Environmental Engineering Reference
In-Depth Information
$0.35 to $3.50/bbl. In many locations where the disposal wells are adjacent to hydrocarbon-
producing wells, reinjection is economically viable. However, in a limited number of loca-
tions, trucking costs for transporting the produced water from the production formation
to the disposal formation far exceeds the disposal well costs themselves. These costs may
range as high as $23/bbl. In the Marcellus formation in Pennsylvania, the planned aver-
age cost of disposal is approximately $8.45/bbl. Even at this price point, injection disposal
is generally the most attractive management practice.
17
A very small minority of land-
based locations, accounting for under 2% of North American production, are obligated
to recycle and process the waters. This obligation is generally in the form of regulatory
requirements. Parts of Canada, and individual US states, including Alaska, Wyoming, and
Colorado, have obligations for producers to recycle some portion of the produced water.
Unlike onshore production, when oil production moves offshore, especially in the EU
North Sea, regions in offshore Brazil, and some other locations, operators face three chal-
lenges. The irst is a lack of disposal wells; the second is a stronger regulatory obligation in
many places to protect marine environments; and inally a severe limitation on footprint/
weight, which makes storing even small quantities of produced water on offshore plat-
forms physically impossible. In offshore produced water management, complex mechani-
cal, chemical, and adsorptive systems are used to manage the tens of thousand of gallons
of produced water created daily. Approximately 60%-75% of the equipment observed on a
producing oil platform offshore is for the treatment of produced water. A number of well-
established technologies are generally bolted together in a “treatment train” for offshore
water handling. An excellent survey of the most common technologies in water treatment
trains was reported by Igunnu and Chen in 2012. The primary conclusion is that there is
not a single method that solves all the water-processing challenges posed by produced
water management.
To provide a framework to the current situation and economics involving produced
water management, four short examples are provided:
Hydraulic fracturing drill site, Central Ohio, USA, Summer 2012
:
Site managers reported
to the authors that 50% of low back and produced water from drilling is remixed
with no treatment and reused in the drilling operation. This “on-site” reuse cost
was approximately $0.50/bbl in handling and electrical pumping costs. The other
50% of the produced water was hauled offsite for disposal wells at a total cost of
$4-$8/bbl. The variable to this cost is the trucking distance, as multiple disposal
wells had to be used at this location. Trucking distances were 2.5-5.5 h round-trip
for each trip to one of three disposal wells.
A major service company near Pittsburgh, Pennsylvania, USA, Marcellus plays, reported to
the authors
:
Close to 100% of low back and produced water recycling was done on
site, using ozone as a biocide. The total cost was approximately $4/bbl for ozone
treatment and handling. In the few situations where a full recycle for on-site reuse
was not possible, costs of $7-$11/bbl were paid to dispose at disposal wells in a
neighboring state. Again, the variable in disposal costs was the trucking costs.
Onshore in the Green River Basin of Wyoming, USA
:
A limited portion of produced water
from oil and gas operations is legally obligated to be recycled and put to beneicial
reuse for agricultural or wildlife habitat. Numerous technology efforts and varia-
tions on solutions have been undertaken. The authors developed technology for
this market capable as one portion of a ive-step treatment train. The total cost of
treating the produced water from wellhead to beneicial reuse was approximately
