Borehole summaries:

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Shell Eatha Ev 13-31-96-6W4   back to top

A relatively narrow interval of Cretaceous and Devonian sediments were analyzed from this well. All samples are organic-lean (0.5% TOC) except for that from 190 ft which is probably a heavy oil interval within Mannville strata. Tmax values give no indication of maturity but regionally in this area the Cretaceous is immature with respect to hydrocarbon generation.
Mutex IOE Edra 4-26-104-1W5   back to top

A discontinuous Devonian section was analyzed in this well. Almost all the samples are organic-lean except for some between 2080 and 2150 ft in the lower part of the Muskeg Formation which have TOC contents of between 1.01 and 1.40%. These latter samples have extremely low Tmax values (as low as 317 C) and very high OI values (>200) suggesting they represent contamination rather than thin source rock intervals. No reliable assessment of maturity can be obtained from this Rock-Eval data. Unfortunately, the section where cuttings were not obtained for analysis includes the Keg River Formation. A number of Keg River Formation organic-rich intervals (some >10%) have been sampled from core between 719.94 and 759.56 m (2362.0-2492.0 ft) from this well. The organic matter is Type II (HI values commonly 500-600) and is marginally mature with respect to hydrocarbon generation (average vitrinite reflectance equivalent of 0.57% Ro).
CPOG Farmington 11-11-80-17W6   back to top

This well penetrated a Late Cretaceous to Precambrian section. The upper part of the well, down to about 3700 ft (~ base of the Notikewin Member) shows moderate to good TOC contents (0.5-1.5%) with HI values mostly in the 200-300 range. As the section is in the early part of the oil window, it could have significant hydrocarbon potential especially for gas. Many samples within the Gething Formation over the 3830 to 4250 ft interval are organic-rich, with some having excellent hydrocarbon source potential such as those at 3960 ft (TOC = 6.40%, HI = 503) and 3970 ft (TOC = 7.40%, HI = 482). No oil-prone source rocks to our knowledge have previously been described from this part of the stratigraphic column in this area. The Nordegg source rock is apparent between 5080 and 5160 ft. It is at the beginning of the gas window and has lost most of its generative potential which is why it has such low HI values. The sample at 5260 ft has a TOC content of 3.28% but its HI is much higher and its Tmax value much lower than what they should be for the level of maturity of this section, implying it is not a source rock. The high PI value for this sample could indicate this Baldonnel sample is stained. TOC contents of Charlie Lake and older sediments are very low suggesting that these strata have no significant hydrocarbon source potential. Tmax values from Late Cretaceous samples at the top of the well suggest these strata are in the early part of the oil window. The Tmax profile shows a ‘jump' at around 3880 ft within the Gething Formation suggesting a possible unconformity with samples at a level of maturity around the end of the oil window or wet gas generation zone. Tmax values increase gradually down to the Nordegg Formation which is in the gas generation zone. Below this, there is no trend apparent in Tmax values because of the high maturity of the section.
Hess Mink Lake 11-28-92-13W4   back to top

Early Cretaceous to Devonian samples were analyzed from this well. High TOC samples that also have high PI values (630 and 650 ft) within the Wabiskaw Formation at the top of the well are probably heavy oil intervals. The Devonian section is organic-lean. Tmax is not a useful parameter for indicating maturity in this well. Our regional data indicate that the Mannville Group is immature and the Elk Point Group is immature to marginally mature in this area.
Husky Mobil Rainbow 2-4-109-7W6   back to top

This well penetrated Cretaceous to Middle Devonian strata. High TOC contents in the lower part of the Cretaceous to Mississippian section (~900-1760 ft) associated with high PI values suggests staining over this interval. While most of the Devonian samples have low TOC contents, there are potential source rocks within the Muskwa Formation between 4880 and 4940 ft and within the Muskeg Formation at 5540 ft. The Keg River Formation is considered a source rock for many of the Rainbow oils (Creaney et al. 1995) but no source rock intervals are evident from this data. There is a high TOC sample from 6320 ft but its low Tmax value (350 C) suggests it is contamination. Tmax values show a good trend with increasing depth over a maturity range of immature to marginally mature for the ~900 to 3600 ft depth interval. The organic-rich Muskeg Formation samples appear to be in the middle of the oil window.
AEC et al. Senex 14-3-93-3W5   back to top

A Devonian section was analyzed from this well. Cuttings throughout the well have very high PI values (0.70) suggesting that the whole interval is extensively stained or that an oil-based mud was used to drill this well. The former possibility cannot be completely ruled out, at least for some portions of the well. The interval between 910 and 1080 m within the Beaverhill Lake and Slave Point formations that shows elevated TOC contents, corresponds to the zone of oil production from the Senex Field. A marginal Lower Keg River Formation potential source rock has been sampled in core between 1256.0 and 1288.8 m as part of the Chow et al. (1995) study. It may be represented by the 1295 and 1300 m cuttings samples which have TOC contents of 1.72 and 2.14% respectively. The organic matter in the core samples is marginally mature and has PI values less than 0.4. As this is considerably less than the PI values of the cuttings samples, this supports the notion that the cuttings have been contaminated to some degree by a drilling additive (possibly diesel). The Keg River sequence sampled in core has a lower hydrocarbon potential than at other locations in the La Crete Basin (e.g. Chow et al., 1995), containing Type II-III rather than Type II or Type II-I organic matter.
Imperial Pac. Siphon Creek 1-26-86-16W6   back to top

This well penetrated a Late Cretaceous to Precambrian section. As observed for the Farmington 11-11-80-17W6 well, the Gething Formation shows elevated TOC contents and HI values compared to surrounding samples (e.g. 3630 ft, TOC = 5.07%, HI = 323) which could be additional evidence of a possible source rock in this unit in this part of the basin. The Nordegg source rock is apparent between 3870 and 3930 ft with TOC contents between 2.62 and 3.03 % and HI values of between 242 and 349. It is in the middle of the oil window at this location and has lost much of its generative potential, as indicated by the relatively low HI values compared to those published on immature samples (Riediger et al., 1990). Some samples with somewhat elevated TOC values between 4860 and 4950 ft, within the interval designated as Spray River Group, could represent the Doig Formation source rock. The sample from 8320 ft with a TOC content of 1.03% is at the right depth to represent a very mature Exshaw source rock. Three samples in the Devonian part of the well (9670, 10110 and 10390 ft) have TOC contents of 2.19-2.34%, very similar HI values (41-47) and low Tmax values (409-412) suggesting they represent contamination.

Tmax values show a general trend of increasing with depth in the Mesozoic portion of the well. There is a step in the profile at about 1370 ft where the maturity of the organic matter apparently becomes lower before increasing steadily again. It decreases from Tmax values of about 431-433 C to about 420-422 C (i.e. from early mature to immature) at this depth. It is possible that this represents a fault. However, this step also coincides with an interval of elevated TOC contents. Tmax values appear to be back on the original trend by about 1700 ft suggesting the possibility of Tmax suppression (Snowdon, 1995) over this interval. Overall, the upper part of the well appears to be early mature with maturity increasing so that at the base of the Mesozoic the end of the oil window has been reached. Paleozoic sediments are in the gas generation zone.
Rex W. Stoddart 11-10-86-20W6   back to top

It should be noted that the stratigraphy supplied by the operator for this well is suspect. The 4220 and 4250 ft samples have relatively high TOC contents (1.20 and 1.82%) and HI contents (461 and 412) and could delineate the Nordegg Formation source rock at this location. There are a number of samples designated as Spray River Group over the 5450 to 6020 ft interval that have high TOC contents (>1%) and PI values which could be due to reservoired hydrocarbons within this part of the sequence. Tmax values show a reasonable trend with increasing depth. Samples appear to be early mature at about 2000 ft and have reached the middle of the oil window around 5500 ft.
Amoco ICG Tall Cree 3-26-104-12W5   back to top

Mostly Devonian-aged cuttings were analyzed from this well. These data do not indicate any significant hydrocarbon source potential in this section. Higher TOC samples from 850 and 910 ft are contamination. Keg River Formation potential source rocks have been observed in cores from wells drilled a little to the east of this one but are not obviously evident from this data although a sample from 1130 ft (TOC = 0.77%, HI = 432) could indicate that thin intervals are present in this well. Tmax values are not useful for evaluating maturity in this well. Rock-Eval and optical data indicate that the Elk Point Group is marginally mature in this area.
Co-Enerco Zama 12-20-116-5W6   back to top

A presumed discontinuous Cretaceous to Middle Devonian section was analyzed from this well. The post-Mississippian section contains a good immature potential source rock between 470 and 760 ft. It is possibly equivalent to the Second White Specks. The Devonian section is suggested by this data to be organic-lean. However, a section within the Keg River Formation, the probable source of oils in the Zama sub-basin (Fowler et al. 2001) was not available for analysis. High TOC contents (up to 5.82 %) have been obtained from Keg River Formation core samples from wells drilled in the 117-6W6 area (Fowler et al., 2001). Tmax values generally increase steadily with depth. Strata at the top of the well appear to be immature to marginally mature with respect to hydrocarbon generation. The potential source rock at 470-760 ft shows suppression of Tmax values similar to what has been described for the Second White Specks (Snowdon, 1995). There is a ‘jump' in Tmax values at around the Fort Simpson-Muskwa contact (~3980 ft) with Muskwa and older samples being in the oil window.