Detailed reservoir study of the Lower Jurassic Tilje Formation around the Noatun and Linnorm discoveries, Halten Terrace, Norwegian Sea

Abstract

Tilje Formation in Halten Terrace is significantly affected by the strongly heterolithic nature of its component of lithofacies and the complicated reservoir architecture, which largely controlled by eustatic process of relative sea level fluctuations. Sedimentological analysis from the core samples and log responses from 5 surrounding wells (6406/9-1, 6406/9-2, 6407/7-8, 6406/6-2 and 640774-1) were used to identify the variability of lithofacies, depositional element and depositional environment of Tilje Formation. Seven depositional elements was identified from the lithofacies and four main electrofacies classifications was characterized and combined into five generalized facies association classifications to reconstruct reliable facies models, which covers the wave-tide dominated delta to marine offshore environments. Sequence stratigraphic analysis has allowed the recognition of three intervals of 4th order genetic sequences during the regressive-transgressive events. Sequence 1 consists of lower delta plain and wave-tide influenced delta, sequence is dominated by tide dominated delta deposits, which alternates with lower delta plain and estuarine deposits. Sequence 3 consists of tide dominated delta, estuarine and marine offshore deposits. The integration analysis based on fault timing activity and stratigraphic interpretations indicates that Tilje Formation deposition was somehow affected by tectonic event in the early stage, and identified as early syn-rift deposits with SE-NW sedimentation trend within a NE-SW oriented half graben with local N-S normal fault trend. The result of this study is an integrated data analysis and facies model which represents the paleoenvironment and tectonic evolution within the deposition of Tilje Formation.