Research Projects and Publications

Hydraulic Well Stimulation in Low-Temperature Geothermal Areas for Direct Use

Geothermal Engineering and Exploration ÍSOR Show all

Author: Cari Debra Covell

Year: 2016

Supervisor: María Sigríður Guðjónsdóttir & Sverrir Þórhallsson

The project was conducted in cooperation with ÍSOR.



Direct use of hot water through renewable energy resources is globally in demand.
Thermal energy stored in fractures and pores within geothermal reservoirs contains natural fluids.
At times, extracting natural fluids, or hot water in low-temperature areas, can be a challenge.
Hydraulic stimulation is one technique to overcome this challenge.
Research about hydraulic stimulation methods was done based on theory, fluid treatment, and well testing; in order to see unique trends for low-temperature geothermal applications.
Furthermore, a literature review of all hydraulic stimulation applications was conducted to understand reasons for success or failure.
In order to predict the effects of hydraulic stimulation before an actual operation, a case study was performed on well HF-1 in Hoffell, Iceland.
First, a preliminary production flow model was performed using updated data at the completion of testing in 2014.
After evaluating the need for stimulation, a fracture model using MFrac was done in two scenarios with an open-hole packer; injection below the packer and injection above the packer.
The packer was placed in a conservative interval of 1070-1110 m depth to isolate the main fracture at 1093 m depth.
Injection below the packer failed, therefore results from injection above the packer were only suitable moving forward.
Subsequently, MProd software was used to find an improvement ratio after simulating stimulation above the packer.
The improvement ratio of 1.096 was then applied to the original production data of well HF-1 and a LPM was performed yet again.
Reservoir properties of S, T, II, and PI were calculated and compared to original production data.
Results indicated the lumpfit model to be very optimistic and improvement of only 4 l/s flow over a 10 year well lifetime was observed.
Therefore, the well is not a good candidate for stimulation. However, improvement was seen which proves the potential for this methodology to be implemented in other low-temperature geothermal areas.