Brian C. Gahan, P.E., president of Laser Rock Technologies LLC, is a man on a mission. Laser Rock Technologies develops high-power laser cutting applications for rock, concrete and other earth materials. He launched the new company to transition the technology from the lab to field applications and commercialization.
As Gahan describes it, “this alternative method to mechanical cutting techniques has been developed over the past decade, primarily for subsurface well construction and completion in oil and gas wells. Distinct advantages have been identified and tested, offering revolutionary changes in how the industry has mechanically drilled and perforated rock for over 100 years. We have been working with industry partners to prove concepts in the lab, and are excited to bring this technology’s unique solutions to the industry.”
The lead investigating team that developed the technology is now working through Laser Rock Technologies. “We are working with a major oilfield technologies and service company and laser manufacturer IPG Photonics Corporation to develop several commercial field applications,” he said. “Fiber laser technology is the key to allowing successful field applications in several industries that cut, drill, and ablate rock and concrete.”
Gahan said they are also developing a downhole application for geothermal well construction and ticks off a list of other industries with potential applications, including hard rock and ore mining, military, pipeline, space, construction, and demolition. He says applications in the oil and gas industry could include perforation, remediation or re-completion, slotted liners and screens, casing windows, multilaterals, casing cutting, offshore platform abandonment and more. He visualizes the laser as a multipurpose tool through development of job-specific attachments, similar in concept to home construction tools that have saw, drill and sander attachments for a single platform.
“To many in the laser industry, fiber lasers are now a serious alternative to solid-state and carbon dioxide lasers for industrial material-processing applications. Over the past two years, commercially available fiber lasers have increased in power from several watts to kilowatts. They are now capable of efficiently delivering requisite power via fiber optics to targets downhole, and have rapidly evolved into the leading candidate for on-site applications in well construction and completion. When compared to conventional industrial lasers, fiber lasers offer an order of magnitude greater wall plug efficiency, better beam quality, increased mobility due to their considerably smaller footprint and essentially maintenance-free operations over their lifetime. Their use as an alternative method to conventional explosive charges could reduce or eliminate perforation damage and significantly boost production rates, cumulative production and overall economic returns,” Gahan and coauthors Samih Batarseh, Bhargav Sharma and Sherif Gowelly said in a paper (SPE 90661) published three years ago.
The key to field applications is centered on fiber laser technology. Although fiber lasers have been available since the early days of laser technology, their role was limited to low power optical signal amplifiers in the telecommunications industry. Recent and rapid advances in fiber-laser development have made them a commercially viable alternative to competing solid-state and carbon dioxide lasers. They have also been successfully used in the battlefield as part of the US Army’s Zeus Humvee to destroy landmines and other explosive devices at safe distances.
“Fiber lasers present a number of advantages over other industrial lasers that, together, have advanced the realization of high power laser applications for well perforations and other well construction and completion methods. Many of the deployable characteristics required by the industry for a commercially successful system seem to have been met in this most recent technical breakthrough,” said the authors.
Earlier work performed by the authors explored the use of high power laser energy as a non-damaging alternative to conventional explosive perforation methods. Several variables were investigated to determine the technical feasibility of laser perforation with a 5.34 kW Ytterbium-doped multiclad fiber laser exposed to rock, cement and steel samples. The fiber laser was capable of penetrating these materials under a variety of conditions, to an appropriate depth and with reasonable energy requirements. It was determined that fiber lasers are capable of cutting rock without causing damage to flow properties. Furthermore, the laser perforation resulted in permeability improvements on the exposed rock surface.
Tests were also performed to determine the effect of downhole pressure conditions on the application. A sophisticated tri-axial cell was designed and tested using Berea sandstone, limestone and clad core samples, lased under various combinations of confining, axial and pore pressures. Clad core samples consisted of steel cemented to rock in an effort to represent material penetrated in a cased hole. The results proved the viability of the laser’s effectiveness downhole, and will assist in the development of downhole laser prototype tools.
Gahan is speaking to the industry about the technology as a participant in the 2008-09 SPE Distinguished Lecturer circuit. For more information about Laser Rock Technologies, visit www.laserrocktech.com.