Cement slurries comprising hydrophobic polymers
AssigneeInstitut Francais du Petrole
InventorsAnnie Audibert, Christine Noik, 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.
Claims7
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, water and a determined amount of at least one polymer with hydrophilic (Hy) and hydrophobic (Hb) units in aqueous solution, said hydrophobic units (Hb) containing C1-C30 alkyl, aryl or alkyl-aryl groups, said polymer having the following structure :
- —(Hb)—(Hy)— with a statistical distribution, and:
- Hy has the following form:
- 3
- where R5 is H or CH3, and Z1 is COOH or CONH2 or CONHR1SO3−, or CONHR″1, R″1 is CH3;
- HB has the following form:
- 4
- where R′5 is H or CH3 and Z2 is COOR7, C6H4SO3H, COOR′1, CONR1R′1 or CONR1R7, R7 being a non-ionic surfactant consisting of an alkyl polyoxyethylene chain, R1 is H or a C1-C30 alkyl, aryl or alkyl-aryl radical, and R′1 is a C1-C30 alkyl, aryl or alkyl-aryl radical.
A slurry as claimed in any one of the previous claims, comprising at least one of the polymers selected from the group consisting of:
- HMPAM, where R5 is H and Z1 is CONH2, R′5═CH3 and Z2 is COOR′1 with R′1═C9H19,
- S1, S2 where R5 is H and Z1 is CONH2, R′5═H and Z2 is C6H4SO3H,
- Hb1 where R5 is H, Z1 is COOH, R′5 is H and Z2 is COOR′1 with R′ 1 being C4.
A slurry as claimed in any one of the previous claims, wherein the mineral filler consists of silica whose grain size ranges between 5 and 200 μm and microsilica whose grain size ranges between 0.1 and 20 μm.
An additive for cement slurry, characterized in that it essentially comprises a polymer with hydrophilic (Hy) and hydrophobic (Hb) units in aqueous solution, said hydrophobic units (Hb) containing C1-C30 alkyl, aryl or alkyl-aryl groups, said polymer having the following structure:
- Hy has the following form:
- 5
- where R5 is H or CH3, and Z1 is COOH or CONH2 or CONHR1SO3−, or CONHR″1, R″1 is CH3;
- Hb has the following form:
- 6
- where R′5 is H or CH3 and Z2 is COOR7, C6H4SO3H, COOR′1, CONR1R′1 or CONR1R7, R7 being a non-ionic surfactant consisting of an alkyl polyoxyethylene chain, R1 is H or a C1-C30 alkyl, aryl or alkyl-aryl radical, and R′1 is a C1-C30 alkyl, aryl or alkyl-aryl radical.
Dependencies are inferred from the claim text.