ABERDEEN, UK – Ithaca Energy has sanctioned the Captain enhanced oil recovery (EOR) Stage 2 project in the UK central North Sea.
This follows approval for its field development plan addendum from Britain’s Oil and Gas Authority (OGA).
EOR Stage 2 is the next phase of a project designed to increase hydrocarbon recovery from the heavy-oil Captain field, originally developed by Texaco.
It involves injecting polymerized water into the reservoir supported by additional subsea wells, subsea infrastructure and new topsides facilities.
According to Ithaca, Stage 1 of the project proved that polymer EOR technology works, with a production response in line with or better than expected across all injection patterns.
Captain is a billion-barrel field in block 13/22a in the outer Moray Firth region, which started production in March 1997.
Main surface facilities are a wellhead protector platform and bridge-linked platform connected to an FPSO, with horizontally drilled wells equipped with downhole pumps.
Ithaca operates with an 85% interest, in partnership with Dana Petroleum (15%).
Polymer EOR has been trialled at Captain since 2010 with the Stage 1 scheme sanctioned in September 2017.
The scope has included polymer injection in up to six long-reach horizontal wells and associates brownfield work scopes, with bulk provision of polymer designed for the reservoir conditions.
For many years the field had been under waterflood, but the associated coning effect in the reservoir led to substantial volumes of bypassed oil.
The EOR technique is designed to reduce the mobility contrast between the polymerized water and viscous oil. Various pilots demonstrated that Captain’s reservoir conditions – pressure, temperature, type of rock and oil properties – were all suitable for polymer EOR.