Examples of Exp tool to export data from Oracle db table to text file

The free and open-source SchemaCrawler tool that I wrote will do what you need. SchemaCrawler outputs details of your schema (tables, views, procedures, and more) in a diff-able plain-text format (text, CSV, or XHTML). SchemaCrawler can also output data (including CLOBs and BLOBs) in the same plain-text formats. You can use a standard diff program to diff the current output with a reference version of the output.

https://www.SchemaCrawler.com

You will need to provide a JDBC driver for your database.

You might consider a logical standby database as the read-only copy, and cobble together a manual archive log transfer process that copies and registers all the logfiles each sync interval from your transfer media. This has the advantage that you're only using files naturally created by Oracle, and it's a pretty speedy process. It also incurs no downtime on the logical standby.

A handy section I found in the Data Guard documentation which could be helpful is the section on resolving archive log gaps.

EDIT: I just noticed you're not a DBA. You'll need a competent DBA's help to do this, not to mention the privileges required. However, most competent DBA's would consider this fun ;-)