An innovative test apparatus for oil well cement: In-situ measurement of chemical shrinkage and tensile strength

• Cement chemical shrinkage under pressure can be measured by an injection pump.
• Chemical shrinkage increases with increasing temperature during early stage.
• Curing pressure up to 13 MPa has relatively little effect on chemical shrinkage.
• Hydraulic fracture method may be used to obtain the in-situ strength of well cement.

An innovative apparatus has been developed in this study to cure and test oil well cement specimens under simulated down-hole conditions with high temperature and high pressure. The test apparatus can be used to monitor cement chemical shrinkage in real time and measure fluid pressure tensile strength under in-situ conditions, i.e. without changing the temperature or releasing the pressure of the specimen. This paper describes the basic principles of this newly developed test method and detailed configuration of the test apparatus. A series of tests were performed on different classes of oil well cement to evaluate the functionality of the test device. Specimens in groups of four were cured at temperatures ranging from 24 to 60 °C and pressures ranging from 0.69 to 13.1 MPa.