WELL LOG ZONATION AND CORRECTION BASED ON VARIATIONS IN AMPLITUDE AND LAYER THICKNESS

Abstract

Well log zonation is the usual practice to carry out well log analysis. Definition of bed boundaries at a very detailed level is difficult and time-consuming, and therefore some data is frequently untapped, especially when thin beds are present in the formation. Proper layer delimitation could provide useful information, leading to an improvement in the evaluation of the potential of hydrocarbon reservoirs.

In the meanings of this, a fast and flexible tool to perform zonation and segmentation of any log has been developed through a friendly interactive graphic interface where the user canselect the input parameters that control the zonation process and generate blocked logs to be usedin subsequent geological applications. The method is based on inner amplitude variations of the log and permits the determination of layer amplitudes and thicknesses after bed boundaries are assigned.

To show the applicability of the tool, the LLD log data of a thin-bedded shaly intervalfrom the well 33/9-1 located in the Statfjord field was segmented and analyzed to evaluate theeffects of layer thickness and shoulder beds in resistivity measurements. A correction algorithmwas implemented using the digitized data of available bed-thickness correction charts. Aftercorrections were applied, substantial increments in the resistivity values of several layers wereverified, which leads to the possible improvement of the producing potential of the formation byincluding thin beds with reservoir conditions.