I. Introduction The M Field, located in 500–600m of waterdepth in offshore Sabah, Malaysia, was discovered in 2004. In 2012, Shell took Final Investment Decision (FID) on the project which will include drilling of several producers and water injectors, with production via a Tension Leg Platform (TLP). The main reservoirs of the M field are the K-1 and K-2 sands; both are located at relatively shallow depths below mudline. They are structurally complex, significantly compartmentalized and underlie a complex overburden with presence of gas. To improve reservoir and structural mapping for well positioning and well planning, a Multi-AZimuth (MAZ) broadband 3D survey was carried out over the field. A fast track Post Stack Time Migration (PoSTM) datasets was delivered three months after the last shot of the survey which was critical for geohazards interpretation for top hole well trajectories. A Pre Stack Time Migration (PSTM) volume was delivered after five months from the last shot and a final Pre Stack Depth Migration (PSDM) is expected in August for the structural interpretation and reservoir characterization at the reservoir level. II. Geophysical Challenges The imaging challenges at the M Field are caused by the rugose seabed morphology and hard shallow authigenic carbonate bodies (Figure 1), gas wipeout zones and the presence of thick wedge of bright amplitude events. Figure 2 illustrates the Poor Data Zone (PDZ) over the center of the field, characterized by weaker amplitude and lower dominant frequencies. This zone extends up to the seabed. Amplitude brightening near the seabed overlying the PDZ indicates the presence of materials that generate high-impedance contrasts. Core samples taken showed they are authigenic carbonate that forms a hard crust and acts as scatterers of seismic energy. Presence of gas below the authigenic carbonates further weakens the seismic energy through absorption. The presence of the thick wedge (Figure 2) has a similar effect to the underlying events. In general, the seismic data over the structurally complex M Field is highly variable.

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