It's sloppy and there is probably a better way, but this should get it done if this is a one-time thing:
DECLARE
@db_name SYSNAME,
@sql VARCHAR(1000)
DECLARE db_cursor CURSOR FOR SELECT Name FROM sys.databases
OPEN db_cursor
FETCH NEXT FROM db_cursor INTO @db_name
WHILE (@@FETCH_STATUS = 0)
BEGIN
SET @sql =
'SELECT
''' + @db_name + ''' AS [Database],
USER_NAME(role_principal_id) AS [Role],
USER_NAME(member_principal_id) AS [User]
FROM
' + @db_name + '.sys.database_role_members
WHERE
USER_NAME(role_principal_id) IN (''db_owner'', ''db_accessadmin'')'
EXEC(@sql)
FETCH NEXT FROM db_cursor INTO @db_name
END
CLOSE db_cursor
DEALLOCATE db_cursor