Mostrando las entradas con la etiqueta seismic. Mostrar todas las entradas
Mostrando las entradas con la etiqueta seismic. Mostrar todas las entradas

miércoles, 2 de diciembre de 2015

Interview: Matt Hall from Agile Geosciences

Matt has a PhD in sedimentology from the University of Manchester, UK, and a BSc in Geology from the University of Durham, UK. Since then, he has accumulated nearly 20 years’ experience in the energy industry. He has worked for Landmark as a volume interpretation specialist, Statoil as an explorationist, and ConocoPhillips as a geophysical advisor. Matt has written over 50 papers, articles, conference papers, posters, and book chapters.

What do you do in your job?
I see you started with the hardest question. Fine.
I tell most people I’m a geologist. If I think they can handle it, I tell them I’m a geophysicist. So on some level, I ‘do geoscience’ — interpretation, data munging, making pretty pictures, that sort of thing. Increasingly, all of us at Agile are doing more and more programming, which has been, and is, a fun adventure.
I also try to look after the business side of Agile, which involves everything from finance to marketing to HR. I am horrible at all of those things, but they have to be done. In my spare time I dabble in book publishing, and I’m a co-founder of a coworking space in my town.

What drove you to change from employee to entrepreneur and how difficult was the process?
There are a few parts to it. I was not dissatisfied with my job — that wasn’t part of it at all. I was happy and comfortable at ConocoPhillips. I got good performance reviews, had fascinating, challenging work, and was horribly overpaid like everyone else. And yet…
My wife and I are both from the UK originally and had been in Calgary 10 years. We fancied a change of scene, wanted to stay in Canada, and not move further west. We’d been to Nova Scotia before and loved it so we packed up and moved to a beautiful town by the sea with a population of 900 people. So I really had no choice other than working for myself. Fortunately, I had a bit of a plan.
I had been a network leader at ConocoPhillips (‘networks’ are technical communities of practice inside the organization; I was the leader of the geophysics community). This experience left me with the conviction that it’s possible to be highly connected with a distributed community, regardless of where you are.
At the same time — about 2006 to 2009 or so — I was becoming increasingly aware of the new technology landscape. In 2000 you needed a $250,000 workstation and $125,000 of software to do volume interpretation. In 2004 you needed a $25,000 Linux PC. By 2008 you needed a $2500 laptop and free software. Meanwhile, my home Internet speed saw a similar 100-fold improvement.
Alongside those changes, I was intrigued by the new possibilities offered by the Web —blogs, social media, crowdsourcing, mobile apps, wikis, and so on. I was sure they could have more impact in applied earth science, and I wanted to be there when it happened. I felt like exploring that new world would be much easier outside of a corporation than inside one.
The final piece was that I knew a guy in Halifax (about an hour from where I live), who we had tried to hire into ConocoPhillips. I knew Evan was awesome, so I called him up to see if he’d be interested in joining forces. He was — so he became employee number 1 (before me!).
All this aligned to get Agile off the ground. The final piece was getting our first customer, which enabled Agile to hire me as well so it could start giving me money, instead of the other way around!

Having worked with many geoscientists around the world, what are some similarities that people working in a particular field have in common? What are some of the biggest differences?
I’m wary of generalizing — of course there are brilliant and there are dull people everywhere. But I suppose I do have some lasting impressions of the places I’ve worked.
Most people in the industry in the UK have a postgraduate degree, which is a great contrast to Canada. So there’s a tendency to find more academic-style analysis in the North Sea than in the Western Canadian Sedimentary Basin, say, where things are much more practical. I found things in Norway to be somewhere in the middle. As usual in these things, the middle is the place to be.
There are some ubiquitous features of the industry: the software, the data management practices (or lack thereof), most business processes.

What’s one of the most challenging things you have faced as a geoscientist?
2015. Or 2009. Or 2003. Or 1998.
Seriously, it’s the downturns. These crazy glitches in the business side — which I think are at least 50% down to our practices as an industry — are incredibly disruptive. Like a spoilt toddler, the industry seems determined to stagger from one candy binge to the next, punctuated by grotesque sugar crashes during which it smashes all its toys and pokes all its friends in the eye.
We all know the industry has to die, but for now the world needs oil and gas. The least we can do is stop running around like a crazy 3-year-old, have some self-respect, and manage our diet more responsibly. There is such a thing as dying with dignity, we don’t have to plummet into a diabetic coma first.

In your opinion, what are some of the best advances made in exploration geosciences in recent years?
What’s going on in seismic imaging is remarkable — driven by amazing advances in acquisition, and clever processing algorithms running on ridiculously large clusters. Without wanting to sound like a Luddite, I do wonder a bit if the advances aren’t now beyond what we’re actually capable of interpreting and analyzing…
I’d go further than that: I think they are beyond it. The seismic analysis revolution is yet to come. I think it’s clear now that it will be driven by machine learning . It will involve prestack data, spectral decomposition, and petrophysics — all sub-fields that have yet to bring about the revolutions their practitioners have been promising.

What are some of the challenges that still remain unsolved in the industry?
Great question! I always remember what one of my previous managers said to me when I asked her what she thought might be the biggest unsolved problem in geophysics: “Find oil and gas.”
That’s funny, and true, but I think the most urgently needed advances are ‘soft’. The one that is still, I suspect, years away is a transformative level of openness. I believe this will eventually be required — the resources will be too precious to allow the present state of ultra-pseudo-secrecy to prevail. Open data, and open software will have a big impact on our effectiveness as an industry one day; I hope I live to see it!
The next one is pervasive programming skills. On the face of it, this might sound geeky and irrelevant, but with broader technology skills among professional and student geoscientists, I think we will start to see less reliance on ‘industry standard’ — but fundamentally limited — software tools and commensurately more creativity in solving problems. We’ll also see an exponential increase in entrepreneurship, driven by the availability of open data, open libraries, and web APIs.
One of my hobbies is collecting ‘unsolved problems’ and I keep a list of them here

What’s your advice to students?
Learn to program. I can’t stress this enough. Apart from the superpowers it will give you in geoscience, it’s also a great form of insurance against the next downturn — there’s lots of demand for numerate programmers right now, and the expectations of what ‘numerate’ means have gone way, way up.
Realize how much freedom you have as a student, and as you move into work. If you feel even slightly drawn to a less conventional career — as an entrepreneur, or independent researcher, or anything — find 2 friends and do it as soon as you can. Do not listen to the voice in your head telling you to “Just get a corporate job for a few years, to pay off the student loan, you can always go back to university later”, etc. That voice is lying.
Last thing: listen to advice, then ignore it.

What’s your advice to young professionals?
Learn to program! See above.
I think the number one thing is to not get sucked into a corporation. If downturns have taught us anything, it’s that you are expendable, whoever you are. So don’t invest yourself too much in your employer — instead, invest in yourself and in your professional community, because those are invariant.
Watch out for the following utterances, all of them red flags that indicate that you may have gone over to the dark side:
- “That’s not how we do things here” (maybe it should be)
- “You have to play the game” (no you don’t)
- “Thank goodness it’s Friday” (the white flag of surrender)


Oh, and ignore old professionals like me. See above. 

martes, 13 de octubre de 2015

Seismic Interpretation

October 13, 2015- GrilledSeismic

What is seismic interpretation?

Seismic interpretation is the process of obtaining geologic information from seismic data, especially from reflections in the case of the oil and gas industry. This is the simplest explanation in which most geophysicists would agree. Nonetheless, we could write thousands of pages trying to explain everything involved around this methodology. For this post, we will only focus on the basics.

Seismic reflection.- Is the branch of exploration seismology dedicated to the acquisition, processing and interpretation of data from the reflections of acoustic waves in the different layers of the earth. Said reflections are generated  in seismic exploration through controlled sources such as dynamite and seismic vibrators, known as vibroseis, in land and, air guns (mostly) in the sea. This method is ruled by the acoustic impedance (Z) property of the rocks in which the seismic waves travel through the earth. Acoustic impedance (Z) is the result of the velocity of the seismic waves (V) times the density (ρ) of the rock in which the waves travel (Z=V ρ). When the seismic waves travel through the subsurface and find an interface with different acoustic impedance, part of the energy of the waves is refracted and the other part is reflected. The reflected waves are the ones of interest to us and we measure their travel time from the source to the receivers. Knowing the travel time and the velocity of the seismic waves we can reconstruct the path that the waves traveled to generate an image from the subsurface through seismic processing.

Fig. 1.- (Stein and Wysession, 2003)

Seismic reflection data comprise:
- Continuity of the reflections indication a geologic structure.
 - Variability of the reflections indicating stratigraphic changes, fluid  presence and the reservoir structure.
- The seismic wavelet.
- Noises of different kinds and data deffects.
Seismic interpretation is the thoughtful process to separate this effects.

The seismic wavelet starts as a pulse, which is generated through some artificial source and then travels down through the earth, it reflects in an interface and travels back up to the surface where is recorded by the receivers, bringing geologic information with it. This wavelet is minimum phase and it has some bandwidth of some frequency and, during data processing is converted (ideally) to a zero-phase wavelet, making the interpretation easier and more accurate.
Fig. 2 Seismic line from the Gulf of Mexico
The interpreter is not interested directly in the wavelet, but rather in the geologic information it carries. Because of this, understanding the wavelet and distinguishing its characteristics to define geologic details is one of the most important tasks to the interpreter.

The interpreter needs to know enough about the acquisition and processing of the seismic data to take into account the effects of undesirable noise in the data and not to think of it as the geologic features he is looking for. Noise is always present in the data and it can be random, multiples reflections, refracted energy or energy from an unknown source.

Fig. 3.- Vertical slice through a seismic volume showing the (a) before and (b) after a structural filter, and (c) difference. (Causes and Appearance of Noise in Seismic Data Volumes By Satinder Chopra, Kurt Marfurt).

Another step of seismic interpretation is the definition of the structural frame, which is accomplished by following the continuity of the reflectors through the seismic data, be it 2D or 3D. The continuity of the reflectors is ruled by the sedimentary boundaries created at the time when they deposited, and the structure imposed by the tectonic forces that worked on them. Following these continuities in an area and create structural maps is then, one of the most basic and traditional activities in seismic interpretation.

Once the structural frame has been defined, it is time to go to the interpretation of stratigraphic features and the look for hydrocarbons. The most important part of this activity is the seismic amplitude, which can be presented or extracted in many ways. The data loaded to the workstation must then be true amplitude and zero-phase, and the interpreter must check that his data meets this standard.

Fig. 4 Shows two vertical slices, interpreted faults and an interpreted horizon inside a seismic volume.

The interpreter can continue to more advanced steps in the interpretation, such as seismic attributes extraction, AVO (amplitude vs offset) analysis and seismic inversion, but that will be the subject or other posts later.




References.

STEIN, S. & WYSESSION, M. 2003.An Introduction to Seismology, Earthquakes, and Earth Structure.