Description:
This paper investigates the technical feasibility of improving
the productivity of superheated steam production wells by low-rate
water injection downhole. A combined numerical simulation
model of the reservoir and well bore was developed to analyze
the physical and thermodynamic processes associated with
such downhole injection. The model consisted of a geometrically-
increasing radial grid with 12 horizontal layers, the vertical
stack of the central grid blocks representing the well bore. The
model was calibrated against the temperature and pressure profiles
from two flowing wells at The Geysers steam field in California.
The modeling of low-rate downhole injection (through a
tubing) so far indicates that up to a third of a megawatt (MW) of
additional power can be easily gained by injection at 7,500 feet
(ft) in a superheated steam well. Of this additional steam, about
half results from de-superheating of steam and the rest from extraction
of heat from the formation surrounding the well bore. In
addition to increasing the power capacity, downhole injection
allows neutralization of acidic steam through the addition of caustic
soda to the injection water, scrubbing of chloride, and dilution
of the non-condensable gases in the produced steam.
