Hydrocarbon Exploration and Production in the

Open University Field Trip To and 7th October 2016 Itinerary

• 10.00 Godlingstone Look-out • 10.45 Pick up bus at Norden Park and Ride • 11.00 Gathering Station • 11.30 X-Site • 12.00 M/F-Site • 12.45 Norden Park and Ride • 13.30 Kimmeridge car park for lunch • 14.30 Kimmeridge Oil Field • 15.30 Extraction • 16.00 Finish

2 Safety Risks and Controls

Insurance information - Each person attending a field meeting does so on the understanding that he/she attends at his/her own risk. The OUGS has Public Liability Insurance cover for field and indoor meetings but Personal Accident and Personal Liability cover remain the responsibility and personal choice of the participant.

Field/Safety Equipment Needed: Sturdy and waterproof footwear, waterproof clothing. A hand lens. A geologist’s hammer is not required. Collecting bags can be useful too. Water in case it is hot.

Transport and Driving Hazard: Cars and other vehicles, accidents Control: This is the highest risk. Keep aware at all times, Wear seatbelts No mobiles while driving

Weather Hazard: cold, wind, sunshine, visibility Control: waterproofs, warm clothing, hat, suntan lotion, sunglasses, food/water Do not stray from the group

Sea Hazard: falling in water, ’freak’ waves, cut-off by tides Control: Do not enter sea, care close to water, check tide timetables

Rough Terrain, Cliffs Hazard: Steep ground, unstable and uneven surfaces, slippery rock, falling rocks Control Sturdy boots, trekking pole Take extra care near cliff edges (top and bottom)

Industrial Sites Hazard: Machines, inflammable liquids, energy potential Control: Follow leaders instructions, stay with the group, no smoking, seatbelts Follow leader for emergency procedures if required

Wildlife Hazard: Wasps, Adders, Ticks Control: Be aware. Alert the leader and do not touch, Wear long sleeves, care around bracken 3 7

2 8 3 1 4 5 6

1= 2= 3=West Bay 4=Langton Herring 5=Whiteways Hill 6=Kimmeridge 7=Wytch Farm 8=Godlingstone 4 Generalised stratigraphy of the Wessex Basin

Alpine Orogeny

R The Wessex Basin is a complex of fault bounded sub-basins initiated in the Cimmerian Unconformity Permian that underwent rift related subsidence throughout the Mesozoic. That is from around 260my S 6. Kimmeridge Clay S Kimmeridge to 70my. Basin subsidence R 4. Frome Clay Lst and sedimentation was R Langton Herring interrupted by the Alpine R 3. Bridport Sands orogeny at the end of the S Reservoir West Bay Cretaceous which caused 2. Lias source rocks basin inversion, reversing Lyme Regis the movement on pre- R 1. Sherwood Sst Reservoir existing intrabasinal faults. Ladram Bay After the Alpine Orogeny R more localised subsidence continued within the Tertiary . Variscan Orogeny Godlingstone look-out point – Locality 8

Arne Furzey Goathorn Brownsea Sandbanks Peninsular Island Peninsular Island and

Wytch Farm is set in a very environmentally sensitive area, and surface operations have been hidden in coniferous forests on Wytch Heath. In 1995,the field won The Queen's Award for Environmental Achievement and the field remains largely unnoticed by the general public. 6 Wytch Farm Reservoirs

7 Wytch Farm Production

120000 T47 rig Long Reach finishes Drilling 100000

80000 Discovery Sherwood of Sherwood Production 60000 Reservoir 1992 water cut 35% 40000 takes over Bridport BP operatorship Wytch Farm Production Production Operates ~16,825bbl/day 20000 in Oct 2016

Average Oil Production (bbl/day) 2009 water cut 93% 0 1975 1980 1985 1990 1995 2000 2005 2010 2015 Year • Discovered by British Gas 1973 & began Bridport production in 1979, Sherwood in 1989 • BG privatised & Wytch Farm sold to BP & bidding group in 1984. BP sold to Perenco in 2011 • Production peaked in 1997 at ~110,000 bopd. Reserves of 43 Mmbo remained in 2011 • By June 2012, 102 wells drilled from 13 wellsites with a combination of producers and injectors Structure of Wytch Farm

Chalk

Bridport

Bridport Sherwood

Sherwood

9 Wytch Farm 1998 3D Seismic Survey Example “Dip-Line”

S 98/06-7 N

Base Chalk

Apto-Albian Unc.

Corallian

Cornbrash

Inf. Oolite

Rhaetic - Penarh

Sherwood Locality 6 (SY 909 790)

The Kimmeridge Clay which is upper in age was deposited around 150 million years ago in a deep water environment. The sea bed was probably anoxic, that means without oxygen, so that there was very little life on the seafloor. The lack of oxygen reduced predation and helped to preserve organic matter in the fine grained muddy sediments. Marine plankton living in the sea included phytoplankton with organic walls and plankton with carbonate tests. The hard bands that stand out on the foreshore and in the cliff are limestones which include more carbonate plankton microfossils. Fossils found here include thin shelled bivalves and ammonites. The ammonites include Aulacostephanos and the smaller Amoeboceras. The bivalves include a small oyster called Liostrea; Lucina which is small, and Protocardia which is rounded with a faint rib pattern.

Lucina Protocardia Aulacostephanos Amoeboceras serratum 11 Integrated Seabed Map (DORIS) with Onshore Topography (Courtesy of Infrastrata)

Wytch Farm

Purbeck Monocline

Purbeck Dorset Seabed Map with Basic Interpretation

Purbeck Anticline Lulworth Banks Anticline

Purbeck Anticline Regional Seismic Line Portland to Dorchester

Base Gault

Top Inferior Oolite

Top Junction Bed

Penarth Group

Top Sherwood Base BSPB Base Aylesbeare Mudstone

1km

14 Licenses. Kimmeridge Oil Field Petroleum Production Act 1934 covering 2227 square miles2 in S.. Mining licence ML5 in 1964. Now under a conventional oil and gas license from 2014. D’Arcy Exploration in 1935 who targeted the Jurassic in large anticlines (Porstdown, Henfield and Kimmerige) Summary. Small oilfield drilled in 1959, Today on production since 1961 and is currently still producing around 80 bopd (12,720 litres). First “English gusher” and in 1968 1st well to produce over 100k tons of crude oil. Over 3 million barrels produced in 57 years ! The only producing field in the hanging wall of the main Purbeck disturbance. Many myths about the location and longevity of the field.

Reservoir. The oil is produced from extensive fractures in Cornbrash limestone 20m thick, 1% f and 0 k

Structure. Cornbrash reservoir in an 1959 anticline close to the main inversion axis and the structure is very small.

Source. Lower (Blue) Lias but lighter (API 45) than Wytch Farm (API 35) so from more mature source or fractionation during migration. Not Kimmeridge Clay.

Seal and Trap. Overlying Oxford Clay. Trap is simple faulted anticline. Structure poorly imaged on seismic data. 15 History of Kimmeridge Oilfield Reservoir Production history (barrels of oil per day)

Production. ~800bbl/day.in. 2016

2005 2010 2015 2020

Broadbench-1 (1936-37) West Kimm Bay. Found light oil in the Sandsfoot Grit at 252m. Bencliff grit target drill string broke in the hole. The well was abandoned at 287m in Osmington Oolite. Then war.

Broadbench-2 (Kimmeridge-1, 1959). Beside army area. Oil found in Cornbrash at 512mSS. Production test 30bbl/day up to 4300bbl/day after 2 acid treatments. Completed as a production well.

Kimmeridge-2. (1960). Drilled in 1960 670m to East of Kimmeridge-1. Cornbrash at 583m subsea. Mud losses in Corralian. Tests in Oxford clay produced 4bbl/day an worse after acidising. In pressure communication. Kept as observation well.

Kimmeridge-3. (1959-1960) 762m SW of K-1. Test Great Oolite and Upper Lias. Losses in Forest Marble/Cornbrash. 26.5 bopd & 4.5mwpd after 3 acid stims. OWC 533mSS. Observation well until 1992 when produced for a while.

Kimmeridge-4. (1960) appraisal well 412m NW of K-1. Plugged and abandoned at 262mSS with mechanical failure.

Kimmeridge-5. (1980) near K-1 to test deep reservoir after successful deep appraisal of Wytch Farm in 1978. Drilled to Aylesbeare. Weak gas shows in Jurassic. Sherwood had oil shows but was deep (2273mSS) and poor reservoir quality. 16 Contours to top Cornbrash (mSS) using seismic, wells & surface outcrops. History of Kimmeridge Oilfield (Ian West, redrawn from Evans, Jenkins and Gluyas 1998).

17 Kimmeridge Enigmas

• Why was oil found in only 1 well ? • How can it have produced so much oil from such a small reservoir • Is oil seeping up a fault and replenishing from a deeper reservoir ? • Why is this the only field in the hanging wall of the Purbeck monocline ?

Observations • Fractured reservoir. Fractures probably extend into Kellaways, Forest Marble and Oxford Clay so much larger than it seems • Low reservoir pressures and little water production indicate sealed system so migration from deeper reservoir is very unlikely. • Reservoir decline is relatively normal for fractured reservoir. GOR increases leading to solution gas drive which increases production. Likely to be gas cap in the Oxford clay supporting oil production. Recovery factor will be about 15-30%. STOOIP approximately 10-25mmbbl.

Prediction • At some point the well will “gas out”. The relative permeability to oil means that oil will be backed out and production will be 100% gas. There will be a short period of “blow down” which could be lengthened with compression followed by abandonment of the field. Could happen very soon. Probably predictable from the GOR readings. 18 History of Shale Oil Industry Blackstone armlets (John Parkins)

Iron Age • Local ’Blackstone’ polished with beeswax • Used as substitute for jet (lignite) • Share working on bay made bracelets using primitive lathes. Romano- British Table • Discarded cores known as Kimmeridge coal money. leg from Blackstone armlets Blackstone Romans

• Industry continued with two factories. Romano-British • Two sizes of bracelets from the same core Shale Factories • Used flint tools and later iron. • Also made gold studded mace heads, spindles, tesserae and table legs • Examples found as far away as Switzerland

17th Century – James Clavell • Locals burned the shale but it gave off fumes

• First venture producing Alum e.g. KAl(so4)2 • Alum used in wool making, dyes, medical 19th Century Jetty • Next used for extraction of salt from seawater • Built a quay ~1620. Destroyed 1745. • Restarted Alum works and glassmaking Diagram • Sent to Mashalsea prison – selling illegal glass modified from th John Parkins 17 Century • (Tower built in 1830 by Rev. John Richards Clavell Pier 19 History of Shale Industry -19th C

• Bituminous Shale Company opened factory in Weymouth in 1848 to process the shale. • Shale heated in distillation retorts to make naphtha, paraffin, paraffin wax, grease and pitch. • Wound up in 1854 after fighting a patent and indicted as a nuisance because of the foul smell • In 1855 factory set up in Wareham to extract Burning the Blackstone with curly flame and sulphorous fumes (Ian West) fertiliser Failed but then converted to Wareham Oil and Candle Co • Help of French Ambassador secured contract to light Paris Collapsed Adit • Monthly av. Prod’n 50tons shale oil, large amount of gas. Blackstone • Also 200 toms of fertiliser sold as “Kimmeridge Guano”. • Exported to America as well as France. • Eventually forced out of business by coal products. Blackstone at Clavell’s Hard (Ian West) Prospectivity in Wessex Basin

• Seismic Survey from East Dorchester to Wareham in 2013 • Node transition zone survey over Southard Quarry field in 2016 • Infrastrata-led group to drill well in California Quarry late 2017 21 Geological Map of the English Channel (after Ian West) 22 Seismic Database

16°W 14°W 12°W 10°W 8°W 6°W 4°W 2°W 0° 2°E 4°E

Exploration Wells 2015 Released 2D Data 2016 Planned Acquisition 2016 Planned Reprocessing N ° 0 6 N ° 0 6 N ° 8 5 N ° 8 5 N ° 6 5 N ° 6 5

Seismic Activity by the Oil and Gas Authority N ° 4 5 N ° 4 Pink lines: Newly acquired seismic data in 2016 5 Orange lines: Reprocessed seismic data in 2016/2017 Dots: Wells N ° 2 5 N ° 2 5 N ° 0 5 N ° 0 5 N ° 8 4 N °

1:1,600,000 ED50 UTM 30N 8 4

0 50 100 150 200 Kilometers

12°W 10°W 8°W 6°W 4°W 2°W 0° 2°E 23