Topseal integrity assessment using seal properties and leakage phenomena

We present a novel seismic interpretational workflow applied to large gas-chimney located above the Marjoram Gas Field, offshore NW Borneo. The is hosted by clay-dominated sealing sequence characterised meter-scale silt beds. affected complex network of normal faults. gas chimney, interpretable as vertical anomaly cluster, composed several discrete amplitude anomalies and result leakage from crest ?500 m thick carbonate pinnacle-reef below. By analysing seal properties composing cluster we argue that consistent with migration either along faults or using via cross-fault-plane juxtapositions. show this process focussed within narrow pathway rather than spread over fault network. Mode I opening in response capillary pressure exerted long column subjacent Field postulated be cause leakage. • multi-trillion cubic feet reservoir obscured chimney. Analysis chimney provides precise for across overburden. Leakage occur mode dilation fracture induced reservoir.