Photo: Valaris MS-1 on location for drilling of Sasanof-1; Source: Western Gas

Western Gas spuds high-impact exploration well off Australia

Australia’s Western Gas has informed that a Valaris-owned semi-submersible rig has started drilling its operated high-impact Sasanof-1 exploration well located offshore Australia.

Crew on the rig floor - Western Gas
Crew on rig floor of the Valaris MS-1 constructing the bottom hole assembly for drilling of Sasanof-1. Source: Western Gas

The Australian company has been preparing to drill the Sasanof-1 exploration well since last year. The company found a partner to fund half of the drilling costs, secured an acceptance of its environment plan for the operations from the country’s regulator, and hired the Valaris MS-1 rig for the well.

By 12 May, the rig was anchored in the Dampier outer harbour and was on schedule to begin tow to the Sasanof-1 location several days later. The rig started mobilisation activities on 18 May and arrived at the exploration well location on the North West Shelf on 23 May.

In its latest update, released on Friday, Western Gas said that the well was spudded with the jetting of the 36” conductor at a water depth 1068.3m below mean sea level (BMSL). Drilling is now underway on the 17-1/2” intermediate hole section to a depth of 2030m (BMSL), 13-3/8” casing will then be run and cemented.

This will be followed by the drilling of the 12-1/4” hole section through the target reservoirs to a total depth of 2500m (BMSL).

Western Gas anticipates drilling through the target reservoir section will occur between 2 and 5 June 2022.

The Sasanof Prospect covers an area of up to 400 km2 and is on trend and updip of Western Gas’ liquids rich, low CO2 Mentorc Field. ERCE estimates the Sasanof Prospect to contain a 2U Prospective Resource of 7.2 Tcf gas and 176 Million bbls condensate (P50), with a high case 3U Prospective Resource estimate of 17.8 Tcf gas and 449 Million bbls condensate (P10).

Sasanof-1 will be Western Gas’ first well drilled from its extensive exploration portfolio surrounding the existing Equus Gas Project that contains a discovered resource of 2 Tcf and 42 MMbbl and has a historic exploration drilling success rate of 88 per cent, with 15 discoveries from 17 wells.

Western Gas is the operator of this prospect with a 52.5 per cent interest and its partners are Global Oil and Gas with a 25 per cent, Prominence Energy with a 12.5 per cent, and Clontarf Energy with a 10 per cent interest.