Stratigraphic Analysis of Microseismic Signatures during Hydraulic Stimulation

This paper presents a novel workflow to enhance the interpretation of microseismic events by comparing the temporal evolution of the microseismic cloud between adjacent stages from two different wells stages. The stratigraphic properties of identified rock layers along with changes within the local stress field distribution were used to determine the propagation path and aperture of the hydraulic fracture. Hydraulic fractures however are largely aseismic, and thus identified microseismic signatures surrounding the hydraulic fracture may indicate important surrounding damage-zone fracture formation. A comparison of each microseismic event and towith the local rock stratigraphy of the loci determined certain regions where rock composition and larger formation layers influenced the moicroseismic signals of events. This analysis allowed for the classification of microseismic events by formation layers and can elicit different in-situ stress states during hydraulic stimulation. Principal Component Analysis of each formation microseismic cloud can quickly show dominating stresses in the microseismic signals. The changes in the microseismic cloud between the first and second stimulated and second wells during a zipper hydraulic fracture stimulations shows the significant changes in formation stress from one well to another in a multi-well system.