Reservoir Response to Optimised Reinjection Scheme of Tongonan-1 Production Field, Leyte, Philippines

Abstract

Reinjection of the separated geothermal brine fioni Tongonan-I production jield to hlahino nnrl Sambaloran reinjection wells started as eariv as 1981. Changes in chemical and ph-vsical characteristics of most of the production wells in Lower Alahiao and Sanibaloran sectors indicate a major reinjection, fluid breakthrough in these sectors. The reinjection jluid is believed to be dispersed through Mahino Enst, C'rangon and Sanibaloran faults.

Optimized utilization of reinjection wells 2R3D and 2R1D in Sanibaloran sector ajer successjiil acidzing of 2R1D in 1991 resulted to signijcant recovev of Sanibaloran production jieldfiom reinjection fllrid breakthrough. Continued chenrical nnd ph.vsical recoverv of Sambaloran wells fioni reinjection fluid due to reduction of wastewater load at wells 2R3D and 2R1D induced pressure drawdown in this sector. This is nianjfisted b.v the continuous increase in discharge enthalpv, concentration of C02 in the total discharge and reservoir chloride. The effects of drawdown are most notable in wells 212 and 213 in Sanibaloran sector.