US-based oil and gas firm VAALCO Energy has started drilling its first exploration well on Block 5 offshore Angola.

The Transocean Celtic Sea semi-submersible rig is being used to drill the Kindele-1 well to a planned total depth of 2,250m, at a water depth of about 100m.

The company will test a fault block adjacent to the Mubafo discovery, which tested oil from the Mucanzo sand section within the Pinda group formations.

Meanwhile, Vaalco is nearing finalisation of the seismic processing in the outboard part of Block 5, which was carried out to image pre-salt structures as potential targets for future exploration wells on the block.

"After nearly nine years of continued commitment to our Block 5 licence, we are embarking on an important phase in our efforts to explore for hydrocarbons from a second West African country."

Vaalco Energy chairman and CEO Steve Guidry said: "After nearly nine years of continued commitment to our Block 5 licence, we are embarking on an important phase in our efforts to explore for hydrocarbons from a second West African country.

"We continue to believe that Block 5 is within an area with potential in both post and pre-salt formations, including the syn-rift and sag play."

Vaalco Energy and Sonangol P&P entered into the subsequent exploration phase (SEP) on Block 5 in October 2014.

Under the SEP, both the companies have committed to drill a total of four exploration wells in the exploration extension period, which completes in November 2017.

It includes the original two-well commitment under the primary exploration period that moves over to the SEP period.