Discussion of Fracture Width Logging While Drilling and Drilling Mud/ Loss-Circulation-Material Selection Guidelines in Naturally Fractured Reservoirs

摘要

The discussion of drilling mud losses in naturally fractured reservoirs by Lietard et. al. (SPE 57713, SPEDC, September 1999, page 168) provides valuable insight to a common drilling problem. The authors derived a differential equation describing the transient radial mud-loss invasion from a borehole into a fracture plane. They used numerical methods to solve the equation, having concluded that an analytical solution was not possible for muds with positive yield values. The results were used to produce the type curves for the mud losses. Further analysis shows that an analytical solution exists and confirms the efficiency of the numerical algorithm employed by the authors. Unlike the numerical method, the analytical solution exhibits no problem at startup. A comparison between the analytical solution and the numerical results is presented in Table 1. It is hoped that the simplification afforded by the analytical solution provides greater encouragement to those wanting to try the technique.