An Empirical Look at Bed Boundaries in Sand Shale Sequences


T. B. McFadzean, Dresser Atlas



An investigation is made into the accuracy with McFADZEAN which bed boundaries can be determined from various log curves. Gamma Ray, Spontaneous Potential, Induction Resistivity, Short Normal, Micro Resistivity and Caliper Curves are used in the study. A review is made of some of the methods available for picking bed boundaries from these curves. Assumptions that must be made to make these met- hods give accurate results are discussed. The ability to deter- mine net pay thickness from the above mentioned curves is also discussed. Net pay estimates from logs invariably give optimis- tic results when compared to core description.