Brian C. Gahan

Rock removal using high-power lasers for petroleum exploitation purposes

This paper describes the experimental results of selective rock removal using different types of high power lasers. US military owned continuous wave laser systems such as MIRACL and COIL with maximum powers of 1.2 MW and 10 kW and wavelengths of 3.8 and 1.3 mm respectively, were first used on a series of rock types to demonstrate their capabilities as a drilling tool for petroleum exploitation purposes. It was found that the power deposited by such lasers was enough to drill at speeds much faster than conventional drilling. In order to sample the response of the rocks to the laser action at shorter wavelengths, another set of rock samples was exposed to the interaction of the more commercially available high power pulsed Nd:YAG laser. To isolate the effects of the laser discharge properties on the rock removal efficiency, a versatile 1.6 kW Nd:YAG laser capable of providing pulses between 0.1 millisec and 10 millisec in width, with a maximum peak power of 32 kW and a variable repetition rate between 25 and 800 pulses/sec was chosen. With this choice of parameters, rock vaporization and melting were emphasized while at the same time minimizing the effects of plasma shielding. Measurements were performed on samples of sandstone, shale, and limestone. It was found that each rock type requires a specific set of laser parameters to minimize the average laser energy required to remove a unit volume of rock. It was also found that the melted material is significantly reduced in water saturated rocks while the drilling speed is still kept higher than conventional drilling.

Drilling large diameter holes in rocks using multiple laser beams

Studies on drilling petroleum reservoir rocks with lasers show that modern infrared lasers have the capability to spall (thermally fragment), melt and vaporize natural earth materials with the thermal spallation being the most efficient rock removal mechanism. Although laser irradiance as low as 1000 W/cm2 is sufficient to spall rock, firing the beam on a single spot for too long at that intensity causes rock melting and reduces removal efficiency. Also, it is difficult to visualize an efficient way to create a six or eight inch hole by sending one large beam down hole. Alternatives are either to raster the beam to cover the 20 cm hole area or, using a pattern of many small beams illuminated sequentially or in groups, create a nearly circular work face. This paper will present the testing results of the multiple small beam method. The effect on rock removal efficiency of several parameters, including relaxation time between laser bursts, basic patterns of multiple beams, and beam spot overlapping amounts are determined and presented.Studies on drilling petroleum reservoir rocks with lasers show that modern infrared lasers have the capability to spall (thermally fragment), melt and vaporize natural earth materials with the thermal spallation being the most efficient rock removal mechanism. Although laser irradiance as low as 1000 W/cm2 is sufficient to spall rock, firing the beam on a single spot for too long at that intensity causes rock melting and reduces removal efficiency. Also, it is difficult to visualize an efficient way to create a six or eight inch hole by sending one large beam down hole. Alternatives are either to raster the beam to cover the 20 cm hole area or, using a pattern of many small beams illuminated sequentially or in groups, create a nearly circular work face. This paper will present the testing results of the multiple small beam method. The effect on rock removal efficiency of several parameters, including relaxation time between laser bursts, basic patterns of multiple beams, and beam spot overlapping amounts ...

Deep hole penetration of rock for oil production using ytterbium fiber laser

This study provides experimental results in investigating the use of a 5.34 kW ytterbium-doped multiclad fiber laser with an emission wavelength of 1.07 microns for creating deep hole configurations in different types of rock for production applications in oil and gas wells. Recent developments in high power fiber lasers offer technical advantages when compared to other industrial lasers that may now allow economic subsurface applications to rock formations, delivering the beam through optical fiber from the surface via the wellbore. Successful applications in this manner would provide an alternative to conventional methods that employ rotary drilling and shaped charge explosives. Various parameters affecting laser penetration into samples of sandstone and limestone were studied and optimized. A maximum penetration depth of 30 cm for 8.9-mm hole diameter was achieved in limestone, while 15 cm penetration depth was achieved in sandstone with the same hole diameter. In all cases, the hole diameter was no greater than the beam diameter applied.

Laser Drilling - Drilling with the Power of Light

Gas Technology Institute (GTI) has been the leading investigator in the field of high power laser applications research for well construction and completion applications. Since 1997, GTI (then as Gas Research Institute- GRI) has investigated several military and industrial laser systems and their ability to cut and drill into reservoir type rocks. In this report, GTI continues its investigation with a 5.34 kW ytterbium-doped multi-clad high power fiber laser (HPFL). When compared to its competitors; the HPFL represents a technology that is more cost effective to operate, capable of remote operations, and requires considerably less maintenance and repair. Work performed under this contract included design and implementation of laboratory experiments to investigate the effects of high power laser energy on a variety of rock types. All previous laser/rock interaction tests were performed on samples in the lab at atmospheric pressure. To determine the effect of downhole pressure conditions, a sophisticated tri-axial cell was designed and tested. For the first time, Berea sandstone, limestone and clad core samples were lased under various combinations of confining, axial and pore pressures. Composite core samples consisted of steel cemented to rock in an effort to represent material penetrated in a cased hole. The results of this experiment will assist in the development of a downhole laser perforation or side tracking prototype tool. To determine how this promising laser would perform under high pressure in-situ conditions, GTI performed a number of experiments with results directly comparable to previous data. Experiments were designed to investigate the effect of laser input parameters on representative reservoir rock types of sandstone and limestone. The focus of the experiments was on laser/rock interaction under confining pressure as would be the case for all drilling and completion operations. As such, the results would be applicable to drilling, perforation, and side tracking applications. In the past, several combinations of laser and rock variables were investigated at standard conditions and reported in the literature. More recent experiments determined the technical feasibility of laser perforation on multiple samples of rock, cement and steel. 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. This report has been prepared in two parts and each part may be treated as a stand-alone document. Part 1 (High Energy Laser Drilling) includes the general description of the concept and focuses on results from experiments under the ambient lab conditions. Part 2 (High Energy Laser Perforation and Completion Techniques) discusses the design and development of a customized laser pressure cell; experimental design and procedures, and the resulting data on pressure-charged samples exposed to the laser beam. An analysis provides the resulting effect of downhole pressure conditions on the laser/rock interaction process.

Cement Pulsation Treatment in Wells

Cement pulsation is a novel technology for enhanced frequency, hydraulic pressure pulses to the wellhead. Data are presented from over 80 wells in drilling and after cementing.

Geological Investigation of Lunar and Martian Subsurface Using Laser Drilling System

Recent program objectives for human exploration of the Martian surface will require geological investigations of the planetary surface and subsurface. Planetary exploration systems to support both indirect and direct investigation must be light in weight and robust to support operations in a dry, cold, dusty environment. Although indirect methods are more likely to reach these objectives more easily, direct methods are required for tasks including sample retrieval, geochemical analysis, and the search for subsurface accumulations of water. Direct methods, particularly conventional drilling/coring systems, have a severe weight and volume penalty to reach depths of more than a few meters into the subsurface. A potential alternative to conventional systems may include recent advances in laser technology and investigations into their application to drill and break rock, thus providing an attractive option for future planetary exploration. Photonic beams from a 5.34 kW ytterbium-doped multiclad fiber laser were directed onto rock samples representative of lunar and Martian lithologies. Energy requirements per unit volume of material removed were observed for each rock type given the laser/rock destruction techniques tested.

Evaluation of high power ytterbium fiber lasers for rock cutting and removal applications

Since 1997, GTI has been investigating the application of high-power laser energy to several rock lithologies for oil and gas well construction and completion. Beginning in 2003, GTI advanced its laser/ rock cutting research by performing additional rock cutting tests with a 5 kW ytterbium-doped multi-clad fiber laser.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 and have rapidly evolved into a leading candidate for on-site applications including hard rock mining, tunneling, pavement cuttings and rock drilling. When compared to conventional industrial lasers, fiber lasers offer up to an order of magnitude greater wall plug efficiency, better beam quality, increased mobility due to their considerably smaller footprint and predicted maintenance-free operations over their lifetime.This paper explores the use of fiber lasers as an alternative means to conventional rock cutting techniques that could offer greater cutting efficiencies, quality control, and economic returns. A series of tests were performed on sandstone at atmospheric conditions to determine the minimum energy required to remove rock material. Laser parameters including power level were optimized. Rock removal efficiency of fiber laser was compared with other high power lasers employed for similar research.Since 1997, GTI has been investigating the application of high-power laser energy to several rock lithologies for oil and gas well construction and completion. Beginning in 2003, GTI advanced its laser/ rock cutting research by performing additional rock cutting tests with a 5 kW ytterbium-doped multi-clad fiber laser.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 and have rapidly evolved into a leading candidate for on-site applications including hard rock mining, tunneling, pavement cuttings and rock drilling. When compared to conventional industrial lasers, fiber lasers offer up to an order of magnitude greater wall plug efficiency, better beam quality, increased mobility due to their considerably smaller footprint and predicted maintenance-free operations over their lifetime.This paper explores the use of fiber lasers as an alternative means to conventi...

Rock phase control by using high power laser for production enhancements

This study is part of a more extensive research effort by Gas Technology Institute to apply high power laser technology in well construction and completion techniques for the oil and gas industry. It has been demonstrated that by altering laser parameters, including power and duration, changes in rock properties and phase behavior can be controlled. This paper presents the results and analysis of high power laser interactions, including the Mid-infrared Advanced Chemical Laser (MIRACL), Chemical Oxygen Iodine Laser (COIL) and carbon dioxide lasers in limestone, sandstone and shale samples. When laser energy was allowed to melt minerals within the rock matrix, an impermeable barrier with ceramic-like characteristics was created that may provide in-situ fluid flow control and wellbore stability. A porous ceramic barrier could also be created on demand through the application of a high velocity purging system for applications in unconsolidated rock formations, preventing sand production and tunnel collapse, critical concerns in well completion and production operations.This study is part of a more extensive research effort by Gas Technology Institute to apply high power laser technology in well construction and completion techniques for the oil and gas industry. It has been demonstrated that by altering laser parameters, including power and duration, changes in rock properties and phase behavior can be controlled. This paper presents the results and analysis of high power laser interactions, including the Mid-infrared Advanced Chemical Laser (MIRACL), Chemical Oxygen Iodine Laser (COIL) and carbon dioxide lasers in limestone, sandstone and shale samples. When laser energy was allowed to melt minerals within the rock matrix, an impermeable barrier with ceramic-like characteristics was created that may provide in-situ fluid flow control and wellbore stability. A porous ceramic barrier could also be created on demand through the application of a high velocity purging system for applications in unconsolidated rock formations, preventing sand production and tunnel collapse, ...

Laser Drilling: Drilling with the Power of Light Phase 1: Feasibility Study

A laser drilling research team was formed from members of academia, industry and national laboratory to explore the feasibility of using modern high-powered lasers to drill and complete oil and gas wells. The one-year Phase 1 study discussed in this report had the goals of quantifying the amount of pulsed infrared laser energy needed to spall and melt rock of varying lithologies and to investigate the possibility of accomplishing the same task in water under atmospheric conditions. Previous work by some members of this team determined that continuous wave lasers of varying wavelengths have more than enough power to cut, melt and vaporize rock. Samples of sandstone, limestone, and shale were prepared for laser beam interaction with a 1.6 kW pulsed Nd:YAG laser beam to determine how the beams size, power, repetition rate, pulse width, exposure time and energy can affect the amount of energy transferred to the rock for the purposes of spallation, melting and vaporization. The purpose of the laser rock interaction experiment was to determine the threshold parameters required to remove a maximum rock volume from the samples while minimizing energy input. Absorption of radiant energy from the laser beam gives rise to the thermal energy transfer required for the destruction and removal of the rock matrix. Results from the tests indicate that each rock type has a set of optimal laser parameters to minimize specific energy (SE) values as observed in a set of linear track and spot tests. In addition, it was observed that the rates of heat diffusion in rocks are easily and quickly overrun by absorbed energy transfer rates from the laser beam to the rock. As absorbed energy outpaces heat diffusion by the rock matrix, local temperatures can rise to the melting points of the minerals and quickly increase observed SE values. The lowest SE values are obtained in the spalling zone just prior to the onset of mineral melt. The current study determined that using pulsed lasers could accomplish removing material from rock more efficiently than continuous wave lasers. The study also determined that reducing the effect of secondary energy absorbing mechanisms resulted in lower energy requirements in shale and, to some extent, in sandstones. These secondary mechanisms are defined as physical processes that divert beam energy from directly removing rock, and may include thermally-induced phase behavior changes of rock minerals (i.e., melting, vaporization, and dissociation) and fractures created by thermal expansion. Limestone is spalled by a different mechanism and does not seem to be as affected by secondary mechanisms. It was also shown that the efficiency of the cutting mechanism improved by saturating porous rock samples with water, and that a laser beam injected directly through a water layer at a sandstone sample was able to spall and melt the sample.

Field Evaluation of Pre-Job Test Protocol for Cement Pulsation

Cement pulsation is a relatively new technology to counteract the problem of flow after cementing by delaying the development of gel strength and suppressing the loss of wellbore pressure that can cause flow after cementing. A cement testing protocol for cement pulsation and our experience applying it to an actual, instrumented, cement pulsation job in the field are described. The protocol uses conventional mud and cement lab test equipment to measure the mud and cement properties that determine the feasibility of, and allow simple performance predictions for, cement pulsation for a particular field application.