A marine controlled-source electromagnetic imaging of gas hydrates and gas sources in the Shenhu area,South China Sea
The presence of a bottom simulating reflector(BSR)on seismic profiles serves as a reliable indicator of the lower boundary of natural gas hydrate accumulations,a phenomenon that has been confirmed by drilling data.The Shenhu area in the South China Sea is a prominent region for natural gas hydrate(referred to as"hydrates")research.However,the complex geological structures andlimited spatial coverage of drilling sites pose significant challenges to comprehensively characterizing hydrate distribution and associated gas source channels through seismic and drilling data alone.The distinct electrical resistivity contrast between hydrate-bearing formations and surrounding rocks presents a unique opportunity for geophysical exploration.Marine controlled-source electromagnetic(MCSEM)data,which effectively captures this resistivity contrast,provides a valuable toolfor detecting both hydrates and gas source channels.This study presents the findings of MCSEM exploration research conducted in the Shenhu area.Electromagnetic field data were collected at 15 discrete sites along a designated survey line.Subsequent data processing and two-dimensional inversion yielded two-dimensional resistivity images of the seabed.The reliability of the MCSEM inversion results was rigorously evaluated through sensitivity analysis.By integrating logging-while-drilling(LWD)data from the SH-W07-2016 well and seismic data,the two-dimensional resistivity profile was interpreted to infer the distribution of hydrates and free gas along the profile.Two distinct forms of hydrate reservoir structures were identified,and their structural origins were subsequently analyzed.
marine controlled-source electromagneticsgas hydrateShenhu areatwo-dimensional inversionresistivity model
万方数据
维普
