This book was initiated by a study conducted at Rosenstiel School for Marine and Atmospheric Sciences for Shell Research. For the present book this study has been considerably enlarged and modified. The book has benefited from discussions with numerous colleagues, and numerous colleagues have provided us with unpublished data and information. Without this support, this book would not have been possible.

Heterogeneity is an intrinsic property of all carbonate reservoirs. The properties of these reservoirs considerably change both laterally and vertically. Lateral changes are usually the result of various depositional settings, while vertical heterogeneities are caused by basin evolution through time. Available data from these reservoirs are very limited and so predicting the distribution of properties between the wells is very complicated. The hydrocarbon in place is calculated using these predictions and so they are very important. In fact, many aspects of the reservoir studies are about heterogeneities. Facies analysis and classifications, determining sedimentary environments, reservoir rock typing, flow unit determination and sequence stratigraphy are some examples. <...>

ТЬе intention of this book is to provide а detai!ed synthesis of the enormous body of research which has Ьееп published оп carbonate sediments and rocks. Such rocks аге worthy of attention for severa! reasons. ТЬеу аге vo!umetrically а most signifcant part of the geo!ogica! record and possess тисЬ of the fossil гес-ord of !ife оп this p!anet. Most importantly they contain at !east 40% of the wor!d's known hydroсагЬоп reserves. ТЬеу a!so р!ау host to base meta! deposits and groundwater resources, and аге raw materia!s for the construction and chemica! industries. No other rock type is as economically important.

A very large part of our understanding of carbonate sediments and rocks is derived from studies made with the microscope. Field work lays bare the gross relationships, but is apt to be hampered by the failure of many limestones to reveal themselves clearly in the hand specimen-a serious handicap in so complex a group of rocks. Geochemical and X-ray studies, though profoundly influential, suffer not only from the length of time between question and answer, but, above all, from their inability to take cognizance of the complex fabrics which are of such critical importance in this group of multicomponent rocks. The immediacy of the microscopical approach has sustained this method as the major research tool throughout the rapid expansion of carbonate studies since World War 11: the newer and more discerning classifications depend on it. The development of refined staining techniques, of replication, including the shadowing of acetate peels, combined with the use of the transmission and scanningelectron microscopes, have shown, along with the subtle methods of cathodoluminescence, that the microscope has a rich future <...>