CO2 Restimulation in the Michigan Basin: A Second Chance for the Prairie Du Chien

摘要

The Michigan Basin is widely viewed as having only mature reservoirs with limited availability for new treatment designs. The latest re-stimulation program using CO2 might give rise to the opportunity of enhanced production in Michigan as well as benefit new completions. The Prairie Du Chien (a.k.a. PDC) is a sandstone formation with depths that vary from 8,000 to 11,000 feet and formation thicknesses ranging from 50 to 200 feet. Stimulation treatment designs over the past two decades since the PDC's initial drilling have been marked by vast differences in natural gas production numbers from wells within the same field. Restimulation treatments have included cross-linked fluid or nitrogen foam, providing mixed success rates. Problems such as excessive surface treating pressure, limited down-hole sand concentration, early screen outs, and water retention have been experienced in these stimulations. Many existing wells within established PDC fields have declining production numbers despite reasonable reservoir pressure still present. Formation characteristics and well history will be detailed to shed more light on the current wells and re-stimulations taking place in the PDC. The advantages of the CO2 treatment design marked with increased fluid recovery capabilities by gas assist along with the hydrostatic advantages will be expanded upon. Treatment design details with pressure response along with production results from the first set of wells will be included. This paper will expand re-stimulation ideas as well as spur a desire for further investigation into the use of CO2 in the Prairie Du Chien. It also hopes to change the perception of the Michigan Basin to one of a viable, rediscovered source of natural gas in the ever tightening world supply.