Gas migration during primary cementing is considered as an oil and gas industrial problem for many years. Currently, the gas migration problem is mitigated using modified cellulose based polymer (synthesized with carbonates) in cement slurry at high temperature. However, there is no widely accepted single polymer that can prevent gas migration without synthesization for high temperature cementing application.
This study presents an experimental investigation for prevention of gas migration through cement column during transition state of cement slurry. A natural polymer Hydroxypropylmethylcellulose (HPMC) is used for the first time ever as a cement additive to achieve desire prevention, which is stable at high temperature. The gas migration through cement slurry was determined using Cement Hydration Analyzer (CHA). HPMC was found to develop an impermeable barrier for prevention of gas migration. The experimental results showed that HPMC based cement slurry was gas tight as pore pressure remains low as 16 psi with constant gas injection of 150 psi for continues 08 hours. Further, API properties of cement slurries were determined using 0.20 to 0.50 gallon per sack of HPMC. The test results showed 04 to 06 hours thickening time, less than 30 minutes transition time, low fluid loss and high compressive strength at 190 °F. It is concluded that HPMC prevents the gas migration and significantly improves the API properties of cement slurry. In field applications, the presented HPMC polymer can simplify the design of cement slurry and prevent gas migration through cement slurry at high temperature.