Determination of Mud Invasion Characteristics of Sandstone Reservoirs Using a Combination of Advanced Core Analysis Techniques

ABSTRACT

A combination of novel petro-physical methods has been used for an integrated investigation of the saturation conditions and characteristics of saturating fluids near the well-bore in sandstone reservoirs. The applied methods include Magnetic Resonance Imaging (MRI), Magnetic Resonance Relaxometry (NMR), Ultra-centrifuge and Gas Chromatography (GC) in combination with Mass-Spectrometry. Routine petro-physical analysis has also been done. The recovered results were used as a basis for the investigation of different objectives. One such objective was the demonstration of NMR logging tool applicability for the study of the invasion. The following subjects were investigated:

· Similarities and differences of NMR instrument results from imaging and relaxometry.
· The three dimensional porous structure of the core samples.
· The effective porosity determination by the NMR method and the evaluation of different models for permeability estimation under invaded zone conditions.
· The informative NMR parameters for the identification of the saturation conditions near the well-bore.
· The wettability alteration of porous media as a result of different kinds of treatment.
· The influence of porous structure and lithology on the fluids interaction with pore surface.
· The physical-chemical parameters of oil in the porous media and in the bulk volume before and after displacement.

The results of the performed project can be used as a guideline for the determination of native state reservoir characteristics and the estimation of the saturation conditions near the wellbore during the different drilling/completion/production stages.

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