| Abstract |
Tracer fesf using Naphthalene Disulfonates (NDS) was recently conducted in the Palinpinon-ll sector of Southern Negros Geothermal Production Field. The fesf was designed with the following objectives: 1) to quantify the rate and extent of injection returns, 2) to identify fluid flow paths/channels of injection returns and 3) to predict thermal breakthrough or possib/e cooling of production wells due to injection returns. The resulfs would help refine the hydrological model af Palinpinon-ll, which would be the basis for prediction of reseruoir response to increased /nass extraction rate and brine injection load from a proposed additional 20 MWe power plant. lnitial resulfs show tracer recovery in NJ3D, NJSD and OKi in 5 to 7 days after injection. Calculated tracer /nass recovery ranged from 6.6 to 23.8 %. Based on simulatian using the software package ICEBOX, brine injection into NJ2RD af /s maximum injection capacity of B0 kg/sec will cause a thermal decline in production wett NJSD from 265 to 25f,C in the next two years. With projected brine flow of 164 kg/sec upon commissioning of the additional 20 MWe Nasu/o pawer plant in January 2048, ff is predicted that the temperature will drop to 230oC within I months if injection will be confined in the Nasuji secfor. Ihese cooling effects would result to significant steam flow decline. lncreasing the injection rate into SG2RD in the Sogongon sector will a/so have similar effects. Thus, it may be necess ary to drill a new reinjection well north of NJ2RD to, at least, minimize the adverse effect of injection retum and to susfain the steam supplyr equirementso f Nasulo,N asujia nd Sogongon modular power plants. A detailed evaluation to integrate tracer data with other reseruoir information must be conducted to determine appropriate timing for drilling of another injection well. |