Well Discharge Stimulation of Some Geothermal Wells in the Philippines by Nitrogen Gas Injection

Abstract

Most geothermal wells in the Philippines require some method of stimulation to initiate flow. In exploration projects, nitrogen gas injection has been recently employed for this purpose, and was also found to be successful' in initiating flow of hard-to-discharge wells in developed fields. Gas injection reduces the wellbore pressure ht the main permeable zone to its saturation pressure by lowering the weight of the water column, and thus initiating well discharge.

The present study investigated some field data of gas lifted wells and compared these with predicted data using two-phase flow correlations and equations. The results confirm the significant effect of injection depth on the gas lip process. A statistically derived factor was obtained to predict this injection depth. The Harrison-Freeston correlation was used to estimate the flow rates and volume relative to the gas velocity and water column. The results are closer to the actual values when the submergence ratios are within 0.70 to 0.80.