Wireline Log Signatures of Organic Matter and Lithofacies Classifications for Shale and Tight Carbonate Reservoirs

This chapter discusses the wireline log signatures of organic matters and presents classifications of lithofacies and rock types for shale and tight carbonate reservoirs. Lithofacies represent an intermediate scale of reservoir properties in the hierarchy of subsurface heterogeneities. The characterization of lithofacies is important for describing heterogeneities in unconventional formations. Yet, lithofacies data have been traditionally limited to interpretations from cored intervals. Wireline logs are generally more abundant than core data. Here, we present several methods for lithofacies prediction using wireline logs for different types of unconventional formations. Some newer log suites generate mineral compositions of the formation, which enables a more detailed lithological evaluation than in the past. Uses and limitations of the methods are elaborated through several examples for a variety of unconventional resource plays.