Salvaging Restricted Entry Unconventional Lateral Sections Through the Utilization of Multi Stage Diversion Frac

Abstract

The objective of the paper is to introduce a design procedure aimed at targeting the stimulation of unconventional lateral sections that are inaccessible using the conventional plug-and-perf (PnP) method. This salvaging process utilizes the diversion frac technique allowing for the stimulation of challenging lateral sections with minimum well intervention. Consequently, improve stimulation efficiency and minimize intervention costs. When a certain section of the lateral cannot be accessed while running in hole performing PnP operations, an immediate investigation procedure is carried out to determine whether that was due to an equipment failure or a deformed section of the wellbore. If the passage of PnP BHA cannot be rectified, the diversion frac technique presents an ideal solution to stimulate the challenging section salvaging valuable lateral footage. The design for a successful diversion frac is based on multiple variables including the length of the attended lateral section, number of perforating clusters, cluster efficiency, diverter selection and frac design. The restricted section is entirely perforated to minimize the number of well intervention post frac stages. During the stimulation phase, fluid diverters are then pumped to divert fluid flow from clusters taking fluid to the next. Hence, an upward trend in frac treating pressure is noticed with more diverters pumped indicating fluid diversion from existing perforations to new ones. The implementation of the diversion frac technique resulted in salvaging in excess of 1,300 ft of lateral footage per restricted well. Additionally, it is now serving as a salvaging option if restricted sections were encountered in future wells. This process was performed successfully on multiple unconventional wells in Saudi Arabia. Evaluation of this approach was conducted simultaneously with field implementation and hence, modified to reach the optimum design accounting for cluster efficiency, frac design and diverters selection.