Automatic cementing system with improved density control

Abstract

An automatic cementing system and method are disclosed for precisely controlling the density of a slurry during a continuously mixed cement application. The system includes an input water line and a dry cement hopper for supplying water and cement, respectively, to a mixing chamber. The mixing chamber includes two chambers, Chamber A and Chamber B, for thoroughly mixing the water and cement together to form a cement slurry. Chamber B includes a level sensor for measuring the change in slurry level. The input line includes a pump for supplying the water to the mixing chamber, and a flow meter for measuring the rate at which the water is supplied. Similarly, the hopper includes a slide-gate valve for regulating the rate at which the dry cement is supplied to the mixing chamber. A discharge line with a discharge pump and a discharge flow meter receives and discharges cement slurry. A recirculation line is included for density control during initialization. A system controller receives operational parameters from the operator, including desired slurry density, mix water density, and dry cement density. As the slurry discharge rate increases to the desired value, the mix water flow rate increases to maintain the calculated volume percentage of mix water in the discharge slurry constant. The tub level drops, causing the slide-gate valve to open and add cement, raising the tub level to the setpoint level and maintaining an accurate discharge slurry density.