The contracts include four one-year options and are valued at approximately Nkr800m ($91.2m).
Equinor said that the contract value also includes costs associated with Havila Charisma modifications. These modifications are expected to support seismic study and reservoir monitoring.
Equinor chief procurement officer Peggy Krantz-Underland said: “We have received safe and efficient deliveries from Havila Shipping for several years and look forward to continuing our cooperation with the shipping company.
“Long-term contracts bring predictability to both Equinor and our suppliers, and form the basis of continuous improvement.”
Havila Foresight has its home base at Equinor’s supply base in Mongstad, Norway.
Equinor NCS supply vessel activities lead Morten Sundt said: “The supply vessels along the entire Norwegian coast are the vital nerve of the more than 40 fields we operate on the NCS.
“By modifying Havila Charisma to provide seismic services in addition to supply services, we are utilising our scale advantage to achieve higher efficiency and flexibility in our operations.”
The Havila Charisma and Havila Foresight vessels are equipped with a battery and adapted for power-from-shore capability, increased safety and reduced carbon dioxide emissions.
Nearly 20 vessels on longer-term contracts with Equinor already or will have a battery and a shore-power system within next year.
Last month, Equinor said it will raise production capacity at the Johan Sverdrup field by 500,000bpd by the end of this year.