Parcels 7-11 are all located on the Scotian Slope outboard the Sable Subbasin (Figures  1, 29 and 51). Six wells have been drilled in these parcels since 1984, Evangeline H-98, Newburn H-23, Weymouth A-45, Balvenie B-79, Annapolis G-24 and Crimson F-81.Husky’s Evangeline H-98 well, spudded in 1984, was drilled to test a rollover anticline structure. The well targeted Logan Canyon and Missisauga sands trapped on the hanging wall of a listric fault on the outer shelf, but instead encountered a significantly expanded upper Logan Canyon section dominated by shale (approx. 2600 m). No reservoir quality sands were encountered and the well did not penetrate deep enough to test for any Missisauga equivalent sands.

Newburn H-23 is also within parcel 7 and was drilled by Chevron and its partners in 2002. Chevron anticipated finding lower Missisauga equivalent turbidite sandstone within a detachment fold. Four thin reservoir sands were found above and within the target section. Three of these zones had thin gas pay. Average porosities within these zones range from 14% to19%. Also of note was a channel lag deposit that was recovered from a sidewall core in one of the intervals, this may indicate that the well is located in a bypass or upper slope position. Newburn H-23 established that an active hydrocarbon system is present in the deepwater portion of the southwestern Sable Subbasin, and the presence of coarser clastics indicates that there were periodic influxes of vigorous sediment gravity flows into deepwater during the Early Cretaceous (Chevron et al., 2002). 

Weymouth A-45 was drilled by EnCana in 2003/2004. It targeted an anticlinal fold interpreted to contain turbidite sands equivalent in age to the Missisauga Formation.  This was the basin’s first subsalt test.  The well did not encounter any significant hydrocarbons or reservoirs, with the targeted interval consisting mostly of shale and siltstone.  Ongoing studies imply that Early Cretaceous sand transport into the Weymouth area may have been hindered by a complex arrangement of salt-related positive bathymetric highs that existed upslope from the well location at the time of inferred reservoir deposition.  Sand delivery, therefore, may have been diverted to the east or west of the Weymouth location. 

**The following discussion regarding well results at Balvenie B-79, Annapolis G-24 and Crimson F-81 are direct excerpts from the CNSOPB’s report “Nova Scotia Deepwater Post-Drill Analysis 1982-2004”. For a full comprehensive review of the deepwater well results including the figures that accompany the below text the reader is directed to the full report link: http://www.cnsopb.ns.ca/geoscience_publications.php.

Balvenie was Imperial’s first venture into the deepwater and was drilled in 2003. Four potential target objectives were identified ranging in age from Aptian to Cenomanian. The primary reservoir objective was the Albian level with several amplitude anomalies exhibiting modest AVO response. The Balvenie well reached total depth in the early Albian. It encountered two thin (~2m thick) poorly cemented, fine- to medium-grained sands of late Maastrichtian age that were shown to be wet on logs. This was expected as there is no closure indicated at this depth. Within the Albian target interval, several thin, tight, gas-charged siltstones were encountered. These siltstones ranged from 1–8m thick and produced considerable mud-gas shows during drilling. The Balvenie B-79 Well History Report noted that the AVO anomalies targeted on the seismic in fact tie to the gas charged silts encountered in this sequence.

Annapolis B-24 was drilled in 1740 metres of water using the West Navion drillship. It was spudded on December 26^h, 2001 but encountered major mechanical problems with the riser and sheaves and a gas kick at 3496m (near top of the Maastrichtian Wyandot formation chalks) which resulted in the drillpipe getting stuck and the eventual loss of the well. The B-24 location was abandoned and the drillship moved about 900 metres to the northwest to the G-24 location which was spudded on April 17, 2002. The main objectives were Early Cretaceous (Upper Albian to Lower Aptian) lowstand, deep water turbidite sands within a large structural closure formed as a result of adjacent salt withdrawal and listric down-to-basin faulting.  

The Annapolis G-24 well was drilled to a TD of 6182m MD in the lower Missisauga formation equivalent section (Late Berriasian?).  Three main gas bearing zones were encountered from 4842–5528m MD designated by the operator as the H, L and M Sands (Marathon 2002). It should be noted that the H and L “sands” are not individual sand units but gross intervals which consist of interbedded sands, siltstones and shales. 

The H Sand interval extends from 4842–4866m MD and is Mid Barremian age (upper Missisauga equivalent) (Marathon, 2002). It consists mostly of interbedded shales, silts and minor sands. There is a cumulative total of 3.8m net pay across the entire interval summed from a number of very thin sands less than 1m thick.

The L Sand interval extends from 5040.5–5097.8m MD and is also Mid Barremian age (Marathon, 2002).  It is lithologically similar to the H Sand except the sand/silt ratio is higher. The zone has a total of 5.3m of net pay over a 57.3m gross interval. The reservoir quality of the L Sand is also better with an average net pay porosity of 17% compared to 14.8% for the H Sand.

The main reservoir zone in the Annapolis G-24 well is the M Sand interval (Late Hauterivian, middle Missisauga equivalent) (Marathon, 2002) that consists of two sands with fair to very good porosity with a total of 18.2m of net gas pay. The two sands were arbitrarily named M Sand-upper and M Sand-lower and have a porosity range of 12–25% and fair to very good permeability, based on MDT mobilities ranging from 0.4–132 mD/cp. 

Crimson F-81 was Marathon’s second well in the deepwater; a follow-up to Annapolis G-24 gas discovery located about nine kilometers to the southeast. The well was spudded in 2004 and drilled in 2091.5m of water, which to date is the greatest water depth of any well offshore Nova Scotia. The Crimson reservoir objectives were Early Cretaceous deepwater sands deposited seaward of the sand-rich Sable paleodelta. Specifically, the F-81 well was targeting an interpreted more sand-prone area of the Annapolis turbidic submarine fan system within which the H, L and M sands were found to be gas-bearing The target was described as a faulted anticlinal feature developed during the Late Cretaceous as a result of salt withdrawal.  

The Crimson F-81 well was drilled to a TD of 6676m MD in the middle Missisauga equivalent section of Early Hauterivian age strata. No significant hydrocarbon bearing zones were encountered. Reservoir quality was generally much poorer than Annapolis consisting of thin, tight, very-fine to fine-grained sandstones and siltstones in a shale dominated succession.

The only reservoir quality sand discovered in the Crimson well was the O Sand at 6414m MD in the Late Hauterivian upper Missisauga equivalent. The O Sand is 13m thick and consists of fine-grained calcareous sandstone with an average porosity of 13% (maximum porosity 15%). A weak mud-gas show of 30tgu/10u was detected during drilling and there was some increase in resistivity (up to 3 ohms) near the top of the sand that may indicate the presence of a thin ~1.5m thick gas pay zone. It should be noted that while the density log indicates that approximately 12% porosity is present at the top of the sand, the neutron and sonic logs suggest that porosity is decreasing over this interval. Due to the thinness of the apparent pay and the inconsistent log responses across the top of the zone, the presence of gas pay is considered questionable.

Additional seismic mapping by the CNSOPB in the vicinity of the Annapolis and Crimson wells concludes that the majority of the Cretaceous intervals penetrated in these wells are depositional thins that drape structural highs. The fact that reservoir quality sands were found in these locations is promising, but there are much thicker deposits on the slope to encounter. The location of these wells in reference to the thicker slope deposits can be seen in figures 12, 13, and 14 of the Sediment Delivery section of this call for bids package. A recent presentation at an AAPG conference describing the well results of these two wells is also available here:

http://www.searchanddiscovery.com/documents/2010/40622kendell/ndx_kendell.pdf