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US 4,235,291 AGranted
Treating wells to mitigate flow-after-cementing
AssigneeMobil Oil Corporation
InventorJoseph U. Messenger
Life of this patent
Estimating the term…
Abstract
A method of cementing a well drilled into the earth is disclosed wherein there is formed a pumpable thixotropic cement slurry having essentially zero water separation at downhole conditions and being formed of Portland cement, bentonite and water. This cement slurry is injected into a well and allowed to set.
Claims5
A method of cementing a well that penetrates the earth, comprising the steps of:
- (a) blending hydraulic cement with water swellable clay, said clay being present in an amount within the range of 0.05 to 2.0 weight percent based on cement and water to form a pumpable thixotropic cement slurry that exhibits essentially zero water separation at downhole conditions;
- (b) injecting said slurry down said well;
- and
- (c) maintaining said slurry in said well to allow said slurry to set.
1 more element
A method of cementing pipe in a well penetrating an active gas zone to prevent flow-after-cementing, comprising:
- (a) forming a pumpable thixotropic cement slurry that exhibits essentially zero water separation at downhole conditions, said slurry being formed of portland cement, bentonite, silica flour, weighting agent, potassium chloride, filter loss additive, retarder and mixing water and wherein said bentonite is added to said mixing water before any of the other components of the slurry and is added thereto in an amount of about 0.2 weight percent based on cement.
Dependencies are inferred from the claim text.