WELLBORE FLUID

• US 20090291861A1
• Filed: 08/02/2007
• Published: 11/26/2009
• Est. Priority Date: 08/07/2006
• Status: Abandoned Application

• Current Assignee: BP Exploration Operating Company Limited (BP PLC), EP Exploration Operating Company Limited
• Original Assignee: BP Exploration Operating Company Limited (BP PLC)
• Inventors: Sawdon, Christopher Alan
• Application Number:
  US12/309,928
• Publication Number:
  US 20090291861A1
• Time in Patent Office: Days
• US Class Current: 507/110
• CPC Class Codes: C09K 2208/18 Bridging agents, i.e. particles for temporarily filling the pores of a formation; Graded salts
• CPC Class Codes: C09K 8/08 containing natural organic compounds, e.g. polysaccharides, or derivatives thereof
• CPC Class Codes: C09K 8/206 Derivatives of other natural products, e.g. cellulose, starch, sugars
• CPC Class Codes: C09K 8/28 containing organic additives
• CPC Class Codes: C09K 8/32 Non-aqueous well-drilling compositions, e.g. oil-based
• CPC Class Codes: C09K 8/514 of natural origin, e.g. polysaccharides, cellulose C09K8/512 takes precedence

Abstract

There is provided a wellbore fluid comprising a polymeric saccharide having a number average molecular weight of not more than 50,000 which is a fructan or a partially-hydrolysed fructan or partially-hydrolysed starch, said fructan of partially-hydrolysed fructan or partially-hydrolysed starch having been modified by the introduction of one or more groups having the formula R—NH—CO— and/or R—CO—, wherein R represents a group having 4 to 32 carbon atoms.

Claims

1-15. -15. (canceled)

16. A wellbore fluid comprising a polymeric saccharide having a number average molecular weight of not more than 50,000 which is a fructan or a partially-hydrolysed fructan or partially-hydrolysed starch, said fructan or partially-hydrolysed fructan or partially-hydrolysed starch having been modified by the introduction of one or more groups having the formula R—

NH—

CO— and

/or R—

CO—

, wherein R represents a group having 4 to 32 carbon atoms.

17. A wellbore fluid as claimed in claim 16, in which the polymeric saccharide is derived from inulin.

18. A wellbore fluid as claimed in claim 17, in which the inulin has a degree of polymerisation ranging from 3 to about 200.

19. A wellbore fluid as claimed in claim 16, in which R is a linear hydrocarbyl radical having 6 to 20 carbon atoms.

20. A wellbore fluid as claimed in claim 19, in which R is a linear alkyl or mono-unsaturated alkenyl group having 6 to 18 carbon atoms.

21. A wellbore fluid as claimed in claim 16, in which the average degree of substitution of the polymeric saccharide is from 0.01 to 2.

22. A wellbore fluid as claimed in claim 21, which is an oil-based fluid in which the average degree of substitution of the polymeric saccharide is from 0.2 to 2.

23. A wellbore fluid as claimed in claim 21, which is a water-based fluid in which the average degree of substitution of the polymeric saccharide is from 0.01 to 0.5.

24. A wellbore fluid as claimed in claim 16, in which the concentration of the olymeric saccharide is from 0.1 to 20% by weight based on the total weight of the oil and/or water present in the fluid.

25. A wellbore fluid as claimed in claim 16, which comprises a solution of the polymeric saccharide in water, insubstantial amounts, or no, oil being present;

or which is an oil-in-water emulsion.

26. A wellbore fluid as claimed in claim 24, which is an oil-in-water emulsion in which the oil is a crude oil, a refined petroleum fraction, a mineral oil, a synthetic hydrocarbon, or a non-hydrocarbon oil that is capable of forming a stable emulsion with water.

27. A wellbore fluid as claimed in claim 16, which additionally comprises at least one additional fluid loss control agent.

28. A wellbore fluid as claimed in claim 16, which has a plastic viscosity in the range 1 to 100 mPa·

s.

29. A wellbore fluid as claimed in claim 16, which is a drilling fluid.

30. A method of carrying out a wellbore operation using a circulating wellbore fluid, the method comprising circulating in the wellbore a wellbore fluid as claimed in claim 29.