The present invention relates to methods, apparatus and systems for delivering high power laser energy over long distances, while maintaining the power of the laser energy to perform desired tasks. In a particular, the present invention relates to providing high power laser energy to create and advance a borehole in the earth and to perform other tasks in the borehole.
In general, boreholes have been formed in the earth's surface and the earth, i.e., the ground, to access resources that are located at and below the surface. Such resources would include hydrocarbons, such as oil and natural gas, water, and geothermal energy sources, including hydrothermal wells. Boreholes have also been formed in the ground to study, sample and explore materials and formations that are located below the surface. They have also been formed in the ground to create passageways for the placement of cables and other such items below the surface of the earth.
The term borehole includes any opening that is created in the ground that is substantially longer than it is wide, such as a well, a well bore, a well hole, and other terms commonly used or known in the art to define these types of narrow long passages in the earth. Although boreholes are generally oriented substantially vertically, they may also be oriented on an angle from vertical, to and including horizontal. Thus, using a level line as representing the horizontal orientation, a borehole can range in orientation from 0° i.e., a vertical borehole, to 90°, i.e., a horizontal borehole and greater than 90° e.g., such as a heel and toe. Boreholes may further have segments or sections that have different orientations, they may be arcuate, and they may be of the shapes commonly found when directional drilling is employed. Thus, as used herein unless expressly provided otherwise, the “bottom” of the borehole, the “bottom” surface of the borehole and similar terms refer to the end of the borehole, i.e., that portion of the borehole farthest along the path of the borehole from the borehole's opening, the surface of the earth, or the borehole's beginning.
Advancing a borehole means to increase the length of the borehole. Thus, by advancing a borehole, other than a horizontal one, the depth of the borehole is also increased. Boreholes are generally formed and advanced by using mechanical drilling equipment having a rotating drilling bit. The drilling bit is extending to and into the earth and rotated to create a hole in the earth. In general, to perform the drilling operation a diamond tip tool is used. That tool must be forced against the rock or earth to be cut with a sufficient force to exceed the shear strength of that material. Thus, in conventional drilling activity mechanical forces exceeding the shear strength of the rock or earth must be applied to that material. The material that is cut from the earth is generally known as cuttings, i.e., waste, which may be chips of rock, dust, rock fibers and other types of materials and structures that may be created by the thermal or mechanical interactions with the earth. These cuttings are typically removed from the borehole by the use of fluids, which fluids can be liquids, foams or gases.
In addition to advancing the borehole, other types of activities are performed in or related to forming a borehole, such as, work over and completion activities. These types of activities would include for example the cutting and perforating of casing and the removal of a well plug. Well casing, or casing, refers to the tubulars or other material that are used to line a wellbore. A well plug is a structure, or material that is placed in a borehole to fill and block the borehole. A well plug is intended to prevent or restrict materials from flowing in the borehole.
Typically, perforating, i.e., the perforation activity, involves the use of a perforating tool to create openings, e.g. windows, or a porosity in the casing and borehole to permit the sought after resource to flow into the borehole. Thus, perforating tools may use an explosive charge to create, or drive projectiles into the casing and the sides of the borehole to create such openings or porosities.
The above mentioned conventional ways to form and advance a borehole are referred to as mechanical techniques, or mechanical drilling techniques, because they require a mechanical interaction between the drilling equipment, e.g., the drill bit or perforation tool, and the earth or casing to transmit the force needed to cut the earth or casing.
It has been theorized that lasers could be adapted for use to form and advance a borehole. Thus, it has been theorized that laser energy from a laser source could be used to cut rock and earth through spalling, thermal dissociation, melting, vaporization and combinations of these phenomena. Melting involves the transition of rock and earth from a solid to a liquid state. Vaporization involves the transition of rock and earth from either a solid or liquid state to a gaseous state. Spalling involves the fragmentation of rock from localized heat induced stress effects. Thermal dissociation involves the breaking of chemical bonds at the molecular level.
To date it is believed that no one has succeeded in developing and implementing these laser drilling theories to provide an apparatus, method or system that can advance a borehole through the earth using a laser, or perform perforations in a well using a laser. Moreover, to date it is believed that no one has developed the parameters, and the equipment needed to meet those parameters, for the effective cutting and removal of rock and earth from the bottom of a borehole using a laser, nor has anyone developed the parameters and equipment need to meet those parameters for the effective perforation of a well using a laser. Further is it believed that no one has developed the parameters, equipment or methods need to advance a borehole deep into the earth, to depths exceeding about 300 ft (0.09 km), 500 ft (0.15 km), 1000 ft, (0.30 km), 3,280 ft (1 km), 9,840 ft (3 km) and 16,400 ft (5 km), using a laser. In particular, it is believed that no one has developed parameters, equipments, or methods nor implemented the delivery of high power laser energy, i.e., in excess of 1 kW or more to advance a borehole within the earth.
While mechanical drilling has advanced and is efficient in many types of geological formations, it is believed that a highly efficient means to create boreholes through harder geologic formations, such as basalt and granite has yet to be developed. Thus, the present invention provides solutions to this need by providing parameters, equipment and techniques for using a laser for advancing a borehole in a highly efficient manner through harder rock formations, such as basalt and granite.
The environment and great distances that are present inside of a borehole in the earth can be very harsh and demanding upon optical fibers, optics, and packaging. Thus, there is a need for methods and an apparatus for the deployment of optical fibers, optics, and packaging into a borehole, and in particular very deep boreholes, that will enable these and all associated components to withstand and resist the dirt, pressure and temperature present in the borehole and overcome or mitigate the power losses that occur when transmitting high power laser beams over long distances. The present inventions address these needs by providing a long distance high powered laser beam transmission means.
It has been desirable, but prior to the present invention believed to have never been obtained, to deliver a high power laser beam over a distance within a borehole greater than about 300 ft (0.09 km), about 500 ft (0.15 km), about 1000 ft, (0.30 km), about 3,280 ft (1 km), about 9,8430 ft (3 km) and about 16,400 ft (5 km) down an optical fiber in a borehole, to minimize the optical power losses due to non-linear phenomenon, and to enable the efficient delivery of high power at the end of the optical fiber. Thus, the efficient transmission of high power from point A to point B where the distance between point A and point B within a borehole is greater than about 1,640 ft (0.5 km) has long been desirable, but prior to the present invention is believed to have never been obtainable and specifically believed to have never been obtained in a borehole drilling activity.
A conventional drilling rig, which delivers power from the surface by mechanical means, must create a force on the rock that exceeds the shear strength of the rock being drilled. Although a laser has been shown to effectively spall and chip such hard rocks in the laboratory under laboratory conditions, and it has been theorized that a laser could cut such hard rocks at superior net rates than mechanical drilling, to date it is believed that no one has developed the apparatus systems or methods that would enable the delivery of the laser beam to the bottom of a borehole that is greater than about 1,640 ft (0.5 km) in depth with sufficient power to cut such hard rocks, let alone cut such hard rocks at rates that were equivalent to and faster than conventional mechanical drilling. It is believed that this failure of the art was a fundamental and long standing problem for which the present invention provides a solution.
Thus, the present invention addresses and provides solutions to these and other needs in the drilling arts by providing, among other things: spoiling the coherence of the Stimulated Brillioun Scattering (SBS) phenomenon, e.g. a bandwidth broadened laser source, such as an FM modulated laser or spectral beam combined laser sources, to suppress the SBS, which enables the transmission of high power down a long >1000 ft (0.30 km) optical fiber; the use of a fiber laser, disk laser, or high brightness semiconductor laser for drilling rock with the bandwidth broadened to enable the efficient delivery of the optical power via a >1000 ft (0.30 km) long optical fiber; the use of phased array laser sources with its bandwidth broadened to suppress the Stimulated Brillioun Gain (SBG) for power transmission down fibers that are >1000 ft (0.30 km) in length; a fiber spooling technique that enables the fiber to be powered from the central axis of the spool by a laser beam while the spool is turning; a method for spooling out the fiber without having to use a mechanically moving component; a method for combining multiple fibers into a single jacket capable of withstanding down hole pressures; the use of active and passive fiber sections to overcome the losses along the length of the fiber; the use of a buoyant fiber to support the weight of the fiber, laser head and encasement down a drilling hole; the use of micro lenses, aspherical optics, axicons or diffractive optics to create a predetermined pattern on the rock to achieve higher drilling efficiencies; and the use of a heat engine or tuned photovoltaic cell to reconvert optical power to electrical power after transmitting the power >1000 ft (0.30 km) via an optical fiber.
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