DEFINING CLAY TYPE USING NMR AND GEOCHEMICAL LOGGINGMEASUREMENTS

摘要

The fraction of an NMR T_2 distribution less than 3 msis often considered clay bound water (CBW) by theindustry. In a laboratory NMR study Prammer et al.(1996) showed that the clay bound water associatedwith chlorite, smectite, illite, and kaolinite has a distinctrange of T_2 values for each of the clays. In particular,smectite and illite have short T_2 values containedentirely within the 0 to 3 ms range. However, nosystematic downhole data analysis has verified thisstudy. This paper will demonstrate how CBW relates toclay content as validated by core data and claymineralogy derived from geochemical logs. Examplestaken from the Shell Stribling #2 test well in JohnsonCity, Texas and a South American well will be used. Itis suggested that the integrated use of NMR,geochemical data, and geological knowledge provides amore quantitative model of the formation than a simplesand/shale model.