The rebellious proto-Riedel shear zones
Classic Riedel shears are the first subsidiary fractures that form prior to breakthrough of a master fault. They appear as low-angle (~15°) en echelon arrays oriented synthetically to the principal…
Geology & Geophysics
Mid Atlantic ocean floor at outcrop
The island of Maio, Cabo Verde, 600 km the west of Senegal, is the only place where Cretaceous mid-ocean floor of the distal Mauritania – Senegal – Guinea Bissau – Conakry…
What else is hiding in your reservoir brine?
For more than a century, petroleum exploration has focused on hydrocarbons. Yet, sooner or later, every producing oil and gas field also brings something else to the surface: Formation water.…
The tricky part of resource assessments within gas-dominated basins or petroleum systems
When conducting prospect resource assessments within gas-dominated basins, there is a low likelihood of oil or mixed-phase accumulations being filled to spill. If this is not properly considered, prospect resource…
The very first core cut in the UK North Sea
It is boxing day 1964, a day most people in the countries around the North Sea don’t think about spending a day at sea. Yet, the crew of the Global…
What are we risking and why is it important?
Risk is about the chance of finding producible hydrocarbons; uncertainty is about the volume of hydrocarbons that may be found in the case of success. The geological Probability of Success…
Your fault stability analysis might be lying to you
The Mohr space represents stress states and, combined with fault strength criteria, is used to assess fault stability. It is simple, elegant, and widely accepted. It is also, when applied…
Tectonics or soft-sediment deformation?
Soft-sediment deformation (SSD) refers to structures that form during or shortly after deposition, while sediments remain unlithified, water-saturated, and mechanically weak. These features develop prior to significant compaction and cementation,…
You may not be thinking about politics…
I lived here for many years. Worked hard. Played harder. Drink and jazz and mountains and surfing and brass-banding and drink. Foundational geoscience and drilling. I made the best friends…
Not too many, not too few
The Shewashan oil field is located in one of the world’s most famous petroleum provinces – the Zagros fold and thrust belt – not far from the major Kirkuk field.…
Greenland’s unconformity
This fantastic example of an unconformity, where steeply dipping Devonian strata meet Permian sediments, is exposed on the north side of Wegener Halvø in East Greenland (71° 44 ‘ north).…
How to generate an oil accumulation in a gas-prone petroleum system?
Australia’s NW Shelf is characterised by a gas-dominated petroleum system, where Middle Jurassic deltaic coals of the Plover Formation make up the main source rocks. That is why oil occurrences…