Analytical Techniques for Evaluating and Modeling the Alterations of Reservoir Rocks Due to High-Power Lasing

Bailo, El Tahir¹, Ramona M. Graves^2
1 Petroleum Engineering, Colorado School of Mines, Golden, CO
² Colorado School of Mines, Golden, CO

Research for applying laser energy in drilling, completion, and stimulation of hydrocarbon wells became very active in the last five years. In the Petroleum Engineering Department, Colorado School of Mines, research is ongoing to model laser-rock interactions and to quantify the physio-chemical properties of reservoir rocks after being altered by laser energy. Techniques used in the analysis of the rocks include: 1) Petrographic thin sections are used to determine mineral transformations, and fragmentation and tortuousity fractal dimensions for the calculations of permeability and porosity around lased holes. 2) CT imaging is used to calculate volume of rock removed, and pixel density and porosity. 3) Simultaneous Thermal Analysis (STA) is employed to determine thermal properties of rocks such as reaction kinetics, clay disassociation, melting temperature, heat conductivity, and specific heat capacity. 4) Spectroscopic measurements are conducted to determine the absorption coefficient of rocks for particular lasers. 5) Scanning Electron Microscope - Energy Dispersive Spectrometer (SEM-EDS) is used to map laser-induced micro-fractures and mineralogical transformations around the lased areas. 6) X-Ray Fluorescence (XRF) and Coulometeric Analysis are applied to determine major oxides, trace element, and carbon content of rocks. 7) Pressure-Decay Profile Permeameter (PDPK) is used to map point permeability around lased areas.

Data obtained are used to model the specific energy needed to drill reservoir rocks, laser drilling speed, permeability, porosity, and thermally induced strains around the lased zone.