Well Control response and Engineering expertise to support your Geothermal projects.
Over our 50 years of expertise in Well Control response, augmented by Advanced Well Control Engineering and planning, Wild Well Control has supported and guided clients in all facets of drilling and producing environments. Geothermal wells while nontraditional to the oil and gas sector, aren't unique. Careful planning, modeling and execution of Geothermal projects should also comprise a robust well control contingency plan. Sound engineering, multi-disciplinary engineering design, and analysis will ensure a successful outcome.
Geothermal Services
Geothermal Well Control Considerations
Geothermal formations are comprised of reservoirs of hot water that naturally occur or are man-made at varying temperatures and depths below the earth's surface.
Geothermal formations are typically categorized as; Geopressured-geothermal systems which contain water with somewhat elevated temperatures and with pressures well above hydrostatic for their depth; Magmatic systems, with temperature from 600 to 1400C; Hot Dry Rock (HDR) geothermal systems, with temperatures from 200 to 350C. Rock types comprise Granite, Granodiorite, Quartzite, Greywacke, Basalt, Volcanic tuffs.
Well Control
Because formations are usually under pressured (pore pressure less than fluid pressure in a full wellbore), influx into the wellbore is rare. There are two primary causes for loss of control:
An unexpectedly hot formation is encountered at a shallow depth where the annulus pressure is insufficient to keep the drilling fluid or the formation fluid from flashing to steam.
Lost circulation causes the fluid level and the pressure in the wellbore to suddenly fall far enough for the same thing to happen.
If complete control is not lost, simply pumping cold water into the wellbore can usually kill the well.
Compared to the sedimentary formations of most oil/gas reservoirs, geothermal formations are, by definition:
- Hot (production intervals from 160°C to above 300°C)
- Often hard (240+ MPa compressive strength), abrasive (quartz content above 50%)
- Highly fractured (fracture apertures of centimeters)
- Under pressured
- Often contain corrosive fluids
- Some formation fluids have very high solids content [total dissolved solids (TDS) in some brines it can be above 250,000 ppm]
These conditions mean that drilling is usually difficult, with problems that include:
- Rate of Penetration (ROP)
- Corrosion
- Lost circulation is frequent and severe
- Wellbore collapse