Hydraulic Fracturing and Microseismicity: Global Perspective in Oil Exploration

Induced microseismicity is a common phenomenon in oil and gas reservoirs due to changes in internal stress accompanied by hydraulic fracturing and oil-gas extraction. These microseismicity can be monitored to understand the direction and type of hydraulic fracturing and pre-existing faults by precise hypocenter location and focal mechanism studies. Normal as well as strike-slip faulting earthquakes occur due to opening up of new cracks/fractures, and thrust/reverse faulting earthquakes due to compaction or closing of existing fractures. Further, frequency-magnitude relation (b-value) and fractal dimension (D-value) of the spatial and temporal clusterization of induced microseismicity may be much useful to characterize the fractures/ existing faults and the stress regimes. Seismic tomography, on the other hand, can image the heterogeneous velocity structures/perturbations in the reservoir due to fractures and oil-gas-water contents. A few global case studies are illustrated to understand these processes and to draw attention towards importance of these studies in oil industries.