Tag Archives: Wytch Farm

The surprising story of oil in Dorset.

[Please read the important amendment at the end of this article]

A few months ago, I visited Kimmeridge Bay in Dorset in the south west of the UK.  I went  to look at the oil well on the cliffs above the beach and wrote about my experience.  The Kimmeridge oil reserve is quite small but further east there are huge additional reserves of oil extending for several kilometres under Poole Harbour and Poole Bay.  I wanted to write about these much larger deposits and the environmental effects of extraction: my article, which also takes another look at some of the Kimmeridge story, appeared in the May edition of the Marshwood Vale Magazine. Here is the article:

It’s difficult to believe but one of the most beautiful parts of Dorset in the south west of the UK is home to the largest on-shore oil field in Western Europe. And yet the day to day impact on most residents and on the local environment is minimal. Perhaps the Dorset oil experience can help us predict the potential environmental effects of shale gas extraction by fracking in other parts of the UK? Let’s look at the story of oil in Dorset and see what we can learn.

“Kimmeridge Coal”

Medieval times were harsh for most people but if you lived near Kimmeridge Bay in the Isle of Purbeck, you had one thing going for you; some of the rocks exposed in the cliffs would burn so you had a ready-made fuel for heating and cooking. The locals called it “Kimmeridge Coal” and it didn’t matter that it smelt awful, it was available and it was free. The same logic drove Sir William Clavell in the 17th century to set up alum works at Kimmeridge using the fuel. His efforts came to nothing because of patent restrictions so he turned to making salt by boiling sea water and subsequently he set up a glass works, but neither enterprise prospered.

“Kimmeridge Coal” is found in bands of bituminous shale in the cliffs around Kimmeridge Bay but further exploitation of the material had to wait until the 19th century when it was realised that useful hydrocarbons might be extractable. Processing plants were set up at Weymouth and at Wareham making varnish, grease, pitch, naphtha, paraffin and paraffin wax and in 1848 the street lights of Wareham were lit by 130 lamps powered by gas derived from the shale. The industry never prospered, possibly because the high sulphur content made the gas unsuitable for domestic use.

Kimmeridge oil shale is a useful material but it is not a source of conventional crude oil. Ironically, the first discovery of crude oil in Dorset also occurred at Kimmeridge Bay but it comes from rocks lying well below the shale deposits.

The Kimmeridge “nodding donkey”

Oil pump
The Kimmeridge nodding donkey

The search for oil in Dorset began in the 1930s but it was not until 1959 that the first well producing oil and gas was discovered below Kimmeridge Bay. The well is extracted by a single beam “nodding donkey” pump on the cliffs above the Bay that has worked continuously for more than 50 years; it is the oldest working oil well in the UK and the “nodding donkey” is now part of the local scenery. The Kimmeridge well produced 350 barrels of oil a day at its peak but this has now declined to a fifth of that level. Although the Kimmeridge reservoir is not large, the discovery prompted the search for other oil deposits in Dorset.

The largest on-shore oil field in Western Europe – hidden near Poole Harbour

The energy crises of the 1970s led to further exploration in Dorset and in 1974, oil and gas were discovered by the Gas Council at Wytch Farm on the southern side of Poole Harbour. Production started in 1979 and nowadays the Anglo-French company Perenco owns the majority stake in the oil field. There are three large reservoirs of oil 1-2 km below the sea, extending up to 10 km under Poole Harbour, Brownsea Island, Sandbanks and to the south of Bournemouth. Peak production was in 1997 at 110,000 barrels of oil per day; current levels are about 18,000 barrels per day. The field also produces natural gas (for domestic use) and liquid petroleum gas.

nodding donkeys Wytch Farm
Some of the Wytch Farm nodding donkeys (photo courtesy of Perenco)

 

Furzey Island
Furzey Island in Poole Harbour showing the “hidden” oil wells (photo courtesy of Perenco)

 

There are 12 well sites distributed around Wytch Farm, the Goathorn Peninsula and Furzey island from which more than 100 wells have been drilled. There is also a gathering station where the products of the wells are collected, processed and distributed. This is a large industrial enterprise, the largest on-shore oil field in Western Europe and the second largest consumer of electricity in the South of England (after Heathrow Airport).

Hengistbury Head looking west
Poole Bay viewed from Hengistbury Head – oil reservoirs and long distance drills extend under the sea 1-2 km below the surface (from Wikipedia).
The paradox is that this industrial complex operates in an Area of Outstanding Natural Beauty so the site has been developed with this is mind. Buildings are on sites that have been excavated to reduce height and are screened by trees. Facilities are painted a dull brown and the number of well sites has been minimised by drilling long distances horizontally away from the well site in to the oil deposits; until 2008 Wytch Farm held the world record for the longest drill extending 10.1 km under Poole Bay. In consequence, this large industrial complex has minimal impact on the surrounding countryside and most people are unaware of the activity.

Goathorn Peninsula
An oil rig on the Goathorn Peninsula used for long distance directional drilling (Photo from Wikipedia, taken in 2006) .

 

Lessons from Dorset oil

Wytch Farm is a great success story, both in terms of the oil and gas produced and the minimal environmental impact. Some have used the Wytch Farm experience to suggest that fracking (hydraulic fracturing for shale gas) in other parts of the UK will also have a minimal environmental impact, even suggesting, incorrectly, that fracking has already occurred at Wytch Farm.

Although similar drilling technology is used to extract crude oil and to release shale gas, fracking uses large volumes of high pressure liquid (mostly water) to create fissures in low permeability rock and this has not been carried out at Wytch Farm. Also each potential fracking site is likely to be unique and different from Wytch Farm in terms of the density of wells required, the density of population and the nature of the countryside. Dorset oil has been managed to minimise environmental impact but it would be wrong to use the Dorset oil experience to predict the general environmental impact of fracking elsewhere.

There is, of course, one important issue I have not considered here:  should we continue to extract and use oil given the need to prevent global climate change?  Take a look at the complementary article for my views on that.

Important amendment:  In September 2018 it was revealed that the Kimmeridge oil pump has been legally  leaking the powerful greenhouse gas methane into the atmosphere for nearly 60 years.  The story is covered here.  This disclosure changes very considerably my view of the environmental impact of the Kimmeridge oil pump.

The oil well and the beach – a clash of the human and the natural at Kimmeridge Bay

The Isle of Purbeck in south east Dorset is an area of outstanding natural beauty but it is also Dorset’s oil country. I wanted to see how the demands of the oil industry could be reconciled with the demands of nature, so a few weeks ago I drove through the Purbeck Hills to Kimmeridge Bay.

Kimmeridge 10
The view from the limestone ridge down to Kimmeridge Bay

 

The final stage of my journey took me over the coastal limestone ridge into open countryside where the views became wider, the colours and contrasts more intense. The wide sweep of Kimmeridge Bay lay below me in the sunshine: greens and blues, shadow and light, like an image from a travel magazine. From here the road descended, tentatively, through several broad arcs to reach the thatched, stone-cottaged village and the narrow beach access road. I left the car at the cliff-top car park and got out to look. The wide semi-circular bay, backed by moderate cliffs, spread either side of me and narrow, dark-stone ledges extended from the beach like giant fingers. A few white wavelets interrupted the surface of a deep blue sea and across the water, the vast mass of Portland loomed out of the mist.

Kimmeridge 1
Kimmeridge Bay with the limestone ridges. The WW2 pill box shows prominently and its distance from the cliffs gives a rough indication of erosion.

 

I walked away from the cliffs and followed the access road westward around the row of 19th century, grey-stone cottages. The landward side of the road was lined by sodden arable fields enlivened only by a group of pied wagtails, jittering, fluttering. Soon I reached a large wire-mesh enclosure set back from the cliff edge. Inside the enclosure were pipe work, storage tanks and a “nodding donkey” oil pump, its huge black beam moving ponderously up and down as it sucked crude oil out of the reserves buried deep below the cliff.

Oil pump
The oil well and pump

 

The pump has been working here since 1961 and is the oldest continuously working oil pump on the UK mainland. The oil-bearing rocks are located about 350 metres below the cliff, yielding 65 barrels of oil a day together with some natural gas. This is a modest deposit but it led to the discovery of the much larger Wytch Farm oilfield located ten or so miles away, stretching long distances under Poole Bay.

The oil pump itself is virtually noise-free as it is powered by electricity and, when I visited, there was nobody working nearby. The enclosure is some distance away from the centre of the Bay and partially screened by bushes so it is invisible to many visitors. Nevertheless, I find it incongruous to come across an oil well in this isolated, somewhat desolate and very natural place. To give myself some perspective I went to see more of the bay.

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Kimmeridge 6
One of the limestone ledges at low tide. Hen Cliff is prominent with the former fishermen’s huts below and the Clavell Tower above.

 

The beach is accessible down a precarious wooden stairway through a break in the cliffs, the Gaulter Gap, a narrow valley containing a fast-flowing stream. It’s a stony beach with pebbles, rocks and sand of many shades of grey, giving way to the dark stone ledges. These are visible at low tide reaching outwards into the sea and tilting slightly upwards to the west. The ledges provide great opportunities for rock-pooling and Ralph Wightman also speaks of a game of pebble bowls played along them.

Kimmeridge 4
The World War 2 military pillbox

 

Near the Gaulter Gap the natural feel of the beach is rudely interrupted by a white cylindrical WW2 military pillbox standing on the beach looking as though someone planned to take it away but forgot. It used to sit on the cliff and its current position gives us an idea of how much erosion has occurred in the passing of 70 years.

Kimmeridge 5
The rock layering in the cliffs

 

The beach is backed by grass-topped cliffs about 10 metres high containing distinct layers of rocks of different colours and textures. Bands of pale reddish brown and grey rock appear repeatedly in a semi-rhythmic pattern; differences in the hardness of the rocks and their resistance to erosion give the cliffs texture and a fascinating mosaic of colours. The rock layering in the cliffs make this both a geologist’s paradise and a geological time machine as each of the layers represents a discrete event in the Jurassic period, 200-150 million years ago.

Within the grey layers of rock is an oil shale for which Kimmeridge has been justifiably famous in the past. The richest deposits of oil shale, the “Blackstone”, are found in cliffs east of the bay. The Blackstone contains flammable hydrocarbons and used to be called “Kimmeridge Coal”. For many years it was used as a fuel, initially for cooking and heating and later for various industrial enterprises despite its high sulphur content and foul smell when burnt. In the 19th century it was mined here on an industrial scale and processed to make a range of petroleum products in Wareham and Weymouth in a series of short-lived enterprises.

The oil shale contains flammable hydrocarbons but it does not contain crude oil. Crude oil forms when the remnants of microscopic animals and plants accumulate at the bottom of the sea and are subjected to conditions of high temperature and pressure. Organic molecules are gradually converted to crude oil and this is what happened, many millions of years ago, in the rocks deep below the oil pump. The oil shale deposits exposed in the cliffs began in the same way but were never subjected to high enough temperatures or pressures to produce mature crude oil.
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Kimmeridge 8
The Clavell Tower

 

It’s a pleasant walk along the beach and out along the ledges towards the eastern end of the bay with its slipway, its jumble of boats and the cluster of black-painted, former fishermen’s huts. Behind the huts and partially hidden in the bushes is a scrub-lined, stone stairway heading steeply upwards to the top of Hen Cliff, standing 100m over the bay. This is a hard climb but worth it for the coastal views and for getting close to the Clavell Tower, a 19th century folly and observatory. This three story tower with its Tuscan colonnade stands on Hen Cliff with long views over the bay and the coast. Decked out in pink render and pale stone, it certainly looks very smart. But so it should, as starting in 2006 it was taken apart piece by piece and reassembled 25 metres away from the original site to prevent it falling in to the sea as the cliff eroded. It opened again in 2008 as an upmarket holiday rental. The Tower is now an integral part of Kimmeridge Bay but, in the past, reactions were divided. Frederick Treves, for example, referred to a “ridiculous tower” but to the Dorset dialect poet, William Barnes, in his poem “The Leady’s Tower”, it was “stately”.

Kimmeridge 9
The view across Kimmeridge Bay from the cliffs near the Clavell Tower. If you click on the picture and enlarge it you will be able to see (from right to left) the tops of the former fishermen’s huts, the cliff top car park, the stone cottages and the oil well.

 

As I stood on the high cliff by the Clavell Tower, the full sweep of Kimmeridge Bay and its various landmarks were spread out below me. I had expected to be offended by the oil pump, fearing it might intrude on the natural world. But I was wrong: the oil pump is just one of several traces left by human hand at Kimmeridge Bay; it has little or no direct impact on the bay or its natural setting and is now part of the scenery. If you are looking to be offended by intrusions of the human on the natural, you could focus on the slew of wind-blown litter along the sides of the Gaulter Gap valley or the derelict, red fire engine gradually decaying behind the stone cottages.

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A more fundamental question does, however, arise about whether we should continue to extract this oil. Towards the end of last year the Paris Agreement recognised the need to reduce greenhouse gas emissions in order to limit the increase in global average temperature above pre-industrial levels to 2 degrees or less. Although the Agreement can be criticised for its lack of enforceability, it clearly defines the climate change problem as one of greenhouse gas emissions. A major contributor to these emissions is the burning of fossil fuels such as the oil extracted underneath Kimmeridge Bay.

Early in the 20th century, the novelist EM Forster stood a few miles north east of Kimmeridge and wrote in Howards End: “If one wanted to show a foreigner England, perhaps the wisest course would be to take him to the final section of the Purbeck Hills, and stand him on their summit….”. From this vantage point, Forster saw the rivers and landscapes of Dorset and neighbouring counties as a microcosm of all that existed in England. It wasn’t all beauty as he also saw creeping suburbia and its ill effects. Today we might relocate Forster’s vantage point and stand him by the Clavell Tower to look down on an eroding coastline under attack from increased storm activity and rising sea levels. He would also look down on the oil pump working away to extract more fossil fuels. Perhaps this alternative Purbeck view would illustrate some of the tensions inherent in contemporary England.

Kimmeridge 11
Kimmeridge Bay from the stairway up Hen Cliff. Click and enlarge the picture to see the Kimmeridge landmarks. The WW2 military pillbox can be seen standing on the beach below the stone cottages

 

The photographs were taken on February 24th 2016