APT has been designed to address the highly nonlinear nature of geological data and is based on the geological differential method (GDM)1. It integrates various forms of data, preserves the geological identity and produces a true point by point solution of the target parameter. APT produces a true solution in comparison to the statistical methods which can only produce a realisation.
APT maintains the data identity and character throughout the solution process, in contrast to other methods. APT preserves the geological characteristics for each and every lithology along the borehole as illustrated.
The same data is organised in two different ways to predict porosity in a prediction well far a field from the model well.
Case 1 – Data is organised with increasing depth.
Case 2 – Data is organised with increasing porosity.
APT predictions for both cases are identical as shown below:
Predict porosity and water saturation throughout the overburden: in the absence of wireline or logging while drilling (LWD) data by maximising the use of available mud-gas, drilling and Gamma Ray data.