The investigation of the undrained behavior of Resedimented Nile Silty Clay (RNSC) is of great importance to oil exploration projects at and off the shores of North Coast Egypt, especially at large consolidation stresses. The behavior of RNSC is not studied enough despite its uniqueness, due to the dueling effects of the high plasticity of the fine grained components, and its relatively large percentages of sand and silt particles. A program of oedometer and undrained triaxial compression tests has been performed to investigate the effects of consolidation at different stress levels up to 1.3 MPa. The Nile sediments are collected from the field and resedimented in specially fabricated consolidometers to emulate the natural deposition process occurring along the Nile banks. The results are compared to theories of normalized behavior and pressure sensitivity correlations from literature. The effect of isotropic consolidation in triaxial tests is discussed. The undrained shear stress-strain results show significant changes when consolidation stresses exceed the resedimentation pressure in ductility, strains at peak resistance and post-peak strain softening. The undrained strength ratio (suvc) decreases with increasing consolidation effective stress from 0.33 at 100 KPa to 0.18 at 500 KPa which is a faster rate than predicted by correlations from literature.

1. INTRODUCTION

For several decades, Egypt has been a destination for oil exploration. With the recent confirmation of several offshore natural gas reservoirs, companies are exploring deep drilling opportunities in the Mediterranean Sea near the Egyptian shores. The United States Geological Survey (USGS) estimates substantial oil and gas resources in the Nile Delta Basin Province in the Eastern Mediterranean. In May 2010, the USGS issued an assessment for the Nile Delta Basin province, which corresponds to the Nile Delta and Mediterranean Sea sectors of Egypt. The assessment estimates an amount of 6,320 bcm of undiscovered technically recoverable natural gas, and 7.6 Gb of oil and NGLs (Karbuz, 2012).

The deep-sea bed in that region consists of layers of silt and clay of considerable depths historically carried by the Nile River and deposited in what is called the Nile Deep Sea Fan (NDSF) (Ducassou et al., 2008). Throughout history, the Nile has had 7 tributaries carrying sediments and depositing them on the bed of the Mediterranean in the shape of a large cone. Estimates of the extent of the Nile Deep Sea Fan (sediment cone) extends more than 200 km from the Egyptian shores, into the eastern Mediterranean (Aal et al., 2000).

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