We produce oil and gas in the Gulf of Mexico, heavy oil in California and primarily tight gas and liquid hydrocarbons in Louisiana, Pennsylvania, Texas and Wyoming. The majority of our oil and gas production interests are acquired under leases granted by the owner of the minerals underlying the relevant acreage, including many leases for federal onshore and offshore tracts. Such leases usually run on an initial fixed term that is automatically extended by the establishment of production for as long as production continues, subject to compliance with the terms of the lease (including, in the case of federal leases, extensive regulations imposed by federal law).
Gulf of Mexico
The Gulf of Mexico is the major production area in the USA, and accounts for almost 50% of Shell’s oil and gas production in the country. We have an interest in approximately 450 federal offshore leases in the Gulf of Mexico. Our share of production in the Gulf of Mexico averaged almost 180 thousand boe/d in 2013. Key producing assets are Auger, Brutus, Enchilada, Mars, NaKika, Perdido, Ram-Powell and Ursa.
We continued to grow our presence in the Gulf of Mexico in 2013 by adding three additional drilling rigs to our contracted offshore fleet. We also secured 36 blocks in the 2013 Central and Western Gulf lease sales.
We have significant holdings of tight-gas and liquids-rich shale acreage including in the Marcellus shale, centred on Pennsylvania in north-east USA, the Delaware Permian Basin in west Texas and the Eagle Ford shale formation in south Texas where we are in process of selling our Piloncillo Ranch acreage.
In recent years, we have invested significant amounts in our tight-gas and liquids-rich shale portfolio. There is still significant amounts of drilling that must be conducted in certain properties. If future well results do not meet our expectations, there could be additional asset sales and/or impairments. Additionally, management will continue to review the strategic fit of our tight-gas and liquids-rich shale assets. Depending on the outcome of that review and future capital allocation to these properties, additional asset sales and/or impairments could also occur.
We have a 51.8% interest in Aera Energy LLC (Aera), which holds assets in the San Joaquin Valley and Los Angeles Basin areas of southern California. Aera operates more than 15,000 wells, producing approximately 130 thousand boe/d of heavy oil and gas.
We hold more than 410 federal leases for exploration in the Beaufort and Chukchi seas in Alaska. As a result of the grounding of the Kulluk drilling rig at the end of 2012, exploration drilling in 2013 was deferred. We have made the decision to dispose of the Kulluk and contracted a replacement rig. An impairment charge was recognised in 2013. A recent US Ninth Circuit Court decision against the Department of the Interior raises obstacles for our plans for drilling offshore Alaska. As a result, we have decided to suspend our exploration programme for Alaska for 2014, and we will continue to review the situation as we develop our plans for 2015.