Permian Basin’s Evolution of Hydraulic Fracturing Techniques Over the Last Decade: Vertical to Horizontal Wells

Abstract

Hydraulic fracturing has evolved at a rapid pace over the last decade, Permian Basin being the center of all the evolution. In 2011, vertical wells were completed on a day-time operations model with 10 to 13 different frac stages with different volumes of proppants and complex fluid systems. The same engineering & consulting teams in 2013 were challenged with horizontal wells to be completed using cost effective slickwater designs with high volumes of water and proppant on a 24-hour operations model. Finally, in 2018, Operational excellence with engineering accuracy has been possible due to lot of tweaking. This paper would present the successful completion strategies that have been put together from the lessons learnt over 5000 frac stages done in the field. The difference between success and failure is often times determined in the way we rig-up even before the well head is open. Customer’s desire in total clean fluid pumped per stage or total proppant placement efficiency or both. Moving between fluids, slick water systems to linear and cross link fluids is very important to our success. Higher rates with slick water frac-jobs giving us high penetration using low viscosity fluids and the "sand banks" formed in the lower parts of the zone are swept using linear or dirty gel sweeps. Towards the end when there is no width available for the fractures we switch to cross-link fluids that provide more near wellbore conductivity with less penetration and, using high viscosity fluids and resulted in a perfect support system. Application of both the frac-theories on real-time changes was possible with the Men & Machine integration in the Permian basin. The key characteristics of the Hybrid frac-jobs are:Usage of 100 or 40/70 mesh sand helped in fluid loss that also acts as a micro fracture proppant;Spear-heading with 2 batches of acids helped in breaking the zone and cleaning the perforationsDual Slickwater Pads with a pro-slug helped to get the penetration that we needed and also helps in determining the concentrations of the proppant behind the pad. This reduces our chances of screening out.Transition from 30/50 proppant to 20/40 proppant concentration based on the way the zone reacts to the proppant.Use of linear gel spacers allowed for higher sand concentrations in the Slickwater section of the frac-job. This provided us the width necessary.Tail ending with a 20/40 proppant using cross-linked fluids gave us a higher near wellbore conductivity This paper gives a complete outlook to field application of Hydraulic fracturing and the special use of diverters from the lessons learnt in the Permian basin.