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1. US6668927 - Well completion foamed spacer fluids and methods

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

What is claimed is:

1. A method of displacing a first fluid from a well bore with an incompatible second fluid comprising the steps of:
(a) placing a foamed spacer fluid between said first and second fluids to separate said first and second fluids and to remove said first fluid from the walls of said well bore, said foamed spacer fluid comprising water, a weighting material, a dispersing agent, a suspending agent and friction reducer, a mixture of foaming and foam stabilizing surfactants and a gas; and then
(b) displacing said first fluid and said foamed spacer fluid from said well bore with said second fluid.
 
2. The method of claim 1 wherein said water is selected from the group consisting of fresh water and salt water.
 
3. The method of claim 1 wherein said weighting material is selected from the group consisting of barium sulfate, hematite, magnesium tetraoxide and calcium carbonate.
 
4. The method of claim 1 wherein said weighting material is barium sulfate.
 
5. The method of claim 1 wherein said weighting material is present in said foamed spacer fluid in an amount in the range of from about 49 to about 576 pounds per barrel of water therein.
 
6. The method of claim 1 wherein said dispersing agent is selected from the group consisting of naphthalene sulfonate condensed with formaldehyde, sodium polyacrylate, a terpolymer of acrylic acid, alkyloxybenzene sulfonate and methally sulfonate, formaldehyde, acetone, bisulfate condensate, melamine formaldehyde condensate, and mixtures thereof.
 
7. The method of claim 1 wherein said dispersing agent is present in said foamed spacer fluid in an amount in the range of from about 3.5% to about 6% by weight of said water therein.
 
8. The method of claim 1 wherein said suspending agent and friction reducer is selected from the group consisting of sepiolite, whelan gum, xanthan gum, hydroxyethyl cellulose, bentonite, attapulgite, and mixtures thereof.
 
9. The method of claim 1 wherein said suspending agent and friction reducer is xanthan gum.
 
10. The method of claim 1 wherein said suspending agent and friction reducer is present in said foamed spacer fluid in an amount in the range of from about 0.5% to about 2% by weight of said water therein.
 
11. The method of claim 1 wherein said mixture of foaming and foam stabilizing surfactants is selected from the group consisting of a mixture of an ethoxylated alcohol ether sulfate surfactant, an alkyl or alkene amidopropyl betaine surfactant and an alkyl or alkene amidopropyl dimethyl amine oxide surfactant and a mixture of an alpha-olefinic sulfonate surfactant and an alkyl or alkene amidopropyl betaine surfactant.
 
12. The method of claim 1 wherein said mixture of foaming and foam stabilizing surfactants is a mixture of an ethoxylated alcohol ether sulfate surfactant, an alkyl or alkene amidopropyl betaine surfactant and an alkyl or alkene amidopropyl dimethyl amine oxide surfactant.
 
13. The method of claim 1 wherein said mixture of foaming and foam stabilizing surfactants is present in said foamed spacer fluid in an amount in the range of from about 0.5 to about 5% by weight of said water therein.
 
14. The method of claim 1 wherein said gas is nitrogen.
 
15. The method of claim 1 wherein said gas is present in said foamed spacer fluid in an amount in the range of from about 15% to about 70% by volume of said water therein.
 
16. The method of claim 1 which further comprises a well bore wall scouring material selected from the group consisting of diatomaceous earth, crystalline silican, amorphous silica, and mixtures thereof.
 
17. The method of claim 16 wherein said scouring material is crystalline silica.
 
18. The method of claim 16 wherein said scouring material is present in said foamed spacer fluid in an amount in the range of from about 15% to about 30% by weight of said water therein.
 
19. The method of claim 1 wherein said first fluid is a drilling fluid.
 
20. The method of claim 19 wherein said drilling fluid is selected from the group consisting of water based drilling fluids, and foamed drilling fluids.
 
21. The method of claim 1 wherein said second fluid is a hydraulic cement slurry.
 
22. The method of claim 21 wherein said cement is selected from the group consisting of Portland cements, slag cements, pozzolana cements, gypsum cements, aluminous cements, silica cements and high alkalinity cements.
 
23. The method of claim 21 wherein said cement is a Portland cement.
 
24. The method of claim 21 wherein said water in said hydraulic cement slurry is selected from the group consisting of fresh water and salt water.
 
25. A method of displacing drilling fluid from a well bore with a hydraulic cement slurry comprising the steps of:
(a) placing a foamed spacer fluid between said drilling fluid and said hydraulic cement slurry to separate said drilling fluid from said hydraulic cement slurry and to remove said drilling fluid and filter cake from the walls of said well bore, said foamed spacer fluid comprising water, a weighting material, a dispersing agent, a suspending agent and friction reducer, a scouring agent, a mixture of foaming and foam stabilizing surfactants and a gas; and then
(b) displacing said drilling fluid and said foamed spacer fluid from said well bore with said hydraulic cement slurry.
 
26. The method of claim 25 wherein said water in said foamed spacer fluid is selected from the group consisting of fresh water and salt water.
 
27. The method of claim 25 wherein said weighting material in said foamed spacer fluid is barium sulfate and is present in an amount in the range of from about 49 to about 576 pounds per barrel of water therein.
 
28. The method of claim 25 wherein said dispersing agent in said foamed spacer fluid is naphthalene sulfonate condensed with formaldehyde and is present in an amount in the range of from about 3.5% to about 6% by weight of water therein.
 
29. The method of claim 25 wherein said suspending agent and friction reducer in said foamed spacer fluid is xanthan gum and is present in an amount in the range of from about 0.5% to about 2% by weight of water therein.
 
30. The method of claim 25 wherein said scouring material in said foamed spacer fluid is crystalline silica and is present in an amount in the range of from about 15% to about 30% by weight of water therein.
 
31. The method of claim 25 wherein said mixture of foaming and foam stabilizing surfactants in said foamed spacer fluid is a mixture of an ethoxylated alcohol ether sulfate surfactant, an alkyl or alkene amidopropyl betaine surfactant and an alkyl or alkene amidopropyl dimethyl amine oxide surfactant and is present in an amount in the range of from about 0.5% to about 5% by weight of water therein.
 
32. The method of claim 25 wherein said gas in said foamed spacer fluid is nitrogen and is present in an amount in the range of from about 15% to about 70% by volume of water therein.