Reciprocity-based passive monitoring with individual sources

Time-lapse changes in the subsurface can be analyzed by comparing seismic reflection data from two different states, one serving as the base survey and the second as the monitor survey. Conventionally, reflection data are acquired by placing active seismic sources at the acquisition surface. Alternatively, these data can be acquired from passive sources in the subsurface, using seismic interferometry (SI). Unfortunately, the reflection responses as retrieved by SI inherit an imprint of the passive-source distribution; therefore, monitoring with SI requires high passive-source repeatability, which is very often not achievable in practice.We have developed an alternative by using active seismic data for the base survey and a single passive source (e.g., a seismic tremor produced by induced seismicity) for the monitor survey. By constraining the source-radiation pattern of the (active) base survey according to the characteristics of the (passive) monitor survey, we succeed in extracting the time-lapse response in the image domain. We tested our method with numerically modeled data.