Microseismicity Recorded by a Fiberoptic Ocean-bottom PRM Installation Offshore Brazil

Abstract

A significant number of microseismic events were detected over 120 days of passive monitoring with a deepwater PRM pilot array offshore Brazil. The array is installed in 1240-1310m water depth and consists of over 700 four-component stations. Recording occurred during two consecutive two-month periods in between active seismic surveys. The passive monitoring detected distinct event swarms that are highly clustered in space and time. These events occur at an estimated depth of about 5 km with moment magnitudes ranging from 0.2 to 1.9. The seismicity occurs in a depth interval near a currently undeveloped deeper reservoir and is possibly of natural origin. The capture of such seismicity is valuable input for longterm risk assessment and development planning of the lower reservoir.

Reflecting boundary conditions for interferometry by multidimensional deconvolution

“…6,21,28,33,34 In this section, we showcase the advantage of the alternative boundary conditions for the application of MDD to ambient seismic noise recorded by ocean-bottom cables. Their aperture and dense spatial sampling 35,36 make these deployments particularly well suited for the application of MDD.…”

“…This resembles the aperture of contemporary ocean-bottom deployments. 33,35 The receiver boundary is illuminated by 500 randomly placed sources, whose spatial placement is governed by a non-uniform probability distribution; for example, more sources are (expected to be) placed west of the receiver boundary than south. In accordance with the theory of Sec.…”