An evaluation of the prospectivity of the Nyk High, Norwegian Sea

Abstract

The Nyk High comprises the area of study in this Master Thesis. This structural high is found in the northern part of the Vøring Basin and consists of rotated fault blocks. The Vøring Basin is located in the deep-water areas of the Norwegian Sea outside Mid-Norway and was opened for exploration in 1996. The objective in the Master Thesis is to do an evaluation of the prospectivity of the Nyk High. Three prospects named Prospect (1), Prospect (2) and Prospect (3) are studied and they make up considerable structures. If they contain hydrocarbon accumulations they will add significant importance to the gas discoveries already done in this area.

The Nyk High is a highly faulted area and its structures and large faults are results of the last major rifting event that took place in the Vøring Basin from Campanian/Maastrichtian to Paleocene-Eocene when the Eurasia plate and the Greenland plate experienced continental separation. The reservoir sandstones belong to the Nise Formation of Santonian to Campanian age and were deposited in a deep-water fan system. Potential hydrocarbon accumulations rely on sealing faults and shales of the Springar Formation as top seal. Well shave targeted distinct seismic flat spots in this area and proved the presence of gas in the Luva, Haklang and Snefrid South discoveries.

The recoverable gas volumes are estimated to 44.4×109 Sm3 for Prospect (1), 189×109 Sm3 forProspect (2) and 21.1×109 Sm3 for Prospect (3). The corresponding values for the recoverable oil reserves are 96.5×106 Sm3 for Prospect (1), 416.2×106 Sm3 for Prospect (2) and 46.4×106Sm3 for Prospect (3). These hypothetical volumes are high and Prospect (2) is the closure estimated to contain the largest hydrocarbon accumulation. In this context, it should be mentioned that greater risk is connected to the possibility of discovering oil accumulations compared to gas accumulations.

Uncertainties are connected to some of the geological factors in the Upper Cretaceous play in the Norwegian Sea. The probabilities of making technical discoveries in each prospect are estimated to 7.5% for Prospect (1), 10.5% for Prospect (2) and 4.5% for Prospect (3). These results indicate that the possibility of discovering hydrocarbon accumulations is associated with high risk. High risk is connected to geological factors such as source and migration, trapintegrity and retention after accumulation. The source rock’s age, quality and distribution are presently uncertain because a source is unproven in this area. High risk is also connected to the timing of maturation and migration relative to trap formation. The probability of having a reservoir is, on the other hand, set equal to one, meaning that no risk is connected to this factor.