I feel like these figures might be pretty optimistic in the current market. The fact that it would exceed Beach's current market cap probably is an indication that it is optimistic. Do you have a news article link?
In terms of infrastructure I remember the Port Bonython pipeline being singled out a number of times (cost to construct was $450M). I have no idea about the internal pipelines but I assume would be valued by oil/gas reserves multiplied by whatever toll they can get out of the users. The problem is being a declining basin I'm not sure if many buyers would be willing to bet on long-term utilisation of the infrastructure (ignoring any unconventional sources in the future).
DLS Price at posting:
51.0¢ Sentiment: Buy Disclosure: Held