Perpustakaan Digital ITB

Reservoir data is a very important key to successful geothermal well production. In some wells, there can be some geothermal problems such as instability in the reservoir. We know that geothermal wells can produce from multiple feed zones, specifically cases where the upper and lower zone holds a gaseous phase and a liquid phase, respectively. Instability in both discharging and shut-in geothermal wells can be caused by the presence of multiple feed zones and the reservoir permeability and or porosity contrast between feed zones. One of the instability phenomena in geothermal wells is the occurrence of cycling. An example of the many instabilities in geothermal fields is occurrences of zero liquid rate observed in the well head. This condition can have an impact on how we will have to deal with the well, like choosing which separator is best for utilization, predicting flashing occurrences, and predicting the amount of power will be generated. A geothermal well in Indonesia, that has been operating to supply steam for a geothermal plant, has a shut-in PTS (Pressure Temperature Spinner) data which shows the field has a vapor-dominated reservoir overlying a liquid-dominated high temperature reservoir. However, when the well is flowing, only dry steam flow is recorded in the wellhead even though the spinner graph suggests that there is liquid flow in liquid feed zone interval. This phenomenon needs to be analyzed so that we can see what exactly happened in that feed zone. Hopefully, further down the line, benefits of the study can be used for the field optimization. For analyzing this condition, a well and reservoir simulation is required.