Boulder Mancos Field: Development Analogy for Naturally Fractured Reservoirs

Abstract Boulder Mancos Field, San Juan Basin, New Mexico covers approximately 1,700 acres and has produced just over 1.8 MMBO and almost 1.5 BCF of gas from 24 wells. Production is from fractures in the sandy Niobrara member of the Mancos Shale at an average depth of 4000 feet. The field was developed on 80 acre spacing and the small amount of pressure data available along with the production histories indicate that there is communication between wells and that all the wells are producing from a common reservoir. The field was over-drilled and most of the oil could have been recovered from 4 or 5 properly placed wells. The best producers, wells that made over 100 MBO, fall in a trend that cuts northwesterly across the overall northerly trend of the field. This northwesterly trend follows the structural strike and, for the most part, the best wells are either in close proximity to the faults or are at the point of maximum curvature along this flexure. The conclusions from this study are: 1) Boulder Mancos Field is a structural feature with growth at least from Mancos (Niobrara) time through Lewis Time; 2) the trend of high productivity wells follows the strike of this structural feature, with the best producers generally being in proximity to the faults or at the point of maximum curvature along this flexure; 3) there is excellent communication between wells on 80 acre spacing; 4) the wells all appear to be producing from a common reservoir; 5) the field was over-drilled and most of the oil could have been produced from 4 or 5 properly placed wells; and 6) at this depth and reserve potential this would certainly be a commercial development project at today’s economic conditions.