Modeling and analysis of formation boundaries based on LWD natural gamma

An analytic solution of calculating the distance between measurement point and formation boundary using natural gamma flux was given in this paper based on infinite uniform horizontal strata model. Building mathematical model with the spherical coordinates, it is assumed that the probe points are ideal points, and the stratum is similar to horizontal infinite uniform model. The analytical solution form is very simple and easily programming analysis to improve efficiency, and can be developed to separate calculation module which could called for other programs. It also has certain reference value for analyzing techniques such as geologic steering, LWD logging data post-analysis and stratigraphic boundary determination. The model still has space to improve, such as orientation and thin strata identification; besides, further analysis and investigation are also need to make sure the technique being applied in practice as soon as possible.