BLACK ROCK MINING LIMITED — Capital/Financing Update 2012

Apr 30, 2012

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1 May 2012

ASX Market Announcements Australian Stock Exchange Limited 10[th] Floor, 20 Bond Street Sydney NSW 2000

Dear Sirs,

OPTION EXERCISE FOR 20% BACKREEF AREA AND RECEIPT OF $2.5 MILLION

The directors of Oil Basins Limited (ASX codes OBL, OBLOA, OBLOB or the Company ) are pleased to make the following ASX Announcement.

Green Rock Energy Limited (ASX code GRK ) has exercised its option to acquire a 20% beneficial interest in the Backreef Area, Canning Basin through acquisition of an OBL subsidiary, in accordance with a Share Sale Agreement that has been executed by the parties.

The payment of $2,500,000 has been received by OBL from GRK.

Yours faithfully

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Kim McGrath

Executive Chairman

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