Clay stabilization during oil and gas well cementing operations
AssigneeHalliburton Services
InventorsCharles W. Smith, John K. Borchardt
Life of this patent
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Abstract
A process for treating a subterranean formation with an aqueous cement composition and minimizing damage to formation permeability by said composition filtrate comprising mixing with said composition at least one polycationic polymer having a molecular weight of about 400 to 6,000,000 prior to treating said formation.
Claims24
A process for filling a zone adjacent to a permeable formation containing clays and treating said clays with a clay stabilizing organic cationic polymer comprising:
- mixing an aqueous inorganic cement slurry containing a water soluble clay stabilizing organic cationic polymer, said polymer having a molecular weight of about 400-6,000,000 and containing cationic groups of nitrogen, sulfur, or phosphorous or combinations thereof, wherein said polymer is added to said slurry in an effective concentration to produce a filtrate containing polymer in an amount of at least about 0.1% by weight of filtrate;
- and
- introducing said aqueous cement slurry into said zone.
A process for treating a subterranean clay-containing formation with an aqueous cement composition wherein damage to the formation permability as a result of clay swelling or disintegration or migration of fine particles caused by contact with aqueous filtrate fluids from the cement composition is minimized comprising the steps of:
- adding a water soluble clay stabilizing organic cationic polymer to said aqueous cement composition in an amount such that the aqueous filtrate fluids from said composition contain said polymer in an amount at least about 0.1% by weight of said filtrate, said organic cationic polymer being selected from the group consisting of polymers and mixtures of polymers containing substantial portions of repeating polymer units defined by the formula:
- ##STR41## wherein:
- R.sup.1 is an aliphatic, cycloaliphatic, or aromatic radical containing 1-40 carbon atoms;
- R.sup.2, R.sup.3 and R.sup.4 are independently radicals defined as R.sup.1 and containing 0-6 carbon atoms and 0-2 hetero atoms or radicals comprising oxygen or nitrogen;
- Z is a cation independently selected from nitrogen, phosphorous or sulfur;
- X is an anion;
- m is an integer which, with the valence of X, is sufficient to balance the cationic charges of the polymer units;
- n is an integer equal to the number of monomer or polymer units required to give a molecular weight in the range of about 400-6,000,000;
- and wherein the number and arrangement of R groups and heteroatoms are such that the chemical structure and valences produce a stable polymer;
- and
- introducing said cement composition into said formation.
The process of claim 21 wherein said repeating polymer units are of the formula:
- ##STR47##
Dependencies are inferred from the claim text.