Integration of Core-log Data: An Example from ODP Hole 959D

Abstract

Core and log measurements provide crucial information about subsurface formations. Their usage, is complicated by the different measurement methods employed, different volumes of formation analysed and the heterogeneity of the formations. While the problems of comparing core and log data are well known, the way in which these data can be most efficiently combined is not all clear in most cases. This paper shows an example from Ocean Drilling Program (ODP) Hole 959D, drilled in the Cote d' Ivoire-Ghana (CIG) margin. The integration of core and wireline log data helps to interpret the different stages observed as a result from the continental break-up and related transform tectonism associated with the motion between South America and Africa. The main objectives are to evaluate (1) the reliability of both types of measurements and (2) the extent to which the physical properties of the sediments are controlled by the tectonism. The effect of the transform deformation is seen in physical properties data derived from index properties measurements. Major breaks in porosity are associated to the tectoni zed lower Cretaceous and Cenozoic boundary, a trend also reflected in the P-wave velocity measurements. Core and well log data show the presence of a major unconformity between Cretaceous and Cenozoic, marked by an offset in porosity, density and P-wave data. The physical properties an log data are also heterogeneous, reflecting variations in consolidation, age and lithology.