Remaining Life and Corrosion Rate Prediction of Well Casing Material in the CO₂ Environment

Abstract

Prediction of CO2 corrosion is required for predicting remaining life and determination of the required material selection. This paper give prediction of corrosion rate and remaining life of casing in the North Aceh well which is operated almost 14 years. Simulation method application is appropriate with the condition of North Aceh field since the well fluids contain high CO2 gas (35 – 37%) and small amount of H2S gas (0.016%). Based on historical data North Aceh well’s after production almost 14 years, it is possible that production packer leaks and degradation of cement could cause formation gas migrate through micro channelling inside cement. The CO2 gas which is accumulate in casing could cause CO2 corrosion. The corrosion rate calculation based on temperature 141°C, pressure 103.4 Barg and CO2 contain 37% is 0.871 mm/year. After calculating the thickness loss, we found thickness loss of casing K55 is 12.741 mm. meanwhile thickness of K55 casing 10.92 mm, it means the casing already leak before year 14th. Based on simulation and calculation the North Aceh well is assumed to have tubing and packer leaks in annulus #0 and channeling on annulus #1 so that the well is not recommended for re-production because of the communication between the annulus and the loss of the well barrier that can cause wellhead leakage. This condition is very dangerous because the well fluid is flammable and can cause pollution in the sea.