الفهرس 
General Statement
Stratigraphy of the North Western DesertOnly 14 pages are availabe for public view
 |  | from | 358 |  |  |
| | | from | 358 | | |
Abstract
The main goal of this work is to construct a workflow to offer to petroleum geologists to help in conducting a proper evaluation of reservoir potentials. This is in addition of defining the structural pattern, sedimentary structures and depositional environment of the Jurassic Safa Formation of the Syrah field, northern Western desert, Egypt. As figure 7.1 illustrates, integration of all obtained results, as summarized below, helped in the construction of the geological and depositional settings of the studied Safa Formation. The established workflow out of this study is suggested to be executed in the following series of analysis steps when conducting reservoir characterization studies: 1. The petrographic description of nineteen drill cutting samples, selected based on upnormal log phenomena, helped in the identification of 16 microfacies types (7 sandstones, one carbonates, two mudstones and 6 metamorphic) that comprise quartz arenite, dolomitic / ferroan dolomitic quartz arenite, kaolinitic quartz arenite, sideritic quartz arenite, chloritic quartz arenite, quartz wacke, kaolinitic quartz wacke, fe-dolomitic mudstone, mudstone, crystalline dolomite, sideritie, slate, phyllite, quartz-mica schist, meta- basalt, and mylonite. 2. These microfacies have been used as a reference to the integration of gamma ray, density and neutron logs to extract continuous accurate lithological column as summarized below: - Most of the studied section is composed of intercalations of clastic rocks except for some zones with metamorphic rocks that could not be identified directly from logs and are detailed below as detected in the four studied wells: Syrah – 1X, 94 % slate, 4 % quartz mica schist and 2% phyllite, detected at depth from 13917 to 14091ft. • Syrah– 5X, 90 % slate and 10 % quartz mica schist occupying the depth from 14288 to 14510 ft. • Syrah – 6XST has two zones of metamorphic rocks; the first from 13875 to 13925 ft and consists of metabasalt and, the second from 14280 to 14340 ft and consists of 35 % slate, 10% phyllite and 55 % quartz mica schist. • Syrah – 8X has two zones of metamorphic rocks, the first from 14139 to 14177 ft with 70 % slate, 20 % phyllite and 10 % quartz mica schist, and the second from 14311 to 14407 ft with 95 % slate, 3 % quartz mica schist and 2 % phyllite. 3. Spectral gamma ray has proved to be a good environmental indicator as well as clay typing identification in the studied wells as detailed below: • The Upper Safa member has high to intermediate Th/U ratio facies which indicates continental to shallow marine environments. This observation is supported by the presence of mixed layer, illite and glauconite as indicated by both Th-K crossplots and Th/K ratio frequency. • The Lower Safa member has high to intermediate Th/U ratio facies which indicates continental environment in the upper zone of Lower Safa Member while in the middle part it has low Th/U ratio which reflects marine environment. This observation is supported by the presence of mixed layer of illite and glauconite as indicated by both Th-K crossplots and Th/K ratio frequency.