Photo: Valaris MS-1; Source: Western Gas

Drilling ops on track for next week as Valaris rig sets off towards Western Gas well

Since a Valaris-owned semi-submersible rig has kicked off mobilisation activities, Australia’s Western Gas is preparing to drill the Sasanof-1 high-impact exploration well on the North West Shelf next week.

Western Gas informed on Wednesday that the Valaris MS-1 rig – hired in November 2021 – has started mobilisation activities for departure to the Sasanof Prospect on the North West Shelf, explaining that secondary anchors securing the rig at Dampier outer harbour have been pulled, and the rig is secured to the GO Spica support vessel bridle for the tow to the Sasanof-1 exploration well location.

GO Spica support vessel preparing to tow the Valaris MS-1 rig to the Sasanof-1 exploration well location; Source: Western Gas
GO Spica support vessel preparing to tow the Valaris MS-1 rig to the Sasanof-1 exploration well location; Source: Western Gas

Moreover, the Australian company advised that primary anchors will then be recovered by the Solstad Offshore’s Far Senator vessel, and the tow activities will start. Depending on the weather, the transit time is expected to be approximately four days while drilling operations – conductor jetting – are expected to start during the week starting on Monday, 23 May 2022.

Western Gas confirmed that all required equipment has been loaded onto the rig and preliminary preparations for drilling operations are being conducted. These include mud mat, low-pressure wellhead housing and conductors prepared for deployment; 13-3/8” casing stands made up and racked in preparation for deployment on completion of 17- 1/2” hole section; and third party services equipment being installed and tested.

The Sasanof-1 exploration well is expected to be drilled vertically to a total depth of 2500 metres in 1070 metres of water. The drilling programme is anticipated to take approximately 26 days after the rig mobilises from Dampier port.

As a reminder, Western Gas has been preparing to drill this well since last year. To this end, the Australian player found a partner in September 2021 to fund half of the drilling costs. In December 2021, the firm secured an acceptance of its environment plan for operations from the country’s regulator.

In addition, the company disclosed in February 2022 that all necessary government approvals required to drill the Sasanof-1 high-impact exploration well were secured. The Australian player also confirmed last month that the Valaris MS-1 rig would start mobilisation from the Port of Dampier to the well location between 9 to 16 May 2022.

In an update last week, Western Gas revealed that the rig, anchored in the Dampier outer harbour, was on schedule to begin tow to the Sasanof-1 location on 16 May 2022. 

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Covering an area of up to 400 km2, the Sasanof Prospect is estimated by ERCE 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).

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.

According to Western Gas, this is the first well to be drilled from its exploration portfolio surrounding the existing Equus gas project with a discovered resource of 2 Tcf and 42 MMbbl and a historic exploration drilling success rate of 88 per cent with 15 discoveries from 17 wells.