Zubair: An Integrated Understanding from New Well in Majnoon Field

Majnoon is a giant oilfield located 60km north of Basra, Iraq close to the Iraq-Iran border. It was discovered in 1976. Due to various wars the production has been interrupted through time. It is a banana shaped structure with a NNW-SSE orientation in the southern part; nearly N-S in the centre and NNE-SSW in the northern half. The field has multiple proven oil reservoirs, mostly carbonate in origin except for the clastic pulses of Nahr Umr and Zubair Formations. The Zubair Formation occurs in northern Saudi Arabia, Kuwait and most of southern Iraq and Iran. It is stratigraphically placed below the Shua’iba formation and separated from the over pressured Yamama formation by the Ratawi shale. In the First Commercial Phase (FCP) of drilling, Zubair Formation is a major target for sweet oil production. Out of the 18 planned wells, eleven wells target this formation. In Majnoon, there remains a wide range of uncertainty in Zubair reservoir properties and distribution due to sparse data. The major part of our understanding comes from the 10 legacy well penetrations and poor quality 2D seismic data. To supplement this, analogue data and published literature have been used. In this paper, the Zubair formation has been reviewed based on the new information from 10 wells which have already penetrated the Zubair during the FCP phase of drilling.