select 'grant select on ' || owner || '.' || table name || ' to someuser'
      from dba_tables
      where owner in target_schema;

SQL> CREATE OR replace PROCEDURE lucky_proc 
  DECLARE 
    r_owner VARCHAR2(60); 
    r_name  VARCHAR2(60); 
    t_name  VARCHAR2(60); 
    CURSOR c_tabowner IS 
      SELECT owner, 
             table_name 
      FROM   all_tables 
      WHERE  owner IN ('SCHEMA1', 
                       'SCHEMA2', 
                       'SCHEMAN'); 

CURSOR p_grantprivs IS 
  SELECT   'GRANT SELECT ON OWNER.' 
                    || table_name 
                    ||'to user_name1;' 
  FROM     dba_tables 
  WHERE    owner='SCHEMA_NAME' 
  AND      object_type IN ('TABLE', 
                           'VIEW') 
  ORDER BY 1, 
           2, 
           3) 
MINUS 
SELECT grantee, 
       granted_role 
FROM   dba_role_privs 
WHERE  owner IN ('SCHEMA1', 
                 'SCHEMA2', 
                 'SCHEMAN'); 

BEGIN 
  OPEN c_tabowner; 
  LOOP 
    FETCH c_tabowner 
    INTO  r_owner, 
          r_name; 
     
    OPEN p_grantprivs; 
    LOOP 
      FETCH p_grantprivs 
      INTO  t_name; 
       
      CLOSE p_grantprivs; 
    END LOOP; 
    CLOSE c_tabowner; 
  END;  2    3    4    5    6    7    8    9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48  
 49  /

Warning: Procedure created with compilation errors.

SQL> show error
Errors for PROCEDURE LUCKY_PROC:

LINE/COL ERROR
-------- -----------------------------------------------------------------
2/3	 PLS-00103: Encountered the symbol "DECLARE" when expecting one of
	 the following:
	 ( ; is with default authid as cluster compress order using
	 compiled wrapped external deterministic parallel_enable
	 pipelined result_cache accessible rewrite

SQL>