This edition of Energy Insider was perforce prepared before the opening of the bid boxes on Tuesday last week for the 2012 deep water block auction, so I cannot tell you how many companies threw their hats into the ring and for which pieces of acreage.

My four or five readers will themselves know the answer to that by now and be cognisant of which of the six blocks up for grabs attracted most interest. The betting in Ministry of Energy and Energy Affairs (MEEA) circles was that TTDAA 5 might prove the winner in that regard. (The others offered were block 25a, TTDAA 1, TTDAA 6, TTDAA 28 and TTDAA 29).

What was so special about TTDAA 5, you may ask.

Well, it was the only block out of the eight that managed to attract a bid in the 2006 offer of acreage in water depths ranging from 1,700-2,500 metres.

The bidder was Statoil (UK) Ltd, now StatoilHydro.

What attracted the Norwegian company to that particular block?

According to Gareth Burns, manager, commercial and negotiations, Global exploration Americas for Statoil (UK) at the time: "We made a geological evaluation and we do see it as an attractive area. It is not without risk but we have made an assessment and believe TTDAA 5 was the one with the most prospectivity."

Unfortunately, because of the ill-advised decision of the government of the day to convert the production sharing contracts (PSCs) for both the deepwater and the land/nearshore/offshore auction earlier in that year, to a "taxable PSC," as it was called, negotiations between the ministry and Statoil were destined to fail and duly did so. The world economic downturn in late 2007-2008, only exacerbated the situation.

TTDAA 5 was again brought back in the next deep water auction in 2010, along with ten other blocks.

This time, it received no bids at all despite the fact that Helena Inniss-King, the then director of resource management in the Ministry of Energy and Energy Affairs (MEEA), as it had by then been re-named, thought it should have been "one of the most competitive blocks". Instead, only blocks 23a, 23b and TTDAA 14 drew interest from explorationists – bpTT in the case of the first and third and BHPBilliton/Repsol in the case of the second. (bpTT has already formally signed-off on the PSCs for its two blocks and BHPBilliton/Repsol are still negotiating theirs for 23b).

So, in the light of all that, why should anyone think TTDAA 5 would have any special appeal?

Well, prior to the actual launching of the deepwater round in April, it was apparently one of the most nominated of all the open deepwater blocks by those companies interested in the auction (companies are encouraged to indicate to the ministry what deepwater acreage has caught their fancy, which enables the ministry to avoid putting out blocks which no potential bidders are likely to find worthwhile).

They must therefore see something geologically promising in it but why should it rank higher than, say, TTDAA 6, which is just to the north or, come to that, TTDAA 1, which is directly to the south and abuts the maritime border with Venezuela (could there be cross-border gas there as there is in blocks 5b, 6d and bpTT's Kapok block to the west? Probably unlikely).

It will also be fascinating to discover how well block 25a has fared in the auction, which will, of course, be well known by now.

Why? Because this was the only success story, if it can be so called, in the first-ever auction of deepwater acreage in 1996. Nine blocks in water depths of about 1,200 metres were offered to companies, of which five received no bids. Four were eventually awarded under PSCs in 1998: 25a, to Shell and Agip, 25b to Exxon (not yet ExxonMobil), 26 to Exxon and 27 to Arco, Union Texas and Petrobras (bpTT took over operatorship when it acquired Arco).

Shell kicked off the drilling programme and with its very first well, Haydn 1, drilled to 3,500 metres into the Pleistocene formation by the dynamically-positioned Stena Tay semi-submersible rig, identified a working petroleum system, with about 300 billion cubic feet (bncf) of gas. However no oil was discovered which, of course, was what Shell and its partner wanted. 300 bncf of gas in the deepwater just couldn't cut it, even if one of the world's largest majors was prepared to settle for gas.

All of the wells drilled in the other deepwater blocks were more or less dry.

Presumably, some interest must have been shown again in block 25a for it to have landed up in this year's auction.

Following the outcome of Haydn 1, Dr. Luuk Karston, managing director of Trinidad Shell Exploration and Production, declared that "the find was certainly disappointing but the positive thing is that in this completely greenfield area, you find hydrocarbons at all. That is very rare. It doesn't normally happen, even in Saudi Arabia."

Block 23a was one of the five in the 1996 auction which received no bids, though it was taken up in 2010 by bpTT along with block TTDAA 14 directly to the east. TTDAA 28 and TTDAA 29, which were also in the auction which closed last week Tuesday, are respectively adjacent to 23a and TTDAA 14, to the north.

Since the companies must also have indicated some optimism about those blocks, it would seem as though they see prospectivity in both the northern and eastern deepwater areas, where TTDAA 5 is sited.

According to Energy Minister Kevin Ramnarine, the feedback from companies in the wake of the modest take-up of the blocks offered in 2010 was that "the technical risk was too high in the southern part of the deepwater basin because of an inability to map the Cretaceous source rock on the available seismic."

He added: "The companies felt the most likely product would have been natural gas, because the Cretaceous was too deeply buried and had already passed out of the oil window. However, the Cretaceous reflector was clearly visible in the northern part of the basin and co-relative with that mapped in the block 2c area."

So what happened to bring TTDAA 5, which is in the southern part, back into contention? Extensive data reprocessing, that's what.

Both the original 2002 deepwater seismic and lines acquired by GTX Technology under its regional study were looked at again and 2D data by the then Amoco in block 27 on the continental slope re-assessed. This "heightened interest" in all areas of the deepwater.

There is also the "Zaedyus factor" - the discovery of around 800 million barrels of oil equivalent (boe) in offshore French Guiana by Tullow and company.

The energy minister surmises that: "Zaedyus has increased the prospectivity of this entire region."

It will be known by now whether that was, or was not, demonstrated in the bids received last Tuesday.

David Renwick was awarded the Hummingbird Medal (Gold) in 2008 for the development of energy journalism in Trinidad and Tobago.