Quad 9 of the U.K.C.S., North Sea is located 215 miles NE of Aberdeen. It contains four producing fields with over 400 mmbbls of oil and NGL's and 5.1 TCF of gas initially in place. The major reservoir unit is the Middle Jurassic (Bajocian to Bathonian) Beryl Formation, a marginal to shallow marine deposit which varies in thickness from 150' to 1100' across the studied area. It was deposited within the Beryl Embayment, a transfer zone between two actively extending basin bounding faults of the South Viking Graben, prior to the onset of the major rifting phase during the Callovian to Ryazanian. The objectives of the thesis were to provide a revised sedimentological model for the area accounting for the contrasting sedimentary styles present within the Beryl Formation and to unify the different correlation schemes used by the different operating companies in the area. It was based on well data from 58 cored and a further 79 uncored sections spreading nine licence blocks within Quad 9. Reservoir engineering, biostratigraphic and structural data has also been used for a fully integrated study. Initial core logging identified 32 facies and 10 trace fossil assemblages which were subsequently integrated into 14 facies associations. These were then extrapolated further into the uncored sections by wireline facies associations. Correlation was initially driven by comparison of cored sections but finalised by an integration of the reservoir engineering and biostratigraphic data. Outcrop work on the Middle Jurassic of Skye and Companian of eastern Utah provided an analogue study to accompany the downhole data. Quad 9 can be split up into three main areas distinguished by different stratigraphic histories, the southern area consisting of the Buckland and Sorby Fields, the central area consisting of the Beryl, Nevis, Ness and Linnhe Fields and a northern area consisting the Bruce and Keith Fields.

High resolution sampling was performed along the &Uuml / z&uuml / ml&uuml / Formation exposed near the YeniceSihlar village of Mudurnu (Bolu). Field and thin-section analyses showed that the &Uuml / z&uuml / ml&uuml / Formation is composed of cm to m scale cycles of 4th and 5th order. The 4th order cycles are equivalencies of parasequences and have 0.4 Ma average duration. 5th order cycles are interpreted as episodic. Upper Albian (OAE1c or OAE1d) and Cenomanian/Turonian (OAE2) anoxic events are observed as black shale levels in the studied section. Position of black shale levels is interpreted using cyclostratigraphy and sequence stratigraphy. Four types of cycle are determined. A and B-type cycles are placed in transgressive and Highstand System Tract. C and D-type cycles are placed in Lowstand System Tract. Two type 3 and one type 1 sequence boundaries are recorded. The boundary between the Soguk&ccedil / am Limestone and the &Uuml / z&uuml / ml&uuml / Formation is interpreted as the first type 3 sequence boundary. The second one separates the &Uuml / z&uuml / ml&uuml / Formation and the Yenipazar Formation and is observed at the top of the section. Type 1 boundary is represented by a conglomeratic level in the middle of the succession. Provenance analysis of sandstones indicates that during the Cenomanian the source area changed from magmatic arc setting to continental setting.