Controlling salt contaminated drilling fluids by the addition of an admixture of a water soluble chromate and ethylene dicarboxylic acid

Claim 2

METHOD OF CONTROLLING THE RHEOLOGY OF A FRESH WATER DRILLING FLUID THAT HAS BEEN CONTAMINATED WITH A SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND POTASSIUM CHLORIDE AND MIXTURE THEREOF, BY ADDING TO SAID SALT CONTAMINATED DRILLING MUD IN AN AMOUNT OF FROM ABOUT 0.5 TO ABOUT 10 POUNDS PER BARREL, AN ADMIXTURE OF A WATER SOLUBLE CHROMATE AND AN ETHYLENE DICARBOXYLIC ACID OR AN ANHYDRIDE THEREOF, SELECTED FROM THE GROUP CONSISTING OF MALEIC ACID, FUMARIC ACID AND MALEIC ACID ANHYDRIDE, AND MIXTURES THEREOF.

Claim 3

Method of controlling the rheology of a fresh water drilling fluid that has been contaminated with a salt selected from the group consisting of sodium chloride and potassium chloride and mixture thereof, by adding to said salt contaminated drilling mud in an amount of from about 0.5 to about 10 pounds per barrel, an admixture of a water soluble chromate and an ethylene dicarboxylic acid or an anhydride thereof, selected from the group consisting of maleic acid, fumaric acid and maleic acid anhydride, and mixtures thereof.

Claim 4

Method of controlling the rheology of a fresh water drilling fluid that has been contaminated with a salt selected from the group consisting of sodium chloride and potassium chloride and mixture thereof, by adding to said salt contaminated drilling mud in an amount of from about 0.5 to about 10 pounds per barrel, an admixture of a water soluble chromate and an ethylene dicarboxylic acid or an anhydride thereof, selected from the group consisting of maleic acid, fumaric acid and maleic acid anhydride, and mixtures thereof.

Claim 5

Method as claimed in claim 1 wherein said ethylenedicarboxylic acid is maleic acid.

Claim 6

Method as claimed in claim 1 wherein said ethylenedicarboxylic acid is maleic acid anhydride.

Claim 7

Method as claimed in claim 1 wherein said ethylenedicarboxylic acid is fumaric acid.

Claim 8

Method as claimed in claim 1 wherein said admixture is added in an amount of from about 1 to 5 pounds per barrel.

Claim 9

Method as claimed in claim 1 wherein said chromate is sodium chromate.

Claim 10

Method as claimed in claim 1 wherein said chromate is sodium dichromate.

Claim 11

Method as claimed in claim 1 wherein said mixture contains from 0.2 to 1 part by weight of chromate and from 1 to 5 parts by weight of said ethylenedicarboxylic acid or the anhydride thereof.

Claim 12

Method as claimed in claim 1 wherein said mixture contains from 0.25 to 1 part of sodium chromate and from 1 to 4 parts by weight of maleic acid.

Claim 13

Method as claimed in claim 1 wherein said mixture is prepared by mixing said chromate and said ethylenedicarboxylic acid or the anhydride thereof in water, and the resulting aqueous admixture is added to said drilling fluid.

Claim 14

Method as claimed in claim 10 wherein said aqueous admixture is dried at about 200*F. before being added to said drilling fluid.

Claim 15

In a method of drilling wells wherein a fresh water drilling fluid is passed through the well in contact with an earth formation during the drilling operation in contact with a salt selected from the group consisting of sodium chloride and potassium chloride and mixture thereof in the formation, the improvement which comprises contacting said earth formation with a fresh water drilling fluid containing clay solids dispersed therein by a clay dispersing agent, said drilling fluid containing from about 0.5 to about 10 pounds per barrel of drilling fluid of an admixture of sodium chromate and an ethylene dicarboxylic acid or an anhydride thereof, selected from the group consisting of maleic acid, fumaric acid and maleic acid anhydride and mixtures thereof, said admixture being effective to restore the rheology of said drilling fluid in the presence of any contaminating amounts of salt in the formation.

Claim 16

In a method of drilling wells wherein a fresh water drilling fluid is passed through the well in contact with an earth formation during the drilling operation in contact with a salt selected from the group consisting of sodium chloride and potassium chloride and mixture thereof in the formation, the improvement which comprises contacting said earth formation with a fresh water drilling fluid containing clay solids dispersed therein by a clay dispersing agent, said drilling fluid containing from about 0.5 to about 10 pounds per barrel of drilling fluid of an admixture of sodium chromate and an ethylene dicarboxylic acid or an anhydride thereof, selected from the group consisting of maleic acid, fumaric acid and maleic acid anhydride and mixtures thereof, said admixture being effective to restore the rheology of said drilling fluid in the presence of any contaminating amounts of salt in the formation.

Claim 17

IN A METHOD OF DRILLING WELLS WHEREIN A FRESH WATER DRILLING FLUID IS PASSED THROUGH THE WELL IN CONTACT WITH AN EARTH FORMATION DURING THE DRILLING OPERATION IN CONTACT WITH A SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND POTASSIUM CHLORIDE AND MIXTURE THEREOF IN THE FORMATION THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID EARTH FORMATION WITH A FRESH WATER DRILLING FLUID CONTACTING SAID EARTH FO DISPERSED THEREIN BY A CLAY DISPERSING AGENT, SAID DRILLING FLUID CONTAINING FROM ABOUT 0.5 TO ABOUT 10 POUNDS PER BARREL OF DRILLING FLUID OF AN ADMIXTURE OF SODIUM CHROMATE AND AN ETHYLENE DICARBOCYLIC ACID OR AN ANHYDRIDE THEREOF, SELECTED FROM THE GROUP CONSISTING OF MALEIC ACID, FUMARIC ACID AND MALEIC ACID ANHYDRIDE AND MIXTURES THEREOF, SAID ADMIXTURE BEING EFFECTIVE TO RESTORE THE RHEOLOGY OF SAID DRILLING FLUID IN THE PRESENCE OF ANY CONTAMINATING AMOUNTS OF SALT IN THE FORMATION.

Claim 18

IN A METHOD OF DRILLING WELLS WHEREIN A FRESH WATER DRILLING FLUID IS PASSED THROUGH THE WELL IN CONTACT WITH AN EARTH FORMATION DURING THE DRILLING OPERATION IN CONTACT WITH A SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND POTASSIUM CHLORIDE AND MIXTURE THEREOF IN THE FORMATION THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID EARTH FORMATION WITH A FRESH WATER DRILLING FLUID CONTACTING SAID EARTH FO DISPERSED THEREIN BY A CLAY DISPERSING AGENT, SAID DRILLING FLUID CONTAINING FROM ABOUT 0.5 TO ABOUT 10 POUNDS PER BARREL OF DRILLING FLUID OF AN ADMIXTURE OF SODIUM CHROMATE AND AN ETHYLENE DICARBOCYLIC ACID OR AN ANHYDRIDE THEREOF, SELECTED FROM THE GROUP CONSISTING OF MALEIC ACID, FUMARIC ACID AND MALEIC ACID ANHYDRIDE AND MIXTURES THEREOF, SAID ADMIXTURE BEING EFFECTIVE TO RESTORE THE RHEOLOGY OF SAID DRILLING FLUID IN THE PRESENCE OF ANY CONTAMINATING AMOUNTS OF SALT IN THE FORMATION.

Claim 19

Method as claimed in claim 12 wherein said ethylenedicarboxylic acid is maleic acid.

Claim 20

Method as claimed in claim 12 wherein said ethylenedicarboxylic acid anhydride is maleic acid anhydride.

Claim 21

Method as claimed in claim 12 wherein said admixture contains said ethylenedicarboxylic acid or the anhydride thereof in an amount of from about 1 to 4 pounds.

Claim 22

Method as claimed in claim 12 wherein said admixture contains said sodium chromate in an amount of from about 0.25 to 1 pound.

Claim 23

A drilling fluid additive to restore the mud properties of a fresh water drilling fluid that has been contaminated with a salt selected from the group consisting of sodium chloride and potassium chloride and mixture thereof, which comprises an admixture of a water soluble chromate in an amount of from 0.2 to 1 part by weight and from about 1 to about 5 parts by weight of a member selected from the group consisting of maleic acid, maleic acid anhydride, fumaric acid and a mixture of maleic acid and maleic anhydride.

Claim 24

A drilling fluid additive to restore the mud properties of a fresh water drilling fluid that has been contaminated with a salt selected from the group consisting of sodium chloride and potassium chloride and mixture thereof, which comprises an admixture of a water soluble chromate in an amount of from 0.2 to 1 part by weight and from about 1 to about 5 parts by weight of a member selected from the group consisting of maleic acid, maleic acid anhydride, fumaric acid and a mixture of maleic acid and maleic anhydride.

Claim 25

A DRILLING FLUID ADDITIVE TO RESTORE THE MUD PROPERTIES OF A FRESH WATER DRILLING FLUID THAT HAS BEEN CONTAMINATED WITH A SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND POTASSIUM CHLORIDE AND MIXTURE THEREOF, WHICH COMPRISES AN ADMIXTURE OF A WATER SOLUBLE CHROMATE IN AN AMOUNT OF FROM 0.2 TO 1 PART BY WEIGHT AND FROM ABOUT 1 TO ABOUT 5 PARTS BY WEIGHT OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF MALEIC ACID, MALEIC ACID ANHYDRIDE, FUMARIC ACID AND A MIXTURE OF MALEIC ACID AND MALEIC ANHYDRIDE.

Claim 26

A DRILLING FLUID ADDITIVE TO RESTORE THE MUD PROPERTIES OF A FRESH WATER DRILLING FLUID THAT HAS BEEN CONTAMINATED WITH A SALT SELECTED FROM THE GROUP CONSISTING OF SODIUM CHLORIDE AND POTASSIUM CHLORIDE AND MIXTURE THEREOF, WHICH COMPRISES AN ADMIXTURE OF A WATER SOLUBLE CHROMATE IN AN AMOUNT OF FROM 0.2 TO 1 PART BY WEIGHT AND FROM ABOUT 1 TO ABOUT 5 PARTS BY WEIGHT OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF MALEIC ACID, MALEIC ACID ANHYDRIDE, FUMARIC ACID AND A MIXTURE OF MALEIC ACID AND MALEIC ANHYDRIDE.

Claim 27

A drilling fluid additive as claimed in claim 17 wherein said admixture is a mixture of said chromate and said maleic acid in water.