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

Mirotchnik, K., Kubika, P., Randall, L., Starosud, A., Allsopp, K. and Kantzas, A.

Paper SCA 9815, presented at the 1998 International Symposium of the Society of Core Analysts, held in The Hague, The Netherlands, September 14-16, 1998.


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.

A full version of this paper is available on SCA Web Online.