rig mobilised, page-8

Heres one for the hard core researcher
http://www.pgt.com.br/downloads/petroleum_sys_br_over.pdf

I think the clue here is the play types from what i have read.
Both 138 and 59 are pre-rift plays where Block 79A and 96 rift plays.
See Table 2.3 Leads and Volumetric Estimates in the Mercury report.

Also see section 2.5 Prospectivity Summary of the Mercury report
Chapter 1 states
The main reservoir intervals that define the two play systems are the pre-Rift play (Tithonian-Berriasian) Sergi and Agua Grande Fms, proven reservoirs that are widespread throughout the basin, with secondary objectives in the younger, but also proven reservoirs of the Rift play (Valanginian-Hauterivian) Marfim and Pojuca Fms.

We are given 30% probability of success with these systems compared to
330 - 24% probability of success
430 - 27% probability of success

Cheers