This paper presents updates on the field deployment of a chloride-based wireline tool designed to detect and quantify inflows from feed zones in geothermal wells. The Stanford Geothermal Program and Sandia National Laboratories are developing a geochemistry-based wireline tool and methodology to more accurately characterize fracture presence and inflow rate from geothermal wells compared to a pressure-temperature-spinner (PTS) tool. The tool uses an ion-selective electrode (ISE) to measure primarily chloride concentration. A mass balance of different chloride concentration readings around the feed zone can be used to calculate the feed zone inflow rate. The recent developments of the chloride tool focused on preparing and conducting the field deployment at the Utah FORGE site. Laboratory experiments involving single fracture inflows were performed to test different parameters, including chloride concentrations, tool positioning, and feed zone inflow rates. The results showed different behaviors of probes, one exhibiting gradual changes in molarity readings while another displayed faster responses. It was found that while the presence of bromide and sulfate ions in the feed zone fluid caused interference, the combination of these ions stabilized the chloride tool readings. Dynamic experiments were also conducted, simulating field operations by moving the tool vertically. These laboratory tests correctly registered the higher chloride concentrations in the feed zone fluid, and were found to produce more accurate inflow rate inferences in the pull-out of hole (POOH) direction. The tool showed more accurate readings moving from lower chloride into higher chloride concentrations, compared to moving from high to low – which contributed to the results being more accurate in the pull-out-of-hole (POOH) direction than the run-in-hole (RIH) direction. Field deployment occurred in wells 58-32 and 16B(78)-32 on June 12-14 and August 16, 2024, respectively. In both field deployments, measurements were noticeably better during the POOH run than the RIH run, as had been seen in the lab. At 58-32, the measurements suggest there were no internal flows in the well during the logging, which was not unexpected as the well was not producing at the time. To analyze 16B(78)-32 measurement results, several reading points were selected at Stage 5 and Stage 4 to provide information on chloride concentration above, at, and below the feed zones. The calculation yielded flow rates of 4326.49 BPD for Stage 5 and 7822.83 BPD for Stage 4, respectively. Compared to the flow rate calculation from the PLT log obtained a week later, the flow rate values calculated using the chloride method are within the expected range of agreement.

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