The gross gas condensate bearing interval was intersected at 405m, with wireline logging confirming 78m of net pay to date over the Jurassic-aged Lower Vulcan and Plover intervals.
The interpretation has been confirmed via pressure and sampling data, proving excellent mobility in the higher porosity sands in the Lower Vulcan.
Multiple independent hydrocarbon columns have been identified, including an estimated 250m column in the Vulcan reservoirs.
Initial analysis of recovered hydrocarbon samples has confirmed a condensate to gas ratio of 10-25 barrels of oil per million standard cubic feet of gas.
The well will be plugged and abandoned as planned.
Lasseter-1 is approximately 35km east-southeast of Santos' Crown discovery, in water depths of 404m.
"Lasseter is a material discovery that adds to our strong position in the Browse, following our success with the Crown discovery in 2012," Santos exploration head Bill Ovenden said.
"The Lasseter discovery is well positioned, in close proximity to existing and proposed LNG projects in the Browse Basin and other material Santos joint venture exploration prospects.
"The Lower Vulcan reservoir system, which is optimally developed between the Ichthys and Poseidon structural trends, holds great promise."
Santos has a 30% operating interest in the prospect while Chevron holds 50% and Inpex owns the remaining 20%.