Patent ID: 6548452
Filing Date: 2003-04-15
Classification: C09K,Y10S

Abstract:
A drilling fluid comprising a weight material for increasing the density of said drilling fluid where said weight material is finely ground and the smallest particle of said weight material have been removed such that the weight material comprises about 0 to about 10% by weight particles less than about 6 microns in equivalent spherical diameter and about 0 to about 5% by weight particles larger than about 75 microns in equivalent spherical diameter, wherein after use in drilling, said drilling fluid has added thereto, for further use in drilling, additional coarser weight material such that the weight material overall comprises about 0 to about 5% by weight particles larger than about 75 microns in equivalent spherical diameter and about 1 to about 10% by weight particles less than about 6 microns in equivalent spherical diameter.