A PRACTICAL HIGH RESOLUTION PETROGRAPHIC IMAGING SYSTEM FOR ASSESSING RESERVOIR QUALITY

DRILL CUTTINGS REPRESENT A HUGE SOURCE OF VALUABLE DATA BEARING ON RESERVOIR QUALITY ISSUES. CUTTINGS ARE PRODUCED DURING THE DRILLING OF EVERY OIL AND GAS WELL. HOWEVER, TECHNOLOGICAL INNOVATIONS ARE LACKING THAT WOULD ALLOW THESE MATERIALS TO BE UTILIZED FOR ASSESSING STOARGE AND TRANSPORT PROPERTIES SUCH AS EFFECTIVE POROSITY, PERMEABILITY, ELECTRICAL PROPERTIES, CAPILLARY PRESSURE CHARACTERISTICS, AND GEOLOGIC PROPERTIES LIKE FRACTURE DISTRIBUTION, PERMEABLE PATHWAYS, AND DIAGENETIC ALTERATION. CONVENTIONAL CORING AND CORE ANALYSIS CAN BE USED TO SUPPLEMENT WELL LOGGING, BUT THE COST OF THESE OPERATIONS AND THE RISKS THAT ARE SOMETIMES ENTAILED IN CORING DEEP AND HIGHLY DEVIATED WELLS OFTEN PRECLUDE COLLECTION OF VALUABLE RESERVOIR QUALITY DATA. THE PHASE I PROGRAM COUPLES AN ULTRA-HIGH RESOLUTION IMAGING TECHNOLOGY CALLED CONFOCAL SCANNING LASER MICROSCOPY WITH STATE-OF-THE-ART IMAGE ANALYSIS CAPABILITIES TO FORM AN ANALYSIS CAPABILITY FOR DIRECT ESTIMATION OF IMPORTANT TRANSPORT AND RESERVOIR QUALITY PARAMETERS. THE OBJECTIVE IS TO APPLY THIS NEW INTEGRATED TECHNOLOGY TO DRILL CUTTINGS. THE METHOD CAN ALSO BE APPLIED TO SIDEWALL CORES, WHICH OFTEN CAN NOT BE CHARACTERIZED BY CONVENTIONAL CORE ANALYSIS TECHNIQUES OWING TO SIZE CONSTRAINTS AND THE CONDITION OF SPECIFIC SAMPLES WHICH MAY BE DAMAGED DURING RECOVERY. IT HAS BEEN FOUND THAT INSTRINSIC 3-D PROPERTIES OF POROUS NETWORKS, SUCH AS TORTUOSITY, CAN BE DIRECTLY MAPPED BY CONFOCAL MICROSCOPY PERMITTING APPLICATION OF KOZENY-CARMEN RELATIONSHIPS FOR CALCULATION OF TRANSPORT PROPERTIES WITHOUT OVER-RELIANCE ON GEOMETRIC APPROXIMATIONS. DEMONSTRATED CAPILLARY PRESSURE CURVE CORRELATIONS CAN ALSO BE USEFULLY APPLIED TO ESTIMATE PERMEABILITY BY USING IMAGE ANALYSIS METHODS TO MEASURE THE PORE SIZE DISTRIBUTION OF SAMPLES. BIASES INTRODUCED BY SAMPLE SURFACE ROUGHNESS, VERTICAL HETEROGENEITY, AND ARTIFACTS OF IMAGE PROCESSING FOR PORE SEPARATION CAN BE ELIMINATED BY USE OF THE OPTICAL SECTIONING OF CONFOCAL MICROSCOPES.