New Stratigraphic Play
in the Williston Basin:
Islands in the Cambrian Deadwood Sea
Articles in the July 22, 1996 issue of the Oil & Gas Journal, the July 19 Rocky Mountain Oil Journal, and the August 8 Petroleum Explorer describe the results of a well recompletion in the Cambrian Deadwood sandstone in the Newporte Field. The field is located in the Williston Basin in the northwest corner of Renville County, North Dakota (T 163-164 N, R 87 W, about 3 miles (4.8 km) south of the Canadian border). The Larson #23-9 well was one of seven wells drilled into or near the Precambrian basement by Shell Oil in 1977. The #23-9 produced over 7,000 barrels of oil before being plugged by Shell in 1980.
The recent recompletion by Eagle Operating had an IPF of 1,025 b/d and 325 Mcfg with no water.
The Cambrian-age stratigraphic reservoir appears to be trapped by or associated with Precambrian basement topography. Existing seismic data at Newporte lack sufficient frequency to clearly image the Cambrian sandstone reservoirs. Available geologic data and well control suggest that this new play extends into adjacent counties, and may be widespread in the Williston Basin from South Dakota to Saskatchewan and Manitoba. The play may also exist in many other basins. Seismic data (below) over a similar feature in Bottineau County, 50 miles (80 km) east of Newporte, show that the basement interface can be seismically imaged and interpreted.
StratSeis Geophysical Incorportated (SGI) proposes to acquire non-exclusive, pre-funded, high-frequency swath seismic and comcomitant, close-spaced gravity, magnetic, and geochemical data over the Newporte anomaly. The program will tie all seven Shell wells and will provide a clear view of the relationship of Cambrian stratigraphy and facies to Precambrian topography. The newly acquired data will be combined and interpreted with available vendor data, well and core information, newly written reports and available literature. All raw and processed data will be preserved digitally and presented in workstation format.
SGI's goal is to provide a fully integrated, calibrated, correlated, interpreted and documented set of data and supporting information. The final integrated product will involve contributions by several experienced consultants and specialists working in the Williston Basin. They will present their findings at a private closed seiminar where participants will hear and question the consultants involved in acquiring and interpreting these data. The cost per participant is based on one-sixth of the actual documented costs plus 5%. The cost is estimated to be a maximum of $47,500 (US dollars) per participant ($820/mi = $509/km) for the entire integrated, interpreted package. Late sale prices will increase by at least one-third and late participants will lose the opportunity to attend the private seminar.
SGI proposes to:
1. Collect 14.5 swath-mi (23.3 swath-km) or about 58 line-mi (93 line-km) of high-frequency seismic data using a pair of common source/receiver lines located 1,320 ft (402 m) apart in four 3.62 mile-long (5.83 km) swaths that tie all seven wells. Data will be acquired at 80 ft (24.4 m) GPs with long, proprietary SGI nonlinear vibrator sweeps at 400 ft (121.9 m) VPs using four M-18 (or larger) vibrators. Data will be recorded on a high fidelity 24-bit instrument system. The seismic data will be processed by Sterling Seismic Services and be presented in raw and processed workstation-ready format.
2. Record gravity data, magnetic gradiometer measurements and collect surface soil samples for iodine geochemical analysis along the source/receiver lines. Gravity and magnetic data will be acquired with an 800 ft (243.8 m) spacing. Magnetic gradiometer data will also be acquired with continuous sampling between these points. Soil samples will be collected at every 400 ft (121.9 m). The gravity and magnetic data will be processed, interpreted and described by Gibson Consulting. The iodine geochemical analysis and interpretation will be done by ATOKA Geochemical. All data and interpretations will be presented in a workstation-ready format.
3. Acquire maps and interpretations from contractors, vendors, or other sources over the 16 square mile (41.2 square km) Newporte feature. Included are topographic, Landsat, aeromagnetic, gravity and photogeologic surface structure. The maps and interpretations will be scanned or digitized and presented in workstation-ready format.
4. Digitize and provide synthetics of each of the seven Shell wells and tie them to the seismic data. Also digitize and convert to workstation-ready format log curves from the Red River to Total Depth. Additionally, scan and provide all well data and completion information in hard-copy and digital format.
5. Compile a comprehensive integrated interpretation and report ustilizing data from all sources. Included will be raw and processed digital versions of all acquired data, well-log synthetics, digital log traces, core and lithologic descriptions and supporting information. Included will be a report on seismic and other data acquisition (SGI); a report on seismic processing (Sterling Seismic); cross-sections tying the seven wells (Eisel Oil); a report on regional Cambrian stratigraphy (Hendricks & Associates); a report on basement geology and tectonics (Gibson Consulting -- expansion of part of their Basement Tectonic Interpretation of the US); a report on the iodine geochemical results (ATOKA Geochemical); published information, reports, and a field course to a very well-documented, exposed, seismic-scale analog (Hendricks and Associates and SGI) and an extensive bibliography (SGI).
6. Present the final integrated product at a private closed seminar where participants will hear and question the geophysicists, geologists, and geochemists involved in acquiring, processing, analyzing, interpreting, and documenting these data.
If you are interested, please respond as soon as possible.
Contact John Andrew at Tel/Fax (303) 773-0978
or Don Kidd at Tel/Fax (303) 773-3751.
You can also send e-mail to Dick Gibson
for forwarding to Mr. Andrew or Mr. Kidd.
