Considerations of Well Cementing Materials in High-pressure, High-temperature Conditions

As worldwide demand of hydrocarbon is growing fast, the oil and gas companies have been forced to explore reservoirs with more hostile conditions, such as high-pressure, high-temperature conditions. Improved technology, material selection and testing procedures are required to overcome the common problems in these conditions. One of the main phases of well construction is cementing job. Appropriate selection of cementing material can guarantee a successful cementing job. Many researchers investigated the required cement properties for applications in high-pressure, hightemperature conditions. However, the focus of their work was on the mechanical properties of set cement, while the other properties have not been studied enough. The purpose of this work is to produce a high resistant cement system, which can satisfy the other essential requirements at the same time. The main other requirements include free fluid content, thickening time and expansion capability, which have been investigated in this work. The results show that although some cement systems have high mechanical resistant, but their application is limited due to undesirable values of other properties. Therefore, different additives have been used to adjust the properties of the final cement system. The high-resistant cement is produced by adding siliceous material. Free fluid content, thickening time and expansion capability of the high-resistant cements are adjusted by adding polyvinyl alcohol, lignosulfonate and MgO, respectively. The combined effect of these additives is investigated to develop a high-resistant system, which has optimum values of other essential properties too.