3-D Analogue Modelling of Salt Diapirs: Comparisons with a Natural Example in the Great Kavir Province

Frank Despinois, Ken McClay, and Elizabeth Baker
Fault Dynamics Research Group, Royal Holloway University of London, Egham, United Kingdom

Many hydrocarbon accumulations such as those in the central North Sea basin occur in the flanking country rocks and roof strata of salt diapirs. Diapir flanking strata are commonly steeply-dipping and strongly fracturedand are important for reservoir development. Steep dips, salt overhangs and salt injections make detailed seismic imaging of these diapir-flanking structures extremely difficult. In order to understand and to develop realistic 4D models for fault and fracture development in reservoir strata around salt diapir systems scaled physical models have been carried. Dry quartz sand has been used to simulate the sedimentary strata and silicone polymer was used to simulate the salt.

This paper presents physical models of piercement salt diapirs developed under regional extension. These simulate the structural styles around Central North Sea diapirs such as the Pierce diapir system. In the models piercement diapirs evolve from a reactive salt ridge in the footwall of extensional fault systems and they focus inboard of corner points where two intersecting extensional fault systems interact. 3D reconstructions show these diapirs nucleate from reactive salt ridges along the axes of the footwall extensional graben systems. In addition to silicone polymer models new wet clay and silicone polymer models have been run. These models produced piercement and extrusive diapirs and associated radial fault patterns. The analogue models are compared to natural piercement diapirs found in the Central North Sea as well as with salt-cored diapirs in the Great Kavir of northern Iran. High-resolution Quickbird imagery has been used to map the fault and fracture systems around the diapers and these detailed fault maps have been used as analogues for diapir fault systems in the Central North Sea.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas