The unknown underwater processes: Gloria Knolls Slide

In the space exploration era, Mars, exoplanets, comets and other worlds, still we are learning about what geologic processes occur in our own planet. Undersea processes are not easy to spot, with a huge potential for researching.

In Australia, a large undersea landslide has been discovered, occured 300000 years ago. It seems to be 30 times larger in volume that mount Urulu and its most likely triggering mechanism is an earthquake, likely with the involvement of a big tsunami (27 m waves).

North-westerly view of the Gloria Knolls Slide and Gloria Knolls off Innisfail. Depths are coloured red (shallow) to blue (deep), over a depth range of about 1700 metres. Credit: deepreef.org/Creative Commons Attribution 4.0 International Licence.(source: www.geologypage.com)

 I am happy to see that this research have been undergone with a cooperation between different universities, including two of my universities as a student, University of Granada and University of Edinburgh.

How may it be linked to Petroleum Geology? It can be used as an analogue for future carbonate/clastic petroleum reservoirs. Debris gravity flows occur undersea, and when buried by the sedimentary processes, it may be a good reservoir. Reworked carbonates may have a very good porosity and if it is well interconnected, a good permeability allowing to flow. However as it is known, other geologic configuration needs to be added to the recipe to complete the petroleum system, such a seal, a trap, and obviously a source rock.

Read more : http://www.geologypage.com/2017/02/largest-undersea-landslide-revealed-great-barrier-reef.html#ixzz4YSbIUco0

To know even more:

http://www.sciencedirect.com/science/article/pii/S0025322716303759

NORTH SEA INTERACTIVE MAP

Nowadays may be due to the energy challenges, and the decline in the price of crude oil it is a trend to talk about North Sea, in terms of the end of a era.

The following article link from OilPro and written by Jeff Reed, describes perfectly the challenges overcome during the history of the North Sea in oil and gas development. 

Also it emphasizes the eagerness, tenacity and determination that at those times were applied to write a successful history, which with action and changes from the strategies may be repeated again in the future, or at least, extended during more years that initially was thought.

THE GENESIS OF THE OIL AND GAS DEVELOPMENT IN THE NORTH SEA

Besides of the article, as I am a big fan of maps, the North Sea interactive map is a good complement to know what is currently going on in the North Sea . The link below, from the Oil and Gas Authority UK, allows to know the oil and gas fields location, wells, operators and more. 

NORTH SEA INTERACTIVE MAP

Transgression and Regression

In the study of sequency stratigraphy, some elemental concepts must be known. In this case the geologic terms 'transgression' and 'regression' are referred to the changes that the sea level has experimented through geologic history and its sedimentary consequences. A geologist studies this rising and droping of sea level, analyzing the sediments occurred during this events.

Obviously, depending on the size of the sediments carried by currents and washings of the shore and land, and the energy of these processes, the sediments as sand or mud will be deposited on the sea bed as the energy from shore to offshore decreases, being the heaviest (coarse sediment) deposited nearer of the shore than the lightest sediments (fine grain).

Simplifying we could say that a transgression corresponds with  a rising of sea level, and regression is a droping of sea level. However to identify these events in a stratigraphic column, we should know what is the typical facies configuration.

Below this simple and very easy video shows the processes in a general way, that can be even more complicated to identify in a realistic case.

Care must be taken when the limestone are presented at the bottom of the sequence, which could be a general case. I would say that (in my opinion) carbonates generation is a subject to be treated apart, as it depends on if the source of them is available (biogenic generation), so temperatures, shallow waters,...

Anyway thanks to Patrick Baldwin for this material.

PETROWIKI

In my short experience in this Petroleum field, I realized that sometimes it is not easy get information about it from the Internet, and as reasonable, the good information is in books, specific libraries, publications, and probably the best, in the companies (as confidential).

I discovered recently PETROWIKI, a tool developed from the seven volume Petroleum Engineering Handbook (PEH) published by the Society of Petroleum Engineers (SPE). PetroWiki preserves the PEH content in unaltered form (page names that start with PEH:), while allowing SPE's membership to update and expand content from the published version. Pages that do not have PEH: at the beginning may have started with content from the PEH, but have been modified over time by contributors to the wiki.


As its name says it is working in a similar way as wikipedia, however it has very specific information, mainly in engineering terms, but with good geologic remarks applied to the industry. For instance, you can search about LWD, reservoir geology, or underbalanced drilling.

I have decided to include a link in the blog of PetroWiki, I think it is very useful, even for people who is already into the Oil and Gas industry.

The Game of the oil and gas (basic concepts)

In the video below we can watch a good didactic introduction and descriptions of oil and gas properties in the nature, such density, somehow the two main kind of rocks implicate in the processes and the differences between porosity and permeability.
Besides the video presents the more typical subsurface traps, however it is the basic explanation of the multiple possibilities that can occur.

Finally the video finishes with a very clever and motivating game, to apply at the school or university, finding the way to get success researching for an oil well.

THE PRINCIPAL ACTORS: SEDIMENTARY ROCKS

 It is clear that the source (mother) rock and reservoirs or traps are formed by sedimentary rocks. The first due to the moment of the deposition and burying (the organisms are buried between sediments, commonly shale), the second due to the space which is in between the solid particles of the rock (porosity) that allow to migrate the oil to the top of this rocks.

Sandstone: EEUU

 Limestone: Antequera, Spain

 The natural sedimentation is made in horizontal way (just responding to gravitational law), in these two pictures is seen how after the sediments are converted in rocks, they have not suffered any tectonical movement, and keep its horizontal dip. However it is very usual that the rocks lose its horizontal structure as a result of tectonical strengths.

What is it?

It could be explained pages about, but to do it it is already Wikipedia, so basically:
It is a fossil fuel formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneath sedimentary rock (which were sediments at first) and undergo intense heat and pressure.

When tiny organisms die, they sink to the bottom of the sea and are mixed with mud and silt. Over time, hundreds of feet of mud containing the organisms accumulate. Bacteria removes most of the oxygen, nitrogen, phosphorus, and sulfur, leaving mainly hydrogen and carbon. Lack of oxygen keeps the animals and plants from decaying completely. The partially decomposed organisms create a slimy mass, which is then covered with layers of sediments. Over millions of years, many layers of sediment pile on top of the once-living organisms. The weight of the sediment compresses the mud into a fraction of its original thickness. When the depth of burial reaches about 10,000 feet, heat, time and pressure turn the organisms into different types of petroleum.

Article Source: http://EzineArticles.com/786475