Geothermal Well Controls: What are the indicators? – A Case Study in Producing Fields

Abstract

The common drilling positive kick indicators are: flow when pumps are off, increase flow during normal drilling and circulation, and pit gain. These indictors cannot be relied solely drilling through geothermal reservoirs when circulation is lost or when using aerated drilling fluid system. This paper will present alternative and current practices being used by Chevron Geothermal and the industry in general to ensure well control events are handled safely and effectively. It is also the intent of this paper to differentiate well control monitoring that the geothermal industry is using to that of oil and gas that take into account the uniqueness and the difference in the drilling environments and hazards. This paper will also present statistical analysis of well control events in two Chevron geothermal assets in Indonesia to get better picture of what really happened. Field data will be used and analyzed to seek and provide consistent understanding of the events. At the end, the geothermal community has to clearly differentiate well control indicators and well control approach to that of oil and gas and propose the best and proven methods to ensure safe and effective handling of well control events. An open discussion and feedback should enrich this effort.