Formation Of  Oil 

The time period necessary for  formation of oil beneath the surface of the Earth is  estimated to vary between 10 million and 600 million years.

Conventional wisdom has it that at the beginning formation process we have tiny plants and animals (plankton) which die in ancient seas, settling down and decaying  amid the sandy mud sediments lying at the bottom of those seas.With little or no oxygen present these micro-organisms break down into layers of carbon-rich organic compounds  mixed with the surrounding sediments  and eventually formed into a  fine grained shale or source rock.

Over more time new sedimentary layers are deposited on top of  the source rock. The intense pressure and heat so exerted on the source rock results in the organic material being distilled into crude oil and natural gas. The flow of oil from the source rock then accumulates in thicker, more porous limestone or sandstone, called reservoir rock. The crust of the Earth's surface is known to be made up of a number of plates. These plates move against each other.  Movements of the Earth may in places, trap  oil and natural gas which are in the reservoir rocks between  layers of impermeable rock, or cap rock, such as granite or marble.

Searching for oil: When searching for oil,  geologists look for oil traps formed by movements of the Earth.In general there are three types of geological structure in which oil traps are likely to be to be found.  These are where :

• folding takes place. That is horizontal movements of the Earth press inward and move rock layers upward into a fold or anticline. Under such conditions an oil trap may be found between impermeable rock formations where the fold has occurred.
• When faulting occurs the layers of rock crack, and one side shifts upward or downward relative to the other.  Under these conditions an oil trap may be found downwards along the fault line where the oil has been locked by impervious rock.
• A third condition called pinching out is where a tongue of impermeable rock has been squeezed upward into the reservoir rock.  The oil traps in such cases lie along the impermeable rock which has pinched up through the crust of the earth.

Oil reservoir rocks (red) and natural gas (blue) can be trapped by folding (left), faulting (middle) or pinching out (right). Diagrams courtesy of Institute of Petroleum

Fiji

It has been established that there is a substantial area in Fiji where  pinching out has occurred. The area concerned is called the Lau Ridge which shown in the map below published by the Mineral Resources Department.  In addition major fault lines exist.

Tectonic reconstruction of South West Pacific Region published 1993 by Mineral Resources Department, Fiji

Oil exploration

The following comments are taken from a paper prepared by Johnathon A Rodd in 1993 for SOPAC and later published by Mineral Resources Department

Fiji first gained attention as an area of petroleum potential in 1968 following the discovery of oil seeps in neighbouring Tonga. Subsequently, there have been two stages of exploration. The first period from 1969 to 1977 commenced with reconnaissance mapping by Shell Internationale and Magellan Petroleum in 1969 and 1970, which provided the first assessments of source rocks and reservoirs. Following this, the first exploration licence, covering Bligh Water Basin (Figure 1), was awarded to a partnership with Southern Pacific Petroleum as operator in 1969. A total of 1590km of regional seismic data was acquired from which sediment thicknesses and general basin depocentres were established.

In 1971 three licences were awarded to Offshore Oil Exploration, Atlantic and Oceanic Resources, and Investment Corporation of Fiji; and a fourth to International Petroleum in 1972. These licences covered the western Yasawa Platform, central Lau Ridge, Bau Waters Basin and Baravi Basin respectively (Figure 1). A total of 1585km of seismic data was acquired in these concessions from 1971 to 1975. A further 4433km of regional speculative seismic data were acquired by Amoco and Western Geophysical in 1972 and 1973.

From these surveys the Bau Waters Basin and western Bligh Water Basin were outlined and general sediment thicknesses determined on the Lau Ridge. By 1977 all licences granted during the first period of exploration had expired.

Encouraged by high world oil prices, the second period of exploration took place from 1977 to 1987. In 1977, Dakota Exploration was awarded a concession in the Bau Waters Basin and western Koro Sea. Over 1400km of seismic data were acquired offshore which permitted more detailed structural interpretation.

In 1978 three exploration licences were awarded to Pacific Energy and Minerals covering Bligh Water Basin, the Yasawa Platform and Great Sea Reefs Platform. Following farm-out agreements with, or options taken by, Bennet Petroleum, Chevron and Mapco, 6050km of seismic data were acquired which formed the basis of more detailed structural interpretations. Geochemical investigations of sea-bottom sediments in Bligh Water showed one pentane anomaly indicating thermogenic, migrated hydrocarbons.

Exploration drilling followed with Chevron's wells Bligh Water- 1 and Great Sea Reefs-1 in 1980 (Figure 1). During 1981 and 1982 Bennet Petroleum drilled four wells: Buabua-1 and Buabua-2 located on an island in western Bligh Water Basin, followed by Maumi-1 and Cakau Saqata-1 in Bau Waters Basin. Finally, Worldwide Energy as operator of the Pacific Energy and Minerals group drilled well Yakuilau Island-1 in 1982 in western Bligh Water Basin.

All seven wells were drilled to test Tertiary reefal limestone objectives but, none reached its target and a re-evaluation of seismic data shows that six of the wells did not drill valid structural traps. Consequently, Tertiary reefal limestones are still an untested play with considerable potential. On a more positive note, drilling has shown the presence of source rocks and shows of oil and gas in the offshore basins of Fiji (Figure 2; see Petroleum Geology).

By 1987 the second group of licences had expired. In the same year the Fiji Government's Mineral Resources Department completed a major source rock sampling programme. Two earlier evaluations by SOPAC (refs 1 & 2) have been superseded by a major new evaluation (Ref. 3), the results of which are summarised here.

Further details of Fiji's exploration history are given in an earlier publication (Ref. 4). see http://www.mrd.gov.fj/gfiji/petroleum/petroleum.html

Figure: 1

Oil Exploration Techniques

The practice of geology is not confined to physically examining and interpreting surface features, surface rock and soil types, and drilling for  core samples.

The range of tools available to oil geologists now include

• satellite images which may be used to examine surface rocks and terrain
• gravity meters and magnometers  which are able to detect minute changes in the Earths gravitational and magnetic fields  caused by flowing oil. 
• electronic noses called sniffers able to be used to detect the smell of hydrocarbons  
• seismology is also commonly used whereby shock waves are created to pass down through hidden rock layers. The data yielded by the waves which reflect back to the surface is able to be interpreted to determine the structure and type of underlying rock formations. 

Unofficial Activities

• Not mentioned by J A Rodd is a report concerning oil potential in the Lau Group of Islands known to have been completed in 1987 by the husband of a local Suva businesswoman.
• Similarly a Japanese-led oil survey team was known to be working out of Vanuabalavu early in the year 2000 on the question of oil potential in the Lau Group of Islands.  No published work is apparently available but snippets of overheard conversations among the group suggest that their findings were positive.
• It is known that the Lau Group of Island is now closed to prospecting applications and that a license has been issued.  No information concerning the identity of the present holder of the prospecting license is apparently available.

Mining Tenements Map

Some information is able to be gleaned from the Mining Tenements Map published by Mineral Resources Department.  The current Mining Tenements Map is shown below:

Mining Tenements Map: Published by Mineral Resources Dept, Fiji

Comments (5)

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Atatu said:

Dear Wendell, I was very interested in what you wrote. It was in deep thought. It showed that your knowledge was both deep and broad. However, some of your guessing might not be accurate enough. With regarding to the questions you put, some of my opinions were as following: 1.Could it be that the accepted reasons for the George Speight coup of May 2000, namely harvesting of the mahogany forests were completely wide of the mark? My opinion: Not particularly for that. It was mainly for political reason. Certainly, political power also means some commercial benefits. 2.Was the real reason for the George Speight coup the high probability that there is oil is lying under Fiji's sea's waiting to be discovered ? My opinion: Some oil & gas did lie there. However, there is significant uncertainty of the fracture of the reserve. The viability of investment for the exploration or production uncertain too. I doubted that George Speight would like to risk his and his supporters' lives for this highly uncertain opportunity. 3.The Qarase Government clearly intended by means of the Qoliqoli bill to pass the ownership of the seabed from the State into the Native Land Trust Board system: Was the high probability of an oil discovery of oil the real reason for their refusal to budge from that position? My opinion: No quite. Qarase was not really interested in those highly uncertain thingy. He refusal of budging to the military was due to: (1) The pressure from his political party and SDL's political alliance (2) He "thought" that with the strong support from GCC, commander Bainimarama dared not and could not overthrow the government (3) He "thought" that he got strong support from aussie and kiwi;in case something happened, his aussie and kiwi friends could help and save him (4) He is a very "power hungry" man; he concerns much of the his and his party's today instead of tomorrow. 4.Was the Qarase Government in fact backed by an oil exploration consortium? My opinion: According to my info and understanding, No, I don't think that Qarase Government was backed by any oil exploration consortium. I could prove it by some facts. Enjoyed very much of the way of your thinkings. Atatu

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26 December, 2006
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Tim said:

Just to put the quantities in context... According to this article, Bligh Waters has potentially 5,400 to 20,000 million barrels of oil. The Middle East has proven reserves of 708,000 million barrels of oil. It costs $240-$360 million just to drill the wells for one oil rig with structures like Fiji. It costs $500 million to remove the well when the oil runs out. Before it's accident, the Petrobras 36 oil rig had 26 wells and produced 180,000 barrels/day. World consumption is 84,000,000 barells/day. That's about 0.2% of world demand per rig. At the highest estimate (i.e. being able to economically extract the entire) 20 billion barrels, Bligh Water could supply the world with oil for 238 days. That's a lot of money, but it's certainly not on the scale of Kuwait, Iraq, or even Texas - it's closer to Australia, which isn't exactly noted as an oil producer. Tim.

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30 January, 2007
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Exiled Fijian said:

In 1997 I was working with an NGO called SPACHEE. Projects were mostly on Rural Development and Sustainability. I met with some village elders who took me to a site in the village of Ucunivanua, Verata, Tailevu. The elders claim that they use to get pure kerosene from that location untill an exploration company came from the US to do some "explorations" at the site. What the happened after the explorations is still a mystery, as the "kerosene" dissappered never to return. The village elders are adamant the oil will return when the time is right. There are similar stories on minerals around Fiji and most of the people I talk to say these mierals will "surface" when there is a government free of corruption that will make sure all of Fiji benefits from these resources. We can only hope>

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01 February, 2007
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CONCERNED CITIZEN said:

No one can deny that all this talk about oil prospects found in Fiji is very inspiring for Citizens of Fiji and very interesting to all who take interest in Fiian folklores. The program "Noqu Buli kula" comes into mind perhaps. It can be a source of inspiration and also on the downside a spell disaster for Fiji in the future. Oil is undeniably a much sought energy sourcearound the world.It has been the cause of World Wars,currently the mai reason behind the invasion of Iraq.Reading thru some articles concerning Australian Oil interests in Iraq gives me the shivers when I think about the future of any Oil prospects that any future Fiji Govt has.In the Iraq case,the bidding by Australian Company BHP Billiton to tap into the An Fayal Oil Reserve in the South Of Iraq(reportedly the largest)led to the Australian support for the invasion of Iraq,besides what have ordinary Iraqis or Saddam done to hurt Australia? We can never rule out that this would be the case for Fiji in future should the propsects of oil become a reality. It is for this reason that I dread this report of Oil prospects in Fiji.Let's hope that John Howard and Alex Downer his bull terrier have passed on by then!!!

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09 February, 2007
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Sue Cauty said:

An interesting addition to Wendell Archibald?s oil report; and one worth checking out? Is it true that in August last year Qs lot paid for an electronics? engineer to be flown business class from Oz to Nadi; then flown to Rakiraki on a local helicopter; then flown from there, on an unmarked helicopter, to a floating oil exploration rig (ship) in Bligh Waters, to undertake on-board repairs; then returned home by the same methods? Apparently this chap had to sign documents vowing not to reveal anything of this operation ? a rather vain hope, as obviously such an operation would involve quite a number of people. But seems that, with his consequential knowledge of such things, despite being rather deep down, the oil would indeed be commercially viable. Wouldn?t a floating oil-rig (albeit ship-shaped) with a heli-pad and ?copter on board, sitting in Bligh Waters, be rather obvious? In any case, who owns it and where did it come from? We are talking seabed here, not foreshore - ergo, the Qoliqoli Bill?

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26 April, 2007
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