ORA-16000: database open for read-only access on standby database

Hello,

I'm trying to run some specific queries in a standby database with the below configuration and get the subject error:

SQL> select * from v$version;

BANNER

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Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

PL/SQL Release 11.2.0.3.0 - Production

CORE    11.2.0.3.0      Production

TNS for Linux: Version 11.2.0.3.0 - Production

NLSRTL Version 11.2.0.3.0 - Production

Elapsed: 00:00:00.00

SQL> SELECT db_unique_name,

       primary_db_unique_name prim_db_name,

       log_mode,

       open_mode,

       remote_archive remote_a,

       database_role,

       platform_name,

       force_logging

  FROM v$database;  2    3    4    5    6    7    8    9

DB_UNIQUE_NAME  PRIM_DB_NAME  LOG_MODE    OPEN_MODE            REMOTE_A DATABASE_ROLE    PLATFORM_NAME     FOR