Deep Panuke Project Description - Encana

is taken offshore on a special lay vessel where it is straightened and laid on the seabed as a continuouslength. The flowline is trenched in a similar manner to the lay barge method. The “flexible” solutionuses a flowline of non-rigid type. Each flowline is manufactured in one single piece at a specializedfactory and coiled on a large reel and taken offshore. A special lay vessel uncoils the flowline and lays iton the sea bed. Trenching methods are similar to the other schemes. Hook-ups for all three alternativesare carried out by diver/ROV operations.All three methods are technically acceptable with similar environmental effects and the preferredsolution will be chosen following the competitive bidding process.2.10.2.13 Acid Gas Injection LocationAs indicated in Section 2.10.2.7, the option chosen for acid gas handling for the Project is the acid gasinjection technology. The location chosen for the acid gas injection well is D-70. An alternative locationconsidered for the acid gas injection well was H-82. A summary of the investigation is included belowand summarized in Table 2.15.Both acid gas well locations are technically and economically feasible. However, the distance from theMOPU to H-82 is longer than the distance to D-70 (4.8 km versus 1.7 km), which would result in anadditional cost of approximately $1 MM to $2 MM for the extra length of flowline and umbilical for H-82.The possibility of acid gas injection souring the Panuke oil sands is considered to be extremely unlikelyfor both the D-70 and H-82 locations; the likelihood of souring is only slightly greater for the D-70location.The longer flowline for an acid gas injection well at H-82 results in an increased operational riskassociated with a higher risk of hydrate formation in the flowline. In addition, there is also an increasedsafety risk in the very unlikely event of an acid gas injection flowline rupture due to the larger volumesof acid gas contained in the longer flowline to H-82.The environmental impact from both locations would be very similar, although the H-82 location isexpected to have a slightly higher environmental impact due to the following:• longer flowline resulting in larger benthic footprint (greater area of benthic disturbance);• larger safety zone area to include H-82 well and flowline location, resulting in higher impact onfisheries (especially quahog fishery) and other ocean users; and• increased impact to air quality in the unlikely event of acid gas flowline rupture due to largervolume of acid gas contained in the longer flowline to H-82.Deep Panuke Volume 4 (Environmental Assessment Report) • November 2006 2-80