Verkís at GRC 2019 in California

© HS Orka
HS Orka

GRC Annual Meeting and Expo will be held in California USA 15th – 18th of September 2019. The theme of the meeting is Geothermal: Green Energy for the Long Run. Þorleikur Jóhannesson, Mechanical Engineer M.Sc. at Verkís, will participate in a short course with his presentation IDDP wellhead design – Fluid handling at the surface.

The main purpose of the IDDP project is to find out if it is economically feasible to extract energy and chemicals out of hydrothermal systems at supercritical conditions. To study the supercritical hydrous fluid, an advanced drilling technology needs to be applied and a novel fluid handling and evaluation system designed.

Þorleikur JóhannessonThe improvement of this basic idea by the IDDP is to drill deep enough into the roots of a conventional high temperature hydrothermal system to produce water at supercritical conditions and bring it to the surface as 400-600°C superheated steam, at subcritical pressures (<220 bar). In the case of low permeability systems, by injecting cold fluid into the hot rocks, fractures can be induced to complete the thermal mining cycle.

About the presentation:

Designing surface equipment to receive and cope with superhot geothermal fluid can be quite challenging. The aim of the drilling of IDDP 2 at Reykjanes was to reach reservoir pressure as high as 300 bar and temperatures around 500°C.

This requires a design pressure and temperature for the associated surface equipment in the range of 250 bar and 475°C respectively. This provided a challenge as few equipment providers deal with the valve sizes needed for this design rating.

The chemistry prediction was also quite challenging. Low pH, high silica and high risk for metal sulfide scaling, compared to the present conditions at Reykjanes. In some cases a high level of dissolved silica in the superheated steam was to be expected in addition to a high HCL content.

Furthermore, mechanical issues, fluid structure interaction, erosion and vibration were also issues for concern. In cooperation with HS-Orka, Verkís started this design work some 4 years ago. The design premise has however changed, mainly due to unexpected issues regarding drilling and completion of the IDDP 2 well.

In this presentation Þorleikur will discuss the above-mentioned design challenges and present how they were dealt with in order to design a reliable and safe well-head and test flow line.


The IDDP project – website

World goals

© HS Orka