Test apparatus for direct measurement of expansion and shrinkage of oil well cements

A test apparatus for the measurement of the expansion and/or shrinkage of a test sample comprising:

• a vessel assembly housing, one end of which includes a sample-receiving portion;
• a flexible seal extending across the sample-receiving portion to isolate a sample placed therein from the rest of the housing;
• a movable piston sealingly mounted in a bore of the vessel assembly housing and isolating a first pressurized chamber from a second pressurizing chamber in the housing, the first chamber being defined by the flexible seal and one face of the piston, the first chamber being provided with an incompressible fluid, the second chamber being defined by an opposing side of the piston and the end of the housing opposite the sample-receiving portion;
• a source of pressurizing fluid external to the housing and in fluid communication with the second chamber;
• and
• a sensor assembly that is responsive to movement of the piston and an associated display and recording means for measuring the linear movement of the piston.

A method for measuring the expansion and/or contraction of a curable test sample comprising the steps of:

• isolating a flowable test sample in a rigid sample-receiving portion of a test vessel;
• securing a flexible seal over an exposed surface of the test sample;
• contacting a surface of the flexible seal opposite the sample surface with a fixed volume of an incompressible pressurized liquid that is maintained in a first chamber in the test vessel by a proximal face of a movable piston that is sealingly positioned in a bore formed in the test vessel;
• applying to a distal face of the piston a force by a pressurizing fluid that is contained in a second chamber in the test vessel, whereby the liquid in the first chamber and the fluid in the second chamber are isolated from each other;
• measuring any movement of the piston during the curing of the sample;
• and
• correlating the movement of the piston to a volumetric change of the sample.