Abstract

Presence of gas hydrate is identified on the seismic section by bottom simulating reflector (BSR), which is pressure and temperature dependent physical boundary between hydrate and water saturated or gas bearing sediments. High resolution multichannel seismic data used to delineate the BSRs in the Hikurangi margin, New Zealand. Simultaneously, identified BSR characterized using coring and well logging measurements from acoustic impedance inversion and porosity inversion. It is always a challenging task to get the acoustic impedance and porosity information away from well position at the prospective gas-hydrate occurrence zone. Acoustic impedance from model based acoustic impedance inversion and porosity values throughout the seismic profile by using the porosity inversion technique on the post-stack data was performed. Inverted acoustic impedance values ranges from ~3050 to ~3450 (m/s)*(g/cc) along seismic section at and above BSR. Below the BSR decreasing trend of inverted acoustic impedance in the range of ~2600 to ~2950 (m/s)*(g/cc) interpreted free gas zone. Inverted porosity along seismic section above BSR in the range of ~50% to ~60%, whereas the porosity value below the BSR in the free gas zone ranges from ~60% to ~70%. Comparatively low porosity and high acoustic impedance at the upper zone sediment saturated with gas hydrate and high porosity and low acoustic impedance in the lower zone sediment saturated with free gas separated by clear BSR.