Travel-time analysis of tracer tests in two geothermal fields

The most important results from a tracer test are whether or not tracer is detected at each observation well and the travel times to the wells that respond. A method developed by the authors for accurately calculating travel times for tracer movement in general flow fields enables the locations of major fractures in a reservoir to be deduced from the travel-time data. The procedure is applied here to data from Wairakei, New Zealand, and Palinpinon, Philippines.Notation H reservoir thickness, m - porosity, dimensionless - Q _c characteristic well volume flow rate, m³ s^-1 - R _c characteristic length, m - t _d time, s - t dimensionless time - t _td tracer travel time (without dispersion), s - t _t dimensionless tracer travel time - v _d background fluid speed, m s^-1 - v dimensionless background fluid speed - x _d Cartesian coordinate, m - x dimensionless Cartesian coordinate, m - y _d Cartesian coordinate, m - y dimensionless Cartesian coordinate