Microfacies and Depositional Environment of Mishrif Formation, North Rumaila Oilfield, Southren Iraq (original) (raw)

2019, International Journal of Mining Science

Mishrif Formation is the most significant carbonate reservoir unit in Iraq, it includes up to 30% of total Iraqi oil reserves (Aqrawi et al., 2010). The formation is composed of thick carbonates of middle Cenomanianearly Turonian age (Chatton and Hart, 1961), that deposited on a basin-wide shallow water platform, accommodation space was supplied by a major eustatic seal-level rise in the middle Cenomanian (Haq et al., 1987; Gale et al., 2008). The Mishrif and underlying Rumaila formations were originally described in southern Iraq in well Zb-3 in Zubair oilfield (Aqrawi et al., 2010). The contact between the Mishrif and Rumaila Formations is gradational, the Mishrif Formation is unconformably overlain by the Khasib Formation (Aqrawi 1995). The microfacies of Mishrif Formation were classified based on Folk's (1962) and Dunham's (1962), adjusted by Embry and Klovan (1972) and revised by Wright (1992), this classification is depending on the mud-or grainsupported textural types. 1.1. Study Area North Rumaila oilfield is a giant oil field located in southern Iraq which is approximately 32 Km from Kuwait border and about 50 kilometer west of Basra city, between coordinate 47°16'46''-47°26'14'' Easting and 38°28'34''-38°42'30.8'' Northing. The longitudinal axis of the North Rumaila oilfield is 30 km, while the width is 20 km. It is covered an area about 600 km 2. Zubair, Tuba oilfields located at the east, while West Qurna oilfield located at the north and Ratawi oil field in the west of North Rumaila oilfield, it is consists of subsurface anticlines which are trending N-S (Karim, 1992), it is separated by saddle form south Rumaila oilfield subsurface anticlines (Fig. 1).