| Title | Coupled Temperature and Tracer Data Analysis Using a Uniform Porous Channel Model |
|---|---|
| Authors | Co, Carla Kathryn D.; Horne, Roland N. |
| Year | 2012 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Geothermal; tracer breakthrough; connectivity; thermal response; production; injection; porous model |
| Abstract | Characterization of permeable zones is of primary importance for geothermal reservoir management. Spent brine is routinely injected in geothermal systems for pressure support and waste water disposal. Therefore, producer and injector interwell connectivity derived from feedzone characterization will influence the mass and heat transport of the injected fluid. Several model configurations are available in the literature to describe these connections. Analytical models for heat and tracer mass transport related to the uniform porous channel configuration are described in this study. Both tracer and temperature data are used for calibration to constrain the multiple degrees of freedom. Levenberg-Marquardt and Trust-Region-Reflective nonlinear least squares algorithms were applied to determine the optimized parameter values. Calculated parameters included the following: channel width, channel height, porosity, pore diffusivity, and equivalent injection temperature in the channel. Normalized tracer and thermal response datasets from injector-producer well pairs from Hijiori and Palinpinon fields were used for calibration. Results showed a good fit between the analytical models and the measured data points. Wells NJ2RD and NJ5D from the Palinpinon field exhibited the strongest interwell connectivity and highest diffusivity coefficient among the three well pairs. The two Palinpinon field well pairs showed significant mixing with hotter fluids prior to injection which was expected in a conventional hydrothermal reservoir. On the other hand, the well pair HDR1-HDR3 in Hijiori had the lowest diffusivity coefficient and equivalent injection temperature because it was in an EGS reservoir. Combined thermal and tracer data analyses yielded a detailed characterization of interwell connectivity. It was recommended that this method be applied to other models configurations to compare the range of thermal response to injection. |