Shelf Drilling jack-up rig wraps up drilling assignment off Oman

Masirah Oil, a subsidiary of Singapore’s Rex International, has completed its drilling campaign offshore Oman with a jack-up rig from Shelf Drilling. Whether additional drilling is on the cards will be determined by the results of the core analysis.

Following Rex’s announcement from June 2022 about a search for a jack-up rig to drill one firm well and one optional well in the Block 50 concession off Oman, Masirah Oil revealed months later that the Yumna 4 appraisal/exploration well on the Yumna field was spudded on 11 November 2022 with Shelf Drilling’s Compact Driller jack-up rig.

The 1992-built Compact Driller jack-up rig had an upgrade in 2019. This rig is of a Marathon LeTourneau 116-C design. It is capable of operating in water depths of up to 300 ft and can accommodate 146 people.

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In an update on Monday, Masirah Oil confirmed the completion of its 4Q 2022 drilling campaign, which consisted of a workover of the Yumna 3 well and the drilling of the Yumna 4 well, conducted in Block 50 offshore Oman.

The company explained that the workover of the Yumna 3 well consisted of replacing the electrical submersible pump (ESP) in the well. Thanks to the new ESP, this well is now producing an average of 4,050 bopd, as compared to 3,590 bopd with the previous ESP.

On the other hand, the Yumna 4 well was drilled as a dual objective well to test the eastern extension of the Aruma reservoirs of the Yumna field and an exploration target below and northeast of the field. According to Masirah Oil, the well was successful at the Aruma level, where it penetrated 9.6 metres of net oil pay, consistent with the pre-drill prognosis.

Moreover, this well, which was completed for production, has flowed at 4,050 bopd and the flow rate has not stabilised yet, as outlined by the firm. After drilling to the Aruma target and setting a 9 5/8” casing, the well was deepened and directionally drilled to the northeast to test a structural closure in the Khufai carbonate formation at about 3,000 metres.

Masirah Oil explained that the well reached a total depth of 3,416 metres while oil shows were encountered in the Khufai and 16.5 metres of core was recovered from the formation. The core has been sent to a laboratory for detailed analysis.

“However, the planned formation evaluation programme could not be completed due to a stuck wireline tool which could not be fished (recovered) from the borehole. Results of the core analysis will likely determine if additional drilling/evaluation of this Khufai prospect is justified,” concluded the firm.

Masirah Oil has a 100 per cent interest in the Block 50 concession, while Rex International holds an interest of 91.81 per cent in Masirah Oil.