Studies of Reservoir Diagenesis, Burial History, and Petroleum Migration Using Luminescence Microscopy

Abstract

Luminescence microscopy is used to identify stages of cementation in petroleum reservoirs and classify the physical and chemical properties of oils and oil inclusions. The lifetime of fluorescence induced by a pulsed laser is related to the API gravity of oil and can be used to determine API gravity on microliter samples of oil or oil in inclusions. Luminescence microscopy data are combined with geological (burial history, stratigraphy, tectonics, environment of deposition) and geochemical (fluid inclusion P-T-X values, stable isotopes, trace elements, petroleum geochemistry) data to determine the timing of geological events and constrain models of diagenesis, oil migration, and reservoir prediction. This method is applied to studies of reservoir diagenesis and petroleum maturation, migration, and correlation for the Mishrif Formation, Dubai, the Kais Formation, Indonesia, the Ellenburger Dolomite, Texas, and the Great Oolite Limestone, England. In the Great Oolite Limestone, cathodoluminescence of cements shows that occurrence of zoned cements correlates with high reservoir porosity consistent with a model of porosity perservation resulting from diagenesis in a mixing zone between freshwater and marine phreatic environments. Photoluminescence of oil inclusions in cements of the Great Oolite shows that inclusions are more mature near the basin depocenter. In the Ellenburger Dolomite, Texas, several episodes of fracture development and sealing are shown by cathodoluminescence enabling a relative timing to be determined. Temperature and composition data from fluid inclusions are collected with respect to the cathodoluminescence and used toquantify the environment of cementation.