Carbonate Platform Play

Lark Harbour Prospect (previously prospect B and parts of C)

This structure is a large horst oriented NNE-SSW that is bound to the northwest and southeast by basement penetrating normal faults. The horst block gently dips to the southeast. The expected reservoirs are within the St George Group (the Aguathuna and Watts Bight limestones) and the Labrador Group (sandstones and conglomerates). The most likely source rocks for the play are the Green Point shales drilled in the Allochthon sequence and the synrift shales of the Labrador Group. The upper seal is the Lourdes Limestone, the across-fault seal are the Goose Tickle shales and tight carbonates and clastics.  A notable amplitude anomaly near its westerly crest interpreted to be the Watts Bight level of the carbonate platform has been confirmed in recent data reprocessing. (Figure 2.13)

Figure 2.13 - Lark Harbour Prospect - Fault bounded, tilted horst block

Early AVO analysis (Amplitude Variation with Offset) has indicated that the anomaly is consistent with the variation produced by the presence of gas in a carbonate reservoir. The block’s structural closure calculated on the Tablehead Time Structure map is between 40 (minimum) and 100 (maximum) square km placing this prospect among the largest undrilled plays in North America (Figure 2.1.4).

Figure 2.14 - Lark Harbour Prospect Area 40 to 100 Sq. km.

York Harbour Prospect (previously parts of prospect C)

This deeper structure located just east of the Lark Harbour Prospect is a fault block tilted toward the southeast. In its central part the structure has a pronounced roll-over character. The York Harbour Prospect is bound to the northwest by a normal fault that seals the expected reservoirs in the St George and Labrador groups. Nearby mature source rocks for the play are the Green Point shales in the Allochthon sequence and the synrift shales of the Labrador Group (Figure 2.15).

Figure 2.15 - York Harbour Prospect - SE Tilted Block

Inter-formational tight limestones, marls and shale stringers of the non-reservoir sections of the carbonate platform provide northwestern closure (Fig. 2-15 above and 2-16 below). The northwest bounding fault loses throw to the southwest where it continues beyond the boundary of the Exploration License 1120. There are high amplitude reflectors related to the Watt Bight and Catouche levels. The prospect’s structural closure on the Tablehead Time Structure Map is between 25 (minimum) and 65 (maximum) square km (Figure 2.16).

Figure 2.16 - York Harbour Prospect Area 25 to 65 Sq. km.

Bay of Islands Leads (previous Lead A and a series of other poorly defined leads)

A collection of smaller rotated fault blocks are visible on individual seismic lines to the north and northwest of the Lark Harbour Prospect. One of these blocks has been identified as Lead A in a previous attempt to map it. The current interpretation places this and a series of other inadequately defined leads under the collective name of Bay of Islands Leads. All these smaller blocks are fault or multi-side fault bounded anticlines that need more seismic coverage to map their exact closures. Potential reservoirs, seals and source rocks of the leads are similar with the Lark and York prospects.