Exciting news! We're transitioning to the Statewide California Earthquake Center. Our new website is under construction, but we'll continue using this website for SCEC business in the meantime. We're also archiving the Southern Center site to preserve its rich history. A new and improved platform is coming soon!

Bayesian source mechanism inversion of induced seismicity in oil/gas fields and pico-seismicity (acoustic emission) in the laboratory

Chen Gu, German A. Prieto, Ulrich Mok, Youssef M. Marzouk, Brian Evans, & Nafi Toksöz

Published August 16, 2017, SCEC Contribution #7890, 2017 SCEC Annual Meeting Poster #049

We studied the source mechanisms of earthquakes occurred in multi-scales, from induced seismicity in oil/gas fields to pico-seismicity in the laboratory. A Bayesian source mechanism inversion method was demonstrated using data from field to laboratory. The seismicity that occurred in the oil/gas fields is probably induced by fluid injection and extraction in oil/gas fields, resulting in the reactivation of the pre-existing fault network. Double-couple dominant source mechanisms were obtained for the field data and the importance of the regional stress field and local fault networks in generating that micro-seismicity was observed.

Laboratory generated acoustic emissions (AEs) can be used to study different rupture processes (e.g., hydraulic fracturing, stick-slip) in a controllable way. In a loading experiment of intact cylindrical Berea sandstone sample, the sample was subjected to conventional triaxial loading with a constant confining pressure of 10 MPa. The axial load was then increased at a constant rate of 0.16 MPa/s to failure at 70 MPa. We used AE event locations to reveal a pico-seismicity nucleation process during fracturing. After the eventual fracture plane was formed in the sample, the location of the pico-events delineated the topography of the irregular fracture plane. The double-couple dominant source mechanism of these events indicated the dip-slip fracture with the maximum differential stress in the vertical direction.

Key Words
source mechanisms, oil/gas fields, induced seismicity, laboratory, pico-seismicity/acoustic emission

Gu, C., Prieto, G. A., Mok, U., Marzouk, Y. M., Evans, B., & Toksöz, N. (2017, 08). Bayesian source mechanism inversion of induced seismicity in oil/gas fields and pico-seismicity (acoustic emission) in the laboratory. Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups