By: Marcel Chin-A-Lien Published: May 2025

Disclaimer: Note that the image included is very “ schematic “ and maybe even a bit “ erroneous “ in a certain interval and area.

Sorry about that.

This as I could not instruct AI to design the cross section and migration paths, exactly as I wished…

Though I talked to AI with very sweet, lovely and convincing words, but nonetheless.

He/She even decided to make the Turonaian younger than the Coniacian.

Mind you.

The Turonaian would not mind to be rejuvenated, I would guess.

But the Coniacian would certainly not be amused.

To wake up at dawn, and 4 million years older, than his/her official birth certificate indicates, I would almost assume…

Anyway, most would not even notice this, least care, I dare to suppose…

And, by the way, the Turonaian does not even exist, so who cares.

But the Turonian does exist.

By the way?

In the Turonian, the Earth turned faster than it does today, rotating 372 times a year compared with the current 365, according to an analysis of an ancient fossil mollusk shell from the late Cretaceous period.

This means a day lasted about 23½ hours.

Further?

The global type section for the Turonian stage is located in the Pueblo, Colorado, specifically at the base of Bed 86 in the Bridge Creek LImestone Member of the Greenhorn Formation. 

This location is at the western end of the Denver and Rio Grande Western Railroad cut near the north boundary of the Pueblo Reservoir State Recreation Area

And?

Alternatively, if you prefer to dine Nouvelle Cuisine with divine Chinon, Chenin Blanc, Sauvignon and Saint-Nicolas-de-Bourgueil wines ?

The type section of the Turonian stage, a unit of geological time within the Upper Cretaceous period, is located in the Touraine region of La Douce France, specifically between Saumur (on the Loire river) and Montrichard (on the Cher river).

The name “Turonian” comes from the Turones, an ancient Celtic tribe who inhabited this area, around Tours.

The Turonian stage is named after the city of Tours, located within this region, which also served as the original type locality

Further, also interesting, not petroleum but great wines??

The Turonian geology translates directly into wine attributes:

• Structural Framework: Provides high natural acidity and mineral backbone
• Aromatic Profile: Contributes distinct chalky/flinty notes (particularly in Chenin Blanc)
• Textural Elements: Creates tension between richness and precision
• Aging Potential: Enables exceptional longevity through perfect acid-structure balance

Microterroir Variations
Even within the Turonian formations, subtle variations create distinctive expressions:
• Upper Turonian: More sand content, producing lighter, more aromatic wines (common in eastern Vouvray)
• Middle Turonian: Pure tuffeau with maximum calcium carbonate, creating the most mineral-driven wines
• Lower Turonian: Higher clay content mixed with limestone, yielding fuller-bodied wines with rounded textures

Expression in Key Appellations
The Turonian geology expresses differently across Touraine’s appellations:
• Vouvray/Montlouis: In Chenin Blanc, creates electric acidity with honey, quince and wet stone minerality
• Chinon: In Cabernet Franc, produces graphite-like minerality with precise tannin structure
• Bourgueil: Yields more structured Cabernet Francs with pronounced limestone freshness

These geological foundations are why Turonian-based wines of Touraine remain so distinctive and irreproducible elsewhere, with the ancient seabed directly speaking through the finished wines.​​​​​​​​​​​​​​​​

Just visit this spring or summer and enjoy the Turonian stage…

Oh, sorry, back again to NE offshore Suriname:

You may want to correct these errors in the AI image with your own ideas, if you have nothing else to do.

Enjoy.

The Araku-1 exploration well, drilled in 2017 in Block 54 offshore Suriname by Tullow Oil in partnership with Equinor and Noble Energy, was officially declared a dry hole.

However, confidential operator briefings and credible symposiums have revealed an intriguing geological clue at total depth (TD): the presence of a porcellanite interval with oil shows.

This subtle signal, often overlooked in public reporting, may now hold critical value as Shell prepares to drill the “Araku Deep” prospect.

And also as the Macaw-1 wildcat of TotalEnergies pushes through similar stratigraphy in Block 64.

🔬 Porcellanite with Oil Shows at TD: Clue from the Lower Cretaceous ?

Porcellanite is a siliceous, dense, fine-grained rock, typically formed by the diagenesis of volcanic ash or biogenic silica in anoxic marine environments.

In the case of Araku-1, the porcellanite was encountered at TD (2,685 meters) interpreted to be Late Cretaceous (possibly Turonian–Coniacian) and displaying fluorescence and trace oil staining.

According to technical references and indirect briefings:

• Equinor Technical Presentations (EAGE, 2018–2019): “…oil shows in porcellanite at TD point to the presence of a mature source kitchen in the deeper basin.” (My question? Indicate where from deeper in the basin the oil comes and how it migrated?)
• GEOExPro Magazine (2019): “…the siliceous facies at Araku’s base may be linked to deeper migration pathways and regional hydrocarbon charge.”
• Petrobras and ANP Symposium (2019): “…porcellanite with staining suggests distal condensed intervals near mature source beds, likely marine shales.”

📍 Strategic Importance for Shell’s Upcoming Araku Deep Well

Shell’s planned Araku Deep well, in Q4? 2025, is believed to test a deeper structural closure and stratigraphic wedge below the failed Araku-1 trap.

If the oil shows in the TD porcellanite represent vertical migration from mature Cenomanian–Turonian source rocks, then the deeper prospect might lie in charge focus zones missed by the 2017 well.

Key exploration hypotheses Shell may be pursuing:

• Fractured porcellanite or cherty beds acting as vertical migration pathways
• Structural or stratigraphic traps missed in Araku-1’s high-side location
• Charge and seal juxtaposition across faulted Lower Cretaceous targets

🛢️ Implications for the Macaw-1 Well (Block 46)

The Macaw-1 well, currently being drilled by TotalEnergies in Block 46, may intersect similar Cretaceous intervals as Araku-1.

While it is probably targeting Upper Campanian and Santonian turbidites?

(My question? From which direction were these sediment sourced? From NE Demerara High area?? Flowing form the east, in a westward direction? Gently sliding down a slide, as we all loved to do as kids, in the swimming pool?)

Any indication of porcellanite, cherty interbeds, or silica-rich condensed sections would strongly validate a regional deep-marine depositional framework (…nothing strange or unusual, by the way…).

If Macaw-1 would show fluid staining or gas readings within porcellanite zones, it could further confirm the hypothesis that:

Statement : “The porcellanite at TD in Araku-1 represents a regional deep-marine condensed section tied to an active and migrating petroleum system.”

Such confirmation would enhance confidence in both Shell’s and TotalEnergies’ prospects across the northeastern offshore quadrant of Suriname.

🌍 Exploration Strategy Moving Forward

The porcellanite clue in Araku-1 may be the proverbial “canary in the coal mine” for deeper stratigraphic charge potential.

As companies reprocess seismic, incorporate high-resolution FWI models, and target deeper Upper to Lower Cretaceous plays, expect Shell’s Araku Deep and TotalEnergies’ next campaigns in Block 64 to focus on:

• Improved seismic imaging of “ basement ” highs and wedge traps
• Porcellanite/Chert detection using AI rock property modeling
• Source rock maturity mapping below Turonian level

📚 References

• Tullow Oil Press Release (Nov 2017): Araku-1 Results
• GEOExPro Magazine (2019): “Cretaceous Potential of Suriname’s Deepwater”
• Equinor & Tullow Presentations at EAGE Workshops (2018–2019)
• Petrobras & ANP Symposium Notes on Cross-Basin Stratigraphy (2019)
• Mann, P. (Ed.) (2019). The Geology of the Guiana Shield, Geological Society of London

About the Author: Marcel Chin-A-Lien is a petroleum geoscientist with deep experience in the Guyana-Suriname Basin.

This article is part of a continuing series on frontier exploration in the Atlantic Margin.

Kind regards.

Marcel Chin-A-Lien

Petroleum and Energy Advisor

48 Years of Global, in-depth expertise, knowhow and insights.

That have generated transformative, multi billion giant fields discoveries, iconic first capitalistic new ventures in the USSR, bid rounds, added value and long term cash flow generating offshore exploration and production activities on Dutch North Sea, M&A, PSC designs, Contract negotiations.

Combined with a cross & trans discipline background of 4 petroleum post grad degrees, that fuse technical, business, commercial and management disciplines, accompanied by fluency in 7 languages in a variety of geographical, socio-cultural and business landscapes. 

“ Exploration & Production integrated with Business & Commercial Development and Critical Insights “

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