Australia-based oil and gas explorer Rialto Energy has started the initial drilling of the Gazelle-P4 development off the CI-202 block offshore of Côte d’Ivoire.

"Rialto holds an 85% working interest and is the operator of the CI-202 block which contains the Gazelle Field."

The well is located on the southern side of the major field-dividing fault relative to the Gazelle-P3 ST1/2 and Gazelle-2 wells and is a step out well, relative to the IVCO-12, IVCO-21 and Gazelle-1 wells drilled in 1977, 1981 and 1998 respectively.

Transocean GSF Monitor drilling rig is used to test the Gazelle-P4 well for oil potential of the UC-2 and UC-4 oil reservoirs, as well as the gas potential of the UC-3, UC-5, LC-1 and LC-2 gas reservoirs discovered by the IVCO-12 and IVCO-21 wells.

The well will be drilled from the recently installed Gazelle template to a total depth (TD) of approximately 3,200 mMDRT (-2,709 mTVDSS).

It is a deviated well that will appraise six oil and gas reservoirs in the Upper and Lower Cenomanian sands.

Jeff Schrull, Rialto Energy managing director, said: "The well will appraise five additional reservoirs not appraised by the Gazelle-P3 ST1/2 well and will allow the progression of the Gazelle development, with the drilling of the second of four planned development wells."

A total of $28m will be invested to drill the well, which is expected to take 45 days.

Rialto holds an 85% working interest and is the operator of the CI-202 block which contains the Gazelle Field with first production expected by early 2014.