Principles of Drilling and Excavation

Abstract

Predicting the performance of drills requires analytical capabilities that account for the tools characteristics, rock properties and behavior, the temperature, and other parameters. Also, it necessitates understanding the effect of the applied forces, details of the bit, and the interaction with the drilled rock. This chapter covers the principles of drilling and excavation, both analytically and experimentally, and the requirements for optimization of the drilling operation. Physical Properties of Rocks Terrestrial RocksThe vast array of terrestrial rocks can be simplified into a few basic types. One useful classification scheme is to group rocks via their mode of origin, specifically into igneous, sedimentary, and metamorphic rock types. Igneous rocks are those that solidified directly from a molten state, of which basalt is the prime example. Such rocks can be glassy if quickly cooled, or fully crystalline if allowed to cool slowly. Sedimentary rocks, in contrast, are composed of individual mineral or lithic fragments that have been transported and deposited in layers or strata. These strata have been compacted or re-cemented to form a rock-like mass. Finally, metamorphic rocks are igneous or sedimentary rocks that have altered during burial by heat and/or pressure. The original rock fabric, textures, and mineral assemblages are gradually replaced or overprinted as metamorphism progresses.Drilling in Extreme Environments. Edited by Yoseph Bar-Cohen and Kris Zacny Rock response to external loading depends not only on the level of applied loads, but also on rock properties. Based on their functionalities, there are three categories of rock properties often used in the analysis of rock behavior:. Elastic properties such as Youngs modulus, shear modulus, bulk modulus, Poissons ratio, bulk compressibility, and grain or matrix compressibility. They define rock elastic deformation. . Strength properties describing the loading limit a rock could afford and its plastic behavior. There are several strength variables, such as cohesive strength, tensile strength, compressive strength, and internal friction angle. . Transport properties, for example, rock porosity and permeability, describe the ability of fluid to pass through a rock.These properties are essential for any analytical or numerical effort to describe or predict rock mechanical behavior. The reliability of their values is at least as important as the prediction method itself, if not more so. Rock properties from these categories are not independent. Often, it is found that they are related to each other either directly or indirectly. For example, rocks with high strength are likely to have high modulus, low Poissons ratio, and low porosity. In this section, we will first describe each rock property and its connection with others; then, we will briefly discuss the two methods generally applied to determine its value. 2.2.

Geomechanical challenges in petroleum reservoir exploitation

“…1. First order [σ] estimates are made using databases (WSM), offset well data, and geological inference based on tectonic fabric, diagenetic intensity and burial/erosion history (Han et al, 2009). Tectonic fabric and stress history analysis (folds, lateral deformation history, faults) is a robust approach to determining principal stress directions and relative magnitude.…”

Review on research and development of planetary penetrator

“…As early as the 1960s, the former Soviet Union realized the importance of using planetary penetrators for deep space exploration missions. The early Luna-16, Luna-20, and Luna-24 lunar probes set the stage for future planetary penetrators (Han et al, 2009;Huntress et al, 2003). At present, researchers have designed a variety of planetary penetrators to penetrate the planet's soil for sampling, but both penetration and sampling capabilities have not met expectations.…”

Influence of Weight-on-Bit on Percussive Drilling Performance

“…An impact induces a compressive incident wave that travels through the bit assembly to eventually cause penetration by indentation of a collection of bit buttons into the rock [2,3]. Percussion tools are generally more efficient for drilling hard rock formations than conventional rotary equipment [4,5]. Their advantages include lower weighton-bit (WOB) requirement, reduced bit wear due to less contact time with the rock, less borehole deviation and larger chip size [6].…”