GB2112836A - Well completion fluid compositions - Google Patents

Abstract

A composition and method for well completion and workover. The composition comprises water, various halogen salts and an acetylenic alcohol. Optionally, other ingredients can be added to the composition. The method is carried out by contacting the well at sufficient hydrostatic pressures to control the well.

Description

SPECIFICATION Well completion fluid compositions This invention relates to well completion and workover fluid compositions and more particularly to a high density well completion and workover fluid composition that may be employed in petroleum recovery operations without excessive corrosion to ferrous metal tubing and pipe with which the composition may come into contact.

Current practice when completing wells, such as oil and gas wells, is to have drilling fluid, such as mud, salt water, water, or oil, in the well casing and to perforate the casing with a bullet shaped charge, or chemical or punch-type perforator. When the pressure of the formation traversed by the wall exceeds the hydrostatic pressure of the column of oil or water at the completion depth, it is customary to use a composition with a density great enough to exceed the formation pressure in order to control the well while perforating the casing in performing outer routine completion and workover operations.

These compositions are prepared by dissolving certain inorganic salts in water.

The use of these compositions for completion and workover operations, has certain undesirable consequences. For example the compositions are usually somewhat corrosive, particularly towards the ferrous metal conduits with which the composition comes in contact. This problem is particularly acute in petroleum recovery operations which require a high density composition since the increased concentration of salts (needed to provide the high density) in the fluid composition results in greater corrosion damage to the ferrous conduits.

For various reasons, it has become the practice in the petroleum industry to drill deeper and deeper wells, and very often also to complete these wells at a plurality of zones. This of course, has presented additional new unique problems in the art of completing and producing wells. Also, the closely related problems of workover on wells has been greatly magnified by the advent of, and specifically in, multiple completion wells which is at least in part due to prior completion factors. For example, after completing operations on an oil well to place it into production, a completion fluid again is employed to fill the annular space between the casing and the tubing above packers and left there throughout the life of the well or until reworking is required.

The purpose of using such annulus or filled-up fluids to fill the annulus space between tubing and casing above the packer after a well is completed and producing, is to maintain a hydrostatic pressure at the top of the packer. The pressure desired at such points is slightly greater than the highest pressure of all the producing formations. In this way, the hydrocarbons being produced exert on the bottom side of the packer a pressure which is only slightly less than that which the completion fluid exerts on the top side of the packer. Thus, by reducing the differential pressure between the top and bottom of the packer, the crude oil or other fluids exiting from the formation will not leak or bleed around the packer and/or control of the well will not be lost.The disadvantages and deleterious consequences of bleeding around packers by such fluids are well known to those skilled in the art. The consequences of losing control of the well are still better known. Similarly, and especially with regard to multiple completion wells, the consequences of using a completion fluid which is corrosive to ferrous metals is well known and appreciated by those skilled in the art.

In drilling deeper and deeper wells in search for petroleum producing formations, the temperatures encountered have increased giving rise to difficulties not encountered previously.

Temperatures in the order of 2000 to 2500F (930 to 121 OC) or even higher may be encountered in oil and gas wells. At these temperatures, the completion fluids may form corrosive fluids which will damage ferrous metal tubing and pipe with which it may come into contact. It is, therefore, desirable to provide a well completion fluid which will be non-corrosive to ferrous metal conduits with which it may come in contact.

Temperature, as a rule, increases with depth. Many factors affecting temperature may vary in subterranean locations and the subterranean temperatures even in comparably close locations may vary considerably. This is well known in the art. Thus, despite the general rule that temperature increases with depth, comparably high temperatures are sometimes encountered at relatively shallow depths, for example, at 3,000 feet (915 m). At depths beginning at about 1 5,000 feet (4580 m), high temperatures are encountered without exception regardless of location. High temperatures, then, may be encountered at a depth below 3,000 feet (915 m). These temperatures, when encountered regardless of depth, make more severe the disadvantages of prior art completion and packer fluids.

In an effort to overcome the foregoing problems, high density salt solutions for use as well completion fluid compositions have been proposed. For instance, United States Patent 3,126,950 discloses a completion packer fluid made up of a water solution of calcium chloride and zinc chloride, and optionally a corrosion inhibitor. United States Patent 4,292,183 discloses a high density fluid composition consisting of zinc bromide and calcium bromide in water having a density in the range of about 1.74 up to 2.16 g/cc (14.5 up to 1 8.0 pounds per U.S. gallon) and a pH in the range of 3.5 up to 6.0.

These high density fluid compositions have had limited utility. Severe downhole corrosion problems and corrosion to above ground equipment has been encountered with their use.

We have now devised some compositions by which the above problems are reduced or overcome.

According to the invention, there is provided a composition useful as a well completion and workover fluid, comprising: (a) water; (b) a salt selected from aluminum chloride, aluminum bromide, aluminum iodide, ammonium, chloride, ammonium bromide, ammonium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, zinc chloride, zinc bromide and zinc iodide, or a mixture of two or more thereof; and (c) an acetylenic alcohol having the general formula

wherein R is H, alkyl, phenyl, substituted phenyl, or a hydroxyalkyl radical, the composition having a density of about 1.0 to about 2.6 gm/cc (9.0 pounds to about 21.5 pounds per U.S. gallon of composition).

The invention also provides a method of completing a well penetrating a subterranean formation, which comprises: contacting said well at sufficient hydrostatic pressure to control the well, with a composition of the invention.

The invention further includes a method of inhibiting the corrosion of an iron surface in contact with an aqueous salt fluid, said fluid containing salts selected from aluminum chloride, aluminum bromide, aluminum iodide, ammonium chloride, ammonium bromide, ammonium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, zinc chloride, zinc bromide and zinc iodide, and mixtures of two or more thereof, comprising incorporating into said fluid at least an acetylenic alcohol having the general formula:

wherein R is H, alkyl, phenyl, substituted phenyl, or hydroxy-alkyl radical, to form a composition of the invention.

Optionally other ingredients may be added to the above described compositions. For instance, an organic amine selected from mono, di and tri-alkyl amines having from about two to about six carbon atoms in each alkyl moiety, six membered N-heterocyclic amines, quinolines and quaternized derivatives of quinolines, quaternized pyridines, and alkyl pyridines having from one to five nuclear alkyl substituents per pyridine moiety wherein said alkyl substituents have from one to 12 carbon atoms, and mixtures thereof, may be added.

When desired, an acid selected from formic acid, acetic acid, propionic acid, butyric, glycolic acid and mixtures thereof may be added to the compositions.

When the above described method of completion of work-over of wells is employed, the composition of the invention are relatively non-corrosive to any ferrous metal conduits with which they come in contact.

The salts, which may be used in the practice of the present invention, function as weighting agents and increase corrosion inhibition. These salts are presented in the following Table.

Table I Salts suitable as weighting agents Name Formula Specific gravity Aluminum Bromide AlBr3 3.01 Aluminum Chloride AICI3 2.44 Aluminum lodide All3 3.98 Ammonium Bromide NH4Br 2.33 Ammonium Chloride NH4CI 1.53 Ammonium lodide NH41 2.51 Calcium Bromide CaBr2 3.35 Calcium Chloride CaCI2 2.15 Calcium lodide Cal2 3.96 Potassium Bromide KBr 2.75 Potassium Chloride KCI 1.98 Potassium lodide KI 3.13 Sodium Bromide NaBr 3.20 Sodium Chloride NaCI 2.16 Sodium lodide Nal 3.67 Zinc Bromide ZnBr2 2.56 Zinc Chloride ZnCI2 2.91 Zinc lodide Znl2 4.66 The preferred salts and combinations of salts for use in the present invention are sodium chloride, calcium chloride, calcium bromide and the following combinations of salts: sodium chloride and calcium chloride, calcium chloride and calcium bromide, calcium chloride and zinc chloride, calcium bromide and zinc bromide, calcium bromide, zinc bromide and zinc chloride, and zinc chloride and zinc bromide.

The most preferred salts and combinations of salts for use in the invention are calcium chloride, calcium chloride and calcium bromide, calcium bromide and zinc chloride, and calcium bromide and zinc bromide.

The amount of these salts used in the composition of the invention will be the amount necessary to achieve a composition having a density of about 1.0 to 2.6 gm/cc (9.0 pounds to about 21.5 pounds per U.S. gallon of composition).

The acetylenic alcohols which inhibit corrosion of ferrous metal and which may be employed in accordance with the present invention have the general formula:

wherein R is H, alkyl, phenyl, substituted phenyl, or hydroxyalkyl radical. Examples of suitable acetylenic compounds include methylbutynol, ethyloctynol, methylpentynol, 3,4-dihydroxy 1-butyne, 1 -ethynylcyclohexanol, 3-methyl-1 -nonyn-3-oI, 2-methyl-3-butyn-2-ol, also 1-propyn-3-ol,1-butyn-3- ol, 1 -pentyn-3-oI, 1 -heptyn-3-ol, 1 -octyn-3-ol, 1 -nonyl-3-ol, 1 -decyn-3-ol, 3-(2,4,6-trimethyl-3- cyclohexenyl)-1 -propyn-3-ol.

In many instances, the corrosion protection of the compositions of the invention may be increased by adding an organic amine to the above described acetylenic alcohol. Amines that are suitable for this purpose include an organic amine selected from the group consisting of mono, di and tri-aikyl amines having from about two to about six carbon atoms in each alkyl moiety, six membered N-heterocyclic amines, quinolines and quaternized derivatives of quinolines, alkyl pyridines having from zero to six nuclear alkyl substituents per pyridine moiety wherein said alkyl substituents have from one to 12 carbon atoms and mixtures thereof.Examples of these amines include ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, mono, di, tributylamine, mono, di and tripentylamine, mono, di and trihexylamine and isomers of these such as isopropylamine, tertiarybutylamine, aniline, dehydroabiethylamine, pyridine, quaternized derivatives of pyridine, nitro picoline, methyl quinoline alkyl pyridines such as alkyl pyridines having from 1 to 5 nuclear alkyl substituents per pyridine moiety, quinolines, quaternized derivatives of quinolines alkyl quinolines and mixtures.

In some instances, it may be desirable to include an acid in the composition of the invention. The acid, when present in the composition of the invention will remove acid soluble scales in the well bore or open perforations in the well bore. When an acid is desired, suitable acids which may be employed include formic acid, glycolic acid, acetic acid, propionic acid, butyric acid and mixtures thereof.

As stated earlier, the acetylenic alcohol may be used alone with the composition of the invention or an organic amine may be combined with an acetylenic alcohol. The relative proportions of acetylenic alcohol and organic amine may vary over a wide range. Furthermore, it has been found that the concentration of acetylenic alcohol and the concentration of the organic amine are not interdependent and thus significant improvement in corrosion protection can be obtained by varying the concentration of one of the components without varying that of the other. In general, the acetylenic alcohol concentration will vary from about 0.2 to about 5.0-percent by volume of the composition. However, lower or higher concentrations will still be effective when an organic amine is added to the composition of the invention.Thus, the amine concentration will vary over a wide range with really no upper or lower limitations. General, the organic amine concentration when desired will vary from about 0.5 to 3.0 volume percent of the composition of the invention.

A particularly effective blend containing an amine and acetylenic alcohol is set forth below.

Blend I Chemical Percent by vol.

Pure propargyl alcohol 33.94 Cure propargyl alcohol 11.31 Ethyl octynol 16.97 High alkyl pyridines 3.85 Formaldehyde (55%) in methanol 33.94 Another effective composition containing an amine and acetylenic alcohol is given below.

Blend II Chemical Percent by vol.

Pure propargyl alcohol 33.94 Crude propargyl alcohol 11.31 Ethyl octynol 16.97 Alkyl pyridines 3.85 Diacetone alcohol 33.94 Another effective blend containing an amine and acetylenic alcohol is given below. This blend is very effective when the density of the composition of the invention is from about 1 5.0 pounds per gallon to about 16.5 pounds per gallon (1.8 to 2.0 gm/cc) and the salts utilized are calcium bromide and zinc chloride and then the density is from about 16.5 pounds per gallon to about 19.2 per gallon (2.0 to 2.3 gm/cc) and the salts utilized are calcium bromide and zinc bromide.

Blend Ill Chemical Percent by vol.

Crude quaternized quinoline 56.00 Propargyl alcohol 21.00 Ethyl Octynol 13.00 15 Moles of ethylene oxide adduct of nonyl phenol 10.00 Cm212 0.024 grams per milliter of composition The preferred density of the composition of the invention is from about 2.0 to 2.6 gm/cc (16.5 to about 21.5 pounds per U.S. gallon of composition).

The concentration of the acid, when employed in the composition of the invention will vary over a great range. Generally the range of acid is from .2 percent to about 40 volume percent of the composition. The most preferred acid concentration is from about 3 to about 1 7 volume percent of the composition.

In order that the invention may be more fully understood, the following Examples are given by way of illustration only.

Example 1 In order to compare the corrosion inhibiting ability of compositions of the invention, various samples containing 10 percent by volume of formic acid or acetic acid were prepared with various amounts of calcium chloride. Test 1 through 5 contained Blend I as an inhibitor Blend I, as disclosed earlier, contains the following ingredients: pure propargyl alcohol, crude propargyl alcohol, ethyl octynol, high alkyl pyridines and formaldehyde (55%) in methanoi.

Tests 6 through 10 contained, as an inhibitor, Blend Ill. Blend III was made up of crude quaternized quinoline, propargyl alcohol, ethyl octynol, and 1 5 moles of ethylene oxide adduct of nonyl phenol and Cu212.

A coupon of API Type N-80 steel was placed in the acid composition for a period of about eight hours at 2000F. All tests were carried out under atmospheric conditions.

The loss of weight in pounds per square foot was calculated as follows: in2 144 ft2 Corrosion Loss Ibs/ft2= 9.

455 - xSurface Area of Coupon in ] Results of these tests are shown in Table II.

Table II Volume-surface area ratio-25 cc/in2 (25 cc/6.45x1O4m2) Corrosion loss CaCl2 Formic acid Acetic acid Test Inhibitor Ibs/gal g/cc Ibs/ft Kg/m lbs/ft kg/m 1 Blend I - 0.287 1.39 0.296 1.43 2 Blend 1 9.5 1.14 0.052 0.25 0.029 0.14 3 Blend 1 10.0 1.20 0.023 0.11 0.025 0.12 4 Blend I 10.4 1.26 0.005 0.02 0.005 0.02 5 Blend I 11.0 1.32 0.005 0.02 0.004 0.02 6 Blend Ill - - 0.029 0.14 0.019 0.09 7 Blend lil 9.5 1.14 0.009 0.04 0.013 0.06 8 Blend III 10.0 1.20 0.003 0.01 0.009 0.04 9 Blend III 10.5 1.26 0.003 0.01 0.002 0.01 10 Blend III 11.0 1.32 0.002 0.01 0.002 0.01 Table II shows that the composition of the invention effectively reduced iron corrosion.

Example II In order to demonstrate the corrosion inhibiting ability of the compositions of the invention, various samples of a 10 percent by volume acetic acid were prepared with various salts. The density of the samples was ten pounds per gallon of sample (1.2 gm/cc). Tests 4 through 6 and 8 contained Blend I as an inhibitor. The composition of this Blend is the same as disclosed in Example I. Tests 1 through 3 and 7 utilized MBA 29 as an inhibitor. MBA 29 contained, as ingredients, 50 percent by volume crude quaternized quinoline and 50 percent by volume methyl butynol.

A coupon of API Type N-80 steel was placed in the acidic composition for a period of six hours at 2000F. All tests were carried out under atmospheric conditions. The corrosion loss was calculated as in Example I.

The results of these test are shown in Table Ill.

Table III Volume - surface area ratio - 25 cc/in2 Inhibitor Corrosion loss Test Salt 1% v/v Ibs/ft2 kg/m2 1 AlCI3 MBA29 0.004 .02 2 NaBr MBA29 0.004 .02 3 NH4l MBA29 0.003 .01 4 AlCl3 Blend I 0.009 .04 5 NaBr Blend I 0.018 .09 6 NH41 Blend I 0.005 .02 7 - MBA29 0.150 .73 8 - Blend I 0.287 1.39 Table III shows that the composition of the invention reduced iron corrosion.

Example III In order to compare the corrosion inhibiting ability of the composition of the invention, a composition which had a density of 1 9.2 pounds per gallon (2.30 gm/cc) was prepared. The salt utilized in preparing the composition was a mixture of zinc bromide and calcium bromide. A coupon of API Type N-80 steel was placed in the composition for a period of seven days at 2600F (1 270C). All tests were carried out under atmospheric conditions.

Blend III was made up of the same components as described in Example I. Blend II was made up of pure propargyl alcohol, crude propargyl alcohol, ethyl octynol, alkyl pyridines and diacetone alcohol.

Test 9 could not be accurately calculated due to contamination of the sample during the test.

Results of these tests are shown in Table IV.

Table IV Volume -- surface area ratio 25 cc/in2 (25 cc/6.45 xl 0-4m2) Inhibitor Corrosion loss Test 1% v/v Ibs/ft2 Kg/m2 1 -- 0.102 0.49 2 Propargyl alcohol 0.058 0.28 3 Methyl butynol 0.019 0.09 4 Methyl pentynol 0.056 0.27 5 50 percent by volume hexynol 0.026 0.13 6 Ethyloctynol and 10 percent by volume 0.098 0.47 of 1 5 moles of ethylene oxide adduct of nonyl phenol 7 50 percent by volume propargyl 0.013 0.06 alcohol s 50 percent by volume quaternary quinoline 8 50 percent by volume methyl butynol 0.011 0.05 s 50 percent by volume quaternary quinoline 9 50 percent by volume methyl pentynol 0.105 0.51 s 50 percent by volume quaternary quinoline 10 50 percent by volume propargyl 0.044 0.21 alcohol 8 50 percent by volume pyridine 11 mixture of acetylenic alcohol, cyclic 0.052 0.25 amine and linear amines 12 mixture of acetylenic alcohol, cyclic 0.050 0.24 amine and linear amines 1 3 mixture of acetylenic alcohol, cyclic 0.048 0.23 amine and linear amines 14 mixture of acetylenic alcohol, cyclic 0.048 0.23 amine and linear amines 15 Blend II 0.005 0.02 16 Blend lil 0.007 0.03 Table IV shows that the composition of the invention effectively reduced iron corrosion.

Claims (14)

Claims

1. A composition useful as a well completion and workover fluid, comprising: (a) water; (b) a salt selected from aluminum chloride, aluminum bromide, aluminum iodide, ammonium chloride, ammonium bromide, ammonium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, zinc chloride, zinc bromide and zinc iodide, or a mixture of two or more thereof; and (c) an acetylenic alcohol having the general formula

wherein R is H, alkyl, phenyl, substituted phenyl, or a hydroxyalkyl radical, the composition having a density of about 1.0 to about 2.6 gm/cc (9.0 pounds to about 21.5 pounds per U.S. gallon of composition).

2. A composition according to claim 1, which also includes an organic amine selected from mono, di and tri-alkyl amines having from about two to about six carbon atoms in each alkyl moiety, six membered N-heterocyclic amines, quinolines and quaternized derivatives of quinolines, quaternized derivatives of pyridines, and alkyl pyridines having from one to five nuclear alkyl substituents per pyridine moiety wherein said alkyl substituents have from one to 12 carbon atoms, and any mixture of two or more thereof.

3. A composition according to claim 1 or 2, which also includes an acid selected from formic acid, acetic acid, propionic acid, butyric acid and glycolic acid, and any mixture of two or more thereof, said acid being present in said composition in the range of from about .2 to about 40 volume percent of said composition.

4. A composition according to claim 1,2 or 3, wherein said salt is calcium chloride.

5. A composition according to claim 2, wherein said amine is a pyridine or quinoline.

6. A composition according to claim 3 or 5, wherein said acid is acetic acid.

7. A composition according to any of claims 1 to 6, wherein the density of said composition is about 2.0 to 2.6 gm/cc (16.5 pounds to about 21.5 pounds per U.S. gallon).

8. A composition according to any preceding claim, wherein said acetylenic alcohol is selected from methylbutynol, ethyloctynol, methylpentynol, 3,4-dihydroxy 1 -butyne, 1 -ethynylcyclohexanol, 3- methyl-1 -nonyn-3-ol, 2-methyl-3-butyn-2-ol, 1 -propyn-3-ol, 1 -butyn-3-ol, 1 -pentyn-3-oI, 1 -heptyn-3- ol, 1 -octyn-3-oI, 1 -nonyn-3-ol, 1 -decyn-3-ol and 3-(2,4,6-trimethyl-3-cyclohexenyl)- 1 -propyne-3-ol, and any mixture of two or more thereof.

9. A composition according to any preceding claim, wherein the acetylenic alcohol is present in the range of from about 0.2 to 5.0 percent by volume of said composition.

10. A composition according to claim 1 substantially as herein described in any of the Examples.

11. A method of completing a well penetrating a subterranean formation, which comprises: contacting said well at sufficient hydrostatic pressure to control the well, with a composition as claimed in any of claims 1 to 10.

1 2. A method according to claim 11 substantially as herein described.

13. A method of inhibiting the corrosion of an iron surface in contact with an aqueous salt fluid, said fluid containing salts selected from aluminum chloride, aluminum bromide, aluminum iodide, ammonium chloride, ammonium bromide, ammonium iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, calcium chloride, calcium bromide, calcium iodide, zinc chloride, zinc bromide and zinc iodide, and mixtures of two or more thereof, comprising incorporating into said fluid at least an acetylenic alcohol having the general formula:

wherein R is H, alkyl, phenyl, substituted phenyl, or hydroxy-alkyl radical, to form a composition as claimed in any of claims 1 to 10.

14. A method according to claim 1 3 substantially as herein described in the Examples.