Abstract

Procedures used by ARCO for shaly-sand analysis in the B-field and other areas of the (offshore) Northwest Java Sea of Indonesia are described. Merged overlays with sidewall core data have been used in over 500 out of 900 wells for “quick-look” qualitative analysis.

Quantitative shaly-sand analysis is in the stage of development and is being cross-checked using core data. An integrated approach uses computer enhanced high sampling rate logs, Electromagnetic Propagation log results, Formation MicroScanner information. Geochemical log data and a “Textural” parameter derived from the compressional modulus is used to provide an improved estimate of water saturation. This integrated approach gives an estimate of a variable cementation exponent to be used in shaly-sand saturation equations.

Analysis is complicated because the shaly-sands contain of both laminar and dispersed clays. Glauconite, siderite and ankerite are also present, and in some areas the sands also contain potassium rich feldspar.