System and method for characterizing near-wellbore lithology, mineralogy and heterogeneity

A computer system, comprising:

• one or more processors;
• memory;
• and
• one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions that when executed by the one or more processors cause the computer system to:
• a. receive azimuthal gamma ray data from a horizontal well;
• b. calculate a difference between an up-sector gamma ray signal and a down-sector gamma ray signal and normalizing the difference by an average gamma ray value to generate a gamma ray difference value;
• c. use the gamma ray difference value to identify heterogeneous intervals along the horizontal well to generate a heterogeneity index;
• and
• d. use the heterogeneity index for at least one of geomechanical analysis of wellbore stability, drilling performance analysis, fracturing decisions, and production performance diagnosis.