The American Oil and Gas Reporter - January 2012 - (Page 151)
Operators Seek Fracture Consistency
Heterogeneity and variability in rock composition, texture and stress have led to inconsistent production from horizontal shale wells. Achieving a better understanding of the challenges this variability presents to horizontal multistage completions is leading to advanced measurements and processes that achieve more consistent production results and improved fracture efficiency.
By Kyel Hodenfield
PARIS–Advancements in the process efficiency of horizontal well drilling and multistage hydraulic fracturing have enabled the vast economic development of unconventional shale reservoirs in North America. A manufacturing approach to well construction–developed through cooperation between service providers and operators–has driven down costs at an impressive pace; however, further focus is required to achieve better and more consistent performance on production results, as many wells are not economic, especially at current gas prices. This inconsistency of production results has been experienced in all the basins across North America, and provides an opportunity for the next process improvement in the economics of unconventional plays. Hundreds of new-generation production logs have been run in unconventional wells. Analyzing these logs indicates that 15-20 percent of the fracture stages and 3540 percent of the perforation clusters do not contribute to production. Published numerical simulations of shales have shown that as much as 75 percent of each hydraulic fracture does not contribute to production. Often, the fracture is not propped effectively, is isolated from the main fracture or does not clean up effectively. Some imbibition of stimulation fluids takes place, although testing indicates an imbibition rate of less than 5 percent of the total fracturing fluid volume.
JANUARY 2012 151
Table of Contents for the Digital Edition of The American Oil and Gas Reporter - January 2012