Lasers: The Next Bit

Abstract

Abstract Since the early twentieth century rotary drilling has revolutionized the procedure of extraction of crude oil replacing conventional methods like cable tool drilling. However with the advent of new technology it is time to look at future alternative, more efficient drilling methods. This paper acts as an eye opener to the feasibility of using laser drilling over modern currently used drilling techniques. The design and operation of a new laser-mechanical bit is put forth by the medium of this paper. This innovative bit shows probability of reducing rig time and increasing efficiency in drilling. The possible changes to be implemented in the present day drill string due to incorporation of this new bit is accounted for and an analysis of the possible advantages and disadvantages of this bit if implemented is also highlighted. Introduction Rotary drilling has been widely used for extraction, in most of the oil fields in various parts of the world for more than a century. During this period many alternatives drilling techniques have been suggested, worked upon and tried so as to reduce the time and increase the efficiency of drilling. These techniques include the use of niche technology with tools commonly known as novel devices. This category of devices includes Water jets, Electron Beams, Cavitating Jets, Electric arcs, Plasmas and Lasers to name a few. In comparison with all the above devices, laser drilling if developed has shown the potential to be a futuristic advanced tool that will revamp the conventional rotary drilling system. LASER basically is an acronym for Light Amplification by Stimulated Emission of Radiation. It is basically a device which converts energy in one form to electromagnetic radiation beams (photons). These photons are basically produced due to the returning of atoms to their lower energy state after their excitation to higher energy states. When this happens a photon is released. This high energy coherent light radiation can be focused to form intense high powered beams which can be used to fragment, melt or vaporize rocks depending on the input power, type of laser, adjusted focal length and interaction characteristics of the laser with the particular rock type. The other major laser parameters include discharge method (pulsed or continuous), wavelength, exposed time, pulse width, repetition rate, average power and peak power. These parameters determine the effective energy transfer to the rock. Lasers are currently being used as a potent tool with effective results, in various fields such as medical, metallurgical and for military applications. Currently lasers are widely used for precision cutting and welding of metals, ceramics and various other materials. Laser Drilling Majority of research in the field of laser drilling is focused on solely using a laser to vaporize the rock. These methods are proposed to have various advantages over currently used rotary drilling techniques which include:Increasing Rate of Penetration (ROP)-Laser drilling shows the potential of having ROPs that is more than 100 times the presently ROPsProvision of temporary casingReducing trip time and an increased bit life.Lesser dependence on parameters such as weight on bit, mud circulation rate, rotary speed and bit designAccurate and precise drilling since lasers travel in a straight line problems like dog legging are completely eliminated.Providing enhanced well control, perforating and side-tracking capabilitiesSingle diameter bore holeAchieving these breakthroughs with environmentally attractive, safe and cost effective technology1