The giant Johan Sverdrup oil field on the Utsira high in the Norwegian sector of the North Sea is an example of a multibillion barrel oil discovery in a mature and prolific super basin. After 50 yr of exploration in the region, the field had eluded the oil industry. Wells drilled (from 1967 to 2006) had oil shows in both basement and traditional sandstone reservoir rocks. The first significant discovery in the area was not made until 2007 with the Edvard Grieg field, shortly followed by the discovery of the Johan Sverdrup field in 2010. The mainly Jurassic-aged Statfjord and Viking groups constitute the two principal reservoirs in the field containing reserves in the order of 2.2-3.2 BBOE within a productive area of approximately 200 km(2) (similar to 124 mi(2)). Reservoir properties are excellent, with multi-Darcy permeabilities. The stratigraphic succession of the area, from Upper Triassic-Lower Jurassic alluvial deposits at the base to Upper Jurassic-Lower Cretaceous open-marine deposits at the top, records long-term subsidence and marine transgression, although interrupted by significant Middle Jurassic thermal uplift. During this time, accommodation was influenced by phases of extension and the creation of oblique-slip faults, previously not described in this region. The resulting stratigraphic architecture provided the basis for one of the largest oil fields in the North Sea super basin and a major supplier of energy for decades to come.

在评估CO2封存部位的封存能力和封堵风险时,对于断层封闭性的研究是至关重要的,因为断层可以显著影响跨断层和沿着断层的运移/泄露风险以及储层压力的预测.我们针对挪威海上Horda台地北部Smeaheia地区的CO2封存能力进行了研究,主要集中在Alpha构造和Beta构造这两个断层闭合圈闭上.我们的目的是通过此研究来推进对Horda台地北部CO2封存规模扩大潜力的地质认识,并阐明断层封闭性分析在CO2封存项目封堵风险分析和封存能力评估中的重要性.我们的封堵风险分析显示,Alpha构造具有比较低的断层相关封堵风险;因此具有成为封存目标的潜在价值.由于储集含水层与基底跨?ygarden断层系统对接,因此Beta构造显示出巨大的断层相关封堵风险.Smeaheia地区的储集能力将受控于长时期内的泄压和补充压力相互作用.我们的研究表明,在Smeaheia和Troll泄压储层之间的跨断层压力连通很可能是通过Vette断裂系统的一系列转换斜坡进行的.然而,Smeaheia地区也显示出压力补充的潜力,例如通过Base Nordland不整合面上的区域进行压力补充.在新钻的32/4-3S井中观察到的泄压为我们在断层封闭性预测上提供了很好的验证,并为未来动态模拟提供了有价值的参考.

An understanding of fault seal is crucial for assessing the storage capacity and containment risks of CO 2 storage sites, as it can significantly affect the projects on across-fault and along-fault migration/leakage risk, as well as reservoir pressure predictions. We present a study from the Smeaheia area in the northern Horda Platform offshore Norway, focusing on two fault-bounded structural closures, namely the Alpha and Beta structures. We aim to use this study to improve the geological understanding of the northern Horda Platform for CO 2 storage scale-up potentials and illustrate the importance of fault seal analysis in containment risk assessment and storage capacity evaluation of a CO 2 storage project. Our containment risk assessment shows that the Alpha structure has low fault-related containment risks; thus, it has a potential value to be an additional storage target. The Beta structure shows larger fault-related containment risks due to juxtaposition of the prospective storage aquifer with the basement across the Øygarden Fault System. The storage capacity of Smeaheia will be determined by the long-term dynamic interplay between pressure depletion and recharging. Our study shows that across-fault pressure communication between Smeaheia and the depleting Troll reservoir is likely to be through several relay ramps of the Vette Fault System. However, Smeaheia also shows pressure-recharging potentials, such as through the subcropping areas at the Base Nordland Unconformity. The depletion observed in the newly drilled well 32/4-3S gives a good validation point for our fault seal predictions and provides valuable insights for future dynamic simulations. Thematic collection: This article is part of the Geoscience for CO 2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

A consistent stochastic model for faults and horizons is described. The faults are represented as a parametric invertible deformation operator. The faults may truncate each other. The horizons are modeled as correlated Gaussian fields and are represented in a grid. Petrophysical variables may be modeled in a reservoir before faulting in order to describe the juxtaposition effect of the faulting. It is possible to condition the realization on petrophysics, horizons, and fault plane observations in wells in addition to seismic data. The transmissibility in the fault plane may also be included in the model. Four different methods to integrate the fault and horizon models in a common model is described. The method is illustrated on an example from a real petroleum field with 18 interpreted faults that are handled stochastically.