Characterization of a Shallow Horizontal Fracturing Treatment in Western Missouri
Authors: Bybee Karen 
Published: February 2015

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 102342, "Characterization of a Shallow Horizontal Fracturing Treatment in Western Missouri," by L.K. Britt, SPE, NSI Technologies Inc.; S. Dunn- Norman, SPE, U. of Missouri-Rolla; M.B. Smith, SPE, NSI Technologies Inc.; E. Atekwana, U. of Missouri-Rolla; L. Slater, Rutgers U.; A. Gupta, SPE, and D. Numbere, SPE, U. of Missouri-Rolla; J.V. Fontana and J.H. Viellenave, Direct Geochemical; and J. Pelger, SPE, J-Environmental Inc., prepared for the 2006 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 24–27 September.

A research project, sponsored by the U.S. Dept. of Energy, was undertaken to demonstrate a development method for the heavy-oil reserves that exist at ultrashallow depth in southwestern Missouri and southeastern Kansas. The principal objective was to demonstrate an economically viable method of producing the shallow heavy oil by use of a combination of microbial-enhanced oil-recovery treatments and horizontal fracturing in vertical wells.

Introduction

Heavy oil (8 to 25°API) exists in the shallow Pennsylvanian sands that occur over approximately 8,000 sq miles along the Kansas/Missouri border. The area covers portions of the northeast Oklahoma platform and the Cherokee and the Forest City basins. The Cherokee group is a sequence of alternating shales and sandstones with thin coal and limestone beds. The main productive units within the Cherokee group are the Bluejacket and Warner sandstones.

The Warner sand has been drilled throughout Vernon County, Missouri, and several areas of known oil deposits have been defined. In the latter part of 2000, seven boreholes were continuously cored to a total depth (TD) of approximately 220 ft. All wells encountered heavy oil in both the Bluejacket and Warner sandstones. The Bluejacket sand occurred at approximately 130 to 135 ft with 8 to 12 ft of net pay, and the Warner sand occurred at approximately 160 to 170 ft with 15 to 30 ft of net pay. Warner-sand porosity ranged from 14 to 25%, and permeability in the Upper Warner ranged from 100 to 400 md.

Five wells were drilled to produce the shallow heavy-oil deposits in the Warner sandstone, the Fauvergue Wells 1 through 5 (Fig. 1). The Cushard Wells 4 and 5 were cored wells in the project area. These wells were cored to TD and the cores analyzed as part of the project. Although it was believed that older wells drilled in the Warner sandstone had been fracture stimulated, no information regarding any historical fracture treatments, execution, or performance was available.

Geomechanical Data Set

The geomechanical data set includes profiles with depth of Young's modulus, in-situ stress, and fracture-fluid leakoff. Core from the Bluejacket and Warner sandstone formations and surrounding shales was available from the coreholes drilled, and static triaxial compression tests were conducted on samples to determine Young's modulus. Evaluation of the triaxial compression tests indicated that the Bluejacket and Warner sandstones have an average Young's modulus of 3.1×106 and 1.3×106 psi, respectively. The Rowe coal and the bounding shales have an average Young's modulus of 2.0×106 and 1.8×106 psi, respectively.