Seismic Facies Classification of the Internal Architecture of Mass Transport Deposits: Implication for Reservoir Seal Competence
Mass- transport deposits (MTDs) are important stratigraphic elements in many deepwater basins and they constitute a primary component of heterogeneous siliciclastic seal sequences in many of petroliferous basins around the world. Although 3D seismic characterisation of MTDs has been carried out extensively from a number of case studies in a range of basins, no comprehensive scheme has been presented to classify their internal architecture in a manner that is directly mappable onto the problem of defining their potential as sealing sequences. In this work, a qualitative object based seismic facies classification for MTDs is presented based on an extensive review of the internal 3D seismic architecture of MTDs from the Taranaki Basin, New Zealand and other published literatures. In order to ground truth the classification scheme with lithology information and evaluate the leakage or seal potential, lessons learned from outcrop studies of MTDs are briefly highlighted. Three main types of deformation are recognised within MTDs consisting of (1) layered, (2) blocky, and (3) amorphous, based on five criteria including a) external geometry, b) internal reflection configuration, and inferred stress regime, c) reflection continuity, d) amplitude strength and e) RMS amplitude and/or coherency pattern. It is observed that in many petroliferous basins, at least two of the three types of facies are developed in MTDs, and in some, the three types can be found distributed within a single MTD. The seismic facies classes of MTDs would have significantly different implications for hydrocarbon potential. It is proposed in this project that the geometry of the internal seismic character of an MTD and the N/G play an important role in determining the sealing capacity i.e. whether the MTD leaks or not. The seismic facies classification for MTDs provides a seismic interpreter with a rapid analysis of the deposit whose aim is to come up with a risk map that can better inform exploration decision making.
AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017