Well drilling, workover and completion fluids

Claim 2

In a well treating fluid comprising: a. an aqueous suspension medium comprising an electrolyte solution having a density in the range from about 1.0 g/cm 3 to about 1.2 g/cm 3 ; b. a bridging agent; and c. a viscosifier and suspension additive in the amount of about 0.5 kg/m 3 to about 14 kg/m 3 ; the improvement which comprises utilizing as said bridging agent at least one hydrated borate selected from the group consisting of calcium borates, sodium calcium borates, and mixtures thereof, wherein said bridging agent has a particle size distribution wherein the range from about 1 micron to about 2000 microns, said treating fluid being free of polymers which contain two hydroxyl groups positioned in the cis-form on adjacent carbon atoms, or on carbon atoms in a 1,3 relationship which complex and cross-link in the presence of the borate anion of said hydrated borate at an alkaline pH.

Claim 3

The treating fluid of claim 1 wherein said bridging agent is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof.

Claim 4

The fluid of claim 1 wherein the bridging agent has a particle size distribution within the range from about 1 micron to about 800 microns with at least 1% of the particles being greater than 44 microns.

Claim 5

The treating fluid of claim 3 wherein said bridging agent is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof.

Claim 6

The fluid of claim 3 wherein at least 5% of the particles are greater than 44 microns, at least 50% of the particles are greater than 20 microns, and wherein less than 10% of the particles are less than 10 microns.

Claim 7

The treating fluid of claim 5 wherein said bridging agent is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof.

Claim 8

The fluid of claim 1 including a fluid loss additive.

Claim 9

The fluid of claim 1 wherein the viscosifier and suspension additive is selected from the group consisting of water soluble cellulose ethers, xanthan gum, and mixtures thereof.

Claim 10

The fluid of claim 8 including a fluid loss additive.

Claim 11

The fluid of claim 9 wherein said fluid loss additive comprises calcium lignosulfonate in an amount from about 0.5 kg/m 3 to about 28 kg/m 3 .

Claim 12

The fluid of claim 9 wherein said fluid loss control additive is selected from the group consisting of calcium lignosulfonate, chrome lignosulfonate, ferro chrome lignosulfonate, starch, starch derivatives, carboxymethyl cellulose having a degree of substitution in the range of 0.4 through 0.9, and mixtures thereof, wherein the amount of said fluid loss additive is from about 0.5 kg/m 3 to about 28 kg/m 3 of said fluid.

Claim 13

In a well completion and workover method wherein a subterranean formation in a well is contacted with an aqueous treating fluid to form a bridge and seal on said formation, said treating fluid containing an aqueous suspension medium having a density in the range from about 1.0 g/cm 3 to about 1.20 g/cm 3 , said density being obtained by dissolving one or more soluble salts in said aqueous suspension medium, and a bridging agent having a particle size distribution within the range from about 1 micron to about 2000 microns and a viscosifier and suspension additive, the improvement which comprises utilizing as said bridging agent a hydrated borate selected from the group consisting of calcium borate, sodium calcium borate, and mixtures thereof, said treating fluid being free of polymers which contain two hydroxyl groups positioned in the cis-form on adjacent carbon atoms, or on carbon atoms in a 1,3 relationship which complex and cross-link in the presence of the borate anion of said hydrated borate at an alkaline pH.

Claim 14

In a well completion and workover method wherein a subterranean formation in a well is contacted with an aqueous treating fluid to form a bridge and seal on said formation, said treating fluid containing an aqueous suspension medium having a density in the range from about 1.0 g/cm 3 to about 1.20 g/cm 3 , said density being obtained by dissolving one or more soluble salts in said aqueous suspension medium, and a bridging agent having a particle size distribution within the range from about 1 micron to about 2000 microns and a viscosifier and suspension additive, the improvement which comprises utilizing as said bridging agent a hydrated borate selected from the group consisting of calcium borate, sodium calcium borate, and mixtures thereof, said treating fluid being free of polymers which contain two hydroxyl groups positioned in the cis-form on adjacent carbon atoms, or on carbon atoms in a 1,3 relationship which complex and cross-link in the presence of the borate anion of said hydrated borate at an alkaline pH.

Claim 15

The method of claim 12 wherein said bridging agent is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof.

Claim 16

The method of claim 12 which additionally comprises dissolving said bridge and seal off of said formation with an aqueous liquid.

Claim 17

The method of claim 12 wherein the concentration of said viscosifier and suspension additive is from about 0.5 kg/m 3 to about 14 kg/m 3 , and wherein said treating fluid also contains a fluid loss additive.

Claim 18

The method of claim 15 which additionally comprises dissolving said bridge and seal off of said formation with an aqueous liquid.

Claim 19

In a well treating method wherein a subterranean formation in a well is contacted with a treating fluid comprising: (a) pumping said treating fluid in the well and contacting the formation with said treating fluid, wherein said treating fluid comprises: (1) an aqueous suspension medium having a density in the range from about 1.0 g/cm 3 to about 1.20 g/cm 3 , said density being obtained by dissolving one or more soluble salts in said aqueous suspension medium; (2) a bridging agent; and (3) a minor amount of a fluid loss additive to inhibit the loss of fluid into the formation and a suspension additive to prevent settling of said bridging agent particles; (b) controlling the pressure in the well by maintaining the density of said treating fluid in the range from about 1.007 g/cm 3 to about 1.26 g/cm 3 ; (c) forming a bridge and seal on the formation by providing size distribution within the range from about 1 micron to about 2000 microns; and (d) dissolving said bridge and seal from the formation for flow of hydrocarbons therefrom into the well; the improvement which comprises utilizing as said bridging agent at least one hydrated borate selected from the group consisting of calcium borates, sodium calcium borates, and mixtures thereof, said treating fluid being free of polymers which contain two hydroxyl groups positioned in the cis-form on adjacent carbon atoms, or on carbon atoms in a 1,3 relationship which complex and cross-link in the presence of the borate anion of said hydrated borate at an alkaline pH.

Claim 20

In a well treating method wherein a subterranean formation in a well is contacted with a treating fluid comprising: (a) pumping said treating fluid in the well and contacting the formation with said treating fluid, wherein said treating fluid comprises: (1) an aqueous suspension medium having a density in the range from about 1.0 g/cm 3 to about 1.20 g/cm 3 , said density being obtained by dissolving one or more soluble salts in said aqueous suspension medium; (2) a bridging agent; and (3) a minor amount of a fluid loss additive to inhibit the loss of fluid into the formation and a suspension additive to prevent settling of said bridging agent particles; (b) controlling the pressure in the well by maintaining the density of said treating fluid in the range from about 1.007 g/cm 3 to about 1.26 g/cm 3 ; (c) forming a bridge and seal on the formation by providing size distribution within the range from about 1 micron to about 2000 microns; and (d) dissolving said bridge and seal from the formation for flow of hydrocarbons therefrom into the well; the improvement which comprises utilizing as said bridging agent at least one hydrated borate selected from the group consisting of calcium borates, sodium calcium borates, and mixtures thereof, said treating fluid being free of polymers which contain two hydroxyl groups positioned in the cis-form on adjacent carbon atoms, or on carbon atoms in a 1,3 relationship which complex and cross-link in the presence of the borate anion of said hydrated borate at an alkaline pH.

Claim 21

The method of claim 17 wherein said bridging agent is selected from the group consisting of ulexite, colemanite, probertite, and mixtures thereof.

Claim 22

The well treating method of claim 17 wherein the fluid loss additive is in the amount of about 0.5 kg/m 3 to about 28 kg/m 3 of said treating fluid, and wherein said suspension additive is in the amount of about 0.5 kg/m 3 to about 14 kg/m 3 of said treating fluid.

Claim 23

The well treating method of claim 19 wherein said fluid loss additive is selected from the group consisting of calcium lignosulfonate, chrome lignosulfonate, ferro chrome lignosulfonate, starch, starch derivatives, carboxymethyl cellulose having a degree of substitution in the range of 0.4 through 0.9, and mixtures thereof.