With oil and gas exploration activity at a record low, the number of successful new-field wildcats that completed drilling during 2017 was just over 200, similar to 2016 but down from over 400 in 2014. Offshore West Africa reflected the downturn with only four new discoveries made compared to 16 in 2014. Three of these came in Senegal and the Yakaar 1 deepwater gas discovery heads up the 2017 top ten after operator Kosmos reported 45m of net pay in Lower Cenomanian sandstones giving estimates of approximately 15 Tcfg Pmean resources.
Latin America dominated 2017 in terms of discovery size, holding six of the top ten wells. ExxonMobil’s Stabroek Block offshore Guyana saw over a billion barrels of recoverable reserves added through the Payara, Snoek and Turbot oil discoveries made in deepwater clastics. Two significant discoveries were made in Mexico, both holding between one and two billion barrels of oil equivalent in place. Operator Talos Energy encountered 170m-200m of net oil pay in Upper Miocene sandstones of the Zama 1 well offshore in the Salina del Istmo Basin while onshore in the Veracruz Basin Pemex reported the Ixachi 1 gas and condensate well as the largest onshore discovery in 15 years. A significant Atlantic Margin offshore gas discovery was made by BP Trinidad in the Savannah 1 well while Anadarko’s Gorgon 1 discovery offshore Colombia may also prove sizeable with the operator reporting 80-110m of net gas pay.
In the Colville Basin on Alaska’s North Slope, Armstrong Energy made a major onshore light oil discovery with the Horseshoe 1 & 1A wells encountering 45m and 30m of net pay in the Cretaceous Nanushuk Formation. The Armstrong/Repsol partnership estimate contingent resources of approximately 1.2 billion barrels in the Nanushuk play.
In South East Asia there were 18 discoveries recorded during 2017 with the largest, in excess of 100 MMboe, in Indonesia and Myanmar. Pertamina discovered oil and gas in the Parang 1 well in the Tarakan Basin, offshore Kalimantan, with post-drill estimates of 121 MMbo plus 851.1 Bcfg Pmean recoverable resources after targeting Miocene and Pliocene sandstones. In Myanmar’s Rakhine Offshore Basin the MPRL/Woodside partnership drilled the Pyi Thit 1 deepwater new-field wildcat and encountered 36m net gas pay in the objective reservoir which tested at a rate of more than 50 MMcfg/d.
The largest Middle East discovery reported during 2017 came from Lukoil’s Eridu 1 new-field wildcat drilled onshore in the Mesopotamian Basin of southern Iraq. Drilling was completed in December 2016 and during February the partnership with INPEX Corp confirmed it had discovered sweet oil in the Cretaceous Mishrif Formation and recorded a flow rate of more than 6,300 bo/d. It was followed up with two successful appraisal wells with the company anticipating recoverable reserves in excess of one billion barrels.
Northwest Europe saw an upturn in exploration drilling during the summer of 2017 but it still remained low overall for the year and only 13 discoveries were reported, all generally under 100 MMboe. Offshore Norway Statoil and Lundin recorded discoveries in the Barents Sea and Statoil was also successful on the Verbier prospect in the United Kingdom’s Moray Firth Basin. Offshore Netherlands Oranje-Nassau and partners Hansa Hydrocarbons reported that the Ruby new-field wildcat was a significant discovery after testing a Permian Rotliegendes sandstone reservoir at a rate of 53MMcfg/d.
January 2018 commenced with ExxonMobil announcing another potentially significant discovery on Stabroek. Ranger 1, which is the sixth discovery on the block, encountered 70m of high quality oil-bearing carbonates 100km north of the original Liza 1 well and opening a new play.
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