Hydraulic fracturing is a key enabling technology for the recovery of vast oil and gas reserves stored in low-permeability reservoirs such as shales and tight sandstones and carbonates worldwide. Multi-stage fracturing treatments comprising large volumes of fluids and proppants into horizontal wells is increasingly becoming the preferred stimulation strategy to achieve economic production from such reservoirs. Despite a sustained increase in drilling and fracturing intensity over the last decade (longer lateral lengths and higher number of fracturing stages per well), the average production rate in major Basins has plateaued. The need exists for innovative fracturing technologies able to enhance well productivity, improve completion efficiency and optimize completion costs with a more rational use of resources.
The Sequenced Fracturing methodology resorts to degradable materials supported with engineering workflows to enhance wellbore coverage and reservoir contact in horizontal wells. For wellbore coverage, the technique relies on composite pills comprising degradable fibers and particles to promote near-wellbore diversion of proppant and fluids to clusters that otherwise would remain untreated. For reservoir contact, the methodology builds on the channel fracturing technique (SPE 135034) with use of fibers and special pumping protocols to enhance proppant transport and placement and increase the volume of reservoir effectively stimulated. Since its inception in February 2014, more than 4000 sequenced fracturing operations have been performed in over 400 wells for 35 operators in 7 countries. Case studies from the Eagle Ford, Bakken, Haynesville and Anadarko basins are presented to highlight the impact of this technology, which has led to increases in production up to 70% in new wells, over 30-fold increases in production in re-fractured wells and reductions in completion time in new wells in excess of 60% with respect to conventional methods.