Gulf Stream Energy Finds Oil in Two Zones at Zydeco-1, Flow Tests Still to Come
Key Takeaways
- Gulf Stream has logged oil in two sandstone zones at Zydeco-1, the Homeseeker B at 8,935 feet TVD and the Borsum Sand at 3,364 feet TVD, from a single sidetrack.
- The Borsum Sand shows 12 feet of net pay at 32% porosity and 43% water saturation, outpacing the Homeseeker B's 5 feet at 24% porosity and 49%.
- Both discoveries rest on wireline logs only, with no flow test or fluid sample, and no reserves or resources are estimated.
- Casing set at 9,172 feet, about 378 feet above the Tweedle, lets the Upper Tweedle gas and condensate target be tested from the existing wellbore.
- Gulf Stream holds 100% of the Zydeco Project and promises evaluation details shortly, but gives no firm timeline.
Zydeco-1 oil discovery: sidetrack delivers two oil zones
Gulf Stream Energy (ASX: GSE) has announced a Zydeco-1 oil discovery in two separate sandstone zones, with wireline logs identifying oil in the Homeseeker B at 8,935 feet TVD and the shallow Borsum Sand at 3,364 feet TVD. The zones sit within the Zydeco Oil & Gas Project in Acadia Parish, Louisiana, where the company holds a 100% working interest and is operator.
There is an important caveat. The discoveries rest on wireline log interpretation only, and no flow test or fluid sample has yet been obtained from either zone.
The sidetrack reached a total depth of 9,180 feet measured depth, with drilling completed safely and no reported HSE (health, safety and environment) issues.
Joseph Graham, Managing Director
“This is an exciting result for Gulf Stream. Zydeco-1 has found oil in two separate zones – the Homeseeker B, a primary objective of the well, and the shallow Borsum Sand…”
The Homeseeker B was a primary objective of the sidetrack. That matters because the original Zydeco-1 hole was suspended with stuck pipe at 9,393 feet measured depth, as announced on 3 August 2026.
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Two zones, one wellbore: what do the logs show?
The log readings give the first technical picture of each zone. They are interpretations, not production results.
Homeseeker B and Borsum Sand results
| Zone | Depth (TVD) | Net pay | Average pay porosity | Average pay water saturation |
|---|---|---|---|---|
| Homeseeker B (Oligocene sandstone) | 8,935 to 8,978 ft | 5 ft | 24% | 49% |
| Borsum Sand (Early Miocene sandstone) | 3,364 to 3,472 ft | 12 ft | 32% | 43% |
Net pay is the thickness of rock that logs suggest could contain producible hydrocarbons. Porosity measures the pore space in the rock, and water saturation is the share of that space filled with water rather than oil.
The Borsum Sand is well above the Homeseeker B. Because of its shallow depth, it can be evaluated separately from the deeper zones.
How was the discovery determined?
SLB ran wireline logs on 8 October 2026, covering array induction resistivity, density, neutron, sonic and gamma ray measurements. No formation pressure data or mud-gas log was acquired.
What is a wireline log oil discovery?
Wireline logging involves lowering instruments into a drilled well on a cable to measure the properties of the surrounding rock. Different readings, such as electrical resistivity and density, help geologists identify zones that appear to contain oil rather than water.
A log-identified discovery is not the same as a commercially recoverable one. Logs indicate where oil is likely present, but only flow testing and fluid sampling can show what a zone actually produces.
Gulf Stream states that the log-identified discoveries do not establish commercial recoverability. No estimate of reserves, contingent resources or prospective resources is made.
For you as an investor, this is an early milestone with evaluation still to come.
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Upper Tweedle access preserved and next steps
Upper Tweedle remains accessible
Heavy-wall 7-inch casing has been set at 9,172 feet measured depth, approximately 378 feet above the Tweedle. The Tweedle is an undrilled target prospective for high-pressure gas and condensate.
That casing point means the Upper Tweedle can be drilled into and tested from the existing wellbore in a future phase, without the need for a new well. Setting the casing was a primary objective of the sidetrack.
Gulf Stream is clear on the limits. No hydrocarbons have been discovered in the Tweedle, no estimate of resources is made for it, and no decision has been made to drill into or test it.
Evaluation work ahead
The company outlined the following sequence:
- Evaluate the two oil discoveries to assess their potential for commercial recovery.
- Consider any decision on the Upper Tweedle separately, taking into account the results of that evaluation.
- Provide further details of the proposed evaluation work in another announcement, which the company expects shortly.
No timeline is given beyond “shortly”. Gulf Stream also notes that the timing and scope of further evaluation remain subject to operational conditions, engineering review and applicable regulatory requirements.
Gulf Stream describes its strategy as building a scalable US Gulf Coast oil and gas business through the acquisition and development of low-risk, near-term production opportunities. The 100%-owned Zydeco Project represents the first step in that broader growth platform.
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