Laser Technology for Downhole Applications; Past, Present and Future

The objective of this work is to provide an overview of high power laser program since it is inception and to provide the strategy to make it reality. An overview of the past two decades, current and future plan to deploy the technology in the field. Laser attracted the oil and gas industry as an innovative non-damaging technology and alternatives to current practices. The lab success conducted over the past 20 years performing experiments on thousands of representative rock samples proved the key parameter for successful laser operation in the field. The technology is not only a non-damaging but also improves flow properties and communication between the wellbore and the hydrocarbon bearing formation. For the past two decades, researchers attempted to deploy high power laser technology for several downhole applications due to its unique properties such as accuracy, precision, and power. The power of the earlier laser generation was insufficient to penetrate subsurface formations. Recent advancement in the high power laser technology generates new and evolved systems that are more compact, efficient, and cost effective for downhole applications. Thousands of rocks have been exposed to high power lasers radiations for several downhole applications such as perforation, drilling and heating. The success of the technology demonstrated that in all rock types, the flow properties were enhanced regardless of their compressive strength and hardness. Laser also has unique futures such as the precision in controlling and orienting the energy in any direction regardless of the reservoir stress orientation and magnitude. The beam is generated at the surface and delivered downhole via fiber optics cable, it can be targeted directly to the pay zone to enable production from challenging zones that cannot and could not be achieved with current technology. The technology provides small footprint and environmentally friendly technology, it provides waterless technology as an alternative to water base fracturing technology.

Mid-Infrared Multispectral Gaseous Stimulated Raman Scattering Laser

We demonstrated mid-infrared gaseous stimulated Raman scattering lasers in free space. Mixed gases of hydrogen and deuterium were used as Raman gain media in one Raman cell. Pumped by laser pulses at 1064 nm, the first Stokes Raman components at 1560 nm and 1907 nm were generated. A four-wave mixing process with the pump laser at 1064 nm and Raman lasers at 1560 nm and 1907 nm contributed to dramatically reducing the threshold of mid-IR laser generation at 4432 nm. The maximum output peak power of a mid-IR laser at 4432 nm reached 121 kW. Furthermore, by scattering on the rotational transition of deuterium, multispectral mid-IR Raman lasers at wavelengths of 2071 nm, 2266 nm, 2604 nm, 2920 nm, 3322 nm, 3743 nm, 4432 nm, and 5431 nm were also generated. Our results show that this is a convenient method to reduce the threshold and achieve a high power output with mid-IR Raman lasers.

Growth and Optical Properties of the Whole System of Li(Mn1-x,Nix)PO4 (0 ≤ x ≤ 0.5) Single Crystals

A series of single crystals of Li(Mn1-x,Nix)PO4 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.10, 0.15, 0.20, and 0.50) have been grown to large sizes up to 5 mm in diameter and 120 mm in length using the floating zone method for the first time. The comprehensive characterizations of the as-grown crystals were performed before further physical property measurements. The composition of the grown crystals was determined by energy-dispersive X-ray spectroscopy. The crystal structures were characterized by the X-ray powder diffraction method with a GSAS fitting for structural refinement, which reveals a high phase purity of the as-obtained crystals. The polarized microscopic images and Laue patterns prove the excellent quality of the single crystals. Oriented cuboids with sizes of 2.7 × 3.8 × 2.1 mm3 along the a, b, and c crystalline directions were cut and polished for further anisotropic magnetic and transparent measurements. We also first proposed a new potential application in the non-linear optical (NLO) and laser generation application for LiMPO4 (M = transition metal) materials. The optical and laser properties, such as the absorption spectra and the second harmonic generation (SHG), have been investigated and have furthermore confirmed the good quality of the as-grown single crystals.

Atomic Defect Induced Saturable Absorption of Hexagonal Boron Nitride in Near Infrared Band for Ultrafast Lasing Applications

Defect-induced phenomena in 2D materials has received increasing interest among researchers due to the novel properties correlated with precise modification of materials. We performed a study of the nonlinear saturable absorption of the boron-atom-vacancy defective hexagonal boron nitride (h-BN) thin film at a wavelength of ~1 μm and its applications in ultrafast laser generation. The h-BN is with wide band gap of ~6 eV. Our investigation shows that the defective h-BN has a wide absorption band from visible to near infrared regimes. First-principle calculations based on density functional theory (DFT) indicate that optical property changes may be attributed to the boron-vacancy-related defects. The photoluminescence spectrum shows a strong emission peak at ~1.79 eV. The ultrafast Z-scan measurement shows saturable absorbance response has been detected for the defective h-BN with saturation intensity of ~1.03 GW/cm2 and modulation depth of 1.1%. In addition, the defective h-BN has been applied as a new saturable absorber (SA) to generate laser pulses through the passively Q-switched mode-locking configuration. Based on a Nd:YAG waveguide platform, 8.7 GHz repetition rate and 55 ps pulse duration of the waveguide laser have been achieved. Our results suggest potential applications of defective h-BN for ultrafast lasing and integrated photonics.