Rheological parameters evaluation of different test methods in cement slurries for HPHT wells
Rheology, Cementing, HPHT Oil Wells
Temperature is an important factor for the determination of rheological properties of a cement slurry. The American Petroleum Institute (API) recommends in its RP 10B-2 standard that rheological parameters of cement slurries at bottom hole circulation temperature (BHCT) greater than 190 °F must be determined in two steps: (i) the slurry must be conditioned at BHCT conditions using a pressurized consistometer and (ii) cooled down to 190 °F and depressurized to atmospheric conditions so an atmospheric viscometer can be used. Rheology tests of HPHT slurries were carried out on a pressurized HPHT viscometer in which pressure and temperature can be applied as simulated for BHCT conditions and the results were compared to API RP 10B-2 procedures. Different rheological parameters were obtained between these two methods. In addition, hydraulic simulations were performed to evaluate the impact of those differences on cement slurry displacement in a cementing job. Displacement simulation revealed that the difference between those rheological parameters determination method can be impactfull in the evaluation of maximum equivalent circulation density (ECD), washing and slurry displacement efficiency.