WELL INTEGRITY ASSURANCE IN EOR INJECTION WELLS THROUGH THE LENS OF THERMAL PROPERTIES OF PORTLAND CEMENT

Heavy oil production is one of the challenges faced by the Oil and Gas industry today with
reserves of trillions of barrels. When considering production, heavy oil viscosity must be
reduced to gain mobility and have oil flowing. Between all possible techniques, stearn
stimulation is the most promising.
Steam stimulation is one of the viable methods to exmct heavy oil from oil sand reservoirs.
In this thermal pnocess, steam is injected through the well down to the reservoir to warm it up
to 320oC hence, subjecting the well to high temperatures. These injectants are pumped from
the surface at very high temperatures and pressures and are required to enter the targeted zone
with minimal amount of heat loss to the surrounding formation.
The cement sheath in steam injection wells are required to have good thermal insulation
properties to minimise the amount of heat loss to the formation while ensuring the integfity
and flow assurance of the well.
This research focuses on the thermal conductivity of cement and how the stmctural properties
of cement affect heat transfer from the casing to the surmunding formation. Cement samples
cured at varying temperatures are analysed using a Micro Focus X-Ray Computerised
Tomography (CT) System thus, allowing the mapping of porcs and microfractures within the
internal cement structur€. Cement cured at elevated temperatures show significant differences
in microstructure compared to baseline samples. The thermal conductivity (k-values) of the
samples are then measured and correlated to the pore distribution and curing temperahres.
This will allow for thc modelling of heat flow from the casing to the zurrounding formation