The Invention of a Predictor Plot for Evaluating the Response of the Compressive Strength of Geopolymer Cement to Changes in Temperature and Pressure

The design of cement must consider the potential influence of fluctuations in formation pressure and temperature within the wellbore. The possibility of geopolymer cement as an alternative to Ordinary Portland Cement (OPC) is being considered in support of the Paris Agreement. However, previous research on geopolymer has focus on construction industry which the studies were conducted at atmospheric condition, hence limited study available that experimenting both pressure and temperature variation on the cement. Therefore, the current study aims to observe the flexibility of geopolymer cement for well application by conducting compressive strength test for cement that have been simulated at pressure range between 14.7 and 5000 psi and temperature between 60 and 120 °C. The study involves two geopolymer cement formulations and cured for 24 hours at 15 different condition, which the mixing and curing according to American Petroleum Institute Recommended Practice (API RP) 10B-2. The API compressive strength tester is used to perform the destructive compressive strength. The results are recorded and analysed using a 3D surface plot to observe the trend of compressive strength when exposed to various wellbore condition. The research finding indicates that the compressive strength of the cement is notably influenced by temperatures, while it has been observed that the pressure does not exert any discernible influence on the enhancement of compressive strength in geopolymer cement. The impact of simulated pressure on cement compaction, which leads to densification, may not have a major effect on its strength compared to the influence of temperature, which primarily affects the chemical reactions within the cement structure. The anticipated outcomes of the study are anticipated to offer novel perspectives that may enhance the efficacy of geopolymer cement within the context of oil and gas. It is recommended to create 3D plots of geopolymer cement at temperatures and pressures below 60°C and 2000 psi to observe the performance of cement in depleted wells, which are one of the focus CCUS well. The strength can be estimated prior to conduct other functional test such as, thickening time and fluid loss. However, the inclusion of other additives into the formulation might alter the trend, which several points need to validate prior to use the plot for the estimation. Further study recommended that the data from the current research to be combined with similar information from the previous analysis to strengthen the plot. Copyright 2023, Society of Petroleum Engineers.