Petrophysical analysis of carboniferous reservoirs in Loppa High based on advanced well logs and core data.

Abstract

This thesis examines the hydrocarbon potential and reservoir properties for two wells drilled in the Barents Sea off northern Norway. The main target for both wells was a Permian carbonate sequence found in the interval between 2250 to 2450 m (MD). All the results were created from all the well logs, pressure data and conventional coring analyses provided by Lundin Norway AS. Well 7120/1-3 was the first discovery well on the western part of Loppa High in the Barents Sea, the well was drilled into the Late Permian and Triassic strata on the Gohta prospect. The main object for this well was to examine reservoir properties and hydrocarbon potential in Triassic Snadd sandstone and Permian karstified carbonate at the top of Røye formation. A year later, Well 7120/1-4S was drilled as an exploration well 5.3 km northwest of the well 7120/1-3. The purpose of this well was to analyze the hydrocarbon potential and reservoir properties of the Permian carbonate sequence and Triassic sandstones on the western side of the Gohta discovery. Lithology interpretation was determined from well logs, core images and cross plots. Water saturation, shale volume and porosity calculations were computed in Techlog software from Schlumberger. Permeability data was taken directly from the data provided by Lundin Norway AS. The results from the petrophysical analyses of both wells revealed that reservoir properties in both these reservoir interval are quite poor. The main challenge considering the petrophysical evaluation of these reservoir sections was due to several uncertainties regarding reservoir parameters calculations from laboratory measurements, complexity and heterogeneity of the reservoir and mud losses during drilling of the reservoir section.