-nitrophenol or the ammonium, potassium or sodium salts

thereof.

32. The process according to claim 31 wherein said phenolic compound is

phenol or the sodium or potassium salts thereof and said hydroxide-bearing compound is

sodium hydroxide or potassium hydroxide.

33. A foam comprising a dispersed gaseous phase and a continuous liquid phase

wherein said liquid phase is comprised of (a) water in a major portion, (b) a foaming agent in

amounts effective to form a 60 to 99.75%) quality foam, and a (c) corrosion inhibitor wherein

said corrosion inhibitor is comprised of at least one hydroxide-bearing compound in

concentrations sufficient to impart a pH of at least 9 to said liquid phase and an effective

amount of at least one phenolic compound.

34. The composition of matter of claim 33 wherein said phenolic compound is of the formula

preceding acids or alcohols wherein at least two of the above R groups are hydrogen; or

35. The composition of matter according to claim 34 wherein said hydroxide-

36. The composition of matter according to claim 35 wherein said gaseous

sulfide, or carbon dioxide.

37. The composition of matter according to claim 36 wherein said alkali metal

hydroxide is sodium hydroxide or potassium hydroxide.

38. The composition of matter according to claim 37 wherein said gaseous

phase is comprised in major portion of air.

39. The composition of matter according to claim 38 wherein said phenolic

compound is phenol, o-cresol, o-fluorophenol, o-chlorophenol, o-bromophenol. o-iodophenol.

o-nitrophenol, catechol, resorcinol, guaiacol, hydroquinone, salicylaldehyde phloroglucinol, pyrogallol, 4,4-biphenol, 1,3-dihydroxy naphthalene, or o-allylphenol or salts thereof.

40. The composition of matter according to claim 39 wherein said phenolic

or sodium salts thereof.

41. The composition of matter according to claim 40 wherein said phenolic

compound is phenol or the sodium or potassium salts thereof and said hydroxide-bearing

compound is sodium hydroxide or potassium hydroxide.

42. The composition according to claim 33 wherein said foaming agent is

comprised of at least one N-acrylsarcosinate, sodium N-acryl-N-alkyltaurate, alkyl sulfate,

ethoxylated and sulfated alcohol, ethoxylated and sulfated alkylphenol, fatty acid

diethanolamide, amine oxide, alkyl betaine, or amidopropylbetaine.

43. The composition according to claim 33 wherein said foaming agent is

comprised of at least one amidopropylbetaine.

44. The composition according to claim 43 wherein said foaming agent is

additionally comprised of one or more aliphatic or alkyl aryl hydrocarbon sulfonates of

formula

R-SO₃M

wherein R is an oleophilic group having from 10 to 18 carbon atoms and M is an alkali metal

or ammonium cation.

45. The composition according to claim 43 wherein said foaming agent is

comprised of cocoamidopropylbetaine and at least one ethoxylated and sulfated alcohol.

46. In a process for drilling a wellbore or conducting workover or completions

operations in a wellbore wherein foam comprised of a dispersed gas phase in a continuous liquid phase is employed as the principle wellbore fluid, the improvement comprises the

inclusion in said foam of a corrosion inhibitor comprising at least one hydroxide-bearing

effective amount of at least one phenolic compound.

47. The process according to claim 46 wherein said phenolic compound is of the formula

OH

wherein R,, R₂, R₃, R₄ and R₅ independently selected from the group consisting of hydroxyl

groups, alkoxy groups containing from 1 to 6 carbon atoms; alkyl groups containing from 1 to

6 carbon atoms, a phenyl group, NO₂, COOH, COH, sulfonic acids, ketones containing from 1

to 6 carbon atoms, F, Cl, Br, I, hydrogen, or the salts of any of the preceding acids or alcohols

wherein at least two of the above R groups are hydrogen; or phenolic mixtures thereof, and

the resulting compound is water soluable or dispersible.

48. A process according to claim 47 wherein said hydroxide-bearing compound

is an alkali metal hydroxide or ammonium hydroxide.

49. A process according to claim 48 wherein said alkali metal hydroxide is

sodium hydroxide or potassium hydroxide.

50. A process according to claim 49 wherein said phenolic compound is

salts thereof.

51. The process according to claim 49 wherein said phenolic compound is

thereof.

52. A process according to claim 51 wherein said phenolic compound is phenol

or the sodium or potassium salt thereof and said hydroxide-bearing compound is sodium

hydroxide or potassium hydroxide.

53. A process according to claim 52 wherein said foaming agent is comprised

of at least one amidopropylbetaine.

54. The process according to claim 53 wherein said foaming agent is

formula

R-SO₃M

or ammonium cation.

55. A process according to claim 53 wherein said foaming agent is comprised

of cocoamidopropylbetaine and at least one ethoxylated and sulfated alcohol.

56. A drilling, completion or workover process comprising the steps of:

(a) intimately mixing a gas and a liquid comprised of (1) water in a major

portion, (2) a foaming agent in amounts effective for a 60 to 99.75%) quality foam, and a (3)

corrosion inhibitor wherein said corrosion inhibitor is comprised of an effective amount of at

least one hydroxide-bearing compound in concentrations sufficient to impart and maintain a

pH of at least 9 to said liquid and at least one an effective amount of at least one phenolic

compound thereby forming a foam; and (b) injecting said foam into either a tubular or annular space in a wellbore

thereby producing said wellbore fluids via the non-injection tubular or annular space.

57. A process according to claim 56 wherein said phenolic compound is of the formula

OH

wherein R,, R₂, R₃, R, and R₅ are independently selected from the group consisting of

58. The process according to claim 57 wherein said hydroxide-bearing

compound is an alkali metal hydroxide or ammonium hydroxide.

59. A process according to claim 58 wherein said alkali metal hydroxide is

sodium hydroxide or potassium hydroxide.

60. The process according to claim 59 wherein said phenolic compound is

thereof.

61. A process according to claim 60 wherein said hydroxy aromatic compound

is phenol, cresol, salicylaldehyde or o-nitrophenol or the ammonium, potassium or sodium salts thereof.

62. The process according to claim 61 wherein said hydroxy-bearing

compound is sodium hydroxide or potassium hydroxide.

63. The process according to claim 52 wherein said foaming agent is

comprised of at least one N-acrylsaracosinate, sodium N-acryl-N-alkyltaurate, alkyl sulfate,

diethanolamide, amine oxide, alkyl betaine, or amidopropylbetaine.

64. A process according to claim 56 wherein said foaming agent is comprised

of at least one amidopropylbetaine.

65. The process according to claim 64 wherein said foaming agent is

formula

R-SO₃M

or ammonium cation.

66. A process according to claim 64 wherein said foaming agent is comprised

of at least one amidopropylbetaine is cocoamidopropylbetaine and at least one ethoxylated

and sulfated alcohol.

67. A process according to claim 62 wherein said foaming agent is comprised

of at least one amidopropylbetaine.

68. The process according to claim 67 wherein said foaming agent is

additionally comprised of one or more aliphatic or alkyl aryl hydrocarbon sulfonates of formula

R-SO₃M

or ammonium cation.

69. A process according to claim 67 wherein said foaming agent is comprised

and sulfated alcohol.

70. A process according to claim 56 wherein said foam is exposed to a

temperature of at least about 200°F.

71. A process according to claim 56 wherein said foam is exposed to a

temperature of at least about 350°F.