Cement slurries comprising hydrophobic polymers
AssigneeInstitut Francais du Petrole
InventorsAnnie Audibert, Christine Noïk, Alain Rivereau
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Abstract
The present invention relates to a cement slurry set in a wellbore. The slurry comprises cement, at least one mineral filler, water and a determined amount of at least one hydrophobically modified acrylamide or acrylate derivative. The present invention also relates to an additive specific to a cement slurry and acting as a filtrate reducer and as a rheological control agent, the additive comprising mainly a hydrophobically modified acrylamide or acrylate derivative.
Claims5
A cement slurry intended to be set in a wellbore through at least one geologic formation having a certain permeability, characterized in the cement slurry comprising cement, at least one mineral filler consisting of silica with a grain size distribution ranging between 5 and 200 μm, water and a determined amount of a copolymer, designated as HMPAM, having hydrophilic (Hy) and hydrophobic (Hb) units in aqueous solution, said copolymer having the following structure:
- —(Hb)—(Hy)— with a statistical distribution, wherein Hy has the following form:
- and
- HB has the following form:
- where said copolymer has weight average molecular weight of between 8·106 and 107 daltons.
A cement slurry intended to be set in a wellbore through at least one geologic formation having a certain permeability, characterized in that it comprises cement, at least one mineral filler consisting of silica with a grain size distribution ranging between 5 and 200 μm, water and a copolymer, designated as Hb1, having hydrophilic (Hy) and hydrophobic (Hb) units in aqueous solution, said copolymer having the following structure:
- —(Hb)—(Hy)—with a statistical distribution, wherein Hy has the following form:
- and Hb has the following form:
- wherein said copolymer has a weight average molecular weight of between 104 and 5·104 daltons and wherein the proportion of Hy units is about 80% and wherein said copolymer is contained In the cement slurry in a concentration ranging between 0.5 and 5% by weight and wherein the cement slurry has a water/cement ratio of 3:10 by weight.
A cement slurry intended to be set in a wellbore through at least one geologic formation having a certain permeability, characterized in that it comprises cement, at least one mineral filler consisting of silica with a grain size distribution ranging between 5 and 200 μm, water and a copolymer selected from the group of copolymers designated as S1 and S2 wherein
- S1 is a copolymer having units of
- with a molar ratio of about 50/50, in aqueous solution, with a statistical distribution, wherein said copolymer has a weight average molecular weight of between 5·105 and 5·106 daltons, and
- wherein S2 is a branched copolymer having the same units as S1, in aqueous solution, with a statistical distribution, wherein said copolymer has a weight average molecular weight of between 5·105 and 5·106 daltons and wherein the branched copolymer is formed by using N,N′ methylene bis acrylamine (MBA) as a branching agent.
Dependencies are inferred from the claim text.