In-Situ Processes
In-situ processes can be technically feasible in
deeper, richer deposits where the rock has natural
permeability or where permeability can be created by
fracturing.
True in-situ processes involve no mining.
?? The shale is fractured, air is injected, the shale is
ignited to heat the formation, and shale oil moves
through fractures to production wells.
?? Difficulties in controlling the flame front and the
flow of oil can limit oil recovery, leaving areas
unheated and some oil unrecovered. (Figure 3)
Modified in-situ (MIS) may involve mining below
or above the target shale deposit before heating to
create void space of 20 to 25 percent.
?? The shale is heated by igniting the top of the
target deposit and recovering fluids from
ahead of or beneath the heated zone.
?? Modified in-situ processes can improve
performance by heating more of the shale,
improving the flow of gases and liquids
through the rock formation, and increasing
volumes and quality of the oil produced.
Environmental Caveat: Both true and modified insitu
processes are challenged by the potential for
contamination of groundwater by pyrolized oil and
other metals and toxics that may be left behind.
Shell ICP: Shell’s new in-situ conversion process
(ICP) could produce high quality fuels in a more,
economic and environmentally sound manner. In this
substantial modification of the “true in-situ” process:
?? Electric or gas heaters, placed in closely spaced
vertical wells, slowly heat the shale for 2-4 years.
?? The slow heating creates microfractures in the
rock that augment natural permeability and
enhance fluid flow from heated zones to
production wells.
?? Resulting shale oil and gases are moved to the
surface by conventional wells and vapor recovery
technology.
?? Slow heating improves product quality; subsequent
product treating is less complex, than for
surface retorts or other in-situ approaches.
?? Much more oil and gas may be recovered from a
given area as shale oil and combustible gas
products can be produced at greater depths than
are accessible by other oil shale technologies.
?? The ICP process involves no subsurface
combustion of the resource, reducing
environmental impacts.
?? Close spacing, adjustable heat sources, and
modern downhole monitoring technologies vastly
improves temperature control.
?? Innovative “freeze wall” technology is being
tested to isolate production areas from intrusion
of groundwater until shale heating, production,
and post production flushing has been completed.
Shell is currently operating a modest field research
effort in northwestern Colorado’s Piceance Basin to
test ICP’s viability on the basin’s world-class oil
shale reserves. Critical issues include:
?? Development of reliable heater technology
?? Improvements of heater durability relative to
down hole rock mechanics
?? Validation of efficacy of freeze wall
technologies.
Figure 3: Conventional True In-Situ Process Schematic
Increasingly SURE FEB 02
Tight Overburden
Low Perm Shale Lower Seal
Lean Shale / Fracture porosity
Rich Shale
Rich Shale
Rich Shale
Producer Heaters
well
Freeze wall
barrier
