Basics of Petroleum Geomechanics

This chapter introduces the basic concepts of petroleum geomechanics, many of the basic parameters needed for making geomechanical assessments, and some of the common ways they are obtained in the lab or in the field. It is written by practicing geomechanicists specifically for the nongeomechanicists who are working in other upstream petroleum subsurface disciplines. Geomechanics has become a prominent discipline over the past two decades, driven by increasingly complex development scenarios and required risk mitigation in the upstream petroleum business. Examples include (but are not limited to) the following: offshore deepwater drilling and development, including depleted drilling needs and high-pressure water flood management; optimizing unconventional resource development, such as oil sands and shale gas; high-temperature thermal recovery processes; and cap rock integrity and fault activation associated with primary, secondary, or enhanced recovery and fluid disposal or sequestration operations. Many nonspecialists have to deal knowingly or not with significant geomechanical impacts, problems, and risks. This section is written mainly for these professionals. The first part presents the concepts of material deformation, strain, and stress and discusses the basic parameters of elasticity, including rudimentary porous and thermal-related parameters. Only a minimal amount of mathematical development is provided, enough to understand the basic concepts, with references provided to sources in which detailed mathematical formulations can be found. The inelastic nature of most porous materials is identified, along with the basics of material failure. The remainder of the chapter focuses on the geomechanical characterization of materials, including the common methods for determining the geomechanical parameters via laboratory and field measurements and observations. Finally, geomechanical field surveillance technologies are discussed, with illustrative references provided. This chapter provides an essential base that should help the reader understand the geomechanical aspects important to the upstream petroleum industry.