The Efficiency of High Power Laser Perforation in Shale Formations

Abstract

Abstract This work introduces the high-power laser for perforation application in shale formations. Shale represents a significant role in unconventional reservoirs and production. Conventional perforation methods cause compaction and reduce permeability around the created tunnel. High-power laser perforation can enhance permeability and porosity while providing unmatched control of the perforation's shape and length. This paper presents the high-power laser perforation process on shale formation and lab-to-field transformation for the first industrial laser perforation. A high-power laser system is used to perforate different types and sizes of shale samples. Laser perforation affects the formation and creates microcracks while interacting and perforating the shale. The rocks are characterized before and after the process using a combined multi-physics and multi-scale approach. Small core plugs and cuttings are used to study the effect at the micro-level using NMR, thin sections, and SEM. Larger samples are used to characterize the effect of the rock's overall structure, such as hardness, permeability, velocity, and micro-cracks mapping. The chemical transformations are captured using differential thermal analysis (DTA), X-ray diffraction and fluorescence (XRD/XRF), and geochemical analysis. The laser interaction is recorded in real-time using high-speed infra-red thermography and optical videos. Experimental results showed that a near-infrared high-power laser could create long and wide perforation tunnels in shale formation with increased permeability due to the creation of micro-cracks, changes in interconnectivity between the pores, and the collapse of clays. This work demonstrates that a high-power laser can be used to enhance the perforation processes in shale formations. The technology can controllably create tunnels of different sizes and geometry. It is a none damaging, safe and precise technology that enables the creation of enhanced tunnels with improved flow properties and the unlocking of unconventional reservoirs.