In the steam pipes at the outlet side of the evaporator of the binary power generation system using dry steam from Moto Hakone No. 38 well, the microstructures of the pipe with scaling and powdered scale from sampling the pipe were analyzed. The main component of adhered scale was soluble sulfur. No corrosion occurred on the stainless steel surface, and soluble sulfur adhered directly to the stainless steel surface. Therefore, soluble sulfur should be considered as a countermeasure against scale formation at binary power plants using steam. In addition, the saturation index (SI) of the soluble sulfur was calculated under the assumed operating conditions. As temperature decreases, SI of the soluble sulfur increased. In evaluating the effect of the H₂S/SO₂ ratio during condensation, it is recognized that it is difficult to completely prevent sulfur scaling because sulfur may precipitate when only a small amount of SO₂ is present in the geothermal steam. In the future, understanding the amount of sulfur scale formation under various conditions will lead to optimal system design.

We propose a cost-efficient diagnostic method for profiling frictional pressure loss in a wellbore using the existing data of conventional pressure–temperature logging, along with well specifications and flow rates. Frictional pressure loss is profiled by decomposing the measured pressure into wellhead pressure, inertial, frictional, and gravitational components. Through the application of this method to actual production and testing wells, anomalies associated with scaling, variations in hydraulic diameter, and the presence of a multistage cementing tool were successfully identified, including their temporal variations. The accumulation of solid particles was inferred from the observed increase in frictional pressure loss near the end of the buildup section of well inclination.