A device that could measure the expansion or contraction of cement would
have a concrete payoff for Saudi Aramco. Science specialist Scott S.
Jennings of EXPEC Advanced Research Center designed just such a device --
the Cement Shrinkage and Expansion Tester -- as a way to measure those
effects. It is so unique that it was patented by the company and adopted by
oil majors around the globe.
A standard mix of Class G cement shrinks two per cent after it sets. In
wells where high pressure is a concern, expansion additives are used to
reduce shrinkage during setting. The new device enables engineers to
evaluate shrinkage or expansion as materials are heated to temperatures
simulating well conditions.
Under U.S. Patent 7,240,545 titled, Test Apparatus for Direct Measurement of
Expansion and Shrinkage of Oil Well Cements, Jennings created an instrument
to approve or reject certain cements for use in oil and gas wells.
Jennings’ Cement Shrinkage and Expansion Tester is designed to fit into
existing ultrasonic cement analyzer cells. Cement slurry is poured into the
cell and separated by a rubber diaphragm. Water serves as a cushion between
a floating piston and the diaphragm. Piston movement indicates shrinkage or
expansion. The instrument allows the company to ensure that selected
materials are up to the task, saving money on costly repairs or shutdowns
and promoting safer operations.