Enhancing geochemical interpretation using high vertical resolution data

The geochemical logging tool (GLT) has been shown to successfully describe the petrophysical properties of shaley sand reservoirs in many parts of the world. One of the limitations, however, has been the relatively poor vertical resolution, which often results in pessimistic producibility estimates in thinly laminated formations. A technique has been developed whereby the high resolution of the attenuation curve from the electromagnetic propagation tool (EPT) is used to modify the geochemically derived clay content. The resulting mineralogy exhibits greatly improved vertical resolution, while retaining the same degree of mineralogical detail as in standard processing. This, in turn, improves the porosity, saturation, and most significantly, the permeability estimates in the thin sand zones sandwiched within the shaley laminations. The technique has been applied to a field example, and the resulting cumulative permeability-feet estimate was increased by about a factor of three