Integrating a microtremor survey and time reverse modeling over a hydrocarbon reservoir: A case study of Majalengka field, West Java Basin, Indonesia

A microtremor survey was carried out over a hydrocarbon reservoir in Majalengka feld, West Java Basin, Indonesia, using a three-channel broadband seismometer. The objectives of this survey were to delineate the lateral distribution of the hydrocarbon potential and to localize microtremor sources, which are associated with the hydrocarbon reservoir. The microtremor survey was conducted by microtremor signal recording, which was divided into two types, namely independent and simultaneous recording. Simultaneous recording is intended for conducting two-dimensional time reverse modeling (2D TRM), which is proposed to localize microtremor sources. In addition, a parameter test was performed to defne a reference for the microtremor responses in terms of amplitude spectrum anomalies of the vertical component, which is associated with the reservoir content. The parameter test was performed on the 10 wellbores, where seven productive wells showed amplitude spectrum anomalies with the increasing amplitude spectrum reaching its peak in the frequency range of 2-3 Hz and then decreasing to a frequency range of 3-4 Hz. Further, delineation of hydrocarbon potential distribution is based on the vertical-horizontal spectral ratio (VHSR) map, which is used to distinguish the amplitude spectrum anomalies stemming from the reservoir signal and horizontal noise. The VHSR map showed that the eastern part of the study area was identifed as a potential zone. In addition, by referring to the TRM result, the depth location of the microtremor source, which is associated with the hydrocarbon reservoir, was predicted to be in a depth range of 1062-1091 meters.