Advances in time-lapse geophysics — Introduction

Abstract

Time-lapse geophysics is becoming an increasingly important and powerful method to measure, monitor, verify, and predict complex time-varying processes in the earth. Applications include resource management (hydrocarbons, groundwater, geothermal…), geohazard risk assessment (natural and induced seismicity, overpressure zones…), environmental issues ( CO 2 sequestration, groundwater contamination and remediation…), geotechnical engineering (dams, roads, bridges…), and fundamental science questions (subsurface flow of fluids, stress and heat, time-variant rock properties, fault dynamics and fracturing, geophysical source mechanisms, near-surface variations in vadose and permafrost zones…). Advances in time-lapse geophysics are being driven by spectacular innovations in theory, data acquisition, and quantitative data analysis. Theoretical innovations include new math and physics developments to properly incorporate 4D space-time variations in modeling, imaging, and inversion methods, and to correctly account for full wavefield or potential field representations of time-lapse geophysical phenomena. Data acquisition innovations include new developments to improve 4D signal/noise levels, and repeat surveys more frequently or continuously, with new source and receiver instrumentation, (semi) permanent arrays, and others. New developments in time-lapse imaging and inversion are allowing us to extract more detailed (and often surprising) information, increasingly in near real-time, to help better understand time-varying processes in the earth’s subsurface. Recent developments in quantitative time-lapse data analysis and interpretation are providing new knowledge to help improve our …