Fawad Ahmad Chuhan¹, Bjørlykke Knut¹
(1) Oslo University, Oslo, Norway

Abstract: The influence of Provenance on diagnesis of deeply buried reservoir sandstones from Haltenbanken and north Viking Graben Areas, Offshore Norway

It is important to understand the factors controlling the development of authigenic illite, to predict reservoir quality in deeply buried sandstones. An extensive mineralogical and geochemical data has been compiled to evaluate the relationship between diagenesis and provenance of the deeply buried ( 3.6 km RSF) sandstones. The sandstones from the north Viking Graben show a bulk K/Al molar ratio less than the K/Al molar ratio in illite (1/3-1/4), indicating the absence of K-feldspar. The petrographic data show that the degree of illitization is moderate to extensive, significant kaolinite is present in most cases, and K-feldspar is absent. In contrast, the K/Al molar ratios in the Haltenbanken sandstones varies, but are greater than the molar ratio in illite in most cases, indicating the presence of K-feldspar. The petrographic data show that the earlier formed authigenic kaolinite is extensively illitized and K-feldspar is present in most cases. However, the western well shows the composition similar to the north Viking Graben sandstones. The presence of significant amount of kaolinite and relatively lower degree of illitization in the sandstones from the north Viking Graben and western well at Haltenbanken area suggests that illitization of kaolinite depends upon a local presence of K-feldspar in the sandstones. The data shows that the amount of initially deposited K-feldspar was higher in most of the Haltenbanken sandstones compared with the north Viking Graben area.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana