Utilization of Former Acidic Wells: A Palinpinon Geothermal Production Field Experience

Abstract

Steam production has been obtained from a number of acidic wells in the Palinpinon geothermal field that were initially not utilized for commercial production. Based on chemistry, the discharged fluids are of acid-sulphate type with no magmatic origin. Most of these wells are located near Area A, the postulated upflow area. The continuous field exploitation has induced pressure drawdown that resulted to lowering of water level in the production sector. This caused some of the production wells to dry up eliminating the acid feed. This also promoted incursion of reinjected fluids suppressing the source of acidity in some of the two-phase wells. Succeeding steam augmentation initiatives were based on this experience which led to further drilling towards Area A as wells drilled have high output. During the discharge tests and production, these new wells discharged fluids with similar characteristics as the neutral wells in the field. Occasionally when these wells were shut or throttled, the initial discharging fluids had low pH but eventually turned neutral with continuous discharge. This experience showed that acid fluids still persist thus adherence to optimal reinjection strategies as well as proper well utilization play a vital role in the sustaining steam supply from these former acidic wells.