Analisis Casing Design Dengan Memperhitungkan Sisa Umur Casing Carbon Steel dan Material Selection Berdasarkan Corrosion Rate Pada Sumur Z

Abstract

This study will discuss the results of casing setting depth and casing design taking into account subsurface geological conditions and CO2 corrosion rate on carbon steel casing at Well Z where based on historical data there are several wells in the YZ field which have been shut in because it is predicted that there will be a casing leak under the packer due to corrosion. casing design is one of the activities in well construction where it is expected to obtain a series of robust casings taking into account factors such as geological conditions, production targets, pipe sticking, kick tolerance, possible hazzard, burst load, collapse load, tension load, and corrosion. Calculation of burst, collapse, and tension values using the StressCheck software, followed by an analysis of the triaxial design limit check to determine whether the casing grade parameters are safe or not for use. Then the calculation of the CO2 corrosion rate is carried out to find out whether the age of the well can reach the production target year or not, especially in the production liner, because the well is in a CO2 environmental condition with a CO2 level of 28% and H2S level of 0.002%. By using the Norsok M-506 method and using an L-80 grade casing with a weight of 29 ppf measuring 7 in (OD) and 6,184 in (ID) the value of CO2 corrosion rate was obtained, which was 0.602 mm/yr. This can be interpreted that the casing will leak before the production target year, which is 21 years. Therefore, re-selection of the casing on the production liner is carried out so that the casing does not leak before the production target year. By considering several factors, the determination of the casing setting depth has been determined, that is surface casing installed to a depth of 2500 ft, production casing installed to a depth of 4450 ft, and production liner installed from 4100 ft to a depth of 8281 ft. To prevent leak problems due to reactions between corrosion compounds and steel, a casing material is selected for the production liner based on the CO2 partial pressure and H2S partial pressure values, that is casing grade L-80 13Cr with a weight of 29 ppf.