Diagenetic Ripening of Six North Sea Chalk Fields

P334 Diagenetic ripening of six North Sea chalk fields Introduction 1 From a study of 178 dry chalk samples from six North Sea hydrocarbon fields (Figure 1) the interrelationship of texture porosity oxygen isotope ratios and ultrasonic velocity was investigated. The samples are from the Ekofisk Formation of Paleogene age and the Tor Formation of Cretaceous age. The ultrasonic velocity of chalk is primarily determined by porosity where low porosity chalk has high velocity and high porosity chalk has low velocity but the ultrasonic velocity of chalk is also controlled by the properties of the solid frame and the pore