Some Potential Long-term Effects of Oil and Gas Development on Water and Oil Shale Resources, Piceance Basin, Colorado

摘要

The projected BLM (2015) oil and gas development in the Piceance Basin (additional 10,000± wells) can significantly reduce the available resources of oil shale and usable water. The potential for leaky annuli in gas wells will require a "no-mining" safety zone around each well that will "sterilize", basin wide, 10's of billions of barrels of synthetic shale oil. Along with leaked gas, the upward flow of saline "formation water" and resulting degradation of ground water will greatly increase mining costs. A largely unrecognized issue, the future widespread deeper drilling and hydrofracturing for gas in the underlying Mancos Shale, can result in a large "new" aquifer, with a capacity of perhaps 20-40± million acre feet. This aquifer will fill with water. From where? Overlying aquifers via leaky O&G wells is an obvious source. Deeper aquifers may provide recharge. When full, the resulting water quality is likely to be unusable, and will discharge, probably to overlying aquifers and streams. Further such widespread drilling in The Mancos in NW Colorado and NE Utah could potentially create "new" aquifers with total capacities of many hundreds of million acre feet. Such implication require further studies. The above developments, which potentially can amount to a trillion± dollars in loss and costs, can be minimized or prevented by effective planning for well spacing, design, and especially by completing oil and gas wells that do not leak along the annulus, and thus minimize sterilization of oil shale. A scientifically designed and operated ground water monitoring system is a must for multiple resource development in The Basin.