Figure 2

Results of onshore gas analyses and comparison with shipboard data. Hydrocarbon gas components in drilling mud gas samples analyzed onshore with a gas chromatograph (GC shorebased; black triangles) and quadruple mass spectrometer (QMS; red dots) compared to shipboard GC-NGA real-time data (GC shipboard, blue squares; [23]). A: C₁ = methane, B: C₂ = ethane, C: C₃ = propane, D: (C₁/(C₂ + C₃)) = Bernard parameter). E: Lithological column modified from [23]. “Underreamer depth” denotes the position of borehole widening and potential additional gas release caused by the underreamer. Borehole widening took place around 40 m above the borehole depth. See Methods section.