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US 5,343,950 AGranted
Drilling and cementing extended reach boreholes
AssigneeShell Oil Company
InventorsArthur H. Hale, Kenneth M. Cowan
Life of this patent
Estimating the term…
Abstract
An extended reach well such as the deviated wells typically drilled from offshore platforms is drilled using a drilling fluid comprising blast furnace slag and water which drilling fluid is circulated during the drilling to lay down a filter cake. Thereafter, an activator is added and generally, an alkaline material and additional blast furnace slag, to produce a cementitious slurry which is passed down a casing and up into an annulus to effect primary cementing.
Claims17
A method comprising:
- drilling a deviated wellbore with a drill string comprising a drill pipe utilizing a drilling fluid comprising granulated water-quenched blast furnace slag and water;
- circulating said drilling fluid down said drill pipe and up an annulus between said drill pipe and walls of said wellbore, thus laying down a filter cake on said walls of said wellbore during said drilling;
- withdrawing said drill string and inserting a casing;
- adding an activator to said drilling fluid to produce a cementitious slurry;
- and
- circulating said cementitious slurry down said casing and up into an annulus formed between said casing and the walls of said wellbore.
3 more elements
A method for drilling an offshore oil well comprising:
- drilling a borehole with a rotary drill comprising a drill pipe and a bit, wherein at least the bottom portion thereof is deviated from the vertical by an angle of at least 30 degrees;
- utilizing a drilling fluid comprising 20-50 lbs/bbl of granulated water-quenched blast furnace slag, clay, starch, partially hydrolyzed polyacrylamide, and barite;
- circulating said drilling fluid down said drill pipe and up and annulus between said pipe and the walls of said borehole thus laying down a filter cake on said walls of said borehole;
- withdrawing said rotary drill and inserting a casing;
- adding grandulated water-quenched blast furnace slag, a lignosulfonate thinner, and an activator comprising a mixture of caustic soda and soda ash to said drilling fluid to produce a cementitious slurry having a total amount of granulated water-quenched blast furnace slag within the range of 100 to 500 lbs/bbl;
- and
- passing said cementitious slurry down through said casing and up into an annulus formed by said casing and said walls of said borehole.
4 more elements
Dependencies are inferred from the claim text.