Fluid loss additive with improved rheological properties
AssigneeSekisui Specialty Chemicals America, LLC
InventorKristy J. Beckman
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Abstract
A polymeric fluid loss additive for hydraulic cement which includes a polymer component which exhibits delayed hydration. The fluid loss additive is suitable for use in cement slurries which may be subjected to elevated temperatures, as is common in oil and gas drilling operations. By way of the invention, cement slurries are provided which have improved fluid loss properties at high temperatures, while maintaining manageable rheologies that are conducive to mixing, pumping, and the like across a broad range of temperatures.
Claims12
A method of making a hydraulic cement slurry exhibiting reduced fluid loss comprising the steps of slurrying a hydraulic cement composition with water and admixing a fluid loss additive therewith, the improvement comprising:
- i providing a polymeric fluid loss additive which consists essentially of a polyvinyl alcohol (PVOH) blend and a dispersant, wherein the PVOH blend includes a first polyvinyl alcohol polymer and a second polyvinyl alcohol polymer, wherein both the first polyvinyl alcohol polymer and the second polyvinyl alcohol polymer have a degree of hydrolysis of at least 99%;
- wherein the first polyvinyl alcohol polymer has a characteristic viscosity of about 10 to 50 cps;
- wherein the second polyvinyl alcohol polymer has a characteristic viscosity which is about 50% to 100% higher than the characteristic viscosity of the first polyvinyl alcohol polymer;
- and
- ii combining the polymeric fluid loss additive with the cement slurry.
Dependencies are inferred from the claim text.