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One tcf gas find: A mixed blessing

By David Renwick

The overwhelming majority of my four or five readers insist that I deal with the subject of the discovery by the biggest energy company operating in Trinidad and Tobago, bpTT, of an estimated one trillion cubic feet (tcf) of new gas reserves with a fourth well in its Savonette field in the East Coast Marine Area (ECMA).

I had initially demurred, believing that everything which could be said about it had already been said.

But on reflection, perhaps not. So here goes.

The find was made, as the company itself revealed, in "a previously untested fault block east of the original Savonette field discovery well," which tells you everything you need to know about Trinidad's onshore and offshore geology and which gave rise originally to the observation that the country is "the graveyard of geological reputations."

Faults break up petroleum accumulations or may even cause them to be lost altogether. At the very least, you have to drill many more wells than a company would normally wish to do. You will notice that bpTT said it is proposing to do yet more drilling in the field.

Faulting forces a company to do just that and if you want one reason why BHPBilliton Trinidad and Tobago has witnessed such a rapid decline in the overall production of its discoveries in block 2c off Trinidad's north east coast, you need look no further than faulting.

Of course, if a company has the money, as bpTT does, then drilling more wells, a very expensive exercise offshore at the best of times, will be no problem, once it is more or less convinced it will be successful.

So much for geology.

There are three other aspects of the field that may perhaps be of some interest to my readers and which have not been sufficiently emphasised.

One is that it shows that the "exploratory resources" number in the annual audit of Trinidad and Tobago's gas scenario by the Ryder Scott Co. is quite capable of being turned into actual "reserves" by well-targeted drilling, which is why you should take with a grain of salt those anguished observations annually by some of my colleagues that Trinidad and Tobago only has so-and-so many years of gas availability based on Ryder Scott's proven reserves figure.

Then there is the "less good" aspect of the find, which is that the Savonette field is not a great condensate producer and means that the gas being retrieved from the new accumulation is not bringing a great deal of condensate(light oil) with it.

BPTT's newer gas fields, like Serrette and Savonette, are not delivering the same amount of condensate per million cubic feet than its earlier fields did.

That mainly explains (in addition to its 'asset integrity" activities, which saw platforms actually shut-in for periods of time), why its condensate output has fallen so drastically and was down to a low of 7,221 b/d in August, the latest figure available to me at the time of writing.

At a time when Trinidad and Tobago is desperately trying to revive its liquids production, Savonette 4 is, in some senses, a mixed blessing.

As the Minister of Energy and Energy Affairs Kevin C Ramnarine said in Parliament a few months ago: "BPTT lost some 8,000 barrels a day of condensate in 2011 and our enquiries to the company have turned up the explanation that it is as a result of the company producing more and more dry, as opposed to wet, gas, which is natural gas produced with liquids, which is condensate."

Any new gas discoveries from other companies exploring in the North Coast Marine Area (NCMA) blocks are also likely to be dry, so we have to get used to having "real" oil finds almost exclusively taking up the burden of kicking liquids production upwards once again.

But the third so far under-stressed factor in the discovery is perhaps the most significant: the depth in the sub-surface at which it was made.

18,678 feet, says bpTT. The company has not told us whether Savonette 4 was drilled vertically or deviated or even horizontally but that 18,678 feet is a mere 390 feet less than the 19,068 foot Ibis Deep well sunk by bpTT in the South East Coast Consortium (SECC) block on behalf of its owners, EOG Resources, Petrotrin and the National Gas Co (NGC) in 2006.

Unfortunately, that well did not identify any gas or oil accumulations, obviously because it was in the wrong place but if you are in the right place, as Savonette 4 was, then there are still discoveries to be made in the deeper continental shelf and substantial ones too: despite what you may have heard. 1 tcf is a great deal of gas and could support several petrochemical plants for a very long time indeed.

So what does the depth of the discovery tell us?

It tells us that the Minister of Finance and the Economy, Larry Howai, undoubtedly advised by his colleague, Minister Ramnarine, was on the right track when he deliberately targeted deeper horizons as an area for encouragement by offering a 40 per cent "uplift" on the tax base for companies drilling successful "approved" wells under Exploration and Production (E and P) licences.

Of course, Savonette 4 does not fall into that category. It was drilled as part of bpTT's on-going effort to extend the reserve volumes in the field. It would have been drilled, incentives or no incentives. Once a company finds producible reserves from an exploration well, it does not really need any incentives; the "incentive" is the money it will be making from selling the hydrocarbons. Which suggests that maybe Howai was wrong to exclude dry holes because companies may be discouraged from making the effort unless they are absolutely sure they are going to find something but that's another story.

Deep horizon drilling has had a mixed history in Trinidad and Tobago, with more failures than successes.

I have already mentioned Ibis Deep but there was, more recently, the Pelican Deep well sunk by EOG Resources Trinidad in the Pelican field in the SECC block which also did not find its desired bounty.

BpTT itself, then Amoco Trinidad Oil Co. (ATOC), drilled an exploratory deep test well in its Samaan field to 16,196 feet in 1993 but that also turned up nothing.

The Morpho 1 well in what was then the S11 block off the south coast of Trinidad, drilled by the then Elf Aquitaine in 1998 on behalf of itself, Amoco and Repsol, went to around 16,500 feet but was likewise unsuccessful.

On the other hand, there was a well actually called Bounty drilled in block 5c off the south east coast by Canadian Superior (the block was subsequently taken over by BG Trinidad and Tobago) which did find a significant "bounty of gas" at depths of between 16,000 to 18,000 feet.

So you never know. But few knowledgeable people are prepared to write off the deep horizon, certainly not messrs Howai and Ramnarine and clearly not bpTT.

In fact, bpTT has been examining the feasibility for some time of taking a stab at a deep well in one of its currently producing gas fields, Amherstia and perhaps even the Poui oilfield (now owned by Repsol, Petrotrin, NGC but bpTT cleverly kept deep horizon rights for itself when it sold out to the trio in 2005).

So, let's all assume that the future will be more favourable to deep horizon exploration than the past.

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

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