UNOCAL'S PARACHUTE CREEK OIL SHALE PROJECT Cloyd P. Reeg, President, Unocal Science and Technology and Energy Mining Divisions 376 S. Valencia Brea, California 92621 Allen C. Randle, Vice President, Oil Shale Operations Unocal Energy Mining Division 2717 County Road 215 Parachute, Colorado 81635 John H. Duir, Vice President, Engineering and Development Unocal Science and Technology Division 376 S. Valencia Brea, California 92621 ABSTRACT Unocal began construction of the United States' only commercial scale oil shale facility north of Parachute, Colorado in 1981. The project includes a 13,500 ton (12,250 tonne) per day mine, a 10,000 Bbl (1,460 tonne) per day above-ground retort, and a 10,800 Bbl (1,400 tonne) per day shale oil upgrading plant. The heart of the project is the Unishale-B Retort, which is an indirectly-heated, counterflow design incorporating Unocal's unique upflow solids feeder. Construction of the project was completed in 1983 at a cost of about $650 million. Plant start-up, which was prolonged by problems with the retorted shale removal, cooling and pressure-letdown system, was achieved in mid- 1986 and completed in 1988. The retort has been successfully operated at 100 percent of design feed rates and has produced raw shale oil at rates up to 70 percent of design. All other components of the project have been successfully operated at or above design rates. The project has demonstrated that shale oil can be produced while protecting the environment, and meet all applicable regulatory requirements. Further, no significant impacts have been identified in extensive investigations of environmental impacts that might be associated with non- regulated substances. To date, over three million barrels (390,000 tonnes) of shale oil have been produced, upgraded into premium quality syncrude, refined by conventional refineries into a complete range of products, 68
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Cloyd Reeg,President, Technology Energy Mining Brea,UNOCAL'SPARACHUTECREEKOILSHALEPROJECT CloydP.Reeg,President,UnocalScienceandTechnology andEnergyMiningDivisions 376S.Valencia Brea,California92621
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UNOCAL'S PARACHUTE CREEK OIL SHALE PROJECT
Cloyd P. Reeg, President, Unocal Science and Technologyand Energy Mining Divisions
376 S. Valencia
Brea, California 92621
Allen C. Randle, Vice President, Oil Shale Operations
Unocal Energy Mining Division
2717 County Road 215
Parachute, Colorado 81635
John H. Duir, Vice President, Engineering and Development
Unocal Science and Technology Division
376 S. Valencia
Brea, California 92621
ABSTRACT
Unocal began construction of
the UnitedStates'
only
commercial scale oil shale
facility north of Parachute,Colorado in 1981. The project
includes a 13,500 ton (12,250
tonne) per day mine, a 10,000
Bbl (1,460 tonne) per dayabove-ground retort, and a
10,800 Bbl (1,400 tonne) per
day shale oil upgrading plant.
The heart of the project is
the Unishale-B Retort, which
is an indirectly-heated,counterflow design
incorporating Unocal's unique
upflow solids feeder.
Construction of the project
was completed in 1983 at a
cost of about $650 million.
Plant start-up, which was
prolonged by problems with the
retorted shale removal,
cooling and pressure-letdown
system, was achieved in mid-
1986 and completed in 1988.
The retort has been
successfully operated at 100
percent of design feed rates
and has produced raw shale oil
at rates up to 70 percent of
design. All other components
of the project have been
successfully operated at or
above design rates. The
project has demonstrated that
shale oil can be produced
while protecting the
environment, and meet all
applicable regulatory
requirements. Further, no
significant impacts have been
identified in extensive
investigations of
environmental impacts that
might be associated withnon-
regulated substances. To
date, over three million
barrels (390,000 tonnes) of
shale oil have been produced,upgraded into premium quality
syncrude, refined byconventional refineries into a
complete range of products,
68
and consumed in the ordinary
course of domestic trade,
confirming that shale oil is
the best alternative source of
transportation fuels to meet
the nation's future energy
needs.
INTRODUCTION
Unocal's long standing
interest and commitment to oil
shale originated more than 60
years ago when the company
began acquiring properties in
the Piceance Basin of the
Green River Formation of
Colorado, Wyoming and Utah.
The company's holdings, in the
Parachute Creek area of
Garfield County, Colorado,consist of about 50,000 acres
(20,200 hectacres), including40,000 acres (16,200
hectacres) of oil shale lands.
The potentially recoverable
shale oil on Unocal property
is estimated to total 3.3
billion barrels (430 million
tonnes). The company's
holdings provide adequate area
for depositing and vegetating
the retorted shale.
Sufficient water rights to
fully develop the resource are
also held by the company.
Unocal began construction of
its oil shale mining and
retorting project north of
Parachute, Colorado, in
January 1981. The project
includes a mine, a shale
retorting plant, a raw shale
oil upgrading facility,provisions for disposal of the
retorted shale, and the
necessary support facilities.
Construction was completed in
1983. The retort is designed
to process 12,800 tons (11,600
tonnes) of shale and produce
10,000 barrels (1,460 tonnes)
of shale oil per stream day.
To reduce the economic risks
of this pioneer project,
Unocal secured a $400 million
contract in 1981 from the U.S.
Government under the Defense
Production Act. This contract
guaranteed a product price of
$42.50 per barrel ($327.00 per
tonne), adjusted for
inflation, and has allowed the
continued operation of this
plant despite the sharp dropin world oil prices that
occurred after the completion
of the project.
PROJECT DESCRIPTION
MINE
Shale for the project is mined
from the rich Mahogany zone of
the Parachute Creek section of
the Green River geologic
formation. The shale
currently being mined has an
average yield of 38 gallons of
shale oil per ton (58 litres
per tonne) .
The entrance to the
underground mine is located
about 1,000 feet (300 meters)
above the valley floor and
opens on the south side of
Long Ridge, which forms the
north wall of the East Fork of
Parachute Creek.
The mine is an underground,
room-and-pillar operation.
The pillars are left in place
to support the roof, but allow
recovery of 60 percent of the
resource from the mine zone.
The mining sequence is a
five-step process:
69
1. A drill jumbo is used
to drill the face;
2. The holes are charged
with ANFO (Ammonium
Nitrate/Fuel Oil), and
then detonated;
3 . Front-end loaders muck
the oil shale, which is
transported by truck to
the underground crushers;
4. Scalers dislodge any
shale that was loosened
by the blasting; and
5. Prototype boltingjumbos stabilize the mine
roof before the cycle is
repeated.
Run-of-the-mine shale is
crushed in four stages to an
average particle size of 0.7
inches (18 mm) and stored in
an underground surge gallery.
It is moved to the surface bybelt conveyors and screened to
remove fines.
RETORTING PLANT
The Unishale-B Retort was
constructed on a five-acre
(two hectacre) bench site just
outside the mine entrance.
Figure 1 is a retort
schematic. Crushed shale
enters the solids feeder
underneath the retort where a
10-foot (3 meter) diameter
piston forces the shale upward
into the retort. Shale oil
product acts as a liquid seal
in the feed chute to maintain
the retort pressure.
As the oil shale rises through
the retort cone it is
contacted by a counter-current
flow of hot recycle gas
entering the top of the retort
dome. The hot recycle gas
provides the heat required for
the retorting process. The
kerogen in the oil shale
decomposes into liquid and
gaseous organic products which
diffuse from the shale
particles, leaving behind a
carbonaceous deposit on the
retorted material. The oil
vapor is cooled and condensed
by the cool incoming shale.
The bulk of the liquid product
trickles down through the
shale and the balance, in the
form of mist, is carried from
the retort by the cooled
gases.
The gas and liquid are
separated from the shale in
the slotted-wall section of
the lower retort cone. Oil
and solids disengage from the
gas in the section that
surrounds the lower cone. The
liquid level in this section
is controlled by withdrawing
oil product.
Retorted shale is forced up
above the retort cone and is
scraped off the pile. It
falls down chutes through the
retort into a cooling vessel
and is cooled by sprayed
water.
Dry, cooled retorted shale
leaves the cooling vessel and
is depressured through a seal
leg. The retorted shale is
transported by conveyors and
trucks to the canyon floor.
It is then spread, compacted,
contoured, covered with soil
and vegetated with native and
introduced species.
The gases leaving the retort
from the disengaging section
70
are scrubbed and cooled in a
Venturi scrubber. The
scrubbed gas is divided into a
make-gas stream and a recycle
stream. The recycle stream is
heated prior to injection into
the top of the retort. The
retort make-gas is processed
in a Unisulf plant to remove
sulfur and used as plant fuel.
After the solids suspended in
the raw shale oil are removed,
the oil is transported bypipeline to the upgrading
facility which is located
eight miles (13 km) south of
the retort.
The retort plant has completed
its startup phase and is now
operating at commercial
production levels. Our
program now is to bring the
plant up to design or greater
oil production rates.
pursuant to provisions of our
contract with the government.
Representatives from DOE and
EPA both sit on a special
Monitoring Review Committee
that reviews all aspects of
the project's environmental
performance. Not only are all
environmental impacts of the
project monitored for
compliance with applicable
standards, the plant continues
to be scrutinized to identify
any other potential
environmental and health
impacts, whether or not
subject to current regulation.
The results to date clearly
affirm that oil shale can be
developed in an
environmentally sound manner,
and further that there are no
significant health or
environmental impacts outside
of the current regulatory
sphere.
RETORTED SHALE DISPOSAL
Retorted shale disposal has
been remarkably successful,
especially in light of early
concerns regarding the
industry's ability to
establish vegetation on
retorted shale and prevent
groundwater contamination. At
Parachute, Unocal has been
able to implement a program
that results in very rapid
establishment of vegetation on
the shale pile. The retorted
shale pile has been
constructed in a manner that
minimizes the potential for
groundwater or surface water
contamination, of which there
has been no evidence.
Unocal's Parachute Creek Shale
Oil Project is one of the most
closely monitored energy
developments ever undertaken,
In most respects,shale-
derived syncrude is equivalent
to conventional petroleum. In
fact, EPA has recently
concluded that shale-derived
syncrude is exactly equivalent
to conventional crude oil and
lifted the regulatory
requirements (PMN) applicable
to new chemical substances
under the Toxic Substances
Control Act, one of the veryfirst products to be so de
listed.
UPGRADING PLANT
Figure 2 is a simplified block
flow diagram of Unocal's shale
oil upgrading process. The
raw shale oil contains
approximately 300 wppm
particulates. To protect the
hydroprocessing reactors from
plugging, the particulates are
71
removed in a filter-bed guard
vessel. The essentiallyparticulate-free shale oil is
then processed in a series of
fixed-bed reactors to remove
arsenic and to saturate
diolefins. This relativelylow pressure process was
developed to prevent rapid
catalyst deactivation and
fouling in the downstream high
pressure reactors.
Arsenic-free, partly upgraded
shale oil is then processed in
the Unicracking/DW unit to
produce high quality syncrude.
The Unicracking/DW process
employs a series of catalytic
hydrotreating and
hydrocracking reactors which
operate at relatively high
pressure and moderate
temperatures. The purpose of
the hydrotreating reactors is
to convert most of the
nitrogen, sulfur and oxygen
heterocompounds to ammonia,
hydrogen sulfide and water.
The hydrocracking reactor is
filled with a special catalyst
and is operated at conditions
designed to reduce the pour
point of the shale oil and to
reduce the molecular weight
and boiling point of the
product. As a consequence of
upgrading, shale oil syncrude
expands in volume
approximately 7 to 8% from the
addition of hydrogen. Thus,
each 1000 barrels (146 tonnes)
of shale oil produced by the
retort becomes 1070 to 1080
barrels (139 to 140 tonnes) of
syncrude .
PROJECT PERFORMANCE
RETORTING
All pioneer plants experience
unexpected problems that
inhibit early performance, and
Unocal's retort is no
exception.
Construction of the plant was
completed in the fall of 1983,
however, start-up was not
achieved until mid-1986. The
plant start-up phase was
completed in 1988 when
commercial production rates
were reached.
For all of 1987, production of
shale oil was 17% of design.
In 1988, production nearly
doubled to about 32% of
design, almost one million
barrels (130,000 tonnes). For
1989, the plant consistently
performed between 50-60% of
design on a short-term basis,but merely matched the