Abstract
In recent years, there has been increased interest in sandstone injectite geological features in the North Sea. They are interpreted as post-depositional features, and are characterized by chaotically distributed, unconsolidated, remobilized sands mostly in the Paleocene and Eocene formations. Porosity, when, present is often high. On seismic sections, they appear as dykes crosscutting the surrounding reflectors and as sills with short lateral extent. Until recently, they have not been considered as potential targets for hydrocarbon production for several reasons:
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In some cases, they were thought to be processing artifacts.
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They are often difficult to image seismically as their thickness is considered beyond the resolution of conventional seismic data and there is generally a low acoustic impedance contrast between the sand and the overlying shale.
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Because they have not been imaged on seismic data, they have often been neglected in favor of deeper targets.
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They have often been considered drilling hazards, as they could be over-pressured.
In this paper, we review three case studies from three different areas in the North Sea: Area 1: Block G34_12 east of Kvitebjoern field, Area 2: Central North Sea, and Area 3: Grane field. In these three areas, we show sandstone injectite features, each having different seismic characteristics: for example, geometry, thickness, and acoustic impedance contrast. We demonstrate that in each case, the injectite can be imaged and visualized as a single object or geobody.
