The Phenomenon of Cooling Geothermal Wells in PT Pertamina Geothermal Energy Fields; Investigation and Handling

Abstract

PT.Pertamina Geothermal Energy operates 9 geothermal areas, including Ulubelu and Hulu lais project.. Ulubelu Geothermal Area is located in Lampung Province, Pulau Panggung District area, Tanggamus Regency – Lampung provice and Hululais Project is administratively located in Lebong Regency, Bengkulu Province. Monitoring well conditions such as pressure and temperatur are carried out since the well has been drilled until the well has been producing regularly. Based on the results of condition monitoring of the wells there were significant decreases in temperature between 100 – 160 oC in several wells in different time. Investigations were conducted to determine the root cause of temperature decline by doing PTS logging and downhole sampling. HSolution for this problem has been done by using remedial casing and squeeze cementing. Evaluation after handling the problem is carried out by conducting a production test and or by a wellbore simulation analysis then compared its condition with previous condition before this problem occurred.