Formation Damage in the Hollín Sandstone: Diagnosis, Evaluation, and Stimulation Practices from Laboratory to Field Implementation, Sacha Field, Ecuador

Abstract

This study describes different laboratory tests used to identify formation damage mechanisms associated in the Hollín sandstone. Traditionally Hollin sandstone is divided into two zones: Lower Hollin or Main Hollin and Upper Hollin, each one with unique characteristics as well as formation damage mechanisms. Laboratory experiments for fluid customization (salinity sensitivity, completion brine sensitivity, regained permeability and relative permeability modifiers (RPM)) are performed to support the different techniques applicable to each reservoir. Acid stimulation was proposed as the main stimulation technique since core flow tests demonstrate improvements up to 400%. Aditional treatments were tested to increase time between interventions such as fines stabilization blends and effective stimulation near water zones (RPM) or as chemical diverters. A workflow for ranked candidate selection is describedwhich includes well, reservoir and mineralogy information available to categorize possible formation damage mechanisms as well as to recommended treatment type, volume and expected productivity post stimulation. Job results from 2016 to August 2021 are included to support the overall investigation. Finally, additional treatment combinations are proposed to improve productivity and to extend the productive life of the well.