Casing Inspection Caliper Surveys: Results and Implications to Operations in Leyte Geothermal Production Field
|Authors:||B.C. Buñing, Z.F. Sarmiento, E.T. Aleman and V.S. Saw|
|Keywords:||Caliper logs, casing inspection caliper, solids carry-over in steam, casing wall erosion, casing wall thinning|
|Conference:||World Geothermal Congress||Session:||20. Corrosion and Scaling|
|Abstract:||14 production wells in Leyte Geothermal Production Field (LGPF), Philippines, manifested potentials for casing wall thinning in mid-2001. These wells were suspected to have flowed steam with solids carry-over, which were subsequently collected in solids traps, pipeline and separators during the preventive maintenance schedule of the power plants. Four of them were prioritized for observation and were subsequently subjected to casing inspection caliper (CIC) logs.
Two of the surveyed wells, 209A and 401, have been assessed to have serious potential problems due to their relatively thinned production casing from about 100m depth to near-surface. The degree of erosion is believed related to the duration of use of the wells and the length of time they have been on steam production (as compared to two-phase or liquid-dominated discharge).
CIC surveys are recommended for the other steam-producing wells. A series of repeat annual CIC surveys is also proposed for representative wells that have recently turned to steam discharge for monitoring the thinning rate of the production casing walls.