Lower Napo Shale Formation in the Oriente Basin: Analysis of Reservoir Formation Conditions and Prediction of Favorable Areas

Abstract

Considering the current situation of Ecuador being rich in oil and poor in gas sources, we evaluate the exploration priority of the shale gas potential of the primary oil- and gas-bearing basin in the country—the Oriente Basin. Richness criteria for shale gas reservoirs are proposed according to the evaluation. On the basis of the main lithological characteristics, geochemical factors, depth, distributional stability, and data availability, the lower shale rock of the Napo Formation in the Oriente Basin is selected from five potential source rocks as the shale rock that shows the greatest potential for shale gas. The reservoir formation conditions of the Napo Formation are studied. The thickness of the lower Napo shale rock is obtained by studying the 38 wells in the basin. Then, the depths of the lower Napo shale rocks are mapped by interpreting 29 seismic lines in the basin. Next, the distribution of the geochemical factors of the basin is derived by analyzing the outcome of the predecessors. Finally, the areas with favorably rich shale gas are predicted by studying the different reservoir formation conditions. The northwest (blocks 11 and 18), east (blocks 12, 67, 18, 31, and 63), and west areas (blocks 29, 20, 22, 28, and 70) of the basin are prospective areas that are rich in shale gas (oil). This study provides guidelines for the exploration and development of the shale gas in the Oriente Basin.