Granulated, hydraulic Blast Furnace Slag (BFS) is finding application as a well-cementing material mixed either in water or in water-based drilling fluids. Unlike Portland cement-based systems, which have been used for well cementing for almost a century, the BFS formulations require chemical activators to achieve set for most well conditions. The most widely used activators are soluble inorganic alkalies.
This paper reports the design, development, and testing of the Proportioning Injector Unit (PIU).This device is placed in the flow line (between the drilling rig mud pumps and the cementing head) when using BFS to cement casing in a well. The PIU includes an inline flow meter to continuously monitor the flow rate of a BFS cement lacking one or more of the activators. The data from the flow meter allows a programmable controller to operate the positive displacement pumps ensuring a precise, predetermined amount of activator solution is injected into the stream prior to the now activated BFS cement entering the cementing head.
A prototype PIU has been fabricated, yard tested, and used for a test mix in the field. It is now available for use in conjunction with drilling rig mud handling equipment to cement casing in wells.