Disclaimer: This is my very own design and prognosis on 19th May, 2025.

As an exploration geologist I always wish to “ see “ a well being drilled “ in front of me.

I find that this makes exploration geology much more interesting, tangible and insightful?

“ What are they looking for, where, how, what, why, how much do they strive to unveil “ etc.

Exploration wells are like “ Intensive Care Patients “, that you have to watch closely.

As I always used to participate in the design of exploration wells as chief exploration geologist, during my extended active career, by supplying critical subsurface data, I have now ventured to make a prognosis for myself.

Of Macaw-1 exploration wells, by TotalEnergies in Block 64, offshore Suriname, indicated to spud on 19Th May, 2025 with the Stena DrillMAX drillship.

For this I have used the very scarce published data, by adding my own knowledge and private prognosis.

That I wish to share, to whom may be interested.

Such data are never published in public, by any Operator on their well.

I always used to have the well prognosis, accompanied by a 1:10:000 scale paper prospect map, pinned on my office wall.

That served as an old-fashion, old style, slow living discussion and musings platform and forum during drilling of the well.

Location: Offshore Suriname, Block 64
Operator: TotalEnergies
Spud Date: 19 May 2025
Water Depth: ~1,200 m
Estimated Well Duration: ~80 days

The Macaw-1 exploration well in Block 64 is a landmark venture into one of Suriname’s most promising deepwater areas.

Designed and executed by TotalEnergies is drilled by the Stena DrillMAX, the well targets, not published, are probably (Lower?) Cretaceous reservoirs, with strategic inspiration from several high-impact discoveries and dry holes nearby and across the Guyana-Suriname Basin.

In companion posts I have published on the specifics of Stena DrillMAX drillship, why it was chosen for this job and the critical, added value adjustments made recently while stationed in Curaçao, how it will serve the drilling of this well.

🌊 Drilling Strategy, Fluids and Casing Design Summary

The robust casing architecture anticipates pressure regimes and stratigraphic complexity:

• 36″ Conductor
• 20″ Surface Casing (~800–900 m)
• 13⅜” Intermediate (~2,000 m)
• 9⅝” Production (~3,200 m)
• 7″ or 7⅝” Liner to TD (~4,500 m)

🛢️ Macaw-1 Exploration Well & Drilling & Casing Design Plan

Location: Block 64, Offshore Sranan
Water Depth: ~1,200 m.
Lat: 8.87967
Long: -55.5757
Target Fm.: Late Cret. deepwater turbidites (analogous Hammerhead)?

1. Well Objectives
      •   Test hydrocarbon-bearing deepwater sandstone reservoirs in the Late Cret. interval.
      •   Evaluate trap potential and validate seismic AVO anomalies (…one of the many proven subsurface ghost around?).

🧱 Casing and Hole Design

Hole Size (in), Csg Size (in), Depth Interval (m; approx.), Purpose
Carbonate crust on seafloor?
36”
30” Conductor
Seafloor to ~100 m BML
Structural foundation, wash/drill
26”
20” Surface Casing
~100 – 1,000 m (BML)
Isolate shallow hazards (gas, water flows)
17 ½”
13 ⅝” Intermediate
~1,000 – 2,800 m
Isolate unstable formations, overpressured zones
12 ¼”
9 ⅝” Casing
~2,800 – 4,200 m
Protect transition zone above reservoir
8 ½”
7” or 7 ⅝” Liner
~4,200 – 5,000 m (TD)
Reservoir section; open-hole logging & testing possible

TD contingent, seismic tie and pressure regime. Adjust casing seats after pore pressure/fracture gradient (PPFG) modeling.

🛠️ Drilling Strategy & Fluids

Hole Section, Drilling Fluid Type, Mud Weight (ppg); Key Objectives
36” & 26”
Seawater/Gel

Fast penetration, shallow hazard control
17 ½”
WBM or Synthetic OBM
10.0 – 11.5
Stabilize formations, monitor kicks
12 ¼”
SBM (Synthetic)
11.5 – 13.0
Manage pressure window, avoid losses
8 ½”
SBM or OBM
13.0 – 14.5
Protect reservoir, maintain borehole stability

📊 Expected Pressure & Temperature Regime
   •   Estimated Bottom Hole Pressure: 10,000 – 13,000 psi
   •   Bottom Hole Temperature (BHT): 280–320 °F
   •   Pore Pressure Gradient (PPG): Increases rapidly below ~2,000 m
   •   Fracture Gradient: 0.75–0.85 psi/ft

🎯 Contingency & Risk Management
   •   Wellhead & BOP: 18¾” x 15,000 psi BOP stack
   •   Managed Pressure Drilling (MPD): Consider for narrow pore-frac window
   •   Well Control: Full MPD/ kick tolerance modeling prior to spud
   •   Stuck Pipe/Collapse Risk: Slim hole below 9 ⅝” section to mitigate
   •   Coring/Logging Plan: Perform coring in reservoir; LWD throughout

⛽ Completion / Testing Option
   •   If hydrocarbons are encountered, “White Smoke Moment“:
      •   DST (Drill Stem Test) in 8½” hole or tie back 7” liner and test through 4 ½” tubing.
      •   Temporary abandonment using balanced cement plug or packer if no test.

Right?
Your own design?

🗓️ Estimated Drilling Timeline & Casing Depths

Date	Activity	Approx. Depth	Comments
19 May 2025	Spud – 36″ with 30” Conductor installed	~100 m	Seafloor sediments and marine clays. Structural foundation, wash/drill 26”
~24 May 2025	Drill 20″ Surface Section	~800–900 m	Set surface casing through marine shales, possible Paleogene. Isolate shallow hazards, gas and water flows.
~2 June 2025	Drill 17½” section	To ~2,000 m	Set 13⅜” casing, entering Cenomanian–Turonian shale section. Isolate unstable formations and overpressured zones.
~12 June 2025	Drill 12¼” section	To ~3,200 m	Transition into Albian-Aptian reservoirs
~25 June 2025	Run 9⅝” casing	~3,200–3,300 m	Porous sands or carbonates; potential oil zones. Protect transition zone (above reservoir?).
~10 July 2025	Drill 8½” section – Run 7” Liner	To TD ~4,500 – 5000 m	Deeper Aptian syn-rift, fluvial sandstones? tight carbonates? or volcanoclastics?
~7 August 2025	Logging & Evaluation	~4,500 – 5000 m	Wireline logs, core samples, pressure tests. TD contingent, seismic tie and pressure regime. Adjust casing seats after pore pressure/fracture gradient (PPTG) modelling

🧭 Stratigraphy & Regional Analogs

Macaw-1 is expected to intersect a complex stratigraphy similar to that seen in both discoveries and dry holes across the basin:

• Upper Tertiary–Paleogene Shales: Marine clays with overpressured zones – similar to initial sections in Liza-1.
• Cenomanian–Turonian: Possible source rocks and seals, as in Hammerhead-1 and Araku-1.
• Albian–Aptian Reservoirs: Main target zone, analog to Liza-1 and Ranger-1, both successful discoveries by ExxonMobil.
• Pre-Albian Syn-Rift: Low porosity carbonates or volcaniclastic rocks. Dry wells like Goliath North-1 encountered such lithologies with limited reservoir quality.

These analogs provided critical calibration for seismic interpretation and casing depth selection:

• Liza-1: First commercial discovery in Guyana; Aptian-age fan sandstones below thick marine shale seal
• Ranger-1: Carbonate build-up discovery; key for identifying stratigraphic traps
• Goliath North-1: Dry hole due to lack of structural closure in Upper Cretaceous
• Araku-1: Deep target with oil shows in porcellanite; source rocks present but no effective trap

🛠️ Operational Significance

Drilled by the Stena DrillMAX and managed by TotalEnergies, Macaw-1 is the first test of Block 64’s deepwater prospectivity. The results could validate an entirely new petroleum system segment and catalyze further investment. Staatsolie’s ambitions to evolve into a regional IOC may well hinge on the success of this well.

Further?

Down #Geo #Memory #Lane.
1990-2005.
These are the most common abbreviations.
On the #Daily #Drilling #Reports, send & received by #fax.
Part of the “ Hot Dope “ sessions, in the morning, beginning the work day.
Good old times, on the Penrod Tri-Pods.

…Miss reading this always poetic, mysterious and exciting drillers jargon.
Each day, while having my first cup of coffee at breakfast…

SPUD, was always exciting.
WOW, was always annoying, not at all wowww.

Abbreviation & Meaning:

Drl. ahead (…Macaw-1…soon, 21th May 2025?)
Drilling ahead (actively drilling)
WOW
Waiting on Weather (very common in North Sea)
WOC
Waiting on Cement
WOO
Waiting on Orders
WOM
Waiting on Materials
NPT
Non-Productive Time
TD (…Macaw-1, some 80 days, maybe secretly planned for 14 Juillet, la Fête de la Fédération:
To celebrate
With a Don Perignon Champagne Brut, Vintage 2015?
The 455 million barrels unveiled…
Who knows, fingers XX
Trailing from GoliathSouth to Macaw-1 ?).
Total Depth
SPUD (…Macaw-1 on 19th May 2025?)
Start drilling operations
RIH
Run In Hole
POOH
Pull Out Of Hole
TIH / TOH
Trip In Hole / Trip Out Hole (alternative to RIH/POOH)
BHA
Bottom Hole Assembly
MWD
Measurement While Drilling
LWD
Logging While Drilling
ROP
Rate of Penetration
FIT
Formation Integrity Test
LOT
Leak-Off Test
Circ.
Circulating
MW
Mud Weight
LD / PU
Lay Down / Pick Up (pipe, BHA, tools)
BOP
Blowout Preventer
Csg.
Casing
Drifted
Checked casing/tubing ID with drift tool
R/U / R/D
Rig Up / Rig Down
PTT
Pressure Test Tubing (common in completions)
ST
Standpipe Test
SD
Shut Down (e.g., “SD due to WOW”)
Tag TOC
Tag Top of Cement
Brk circ.
Break circulation
Drift csg.
Drift casing
Hole cond.
Hole conditioned (e.g., before logging or casing)

---

Author: Marcel Chin-A-Lien – Petroleum & Energy Advisor
Posted: 24 May 2025 | Updated with casing timeline and analog wells

Enjoy.

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 “

Drs – Petroleum Geology
Engineering Geologist – Petroleum Geology

Executive MBA International Business – Petroleum – M&A
MSc International Management – Petroleum

Energy Negotiator Association of International Negotiators (AIEN)

Certified Petroleum Geologist # 5201 – American Association Petroleum Geologists – Gold standard Certification
Chartered European Geologist # 92    – European Federation of Geologists – Gold standard Certification

Cambridge Award  “ 2000 Outstanding Scientists of the 20th Century ”, UK – Gold standard Award
Paris Awards  “ Innovative New Business Projects “, GDF-Suez, France – Two Gold standard Awards, Paris, 2003.

Public Profile: nl.linkedin.com/pub/marcel-chin-a-lien/9/a73/547/

For Advisory Services contact:

Email: marcelchinalien@gmail.com