For the purpose of testing software products against real data there are three options:
1) Equinor and partners have made one test dataset available to the public: the Equinor Volve field decommissioned in 2018.
Learn more about the Equinor Volve database here.
2) Energistics Consortium have password-protected access to some test datasets made available by members.
3) Small sample data are sometimes available on the Developers & Users pages under Developer Resources.