Seismic Velocities and Depth Conversion across the Intisar "D" Field, Sirte Basin, Libya

Salem, Yahya Ahmed Ali (1991) Seismic Velocities and Depth Conversion across the Intisar "D" Field, Sirte Basin, Libya. MSc(R) thesis, University of Glasgow.

Abstract

The Intisar "D" field is one of the oldest fields in the Sirte Basin (Libya), It was discovered by Occidental company in 1966. In 1986 a new 2-D seismic survey was carried out to define the field more accurately, as well as 3-D work being done in the eastern part of the field. This study is concerned mainly with the recent seismic lines and well logs, to produce a new interpretation. The field is situated on the southeast of the Concession 103 area, which lies to the southeast of the Agedabya trough, with the Rakb high to the east and the Zelten platform somewhat farther to the west. The geology of the Intisar "D" field and the Concession 103 was outlined previously by two papers published, more than ten years ago. One was a study of the geology and the depositional history of Intisar "A" field in the northern part of the Concession, while the second paper described the geology and depositional history of Intisar "D" field, together with the exploration techniques and the production system used. The main reservoir is an Upper Palaeocene pinnacle reef containing more than one billion bbl (160 million cu m) of recoverable oil. The reef grew at the same time as the Upper-Sabil platform carbonates were being deposited, At the end of reef growth time near the end of the Palaeocene time, the reefs stopped growing with the introduction of the lower Kheir shales. Seven seismic lines are available, U-14, U-25, U-51, U-53, U-54, U-6, and U-9, and nineteen wells in the field selected for different purposes lithological information, correlation, and velocity information. The main aim of this study, new seismic interpretation of important horizons, and velocity interpretation, with a discussion of why the seismic velocities in the area are inaccurate, and the reprocessing part of line U-14. The tying of well (D1/103) and seismic sections (U14, U25, U51, U53, and U54) are reasonably closely particularly at the Lower Eocene and Upper Palaeocene levels. The other horizons match with small mis-ties approximately (+30 ms). The interpreted horizons are the Upper-Sabil (Upper Palaeocene), Kheir (Upper Palaeocene - Lower Eocene), Gir (top of Lower Eocene), and El-giza (Middle Eocene). The seismic characteristics indicate strongly contrasting acoustic impedance mostly between the sequences of shales from one side and the limestone from the other. The reprocessing of part of line U-14 has resulted in a better defined seismic section, displayed both in migrated time and in depth.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Geophysics, Petroleum geology, North African studies
• Date of Award: 1991
• Depositing User: Enlighten Team
• Unique ID: glathesis:1991-78245
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jan 2020 15:35
• Last Modified: 30 Jan 2020 15:35
• URI: https://theses.gla.ac.uk/id/eprint/78245