Method for controlling the density of a well fracturing slurry

Abstract

An automated density and chemical controller automatically controls the density and chemical proportions of a slurry that is injected into a well during a well fracturing operation. The automated density controller receives from the operator the parameters of the fracturing operation and automatically controls the addition of a proppant to water to produce a slurry with a desired density. The automated density controller measures the incoming flow of water into a blender tub and regulates the delivery of proppant in the blender tub to produce a slurry of the desired density. The performance characteristics of the mechanism used to deliver the proppant are programmed into the controller to enable the controller to regulate the quantity of proppant delivered by controlling the operational speed of the delivery mechanism. The automated chemical controller regulates the addition of chemicals based on the incoming flow rate. The automated density controller also measures the flow of the slurry discharged from the blender tub and, together with the incoming flow rate, calculates the actual density of the slurry. After comparing the actual density with the desired density, the automated density controller calculates a correction factor and recalibrates the performance characteristics of the proppant delivery mechanism. The automated density controller also includes a densiometer for measuring the actual density of the slurry. The density measured by the densiometer is compared with the density calculated by the flow meters to provide an indication of whether the controller is operating correctly.