Laser induced fractures in porous media.

Mostafa, Ayman

Abstract

Hydraulic fracturing is the most effective technique to enhance well productivity in the oil and gas industry. There are many logistical, operational and environmental concerns associated with existing techniques, including the potential risk of underground water contamination and earthquakes - the main reasons for the current debates regarding shale gas development in the UK. An alternative technique using a clean energy source (laser) has been proposed and discussed in this research. In order to evaluate the feasibility of using laser-induced fractures as an alternative technique, an analytical model has been developed to calculate temperature distribution during the laser fracturing method. The novelty of the developed model lies in incorporating melting and vaporisation of rock materials during the laser fracturing process. The developed model has been validated against experimental data obtained by cutting various materials with a laser, including rock and metals. Further, a new waste power's correlation and methodology have been developed in this research, in order to analytically calculate laser power requirements without needing to develop complex numerical models. This correlation is developed from the verified numerical line-source model, which showed good matching to experimental data collected by cutting metals and non-metals by melting. A reservoir simulation model is also developed in this research, in order to identify the potential flow improvement that could be achieved due to laser induced fractures and the Heat Affected Zone (HAZ) around the wellbore. The results indicated that 100 kW average laser power is capable of cutting a range of 5–15 m (average 10 m) of porous media depending on porosity and rock thermal properties, and this can yield a significant improvement in well productivity during transient flow and a reasonable improvement during pseudo steady state flow (approx. 2–3 Fold of Increase, FOI). The range of flow improvement indicated in this research is encouraging and equivalent to the potential improvement that could be achieved - up to a certain degree - by conventional matrix stimulation, including acidizing and hydraulic fracturing techniques. The range of power requirements indicated in this research is within the potential capacity of laser technology, though it could be higher than the available commercial range. However, further investigation is recommended regarding the challenges of using laser under downhole conditions (including footprint, cooling, cleaning, etc.) and to identify any potential modifications to laser equipment that might be required to achieve this target in future.

Citation

MOSTAFA, A. 2020. Laser induced fractures in porous media. Robert Gordon University, PhD thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-2271539

• Thesis Type: Thesis
• Deposit Date: Mar 14, 2024
• Publicly Available Date: Mar 14, 2024
• DOI: https://doi.org/10.48526/rgu-wt-2271539
• Keywords: Wellbores; Lasers; Heat transfer; Petroleum engineering
• Public URL: https://rgu-repository.worktribe.com/output/2271539
• Award Date: Oct 31, 2020