The Deriugin Basin, Offshore Sakhalin: Discovery of a New Play

Bryan Ritchie¹, Ellen Paasche Birkeland¹, Philip Hirst¹, Edouard Koblov², Boris Salnikov², and Alexander Zharov^2
1 BP EOC Ltd, Sunbury-on-Thames, Middlesex, United Kingdom
² Rosneft, Yuzhno-Sakhalinsk, Russia

In the 1990s BP embarked on a major exploration drive offshore Sakhalin, a world-class hydrocarbon province with resources of over 5 bnbbls of liquids and 35 TCF of gas. Until recently only 10% of the area and one single play have been explored and therefore, despite the scale of the discovered resource, the basin is not without risk.

Using BP's Exploration Process, integrating well, seismic and outcrop data, BP developed a detailed regional understanding of the area applying Gross Depositional Environment maps and Play Fairway Analysis to high-grade acreage. In 2001 Rosneft/BP formed an Alliance to explore Sakhalin IV and V, and in 2002 and 2003 the Alliance was awarded licenses for the Kaigansky-Vasukansky, East and West Shmidt blocks, an area with no previous exploration history.

3D seismic interpretation of the Kaigansky-Vasukansky licence generated a number of prospects and highlighted the presence of a new play fairway. During the summer of 2004 the Alliance drilled the first well on the Pela Lache prospect. The well tested Miocene turbidite reservoirs, charged by mature Miocene Pilsk source rocks within a gentle 4-way dip closure. It encountered significant volumes of oil and gas in several high quality sandstone reservoirs, and confirmed a working reservoir and petroleum system in the northern offshore area of Sakhalin. This new play fairway represents a positive step forward in opening a new area for exploration and subsequent development offshore northern Sakhalin. The discovery was followed up this summer by additional exploration drilling of the Udachnaya prospect.