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US 4,120,360 AGranted
Treating wells to mitigate flow-after-cementing
AssigneeMobil Oil Corporation
InventorJoseph U. Messenger
Life of this patent
Estimating the term…
Abstract
This specification discloses a method of treating a well drilled into the earth. In carrying out this method there is formed a lightweight thixotropic cement slurry that is comprised of a low density calcined shale cement, attapulgite and water, in ratios to provide a pumpable slurry that has zero water separation. This lightweight thixotropic cement slurry having zero water separation is placed in a well and allowed to set.
Claims6
A method of cementing a well that penetrates the earth, comprising the steps of:
- blending a low-density calcined shale cement with attapulgite in an amount no greater than about 2 weight percent based on cement and water in an amount to form a thixotropic cement slurry having a density within the range of 11.5 lb/gal to 13.5 lb/gal and having essentially zero water separation;
- injecting said slurry down said well;
- and maintaining said slurry in said well to allow said slurry to set.
A method of cementing pipe in a well penetrating an active gas zone to prevent flow-after-cementing, comprising:
- blending a low-density calcined shale cement with attapulgite in an amount no greater than about 2 weight percent based on cement and sea water in an amount to form a thixotropic cement slurry having a density within the range of 12.5 lb/gal to 13.5 lb/gal and having essentially zero water separation;
- injecting said slurry down said well and into the annulus formed about said pipe;
- and
- maintaining said slurry in said annulus to allow said slurry to set.
1 more element
Dependencies are inferred from the claim text.