Patent EA-003014-B1 (EA)
Title: Fluid for drilling and servicing a well, method for drilling or servicing a well in a subterranean formation
Inventor: BROOKEY TOMMY F
IPC: C09K8/08
Filed: 1999-12-27
Abstract: 1. A well drilling and servicing fluid comprising an aqueous liquid having incorporated therein one or more viscosifiers, an aphrongenerating surfactant and aphrons, the fluid has a low shear rate viscosity as measured with a Brookfield Viscometer at 0.5 r/pm of at least 20,000 centipoise. 2. The fluid of Claim 1 wherein wherein the concentration of aphrons is less than 20% by volume of the fluid at atmospheric pressure. 3. The fluid of Claim 1 or 2 wherein the low shear rate viscosity is at least about 40,000 centipoise. 4. The fluid of Claim 1 or 2 wherein the low shear rate viscosity is at least about 98,000 centipoise. 5. The fluid of Claim 1, 2, 3, or 4 wherein the viscosifier is (1) an alginate polymer selected from the group consisting of sodium alginate, sodium calcium alginate, ammonium calcium alginate, ammonium alginate, potassium alginate, propyleneglycol alginate, and mixtures thereof; or (2) mixtures of xanthan gum and a cellulose derivative wherein the weight ratio of xanthan gum to cellulose derivative is in the range from about 80:20 to about 20:80, and wherein the cellulose derivative is selected from the group consisting of hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, and mixtures thereof; or (3) mixtures of a bentonitic clay and an additive comprising (a) a nonionic, water-soluble polysaccharide selected from the group consisting of (i) a non-ionic, water-soluble cellulosic derivative, (ii) a non-ionic water-soluble guar derivative; or (b) an anionic water-soluble polysaccharide selected from the group consisting of (i) a carboxymethyl cellulose or (ii) Xanthomonas campestris polysaccharide; or (c) a combination thereof; and (d) an intermediate molecular weight polyglycol, selected from the group consisting of polyethylene glycol, polypropylene glycol, and poly-(alkanediol), having an average molecular weight of from about 600 to about 30,000, said polyglycol being used in an amount effective to provide compatibility in the drilling fluid between the clay and the polysaccharide; or (4) compatible mixtures thereof; wherein the components of the mixtures may be added individually to the fluid to effect enhancement of the low shear rate viscosity thereof. 6. The fluid of Claim 5 wherein the concentration of aphrons is less than 15% by volume of the fluid at atmospheric pressure. 7. The fluid of Claim 1, 2, 3, or 4 wherein the concentration of aphrons is less than 15% by volume of the fluid at atmospheric pressure. 8. The fluid of Claim 1, 3, 4 or 7 wherein the fluid is continuously recirculated. 9. The fluid of Claim 1, 3, 4 or 7 wherein at least one viscosifier comprises a biopolymer. 10. The fluid of Claim 1, 3, 4 or 7 wherein at least one viscosifier comprises a bentonitic clay. 11. The fluid of Claim 1, 3, 4 or 7 wherein at least one viscosifier comprises a bentonitic clay and an additive. 12. The fluid of Claim 1, 3, 4 or 7 wherein the aphrons are generated in the liquid enabling to absorb an excessive liquid for drilling or servicing as the fluid exits into the formation. 13. The fluid of Claim 1, 3, 4 or 7 wherein one of viscosifiers comprises a flocculating bentonic clay for a low shear rate. 14. A method for drilling or servicing a well in a subterranean formation comprising circulating the fluid for drilling or servicing in a well wherein an aqueous liquid is used for drilling or servicing in which are dispersed at least one water-soluble aphrongenerating surfactant, at least one viscosifier, the drilling or servicing fluid fluid has a low shear rate viscosity as measured with a Brookfield Viscometer at 0.5 r/pm of at least 20,000 centipoise comprises aphrons. 15. The method of Claim 14 wherein the concentration of aphrons is less than 20% by volume of the fluid at atmospheric pressure. 16. The method of Claim 14 wherein the concentration of aphrons is less than 15% by volume of the fluid at atmospheric pressure. 17. The method of Claim 14 wherein the fluid has the low shear rate viscosity of at least about 40,000 centipoise. 18. The method of Claim 14 wherein the fluid has the low shear rate viscosity of at least about 98,000 centipoise. 19. The method of Claim 14 wherein at least one viscosifier comprises (1) an alginate polymer selected from the group consisting of sodium alginate, sodium calcium alginate, ammonium calcium alginate, ammonium alginate, potassium alginate, propyleneglycol alginate, and mixtures thereof; or (2) mixtures of xanthan gum and a cellulose derivative wherein the weight ratio of xanthan gum to cellulose derivative is in the range from about 80:20 to about 20:80, and wherein the cellulose derivative is selected from the group consisting of hydroxyethylcellulose, hydroxypropylcellulose, carboxymethylcellulose, and mixtures thereof; or (3) mixtures of a bentonitic clay and an additive comprising (a) a nonionic, water-soluble polysaccharide selected from the group consisting of (i) a non-ionic, water-soluble cellulosic derivative, (ii) a non-ionic water-soluble guar derivative; or (b) an anionic water-soluble polysaccharide selected from the group consisting of (i) a carboxymethyl cellulose or (ii) Xanthomonas campestris polysaccharide; or (c) a combination thereof; and (d) an intermediate molecular weight polyglycol, selected from the group consisting of polyethylene glycol, polypropylene glycol, and poly-(alkanediol), having an average molecular weight of from about 600 to about 30,000, said polyglycol being used in an amount effective to provide compatibility in the drilling fluid between the clay and the polysaccharide; or (4) compatible mixtures thereof; wherein the components of the mixtures may be added individually to the fluid to effect enhancement of the low shear rate viscosity thereof. 20. The method of any of Claims 14 to 18 wherein the fluid is circulated continuously. 21. The method of any of Claims 14 to 18 wherein a biopolymer is used as at least one of viscosifiers produced by bacterium, fungi or other microorganisms on a suitable substrate. 22. The method of any of Claims 14 to 18 wherein at least one viscosifier comprises a bentonitic clay. 23. The method of any of Claims 14 to 18 wherein at least one viscosifier comprises a bentonitic clay and an additive. 24. The method of any of Claims 14 to 18 wherein aphrons are used to prevent the fluid loss from penetrating the excess fluid for drilling or servicing into the formation. 25. The method of any of Claims 14 to 18 wherein a flocculating bentonic clay is used for a low shear rate.