Show LANCE CREEK OIL FIELD WYOMING the lance creek oil field niobrara Nio brara county eastern wyoming which is described in a bulletin recently published by the united states geological survey department of the interior was mapped by E T hancock in the fall of 1918 about six months after the discovery well had been completed the beds that are exposed on the surface in and near the oil field were studied in considerable detail and their relations to each other and to the formations exposed in other oil fields in wyoming were carefully determined at the same time some of the more prominent and easily traceable beds were mapped and the geologic structure as exhibited by the surface formations was worked out the work shows that the surface formations range in age from quaternary to upper cretaceous montana the western end of the field is covered by tertiary beds that belong to the white river formation which was deposited after the beds that now underlie the white river formation had been folded to form the lance creek anticline accordingly in this part of the field the geologic structure could not be worked out from the surface evidence to the east and north of the white river beds extensive deposits of pierre shale are exposed in this formation single beds could not be traced that it was impossible for any great distance so to do extremely precise work however many of the be beds dg in the pierre shale showed by their dip and strike the general nature of the folding at the points of and thus the approximate outline and extent of the anticline in the area where the pierre shale is exposed could be ascertained the most prominent structural feature in eastern niobrara Nio brara county is the hartville uplift which connects the rocky mountain front range and the black hills uplift the hartville uplift is an irregular arch whose axis is marked by exposures of granite schist and limestone near hartville and lusk at rawhide butte and at a number of other the position of this axis is also indicated by the old woman anticline which brings to the surface the uppermost beds of the sundance formation the lance creek field which occupies a great arch or anticline of sedimentary beds west of the old woman anticline is separated from the hartville uplift by a broad syncline but the precise nature of the structure in the area which intervenes between the two anticlines anti clines is concealed by the flat lying white river beds the report presents some of the results of drilling and gives information concerning the results obtained in about twenty one wells which had been completed by october 1919 and also describes the quality of the oil and gas found in the field and makes suggestions for development |