Development of a High Temperature Borehole Sampler and Scale Build Up Analysis Using a Wellbore Geochemistry Simulator

Abstract

A high temperature borehole sampler has been developed capable of capturing a high quality, representative sample of wellbore fluid and delivering this to the surface for subsequent analysis. We conducted fluid sampling in a production well of Hot Dry Rock project (HDR) in Hijiori, Japan where severe Anhydrite scale was observed in the well by borehole camera and caliper logs. We collected wellbore fluid samples from the well, which has several feed-zones, and clarified the chemical difference in each feedzone. We then simulated equilibrium conditions of Anhydrite using a wellbore geochemistry simulator 'WellChem'. Based on this simulation, we understood that one of the reasons for Anhydrite scaling was the mixing of fluids from different feedpoints. Furthermore, we obtained 6.5?10-6(mol/s/m2) as a precipitation rate of Anhydrite from the scale buildup calculation using the caliper log.