Optimizing Horizontal Completions in the Barnett Shale With Microseismic Fracture Mapping

Abstract

This article, written by Technology Editor Dennis Denney, contains highlights of paper SPE 90051, "Optimizing Horizontal-Completion Techniques in the Barnett Shale Using Microseismic Fracture Mapping," by M.K. Fisher, SPE, Pinnacle Technologies; J.R. Heinze, SPE, and C.D. Harris, SPE, Devon Energy Corp.; B.M. Davidson, SPE, C.A. Wright, and K.P. Dunn, Pinnacle Technologies, prepared for the 2004 SPE Annual Technical Conference and Exhibition, Houston, 26-29 September. The Barnett shale of north Texas is an ultralow-permeability reservoir that must be fracture stimulated to obtain commercial production. Techniques to optimize hydraulic-fracturing effectiveness have evolved over the past decade. In 2002, the Newark East field produced 202 Bcf, the seventh largest gas producer in the U.S. This pilot study compared production from the first 23 horizontal wells in a “core” area of the Fort Worth basin with vertical wells in the same area. Drilling and completion strategies, fracture-network areas, and fracture effectiveness were compared with the standard procedures used in vertical Barnett wells. Introduction The commercial success of Barnett shale development programs is attributed to a change in stimulation techniques in 1998. Previously, most Barnett shale wells were completed with massive hydraulic-fracture treatments that used crosslinked-gelled fluids, some carrying more than 1 million lbm of proppant. Because of the extremely low permeability of the Barnett, its inability to efficiently clean up fracture damage from gels, and the high cost of massive hydraulic stimulations, most Barnett treatments did not provide an adequate investment return. In 1998, Devon Energy experimented with an old fracturing technique that was regaining acceptance at the time in east Texas. The technique was light sand fracturing, or “waterfracs.” In the Barnett shale, this technique provided a much larger surface area of contact with the reservoir and minimized fracture-face damage, resulting in improved productivity. Even with the success with light sand-fracturing treatments, not every area of the Barnett proved as successful as the core area in Wise and Denton counties. As shown in Fig. 1, the Barnett shale covers a large area, from the Fort Worth basin past the Permian Basin of west Texas, into New Mexico, but the quality and quantity of Barnett pay varies substantially from the traditional core area to the newer plays on the fringes. Successful development in the newer areas will likely require additional changes in completion techniques, and several new strategies are being tested in both core and fringe areas of the Barnett shale.