Offshore Nova Scotia Research Articles

Seafloor sediment characterization improves estimates of organic carbon standing stocks: an example from the Eastern Shore Islands, Nova Scotia, Canada

Abstract. Continental shelf sediments contain some of the largest stocks of organic carbon (OC) on Earth and play a vital role in influencing the global carbon cycle. Quantifying how much OC is stored in shelf sediments and determining its residence time is key to assessing how the ocean carbon cycle will be altered by climate change and possibly human activities. Spatial variations in terrestrial carbon stocks are well studied and mapped at high resolutions, but our knowledge of the distribution of marine OC in different seafloor settings is still very limited, particularly in dynamic and spatially variable shelf environments. This lack of knowledge reduces our ability to understand and predict how much and for how long the ocean sequesters CO2. In this study, we use high-resolution multibeam echosounder (MBES) data from the Eastern Shore Islands offshore Nova Scotia (Canada), combined with OC measurements from discrete samples, to assess the distribution of OC content in seafloor sediments. We derive four different spatial estimates of organic carbon stock: (i) OC density estimates scaled to the entire study region assuming a homogenous seafloor, (ii) interpolation of OC density estimates using empirical Bayesian kriging, (iii) OC density estimates scaled to areas of soft substrate estimated using a high-resolution classified substrate map, and (iv) empirical Bayesian regression kriging of OC density within areas of estimated soft sediment only. These four distinct spatial models yielded dramatically different estimates of standing stock of OC in our study area of 223 km2: 80 901, 58 406, 16 437 and 6475 t of OC, respectively. Our study demonstrates that high-resolution mapping is critically important for improved estimates of OC stocks on continental shelves and for the identification of carbon hotspots that need to be considered in seabed management and climate mitigation strategies.

Self-supervised learning for efficient seismic facies classification

Seismic facies classification is an important task in seismic interpretation that allows the identification of rock bodies with similar physical characteristics. Manual labeling of seismic data is immensely time consuming, given the recent surge in data volumes. Self-supervised learning (SSL) enables models to learn powerful representations from unlabeled data, thereby improving performance in downstream tasks using limited labeled data. We investigate the effectiveness of SSL for efficient facies classification by evaluating various convolutional and vision transformer-based models. We pretrain the models on image reconstruction and fine-tune them on facies segmentation. Results on the southern North Sea F3 seismic block in the Netherlands and the Penobscot seismic volume in the Sable Subbasin, offshore Nova Scotia, Canada, show that SSL has comparable performance to supervised learning using only 5%–10% labeled data. Further, SSL exhibits stable domain adaptation on the Penobscot data set even with 5% labeled data, indicating an improved generalization compared with the supervised learning setup. The findings demonstrate that SSL significantly enhances model accuracy and data efficiency for seismic facies classification.

Machine learning assisted reservoir characterization for CO2 sequestration: A case study from the Penobscot field, Canada offshore

Rising greenhouse gas emissions, especially CO2, intensify global warming. Carbon Capture and Storage (CCS) is vital for reducing emissions from industrial sources, crucial for addressing climate change urgently. This study explores reservoir characterization challenges for CCS in the Penobscot field, offshore Nova Scotia. We used to cross-plots of geophysical logs to establish relationships between petrophysical properties and subsurface litho-facies, differentiating sand and shale facies within the Mississauga Formation (Early to Middle Cretaceous). Seismic impedance inversion distinguished between reservoir and non-reservoir facies. Multi-attribute assisted transformed seismic data and a support vector machine algorithm predicted litho-facies probabilities and effective porosity volumes in 3D space. The permutation predictor importance analysis was performed to assess the relative importance of input features in facies probabilities and effective porosity prediction. The structural component delineated the CO2 injection trap boundary. Integrated analysis of structural configuration, litho-facies probability, effective porosity, and cap-rock sealing integrity validated zones for CO2 storage. The dry, abandoned well L-30 in the structural high zone is recommended as a pilot CO2 injector well. This study provides critical insights into reservoir characterization for CO2 sequestration, aiding climate change mitigation through effective CCS, and recommends geomechanical studies and time-lapse seismic monitoring.

Halokinetically Overprinted Tectonic Inversion of the Penobscot 3D Volume Offshore Nova Scotia, Canada

Halokinetically Overprinted Tectonic Inversion of the Penobscot 3D Volume Offshore Nova Scotia, Canada

Automated seismic semantic segmentation using attention U-Net

Seismic facies mapping from a 3D seismic cube is of significant value to various seismic interpretation and characterization tasks. Traditional facies mapping is based on examining sedimentary environments and stratigraphic sequences that provide distinct characteristics used for facies mapping. Given the complex nature of the task, manual facies mapping is typically time and labor consuming, and the quality of the decisions varies as a function of expertise. This complexity is further increased with the ever-increasing size of 3D seismic data sets. Deep-learning methods have indicated a promising potential to perform fast, accurate, and automated segmentation tasks. We investigate the application of machine-learning techniques, particularly state-of-the-art deep convolutional neural networks (CNNs), as a framework to perform accurate automated seismic facies pixel-wise segmentation. The workflow consists of a CNN-based U-Net architecture that adopts modern computer vision techniques. We develop three major changes to the standard U-Net to boost the performance for seismic semantic segmentation tasks: (1) using residual building blocks in the encoder, (2) using transformer-like attention gates after each residual block, and (3) using frequency spectrum data, in addition to seismic amplitude, as input to the network. We indicate that this implementation achieves higher accuracy metrics outperforming recently published state-of-the-art benchmarks. The performance of our method is validated using two 3D seismic data sets, the F3 Netherlands data set and the Penobscot data set acquired offshore Nova Scotia, Canada. Experimentation involves training on a set of samples and tuning the hyperparameters, followed by quantitative evaluation of the trained network. Our workflow produces high-quality segmentation with significantly reduced artifacts, improved edge detection, and improved lateral consistency throughout the seismic survey.

Re-evaluation of the Mesozoic–Cenozoic biostratigraphy of the Laurentian Subbasin of the Scotian Basin, offshore eastern Canada

We use new and existing nannofossil, palynological, and microfossil biostratigraphic data in conjunction with lithologic and geophysical logs from four wells to establish a series of sequence-stratigraphic events in the Mesozoic–Cenozoic of the Laurentian Subbasin of offshore Newfoundland, eastern Canada. Well biostratigraphic events are integrated with reflection seismic in the area to correlate regional seismic stratigraphic surfaces. The four wells are: Bandol-1, Emerillon C-56, East Wolverine G-37, and Heron H-73. We extend the event stratigraphic scheme previously developed for the Scotian Margin, offshore Nova Scotia, into new areas to the east along the southern Grand Banks, where we recognize four new well-log sequence stratigraphic events, and we modify the definition of a previously recognized regional surface. The new and modified regional surfaces are the Early Albian Unconformity, the Late Bathonian Maximum Flooding Surface (MFS), the Late Bajocian MFS (renamed from Bathonian/Bajocian MFS), the ?Bajocian/Toarcian Unconformity, and the Late Pliensbachian MFS. We recognize the "Avalon Unconformity" and "Base-Tertiary Unconformity" of previous studies as amalgamations of multiple smaller-scale unconformities and refine their age in the studied wells. A major improvement over our earlier Scotian Margin event schemes is the extension of the event stratigraphy into the Early Jurassic using a suite of marine biostratigraphic markers. We compare the Early Jurassic event scheme to Deep Sea Drilling Project Site 547B on the conjugate Moroccan Margin to better constrain potential source rock intervals and the early history of the central Atlantic Ocean.

Cretaceous to Eocene mixed turbidite-contourite systems offshore Nova Scotia (Canada): Spatial and temporal variability of down- and along-slope processes

The identification of several Cretaceous to Paleogene mixed turbidite-contourite systems along the upper to middle continental slope of Nova Scotia provides a unique opportunity to investigate the spatial and temporal variability of their morphological elements. The mixed systems were studied using 3D seismic reflection data and well-established chronostratigraphy from five exploration wells. Seismic interpretations and correlations suggest four main evolutionary stages for the Late Jurassic – Paleogene sedimentary record, characterized by distinctive, diagnostic features at large (>1–10 km) to small (<100 m) scales: 1) initial turbidite systems developed between 160 and 125 Ma with extensive tributary channel networks along the upper continental slope that fed submarine channels and channel-levees further down-slope; 2) onset and growth of mixed systems at 125–78 Ma, characterized by a seaward progradation and NE migration of down-slope elongated mounded drifts and wide, U-shaped channels formed under potentially synchronous interactions between a SW-flowing bottom current and SE-directed turbidity flows; 3) shift of mixed systems at 78–50 Ma with SW migration of the mounded drifts and submarine channels, associated with a potential switch of the bottom current direction at 78 Ma, from SW towards NE; and 4) burial stage post-50 Ma, characterized by several stages of hemipelagic deposition followed by gully erosion at approximately 50, 40, and 35 Ma. The gradual transition from turbidite systems to fully developed mixed systems is associated with the tectonic and sedimentary background of the Nova Scotian margin during the Early to Late Cretaceous, as well as the establishment of a Cretaceous to Eocene paleoceanographic circulation. Comparisons with other ancient and modern mixed systems reveal similar morphological features (e.g., mounded drifts and submarine channels) formed under synchronous and asynchronous interactions between along- and down-slope processes. Their lateral distribution and vertical variability reflect a gradual change between the most influential process, from down-slope turbidity currents to along-slope bottom currents. Secondary depositional features along the mounded drifts, such as N–S oriented sediment waves, result from along-slope sediment redistribution and remobilization near the seafloor. Mixed depositional systems form unconventional plays and may become future targets for energy geosciences in a search for hydrocarbons or carbon capture and storage.

Attribute-assisted interpretation of deltaic channel system using enhanced 3D seismic data, offshore Nova Scotia

Deltaic channels are good exploration targets and form potential hydrocarbon reservoirs. Generally, distributary sand-filled deltaic channels have high porosity and high permeability sandstones hence can form good quality reservoirs. We delineate deltaic channels within Cree Sand member of the Logan Canyon formation in the Penobscot field, offshore Nova Scotia, by devising a workflow that includes seismic data enhancement and attribute studies integrating coherence attributes, amplitude curvature and spectral decomposition attributes. An exhaustive seismic data conditioning improves considerably the signal-to-noise ratio in the conditioned seismic data (-4 dB at dominant frequency) compared to the input seismic (−22 dB at dominant frequency). We perform an integrated seismic attribute study which helps in effectively mapping the deltaic channel systems at different stratigraphic levels of the Cree Sand interval. We carry out a novel attribute analysis by comparing two types of volumetric curvature attributes namely, structural and amplitude curvatures. The structural curvature although depicting the fault patterns clearly, does not delineate the channels due to the absence of any flexure across the channel. Interestingly, the amplitude curvature attribute delineates different channel systems because of the amplitude variation across the channel edges. We identify narrower and thinner channels at the deeper stratigraphic level, while wider and thicker channels appear at the shallower level. Channel width varies from 870 m to 420 m and thickness from 110 m to 52 m from shallow to deeper level. Based on the integrated seismic attributes analysis, we identify varying channel width and thickness at different stratigraphic levels, that correlates to varying sea level.

Chemostratigraphic Analysis of the Cretaceous Logan Canyon Formation, Sable Sub-Basin, Offshore Nova Scotia: Implications for Reservoir Characterization and Fluid Flow

Chemostratigraphic Analysis of the Cretaceous Logan Canyon Formation, Sable Sub-Basin, Offshore Nova Scotia: Implications for Reservoir Characterization and Fluid Flow

Chemostratigraphic Analysis of the Cretaceous Logan Canyon Formation, Sable Sub-Basin, Offshore Nova Scotia: Implications for Reservoir Characterization and Fluid Flow

Chemostratigraphic Analysis of the Cretaceous Logan Canyon Formation, Sable Sub-Basin, Offshore Nova Scotia: Implications for Reservoir Characterization and Fluid Flow

Mixed siliciclastic–carbonate systems and their impact for the development of deep-water turbidites in continental margins: A case study from the Late Jurassic to Early Cretaceous Shelburne subbasin in offshore Nova Scotia

Progradation of deltaic systems that reach the shelf edge is considered a primary mechanism to deliver sand to continental margins. Sediment bypass processes can dominate the outer shelf to upper slope transition, causing poor preservation of reservoir quality sandstones. Turbidites can carry the bulk of the coarse fraction downdip where a thicker sand pile can be deposited once the channel-to-lobe transition is reached. Predicting this lateral and vertical variability along the slope is challenging. This configuration can be further complicated when mixed siliciclastic–carbonate systems are present. The Roseway–Missisauga case study from Nova Scotia is used here to explore potential implications associated with the development of deep-water turbidites that are time equivalent to outer-shelf mixed siliciclastic–carbonate units. Two scenarios are possible: (1) The carbonate factory is dominant, and the development of carbonate reefs and pinnacles on the outer shelf prevents the passage of siliciclastic systems beyond the shelf break; in this case, the siliciclastic component is sequestered within the inner-outer shelf. (2) Favorable conditions for carbonate production gradually deteriorate by the activation of fluviodeltaic systems that prograde outboard reaching the slope region. In this last scenario, low relief and lateral discontinuous carbonate shoals are ubiquitous in the outer shelf representing the last outboard remnants of the carbonate factory. Shelf-edge deltas circumvent or breach these carbonate shoals, establishing sedimentary pathways on the shelf-break region that connect with deep-water turbidites. Observations suggest that this last scenario is the most likely in this part of the Scotian margin during the Late Jurassic to Early Cretaceous.

Assessing Submarine Slope Stability through Deterministic and Probabilistic Approaches: A Case Study on the West-Central Scotia Slope

A simplified geostatistical approach was adopted to assess the effect of spatial variability of soil properties on slope stability analysis in order to understand continental margin geologic processes and potential geohazards for an area of the central Scotian Slope, offshore Nova Scotia, Canada. The analyses are conducted on piston core samples, thus are restricted to ~12 m sub-seabed; however, the approach provides insight into the general effects of spatial and temporal variability. Data processing using geostatistics and assessment of spatial correlation are used to characterize the current dataset. A deterministic assessment was performed for both non-spatially averaged and spatially averaged core sections. The results indicate that the estimated factor of safety increased by about 30% when spatially averaged values were used. A probabilistic model is introduced to assess reliability of the slope. The approach makes use of estimates of both the mean and variance of input random variables (e.g., Su and γb). The model uses an exact probabilistic formulation for the total stress stability analysis and a Taylor series approximation for the effective stress stability analysis. In both cases, the mean and variance of the factor of safety are computed, leading to estimates of failure probability. The results suggest that the deterministic analysis is conservative with respect to slope reliability, although they do not lead to an estimate of the probability of failure. While these results indicate sediment instability is largely unlikely under static conditions, the reality is that many examples of submarine slope failure are observed in the geologic record. These results suggest that cyclic loading (earthquakes) or pre-conditioning factors (elevation of pore pressures) are critical for slope instability on the Scotian Slope.

Continent‐Ocean Transition Across the Northeastern Nova Scotian Margin From a Dense Wide‐Angle Seismic Profile

AbstractTo improve constraints on rifting processes resulting in the formation of the southeastern Canadian margin, we interpret the most detailed regional 2‐D velocity model from offshore Nova Scotia constructed using wide‐angle OETR‐2009 data. This 405‐km‐long profile was collected with 78 ocean bottom seismometers. The presented data analysis and interpretation are supported by a reflection image from the coincident long streamer GXT‐2000 profile. We identify a continental zone where the full‐thickness (~30 km), three‐layered continental crust beneath the inner shelf thins sharply seaward by a listric fault that forms a 12‐km‐deep Huron Subbasin beneath a high‐velocity carbonate bank (~5.8 km/s), creating a shadow zone above tilted crustal blocks. Depth‐dependent and variable initial thinning is evidenced in all three modeled crustal layers, which, nevertheless, pinch out together at their seaward ends. More gradual and regional thinning and a local amagmatic thickening are modeled seaward beneath the slope until 70 km from the shelf break, beyond which a deepwater amagmatic continent‐ocean transition shows velocity characteristics not typical of either continental or oceanic crust. The 100‐km‐wide continent‐ocean transition is characterized by a low‐velocity (5.3–5.4 km/s), low gradient, &lt;2‐km thick upper crust, above a high‐velocity (6.3–7.5 km/s), high gradient, &lt;5‐km‐thick lower crust, which can be interpreted as moderately serpentinized mantle. Underneath this layer is a &lt;5‐km‐thick low‐velocity (7.1–8.0 km/s) partially serpentinized mantle layer. A ~5‐km‐thick oceanic crust is modeled seaward. Our results suggest that amagmatic processes dominated the continental breakup in this area.

Assessment of the effect of mass-transport deposits on fault propagation in Penobscot area, offshore Nova Scotia

Abstract Three-dimensional (3D) seismic data and well logs from the Penobscot area, located within the Scotian Basin offshore Nova Scotia, are used to assess the role of mass-transport deposits (MTDs) on fault propagation. Four MTDs characterized by chaotic seismic facies were mapped, with the earliest hosted by the Late Cretaceous–Recent Dawson Canyon Formation and latest three hosted by the Banquereau Formation. Two types of faults were also mapped. R-faults are regional faults that cut across all the interpreted MTDs in the study area, while P-faults are polygonal faults that cut across MTDs 2 and 3 but tip out at the basal surfaces of MTDs 4 and 2. Representative seismic profiles and isochron maps of the MTDs and throw–depth ( T–z ) and throw–distance ( T–x ) plots allows us to distinguish the families and propagation history of the faults. Our results show that fault propagation is not affected by the presence or thickness variation of MTDs, and is also unaffected by lithological contrast in the Penobscot area of the Nova Scotian Shelf.

Detecting overpressure using the Eaton and Equivalent Depth methods in Offshore Nova Scotia, Canada

Overpressure is an abnormal high subsurface pressure of any fluids which exceeds the hydrostatic pressure of column of water or formation brine. In Offshore Nova Scotia Canada, the values and depth of overpressure zone are determined using the eaton and equivalent depth method, based on well data and the normal compaction trend analysis. Since equivalent depth method is using effective vertical stress principle and Eaton method considers physical property ratio (velocity). In this research, pressure evaluation only applicable on Penobscot L-30 well. An abnormal pressure is detected at depth 11804 feet as possibly overpressure zone, based on pressure gradient curve and calculation between the Eaton method (7241.3 psi) and Equivalent Depth method (6619.4 psi). Shales within Abenaki formation especially Baccaro Member is estimated as possible overpressure zone due to hydrocarbon generation mechanism.

Plane-wave Sobel attribute for discontinuity enhancement in seismic images

Discontinuity enhancement attributes are commonly used to facilitate the interpretation process by enhancing edges in seismic images and providing a quantitative measure of the significance of discontinuous features. These attributes require careful preprocessing to maintain geologic features and suppress acquisition and processing artifacts, which may be artificially detected as a geologic edge. We have developed the plane-wave Sobel attribute, a modification of the classic Sobel filter, by orienting the filter along seismic structures using plane-wave destruction and plane-wave shaping. The plane-wave Sobel attribute can be applied directly to a seismic image to efficiently and effectively enhance discontinuous features or to a coherence image to create a sharper and more detailed image. Two field benchmark data examples with many faults and channel features from offshore New Zealand and offshore Nova Scotia demonstrate the effectiveness of this method compared with conventional coherence attributes. The results are reproducible using the Madagascar software package.

Enhanced structural interpretation from 3D seismic data using hybrid attributes: New insights into fault visualization and displacement in Cretaceous formations of the Scotian Basin, offshore Nova Scotia

Meta or hybrid attributes extracted from seismic data through artificial neural networks enhance structural details in subsurface strata. Cretaceous units within the Penobscot prospect are devoid of such interpretations. Although these units are plausible zones for hydrocarbon generation and accumulation, the role of geologic structures responsible for such entrapment is poorly understood. The present study enlightens these latter geological structures through a case study that uses 3D time-migrated seismic data from the Penobscot prospect in the Scotian Basin. A modern data conditioning approach, used together with multi-attribute analyses and a supervised neural network, have brought out the minute details of subsurface geologic structures through a hybrid attribute, called the fault probability cube (FPC). The present fault displacement analysis reveals that the major fault of the prospect has evolved by the coalescence of different fault segments grown over space and time, and has demonstrated a predominant NNW-SSE structural trend. Such a geometry has structurally modulated the Cretaceous units (the Logan Canyon, the Dawson Canyon and the Wyandot Formations) giving rise to different horst-graben structures and fracture networks, as shown by the FPC attribute. This generates complicated structural deformation and accommodation space, thereby enabling different trapping zones for hydrocarbon accumulation within these units. Such a detailed structural understanding will provide significant input to the future exploration and development programme in the Penobscot prospect.

An improved procedure for pre-drill calculation of fracture pressure

Abstract Pre-drill modelling of fracture pressure (FP) is an essential part of well planning, reserve estimation and evaluation of the potential for inducing seismicity as the result of fluid injection. Estimation of stress ratio or Poisson's ratio values or compaction state with depth is required in frequently used FP models. A new method to estimate FP is proposed which is based on Leak Off (LOT) and pore fluid pressure (Pp) data from offset wells and vertical stress ( S v )–depth relationships. LOT/ S v ratios observed in intervals of offset wells that are normally pressured (hydrostatic) are used to define an expected FP/ S v ratio for hydrostatic Pp conditions for all depths. Typical FP/ S v ratios for hydrostatic conditions derived using LOT data range from 0.81 to 0.89. Observed LOT values associated with Pp greater than hydrostatic (overpressured) in offset wells are used to quantify the rate of increase in FP with increasing overpressure (OP). The expected FP for hydrostatic conditions is compared with observed LOT values from depths where the pore fluid is overpressured and a relationship of increased FP, relative to the expected FP for hydrostatic conditions (residual FP (FPr)) with increasing OP is defined. The FPr:OP ratio typically ranges from 0.24 to 0.43. Fracture pressure models developed by this procedure may be used to predict FP for wells in different water depths and with Pp conditions different from those in the offset wells. The use of the model is demonstrated in three case studies taken from different geological settings: the Scotian shelf (offshore Nova Scotia), offshore Central Gulf of Mexico and the chalk interval from the Central North Sea.

The provenance of Jurassic and Lower Cretaceous clastic sediments offshore southwestern Nova Scotia

Jurassic and Cretaceous sandstones in the Shelburne subbasin and Fundy Basin offshore Nova Scotia, are poorly known but are of current interest for petroleum exploration. The goal of this study is to determine the provenance of sandstones and shales, which will contribute to a better understanding of regional tectonics and paleogeography in the study area. Mineral and lithic clast chemistry was determined from samples from conventional cores and cuttings from exploration wells, using scanning electron microscopy and an electron microprobe. Whole-rock geochemical composition of shales was used to test the hypotheses regarding provenance of Mesozoic clastic sedimentary rocks in the SW Scotian Basin. Lower Jurassic clastic sedimentary rocks in the Fundy Basin contain magnetite, biotite, and chlorite, suggesting local supply from the North Mountain Basalt and Meguma Terrane, whereas pyrope and anthophyllite suggest small supply from distant sources. In the SW Scotian Basin, detrital minerals, lithic clasts, and shale geochemistry from Middle Jurassic to Early Cretaceous indicate a predominant Meguma Terrane source and transport by local rivers. Rare spinel and garnet grains of meta-ultramafic rocks, only in the Middle Jurassic at the Mohawk B-93 well, suggest minor supply from the rising Labrador rift, via the same river that transported distant sediments to the Fundy Basin. Lower Cretaceous sandstones from the Mohican I-100 well contain minor garnet, spinel, and tourmaline from meta-ultramafic rocks, characteristic of sediment supplied to the central Scotian Basin at that time. The dominant Meguma Terrane provenance precludes thick deep-water sandstones in the eastern part of the Shelburne subbasin, but the evidence of Middle Jurassic distant river supply through the Fundy Basin is encouraging for deep-water reservoir quality in the western part.

Spectral decomposition application for analyzing the structure and the reservoir potential: a case study of Penobscot, Nova Scotia offshore, Canada

Faults play a critical role in prospect generation. Even so, to identify the best possible reservoir trapping geometries in a stratigraphically assorted regime is a challenge for exploration. The purpose of the present work is to examine the structure and the lithology by the application of forward Fourier transforms of spectral decomposition technique to a 3D post-stack seismic data set of Penobscot, Nova Scotia offshore, Canada. Seismic interpretation reveals three leads at the Wyandot (20 ms), Dawson Canyon (30 ms), and Mississauga formations (10 ms), respectively. Conventional seismic attributes such as semblance, curvature, dip similarity, and azimuth identify the subtle defects but are unable to detect the possible potential reservoir lithology at the deeper reservoir zone. However, forward Fourier transforms of spectral decomposition have diligently followed the possible faults, channels, and associated reservoir lithology and provided optimistic signs for future hydrocarbon exploration. Therefore, forward Fourier transforms and 3D visualization can be beneficial for discovering the future hydrocarbon prospect of Penobscot, Nova Scotia offshore, Canada.