FROZEN HEAT | Volume 2

Table 3.1-a: Production challenges and associated environmental considerations for permafrost gas hydrate deposits

Reservoir type

Reservoir setting

Production maturity 1

Site survey & foundation considerations

Drilling, completion & production

Environmental response

Onshore – Sand-host sediment

Beneath permafrost – Pore-space occurrence – Temp. 0 to ~12 °C – Sites: Alaska North Slope (USA), Mackenzie-Beaufort/ Arctic Islands(Canada) and Siberia (Russia)

– Discovered technically recoverable resources (Alaska North Slope and Arctic Canada) – With completion of demonstration projects at Mallik site in Mackenzie Delta, currently existing production technologies have been verified. However, market and infrastructure not presently in place.

– Several well described sites have been identified in North America – Environmental and geo-hazard issues related to near surface infrastructure expected to be similar to conventional

– Conventional drilling practice & sand control/flow assurance measures – Dissociation primarily through pressure draw-down (down-hole pump) – Challenges associated with low reservoir temperatures & retaining formation integrity when hydrates are dissociating – Subsurface water-disposal strategy will be required – Flow assurance measures will be necessary to reduce risk of secondary gas hydrate formation in gas production stream – Horizontal wells may be required

– Negligible ground surface interactions are expected as the most prospective gas hydrate accumulations are buried many hundreds of metres below the ground level, beneath a competent permafrost interval – Control on reaction provided by ability to control pressure in the well bore. – Seal integrity expected to be sufficient as the accumulations are likely to be converted, pre-existing, free gas traps.

Within permafrost – Pore-space occurrence – Temp. < 0 °C – Sites: as above

– No technically recoverable resources identified (Seismic evaluation complex due to hydrate-ice similarities) – Development hindered by low reservoir temperatures – No technically recoverable resources identified – Gas hydrate saturation and reservoir extent unclear, additional work needed

Not considered

Not considered

Not considered

Onshore – Other host sediment environments

Within and beneath permafrost – pore and fracture fill

Not considered

Not considered

Not considered

modes in fine grained strata, lithified sediments with low permeability etc. – Sites: Qilian Mtns, China; also likely in other permafrost settings but presently not documented Thick offshore permafrost occurrences are suspected beneath the Arctic shelves (Beaufort Sea, Siberia) where terrestrially formed deposits have been submerged by transgression. Gas hydrate can be expected within and beneath permafrost in settings similar to those described above

Offshore – Variable host sediment environments

– No technically recoverable resources identified – Gas hydrate saturation and reservoir extent unclear, additional work needed

Not considered

Not considered

Not considered

1. Likely commerciality time-line (i.e., produceable/non-produceable in the near future)

FROZEN HEAT 66

Made with