These discoveries are significant due to their size or the fact that they indicate new important exploration concepts, even though no reserves figure might have been announced.
Five hydrocarbon discoveries offshore northeast Brazil (in the Sergipe-Alagoas Basin) were announced in 2012, the last two being in December. The latest (informally known as Cumbe) was discovered by well 1- BRSA-1104-SES, at a water depth of 2,338 metres, found 28- metre interval of light oil in a reservoir with excellent properties.
Another Kenyan onshore oil discovery was made in the Tertiary sandstones with 30 metres net oil pay in the Twiga South 1 well. There were oil and gas shows over a large interval.
A major onshore discovery in Mexico was announced by the Mexican President in November. The well Pozo Navegante 1 was reported to have encountered 315 metres of light crude oil and with a reserves estimate of up to 500 mnboe, is said to be one of the largest discovered in the last ten years.
However, the reserves figure includes proved, probable and possible categories and the actual recoverable reserves could be much smaller. Pemex had also announced two offshore discoveries by wells Trion 1 (August) and Supremus 1 (October), with the reported reserves (categories not defined) of 200 mn bbls and 125 mn bbls respectively.
Delineation wells increase the size of gas discoveries offshore Mozambique. Mamba South 2 and Coral 2 wells drilled by Eni have added about 6 tcf of gas in place to the resources of Area 4. The first well (1,918 metre water depth and 9 km east of Mamba South 1) “encountered 60 metres of gas pay in high quality Oligocene”.
The second well (1,950 metre water and 15 km west of Coral 1) “encountered 140 metres of gas pay in good quality Eocene”. Both discovery wells confirmed hydraulic communication with the reservoirs discovered in the initial discovery wells. Eni will continue its delineation drilling programme in both fields.
However, the results from these two wells have increased the estimate for the gas in place in Area 4 by 6 tcf to about 23 tcf and increased the full potential of Mamba Complex to 75 tcf (gas in place). The testing of Mamba South 2 well led to the estimation of a sustained production rate of 140 mncfpd (or MMSCFPD- million standard cubic feet per day).
A number of wells have proved disappointing or were ‘dry’ in the Iraqi Kurdistan. As another indicator that one cannot take oil/gas discoveries for granted—even in Iraq—ExxonMobil has relinquished its exploration block in Penjwin because “it offered little prospect of exploration success”.