Coal slag universal fluid
AssigneeShell Oil Company
InventorKenneth M. Cowan
Life of this patent
Estimating the term…
Abstract
A composition suitable for drilling and cementing comprising coal slag, water and drill solids, the components of the drilling fluid being chosen so as to have a dual functionality in promoting the drilling fluid and thereafter in being functional constituents of a cementitious slurry. Also, a method for drilling using a drilling fluid containing coal slag so as to lay down a filter cake which is settable and which is compatible with a subsequent coal slag cementitious slurry.
Claims35
A method for drilling, comprising:
- drilling a wellbore, with a drill string comprising a drill pipe, utilizing a drilling fluid comprising water, drill solids and coal slag;
- circulating said drilling fluid down said drill pipe and up an annulus between said drill pipe and walls of said borehole, thus laying down a filter cake on said walls of said borehole during said drilling and producing a used drilling fluid.
A method for drilling and cementing, comprising:
- drilling a wellbore with a drill string comprising a drill pipe utilizing a drilling fluid comprising water, drill solids and coal slag;
- circulating said drilling fluid down said drill pipe and up an annulus between said drill pipe and walls of said borehole, thus laying down a filter cake on said walls of said borehole during said drilling and producing a used drilling fluid;
- withdrawing said drill string and inserting a pipe, thus creating an annulus between said pipe and said walls of said borehole;
- incorporating an activator system into said used drilling fluid to produce a cementitious slurry;
- and
- displacing said cementitious slurry into at least a portion of said annulus between said pipe and said walls of said borehole.
A drilling fluid composition comprising water, drill solids and 1 to 100 lbs/bbl of said composition of coal slag.
Dependencies are inferred from the claim text.