Wireline logging and pressure testing have indicated the presence of 40m of net gas pay in the Jurassic Angel and Triassic Mungaroo formations between 3,614m and 3,721m.
The company has recovered multiple gas samples from the well, which are being analysed.
Winchester is located approximately 135km northwest of Dampier, in a water depth of 75m.
Santos exploration head, Bill Ovenden, said that wireline logging at the Winchester well has indicated the presence of gas discovery with excellent reservoir quality.
"Winchester-1 will now be deepened to evaluate the gas-bearing potential of further objectives within the Mungaroo section," Ovenden said.
Santos Western Australia and Northern Territory vice-president, John Anderson, said the company plans to commercialise gas discovery at Winchester through jointly owned infrastructure, or through proximal existing third party LNG infrastructure, located in WA-323-P.
Santos is the operator of WA-323-P with 75% interest, while Octanex holds the remaining 25% stake.
Image: The Winchester-1 exploration well is situated about 135km to the northwest of Dampier; Photo: courtesy of freedigitalphotos.