Abstract
The quality of oil well cement is very important in maximizing the rate of production from an oil well. Good bonding between cement and casing also between cement and rock formation are essential for effective zone isolation, hence usually the additive should be added in order to improve the characteristics of standard cement.
The purposes of this research are to find the effect of adding expanding material, burnt pure-MgO, on the value of compressive strength and shear bond strength of API class G in high pressure and high temperature condition.
The method that has been used in this research is evaluating data from simulator, which was set up similar to field condition, 100 – 200 °C and 2000 psi.
According to the research, some conclusion can be drawn: adding expanding additives, in fact, will increase shear bond strength but will reduce compressive strength although generally still higher than recommended minimum value. The Appearance of mud cake will decrease shear bond strength. For compositions without expanding additives, shear bond strength was dropped drastically. MgO shows excellent performance, as expanding additive, in increasing the shear bond strength.
For low conditioning temperature, 100 – 135 °C, MgO that are burnt at 1000 °C are reliable, whereas for higher conditioning temperature up to 200 °C, the pure MgO which are burnt at 1200 °C, are more convenient. The concentration of expanding additives, which could be used to increase the shearbond strength of cements, are around 5%.
