Tales from Texas

Back in May, Lorin and I headed across the Atlantic to visit friends (new and old) over in Texas. We planned to spend a week in Houston in the run up to AAPG ACE 2019, followed by a week in San Antonio at the conference.

It was a little different to your usual business trip. As a start-up, it means we had much more flexibility in terms of our travel and accommodation. For starters, we were able to choose from hundreds of Air B’n’B’s and take a few diversions adding in a little road trip here and there.

Nonetheless we had a few hiccups along the way. I had the bright idea of printing my AAPG poster while we were in Houston to save bringing it over on the plane. Apparrently this isn’t so straight forward (even if you put your order through and everything looks hunky dory!) and I strongly advise against trying to print an 8x4ft poster at Office Depot! We ended up having to adapt the design and print it in three 2ft wide panels. It actually worked out as quite a nice way to break up the poster and guide the reader through the content – every cloud and all that.

Watercolour by Jim Koehn

After a week spent in Houston visiting potential clients and sampling a local ‘Ice House’ (above), we drove west over to San Antonio. We arrived at our lovely little Airbnb a few days before the conference and gave ourselves some time off to relax (below) or should I say explore.

Our San Antonio Airbnb

After contemplating numerous road trip options (a particularly adventurous one of Lorin’s was to attempt to make the 16 hour drive to the Grand Canyon) we decided on a relatively short jaunt to the Mexican border city of Laredo.

Here, we thought we would just nip in to Mexico, get a stamp in our passports and head home after sampling some authentic Mexican food and culture. It was our intention to walk over the Rio Grande bridge into Mexico as foot passengers instead of going by car, which is not uncommon for tourists to do.

Our first port of call when we arrived at Laredo was lunch. We stopped at ‘El Maison De San Agustin‘ and I preceeded to order quesadillas for the millionth time on our trip thus far and drank a vat of hibiscus ice tea. Following said lunch, we were both stuffed and ready for our walk across the bridge.

El Maison De San Augustin

Crossing over into Mexico was predictably a lot faster than on the way back. As soon as we were over the border/bridge we had numerous offers of dentistry services!? We had a bit of a wander around, took some photos and then began to head back over the bridge. We didn’t have to queue for long to get back across but were a little disappointed that we didn’t actually get a stamp in our passports!

The Mexico-US border in Laredo over the Rio Grande.

Back in San Antonio a few days later, we kicked off the first day of the AAPG ACE conference at the Henry B. Gonzalez Convention Centre with the ice breaker reception where we bumped into many old friends and colleagues and put some names to new faces.

AAPG ACE Ice breaker reception

The conference had a packed schedule with topics ranging from unconventional reservoir characterisation, deepwater sedimentology, machine learning, and not one but two sessions on source-to-sink (a personal favourite of mine!). I spent Monday afternoon listening to talks from the “Fluvial and Deltaic Depositional Environments: Reservoir Characterisation and Prediction From Multiple Scale Analyses” theme. John Holbrook touched upon braided versus meandering systems and whether or not it is actually that black and white when it comes down to it. James Mullins discussed automated workflows for reservoir modelling using drone data and libraries of photo analogue systems, and Margaret Pataki presented her work on Rapid Reservoir Modelling (RRM) using sketch based models.

AAPG ACE 2019 Exhibition Hall and Poster Sessions

Tuesday morning was spent swithching between the source-to-sink sessions and “Multi-Disciplinary Integration for Subsurface Efforts in the Age of Big Data”. There were lots of interesting provenance and sediment supply studies studies interspersed with sediment routing and recycling in the source-to-sink sessions, inolving talks from Peter Burgess and Jinyo Zhang. The integration and big data session touched upon multi-disciplinary approaches to subsurface studies, including the use of petrography, geochronology and biostratigraphy data in order to produce more accurate chronostratigraphic interpretations when correlating wells, presented by Eugene Syzmanski. It seems that the value of geochronology is gaining more and more momentum in the oil and gas industry recently as people realise that multi-disciplinary approaches lead to more robust interpretations.

That afternoon was our poster session where we presented on “A Source-to-Sink reservoir Quality Prediction Workflow: The Offshore Nile Delta”. It was great to see such a busy poster session (I’m guessing partly due to the proximity of the exhibition hall and free beer at the end of the day!) and we ended up chatting to lots of new and interesting folks about the work that we are doing at Petryx and how it can add value to real world geological problems – particulary with regards to taking the leg work out of data collection and standardisation. All in all, we were stood by the poster for about 4 hours and recieved lots of positive and constructive feedback.

Extended abstracts to be published online soon!

I also had judging commitments that afternoon and headed over to the poster session on “The Digital Transformation in the Geosciences”. There were loads of fantastic posters, all were presented exceptionally well with some great visualisations of some pretty cutting-edge data science.

Subjects included petrophysical facies classifications using neural networks, the use of clustering techiniques to define chemofacies and the application of decision trees to determine failure modes.

In addition to all the technical talks, there were also some great sessions focussing on sustanability and a DEG special session on the environmental impact of the oil and gas industry. Discussions were centered about how geology will remain key in the transition to a more carbon neutral society with the increasing importance of practices such as carbon cap and storage and geothermal energy. Consensus was that we need to stop thinking of ourselves as the bad guys and to start realising the potential that we have as an industry to help with the climate change challenges that lie ahead. This will also be crucial in continuing to attract bright and ambitious talent to the oil industry in order to help us adapt to the digital transformation culture and the ‘big crew change’ that we see on the horizon.

Unfortunately Tuesday was also the last day of the conference for us as we had to head back to Houston for a last minute meeting before catching our flight home. All in all Lorin and I had a great trip gathering lots of feedback, meeting lots of new faces and are looking forward to heading back to AAPG next year, in Houston.

Next week Lorin will be writing an article all about our week in the Start-up area of this year’s EAGE Annual in London.

PRESS RELEASE: Petryx and Getech announce database partnership

Petryx Ltd have partnered with Getech Plc, allowing customers in the Oil & Gas industry to view Petryx Database coverage alongside Getech data products. Covering every major continental mass in the world, the Petryx Database offers hinterland data essential to data-driven source-to-sink interpretations.  

Managing Director of Petryx Ltd, Lorin Davies says: “We are delighted to have partnered with Getech. This brokerage deal provides much higher visibility of Petryx datasets to Oil & Gas explorers and demonstrates Getech’s commitment to innovation. Deals like this emphasise the many ways in which the Oil & Gas industry can support innovative start-ups like ours.” 

Senior GIS Consultant, Thierry Gregorius says: “We are excited to add this valuable new data resource to the extensive product range that we offer our customers. Explorers and geoscientists will now be able to access global datasets from Petryx via Getech, including geochemistry, geo- and thermochronology, and more. With this step we are offering our customers a growing one-stop shop.” 

Petryx Ltd is an innovative digital geoscience start-up who have revolutionised data integration and acquisition processes, giving Oil & Gas explorers fast access to cleaned and standardised datasets. The Petryx Database is a multi-disciplinary geoscience dataset compiled from numerous sources with the collaboration of industry and academic partners. It offers an unrivalled view of the composition of the earth from a single unified platform. 

Petryx at PETEX

This week we have been showing off our wares at the PESGB YP Summit and PETEX conference. If you haven’t had the opportunity to chat to us already, or found one of our web-app postcards then drop me a line.

We are showcasing two unique offerings this week. The first is our web-app. The web-app is a demonstration tool which shows the kind of bespoke coded solution we can provide. It is particularly useful for quick-look analyses or when conducting routine plotting or charting tasks and can probably save you a load of time. We dropped in some XRD data, but we can build tools like this for you quickly and easily for virtually any geoscience dataset. Get to the web-app by clicking here.

Secondly we are showing the Petryx Database. With an estimated 80% of data science projects devoted to aggregating and cleaning data. The Petryx Database offers a global geoscience data resource unequalled in the market. What’s more, Petryx offer a one off purchase commercial model, so you needn’t buy the same data from anyone year-after-year.

If we missed you, or you want to hear more about our data or services then drop us a line!

Lorin Davies

Some notes on the use of heavy minerals in provenance studies

Past industry experience has shown that when geoscientists start to think about sediment provenance, people’s first thoughts often go straight to traditional methods such as petrographic point counting and heavy mineral analyses.  However, it has long been known that the resistance of heavy minerals to weathering and transportation is highly variable and can therefore alter provenance signals.

“Perhaps the most general problem is that of heavy-mineral resistance to both mechanical and chemical processes…The co-operation of all sedimentary petrologists is needed in solving these major problems.” – Sindowski, 1949.

The complexity of heavy mineral analyses means that only a small minority of specialist labs still focus on the method whilst fully taking into account all possible source of bias (e.g. hydraulic sorting effects on grain size, and chemical and mechanical weathering). Automated mineralogy is becoming increasingly popular but still brings its own set of problems. Just as traditional point-counting relies on the experience of the operator, automated mineralogy is highly dependent on the dictionaries used to calibrate the software. However, the reproducibility and the number of samples that can be run means that more data (some might say more noise) can be generated and more samples can be analysed in-situ, removing potential mineral separation bias.

Current academic provenance studies tend to focus more on robust single-grain geochronological techniques, whole-rock radiogenic isotopes or thermochronology. U-Pb zircon geochronology in particular continues to gain popularity when it comes to detrital provenance studies (Spencer et al., 2016).


Figure 1. The increase in popularity of single grain U-Pb analyses (Spencer et al., 2016)

As the popularity of zircon studies continues to rise, an increasing number of studies are also highlighting how the diagenesis of heavy mineral assemblages under burial can severely alter provenance signatures (e.g. Morton and Hallsworth, 2007; Milliken, 2007; Garzanti et al., 2010; Ando et al., 2012; Garzanti et al., 2018). Unstable minerals are rapidly leached out down-section whilst moderately stable minerals increase their relative abundance, giving a skewed representation of the original heavy mineral assemblages associated with a given source area.

“Interpretation of provenance using heavy-mineral data from sandstones likely to have suffered burial diagenesis must carefully consider the possibility that some heavy-mineral species have been eliminated through dissolution.” – Morton and Hallsworth, 2007.


Figure 2. Heavy-mineral dissolution in the Nile Delta succession (Garzanti et al., 2018). This figure illustrates the chemical stability of unstable to stable heavy minerals in Miocene to Pleistocene Nile Delta sands. Unstable heavy minerals are absent in the oldest Nile Delta sample. In the past this has been interpreted as the absence of a particular hinterland (the Ethiopian Highlands), although this has now been shown not to be the case (Fielding et al., 2017).

Geoscientists in industry and academia alike are becoming more aware of this source of bias and are approaching the method with caution. Heavy mineral laboratories such as that at the University of Milano-Bicocca specialise in untangling the complexities of heavy mineral analyses whilst others incorporate the technique into studies using an integrated, multi-disciplinary approach.

Diagenesis aside, the method by which petrographic and heavy mineral data is arrived at has recently come under scrutiny. Dr István Dunkl from the University of Göttingen presented the findings of an Inter-laboratory Comparison for Heavy Mineral Analysis at this year’s Working Group on Sediment Generation (WGSG) in Dublin. The aim of the Heavy Mineral Round Robin was to find a common language when reporting point-counted heavy mineral data. This required each participant to point count two synthetic heavy mineral mixtures to compare the identification of heavy mineral species and quantify their proportions. Trained operator and automated mineralogy techniques were both used as a comparison and found varying results, with the automated methods proving to be much more accurate and reproducible. Several explanations were discussed as to why this could be:

1.      Counting statistics varied across all laboratories.

2.     Aliquot separation techniques. Numerous methods were reported when describing the preparation of the aliquot.

3.     Mineral identification vs operator experience. Mineral identification was inconsistent regardless of operator experience. In many cases, some operators did not detect all 8 mineral phases and occasionally added up to 5 or 6 phases which were not present in the sample at all.

The presentation was certainly an eye opener and I believe the intention is for the findings to be submitted to Sedimentary Geology this autumn. There was talk of a second phase of comparisons where it was suggested that the samples be pre-processed to reduce variation in results based on aliquot separation techniques.

This great study highlights issues not only within the method of heavy mineral point counting but also biases that may occur within other provenance techniques. It also reinforces the need for standardisation when it comes to recording heavy mineral point counts. Wouldn’t it be easier to compare like-for-like if counts were published as points as well as percentages? In the past I have attempted to amalgamate large provenance datasets and have found petrographic and heavy mineral counts to be the most difficult method to standardise (that and fission track!).

Let’s not forget that many heavy mineral studies do work well when specific problems are addressed with a through understanding of sources of bias (e.g. Kilhams et al., 2013; Morton and Milne, 2012).  Heavy mineral analyses of the Clair Group (Morton and Milne, 2012) has been very successful and enables high resolution correlation between wells. This is likely due to factors such as no operator or laboratory variability, and a well understood reservoir, where heavy minerals are a proven discriminator.


Figure 3. High-resolution heavy mineral analyses in use down section in the Clair Group (Morton and Milne, 2012). Analyses focus on the more stable heavy mineral indices, which is key as you can see the point at which the unstable (Unst) heavy mineral concentrations drop off within Unit V .

There is no one ‘silver-bullet’ for provenance studies and the multi-disciplinary approach is key when it comes to accurately recording the evolution of a source-to-sink system.

“Detangling the various interacting factors controlling mineralogical and chemical compositional variability is a fundamental pre-requisite to improve decisively not only on our ability to unravel provenance, but also to understand much about climatic, hydraulic, and diagenetic processes.” Garzanti et al., 2010

For the purposes of this article I have focussed primarily on petrography and heavy mineral analyses. However, surely all other provenance techniques can also be subjected to this kind of bias and alteration? Perhaps the new LinkedIn “Source to Sink” Group could be used as a platform to discuss other sources of bias such as:

–       The controls of mineral distribution on radiogenic isotope concentrations (e.g. Garcon et al., 2014).

–       Introducing bias to U/Pb zircon studies. Hand picking, CL and target analyses vs the ‘blind-dating’ approach (e.g. Fielding et al., 2017 and Garzanti et al., 2018).

–       Hydraulic sorting and biasing effects on ALL provenance techniques (e.g. Malusa et al., 2016, Cascalho and Fradique, 2007, and Nesbitt et al., 1996).

 By Laura Fielding, Geoscience Director.

References

Andò, S., Garzanti, E., Padoan, M. and Limonta, M., 2012. Corrosion of heavy minerals during weathering and diagenesis: a catalog for optical analysis. Sedimentary Geology, 280, pp.165-178.

Cascalho, J. and Fradique, C., 2007. The sources and hydraulic sorting of heavy minerals on the northern Portuguese continental margin. Developments in Sedimentology, 58, pp.75-110.

Fielding, L., Najman, Y., Millar, I., Butterworth, P., Ando, S., Padoan, M., Barfod, D. and Kneller, B., 2017. A detrital record of the Nile River and its catchment. Journal of the Geological Society, 174(2), pp.301-317.

Garçon, M., Chauvel, C., France-Lanord, C., Limonta, M. and Garzanti, E., 2014. Which minerals control the Nd–Hf–Sr–Pb isotopic compositions of river sediments? Chemical Geology, 364, pp.42-55.

Garzanti, E., Andò, S., Limonta, M., Fielding, L. and Najman, Y., 2018. Diagenetic control on mineralogical suites in sand, silt, and mud (Cenozoic Nile Delta): Implications for provenance reconstructions. Earth-Science Reviews, 185, pp.122-139.

Kilhams, B., Morton, A., Borella, R., Wilkins, A. and Hurst, A., 2013. Understanding the provenance and reservoir quality of the Sele Formation sandstones of the UK Central Graben utilizing detrital garnet suites. Geological Society, London, Special Publications, 386, pp.SP386-16.

Milliken, K.L., 2007. Provenance and diagenesis of heavy minerals, Cenozoic units of the northwestern Gulf of Mexico sedimentary basin. Developments in Sedimentology, 58, pp.247-261.

Morton, A.C. and Hallsworth, C., 2007. Stability of detrital heavy minerals during burial diagenesis. Developments in Sedimentology, 58, pp.215-245.

Morton, A. and Milne, A., 2012. Heavy mineral stratigraphic analysis on the Clair Field, UK, west of Shetlands: a unique real-time solution for red-bed correlation while drilling. Petroleum Geoscience, 18, pp.115-128.

Nesbitt, H.W., Young, G.M., McLennan, S.M. and Keays, R.R., 1996. Effects of chemical weathering and sorting on the petrogenesis of siliciclastic sediments, with implications for provenance studies. The Journal of Geology, 104(5), pp.525-542.

Sindowski, F.K.H., 1949. Results and problems of heavy mineral analysis in Germany; a review of sedimentary-petrological papers, 1936-1948. Journal of Sedimentary Research, 19(1), pp.3-25.

Spencer, C.J., Kirkland, C.L. and Taylor, R.J., 2016. Strategies towards statistically robust interpretations of in situ U–Pb zircon geochronology. Geoscience Frontiers, 7(4), pp.581-589.

PRESS RELEASE: New international geoscience consultancy announced

Petryx Ltd, is a new company set up to meet the growing need for modern data science capabilities in the Oil & Gas industry. The company is based in North Wales in the UK and serves Oil & Gas operators worldwide.

Dr Lorin Davies, Managing Director of Petryx Ltd said: “The Oil & Gas industry has fundamentally changed since the heyday of the 1990’s and 00’s. Our customers are modern organisations who look to the service sector for innovative answers to their challenges. We launched Petryx to meet these challenges and to bring technologies developed for the internet software industry to the upstream industry.

The products and services in development at Petryx are truly exciting and will allow our clients to better understand their own data, as well as the answers buried in academic research.”

Petryx offers built-for-purpose data products and services. Petryx data products are designed to be light, responsive and perfectly optimised for clients’ needs. As scientists in the Oil & Gas industry tackle new hurdles with more marginal fields, in deeper water and with smaller teams, the skills and expertise offered by Petryx will help them to make better decisions.