Integrated Analysis for Fracture Identification During Hydraulic Fracturing

Abstract

Abstract In order to improve our understanding of the interaction of the hydraulic fracture with pre-existing structures in reservoirs, we focused on separating microseismicity related to the hydraulic fracture propagation and microseismicity occurring along the pre-existing structures. We analyzed microseismic activity detected during the stimulation job in a horizontal well with ten stages. The microseismicity aligns in two major trends, E-W and NE-SW. The microseismicity in the NE-SW trend is aligned with the maximum horizontal stress and is related to the hydraulic fracture propagation. The E-W trend is related to the interaction of the hydraulic fracture with the pre-existing structures in the area. Some stimulated stages show very clear and distinguished spatial separation of microseismicity related to the two trends while some stages have more complex pattern. We combine several techniques that help to distinguish various types of seismicity: data set separation, geomechanical, magnitude-frequency, and well pressure analyses. The synthesis of the various methods helps to improve our understanding of the well stimulation. Overall, we almost doubled the number of hydrofractures and fault/fracture zones in comparison to the original interpretation based only on the microseismic mapping and we better constrained the half-lengths of the hydraulic fractures. The detailed data analysis strongly suggests that some hydraulic fractures may be aseismic.