Geowell™ Technology > Downhole String Assembly

Geowell^TM has developed a unique string design that focuses on maintainability. By employing a pump string that separates the shorter pump section from the extended stationary umbilical, the submersible pump can be serviced with minimal downtime and cost. The under-housing float serves to insure proper sealing and floats the assembly for ease of re-introducing the pump during maintenance.

Geowell is a unique well bore string design, deployed continuously from spools of polypipe, rather than joining 20' sections of PVC sleeve. A vertical cross-section of the well bore is shown in the Figure.

The SCW operation starts at the submersible pump, which is located approximately 100’ below static water level. The pump supplies water from the well to the building for heat exchange. The water is either heated (summer) or cooled (winter) and this thermal water is then returned to the well annular space. The thermal water traverses the entire length of the bore, exchanging heat with the surrounding formation rock, until it is drawn-in through the bottom perforated section by the suction from the pump. This cycle is characteristic of SCW operation, in which all of the water is returned to the bore, and nothing is netted out of the aquifer.

There are conditions dictated by design decisions which demand x% bleed in order to continue to meet the load with geothermal. By re-directing the bleed water to a separate “diffusion” well, the designer decreases the heating requirement of the supply well, while substituting ambient temperature water made-up from the aquifer. This design approach allows extended operation of the SCW at the expense of a separate diffusion well. Whether this is the “best” cost-effective strategy is debatable. Other options include consideration of a “no-bleed” design, and the use of a backup HVAC system (typically, a pkg. boiler) to pickup where geothermal heating left off.

The Geowell string components are available for sale and use by SCW installers who have qualified by their participation at the SCW Design Course offered by HeatSpring Institute.