Abstract:

As a new parameter of the rock mechanics evaluation, the brittleness index （BI） has an important influence on the later fracturing and reconstruction of the reservoirs. The traditional calculation methods of the BI applied to the geosteering drilling of the shale gas horizontal wells have many limitations. Aiming at the calculation of the BI in real time by the LWD curves, we started with the experimental study on the BI and porosity to provide an experimental basis for calculating the BI by the porosity log information. Then, we used the regression method to analyze the relevance of the AC, DEN, CNL, GR logging values and BI, calculated the BI by using single LWD curves, and through the contribution of different logging curves to the BI, established a BI calculation method by logging while drilling of the shale reservoirs. Finally, we analyzed the feasibility of the model by the examples. The research result shows that the model is effective and adaptable, which provides a reliable basis for the geosteering drilling of the horizontal wells of the shale gas by the BI.

Key words: brittleness index（BI）, Shale gas horizontal well, LWD, Logging curve, Geosteering