Physical Characteristics and Impact of Mass Transport Complexes on Deepwater Jetted Conductors and Suction Anchor Piles

Abstract

Recognition of the importance of sedimentary deposits derived from mass transport complexes (MTCs) has increased significantly as offshore energy industry exploitation and development activities extend into deeper water. This understanding is in part due to improved seismic data. It certainly is the case in the foundation zone, defined in this study as the upper 100 m below the seafloor. The purpose of this study is to assess the physical characteristics of MTCs within the foundation zone and relate these characteristics to installation performance of jetted conductors and design considerations for suction anchor piles. The evaluation of physical characteristics of these features is based on a review of published scientific literature and results of geotechnical soil borings. Three case studies, involving either jetted conductors or suction anchor piles, are evaluated to understand the potential condition that may be encountered while penetrating MTCs in the foundation zone. The important conclusions that emerge from this review of previous data and the examination of three case studies are threefold. First, MTCs appear to be more consolidated, when compared to unfailed, conformable deposits. Second, the identification and characterization of MTCs is vital to assess the performance of jetted conductors and suction anchor piles. Third, presence of MTCs should be considered in the design, in order to minimize costly operational delays.

A Two-Dimensional Post-Stack Seismic Inversion for Acoustic Impedance of Gas and Hydrate Bearing Deep-Water Sediments Within the Continental Slope of the Ulleung Basin, East Sea, Korea

“…4) and are consistent with general physical characteristics of high-energy induced deep-water deposition (e.g., Shipp et al 2004). However, the local vertically disturbed seismic features around both UBGH09 and 10 appear to be relevant to the existence of gas and hydrates as described below.…”

True Volumes of Slope Failure Estimated From a Quaternary Mass‐Transport Deposit in the Northern South China Sea

“…Shear compaction during slope failure can cause overconsolidation of emplaced MTDs. This has been confirmed by identifying losses in porosity and water content in failed sediment (Piper et al, ; Shipp et al, ), by core observations (Strasser et al, ; Tripsanas et al, ), and by observations of trapped free gas underneath failed material (Sun, Alves, et al, ). Multiple DSDP/ODP/IODP wells have been drilled through failed sediment (e.g., Dugan, ; Piper et al, ; Strasser et al, ).…”

MTD distribution on a ‘passive’ continental margin: The Espírito Santo Basin (SE Brazil) during the Palaeogene

“…Bull et al, 2009;FreyMartinez et al, 2005;Gee et al, 2006;Masson et al, 2006;Shipp et al, 2004). Resulting strata, commonly termed as Mass Transport Deposits (MTDs), play an important role in shaping the seafloor (e.g.…”