Geology and Production Performance of the Niobrara Low-Permeability Reservoir in the Denver-Julesburg Basin

Abstract

ABSTRACT This paper presents geologic and reservoir parameters of the Niobrara Formation in Weld County, Colorado. With the use of computer generated contour maps, it is possible to predict favorable areas of profitable Niobrara pay. This predictability is further enhanced when combined with Scanning Electron Microscopy (SEM) analysis and historical production analysis. The SEM results show that the Niobrara in this region is a micrite and not a true chalk. The porosity is, therefore, lower than would be expected in a chalk. The thickness of the second bench and the pore volume appear to have a better relationship to known faults in the Niobrara than present day structure. These parameters were analyzed in order to predict areas of faulting and fracturing, since these areas are known to have the best potential for Niobrara production. Use of these techniques indicates that the northern portion of the study area has the highest potential for successful Niobrara wells. Based on the limited amount of production history available in this region and current market oil and gas prices, the average Niobrara well in this region appears to be uneconomic unless supported by additional production from other horizons. However, computer mapping suggests that current production is not located in the most promising areas. Greater Niobrara production potential may be found in local areas characterized by greater porosity, thicker benches, and proximity to faults.