Hope basin

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Hope basin pic .JPG

The Hope basin is a geological feature that is located off the coast of the Chukchi Sea in Alaska. This basin is described as a wedged shape that covers over 205,000 km. The Hope basin is an independent petroleum basin and is the only one out of the surrounding geological features with exploratory-well control and with considerably large seismic coverage. Although it contains a great amount of seismic coverage, the petroleum potential of this basin is not very well known.

History

The Hope basin is a mountain basin that formed on the Brooks Range-Chukotka orogenic belt. The orogenic belt is bounded by the Anyui Suture and the Kobuk Fault along the south flank of the Brooks Range. The Anyui Suture is said to have originated back in the Cretaceous Period, so therefore the north end of this geologic feature may have existed as early as the Paleogenic era. Throughout most of the Cretaceous period, the Hope basin is said to be mainly a sediment source area. Unfortunately, the specifics on the origin of the Hope basin are uncertain.

Geological Setting

Hope basin 2.JPG

The Hope Basin is described by experts as a successor or "intermontaine" basin that has formed on the Brooks Range-Chukotka organic belt. Of the only exploratory wells drilled within this basin, which were drilled on the far southeast side has often been described as “subbasin” and is separated by westward trending linear basement high. Within this separation, there is a stratigraphic section shown that is composed of nonmarine sandstone and conglomerate features. There are numerous normal faults with both northward and southward vergence and an overall northwesterly trend that characterizes this basin. The deeper parts of these faults tend to show a fanning geometry, with many other faults extending all the way to the seafloor. The total basin fill exceeds 6 km in thickness. The basin trends shows onlap and thinning at the basin's margins and thickening beds as you move towards the basin center. On the western side of the basin, seismic data shows significant thickness of deformed Mesozoic strata in angular relation beneath Cenozoic strata.

Petroleum Elements

There have been no petroleum systems identified in the Hope basin area. There have been slim to non-existing records of indications of gas on seismic records. However, there has been minor hydrocarbon occurrences interpreted as biogenic methane or bitumen derived from organic material. The underlying areas of the Hope basin are thermally mature to overmatured for petroleum generation in the area and reached maturity before the Hope basin was created. In result, petroleum source rocks in the Hope Basin are limited to nonmarine Cenozoic basin fill and likely consist of coal and carbonate mudstone. The petroleum source rocks are postulated to be coal beds and carbonaceous mudstone, so therefore they are predominantly gas prone.

Petroleum Assessment

Seeing that there is a decent amount of data limitations and minimal exploration activity, there is a small chance that the Hope basin contains at least one undiscovered petroleum accumulation. The source rocks for this basin were considered to be coal and carbonaceous mudstone but of unknown quality and thickness. This is a pretty substantial dilemma in the attempt to try and discover this basin. Due to volcanic components in the Paleogene section of the Hope basin, there was a significant destruction of the reservoir quality.

Resource

Geology and Assessment of Undiscovered Oil and Gas Resources of the Hope Basin Province, 2008 (usgs.gov)

https://pubs.usgs.gov/pp/1824/d/pp1824d_.pdf

[1]

  1. Bird, K.J., Houseknecht, D.W., and Pitman, J.K., 2017, Geology and assessment of undiscovered oil and gas resources of the Hope Basin Province, 2008, chap. D of Moore, T.E., and Gautier, D.L., eds., The 2008 Circum-Arctic Resource Appraisal: U.S. Geological Survey Professional Paper 1824, 9 p.,