An Experimental Investigation of the pH Effect on the Properties of Iraqi Cement Class G: A Comparative Study with UAE Cement

The cement process is a crucial operation in the drilling of oil and gas wells, in which errors would be extremely costly and time-consuming to rectify. Some of the technical parameters that influence this process include the pH of water used in the preparation of the cement slurry. This study investigates the impact of water pH on the properties of Class-G cement slurry. The cement slurries have been mixed using distilled water and four water samples at pH 9.5, 10, 11, and 12, respectively, with no additives. Iraqi and UAE cements' physical and chemical analyses were performed according to API standard specifications. The findings indicate that UAE cement largely meets the API specifications. However, Iraqi cement has some deviations due to a difference in manufacturing processes, which caused failures when the tests were conducted with fresh water. The findings of three physical tests demonstrated that mixing cement with alkaline water (pH>7) has a negative effect on the cement physical properties, especially compressive strength and density. On the other hand, the thickening time test for two kinds of cement demonstrated that when the pH level increases, it contributes to a delay in the thickening time of roughly 50 minutes for both types. This study considers pH effects in the preparation of cement slurries to ensure that bonding was not impaired and exclude post-operational failures.