The occurrence of natural gas in Michigan has been recognized for many years, but commercial quantities of gas were not developed until the discovery of the Muskegon field in 1927. The total gas production from the Muskegon field to August 1, 1931, has been 6,420,949,662 cubic feet. The Central Michigan area now shows a potential open-flow capacity of more than 60 million cubic feet from 22 wells, but withdrawals have been small because of inadequate pipe-line facilities.
Gas production is obtained from Mississippian sandstones and porous Devonian dolomitic limestones, the latter being most prolific of gas in structures marginal to the Michigan “basin.” The Michigan stray sandstones of Mississippian age are evidently overlapping sandstone bodies in the central part of the state that are the product of the reworking of the Marshall sandstone by a northwestward transgressing sea. The “Dundee “productive horizon is of Devonian age and its porosity is the result of solution due to the presence of the Dundee-Traverse unconformity.
The structures which have affected the accumulation of natural gas in Michigan are comparatively gentle, asymmetrical anticlines with 50–70 feet of closure. The steep dip on the basinward side varies from 100 to 240 feet per mile and the gentle dip is generally about 50 feet per mile. The general shape of the anticlines in many places is arcuate, and the intersection of the prevailing northwest-southeast structural trend with areas of northeast-southwest cross-folding seems to localize the occurrence of natural gas in the state.
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Alberta is the only western Canadian province in which a production of natural gas and oil has been developed. Natural gas was discovered in 1885, and at present there are seven producing fields and 330 miles of main pipe lines.
Alberta is divided into eight structural provinces; four of these are gas-producing regions, one is prospective, and the others are of no interest as gas areas. The stratigraphic column has three persistent features, namely, the Palaeozoic limestone section, the profound unconformity superimposed on it, and the succeeding Mesozoic section of transgressive-regressive deposits.
The Turner Valley field is the only developed field producing from formations of Palaeozoic age, though there have been significant discoveries suggesting that other fields are present. A theory is advanced in this paper to explain a Palaeozoic origin for the heavy oil and bitumen in the basal sandstones of the Mesozoic. The gas accumulations in the basal sands were later derived from the bitumen and heavy oil. The reserves of gas in Palaeozoic rocks and the basal sands of Mesozoic age are large.
During Mesozoic time there were at least five marine transgressions of the seas, and there is a marked relation between the marine shales and the gas-bearing horizons in rocks of Mesozoic age. Gas is generally found in the sandstones immediately overlying, within, or immediately underlying the marine shales.
Gas is found in rocks of Jurassic age in the Southern Plains and the Southern Foothills. The reserves are estimated to be about 80 billion cubic feet. Only small amounts of gas are now produced from Jurassic horizons. Gas is found in marine formations of Comanche age in northern Alberta, but there are no developed fields, and the reserves are unknown. There are three gas-bearing horizons in the Colorado (Gulf series), with several fields, including the Foremost, Viking, and Medicine Hat fields. The possible reserves are large and are probably in excess of 600 billion cubic feet. The Lower Montana and Upper Montana rocks (Gulf series) produce gas over large areas, but the yields are small and the horizons are of minor importance. There are no marine rocks of post-Mesozoic age, and the only gas occurrences are small flows from lacustrine deposits.
The analyses of natural gases in Alberta when arranged according to geologic horizons and localities appear to show an increase in the proportion of higher hydrocarbons to methane in a westerly direction for a given gas-bearing horizon. This may be due to the effect on the source material of increasing metamorphism westward.