Characterization of a Shallow Horizontal Fracturing Treatment in Western Missouri

Abstract

Abstract Normally, the objective of hydraulic fracturing is to design and execute a fracture treatment that achieves the desired fracture dimensions (length & conductivity) to maximize a wells production rate and reserve recovery. Treatments are most typically applied in reservoirs with in-situ stresses that yield vertical fractures. Case studies of horizontal fractures and identification of the key parameters unique to horizontal fractures are uncommon, in part due to the fact that oil and gas reservoirs occur in relatively deep subsurface formations. A research project, sponsored by the U.S. Department of Energy, was undertaken to demonstrate a development method for the significant heavy oil reserves that exist at ultra-shallow depth in the Pennsylvanian sands in Southwestern Missouri and Southeastern Kansas. The principal objective is to demonstrate an economically viable and sustainable method of producing the shallow heavy oil using a combination of microbial enhanced oil recovery (MEOR) treatments and horizontal fracturing in vertical wells. In this application, the purpose of hydraulic fracturing is to expose additional reservoir surface area for subsequent microbial injection. Once the hydrocarbons are contacted by the microbes, the horizontal fractures are to provide a conductive pathway back to the wellbore for the lower viscosity hydrocarbons to flow. Two wells in the study area, Fauvergue 1 and 5, were cased, perforated, and hydraulically fracture stimulated. Analysis of the treatments with surface tiltmeters confirmed that horizontal fractures were created. Geomechanical studies conducted prior to fracturing confirmed that the Pennsylvanian sands are more competent and have a greater Young's Modulus than previously reported in the literature. This paper provides documentation of the extensive laboratory study conducted to develop an understanding of the elastic properties of the Warner and Blue Jacket sandstones and shale, fracture fluid sensitivity, and embedment testing. The paper also reports the horizontal fracture stimulation execution and pressure analysis. Surface tiltmeter data are reviewed with the hydraulic fracturing performance, to determine whether the treatment objectives were achieved.