A 3D analysis of the occurrence of fractures in hot dry rock reservoirs based on the spatial distribution of natural fractures

Hot dry rock(HDR)geothermal energy is a kind of widely distributed clean energy with huge reserves.However,its commercial development has been constrained by reservoir stimulation.In the early stage of HDR geothermal energy development,properly determining spatial distribution patterns of natural fractures in HDR reservoirs can effectively guide reservoir stimulation.This study analyzes the spatial distribution of natural fractures by using FracMan software based on the actual geological data and log data of well M-2 in the Matouying Uplift area,Hebei Province.The fracture parameters are counted and Monte Carlo simulation technique is introduced to optimize the parameters,which makes the natural fracture model more accurate and reliable.Furthermore,this study simulates hydraulic fracturing using the model combined with the actual in-situ stress parameters and the construction scheme.As verified by fitting the changes in simulated wellhead pressure during hydraulic fracturing with the actual wellhead pressure data detected during construction,the methods for natural fracture modeling used in this study are scientific and reasonable.The preliminary prediction results show that the displacement design scheme with a pump displacement of 2.0-3.0 m^(3)/min,4.0-5.5 m^(3)/min and 6-7 m^(3)/min in the early,middle and late stages,respectively,has good fracturing effect.The results of this study can be utilized as a reference for preparing development schemes for HDR reservoirs.

Whispering Gallery Mode Lasing Performance's Evolution of Floating GaN Microdisks Varying with Their Thickness

Optical gain and loss of microcavity greatly affect the quality of lasing,how to improve optical gain and decrease optical loss is of great significance for the preparation of laser.In this study,four types standard microdisks with different thicknesses of 2.2μm,1.9μm,1.7μm,and 1.45μm were fabricated by micromachining technology process to modulate optical gain and loss of microdisk lasing.The whispering gallery mode lasing in the ultraviolet range of Ga N microdisk devices was investigated for these devices in order to clarify the effect of microdisk thickness on device characteristics.The quality factor Q and lasing mode number for different thicknesses are calculated from the stimulated spectra.The lifetimes of the exciton combination properties of the devices were observed using time-resolved PL spectroscopy.The lasing modes are modulated,and the lifetime decreases,while the Q factor of the devices first increases and then decreases with decreasing thickness.All these results are induced by optical gain and loss competition.