Just had a look at the seismic sections from the Q1 2013 presentation.
The uppermost source rock indicated was seemingly confirmed in the Wingat well. It might also act as a seal for the Wingat prospect. The horizon however is not mapped through the section, so I can't really tell if this theory is vaild.
This source rock might act as the kitchen for the Baobab prospect which will also be drilled in the Murombe well. The source rock is not buried as deep as the one that feeds the Wingat prospect.
So IF the source rock at Wingat generated a wet gas / condensate than the upper one could have generated more liquids. There is roughly a difference in the burial depth of about 300-400m, which equates to ~6°C in a cold basin or up to ~20-20°C in a hot basin. (I do not know the geothermal gradient in the Walvis basin)
Long story short: A possible reason why HRT is optimistic about Murombe might be that they think that Baobab is located above an oil generating source rock.
A potentially gas generating source rock at Wingat could also be due to volcanics which heats up the rock. On the published seismic section however I do not see volcanics. If volcanics were involved they would compeletely change my assumptions.
If anybody has more informations about the spreading of the volcanics in that area, I would be very grateful.
Please note the above is all speculation due to unsufficient data / information.
regards