Well completion optimization using automatic-release guns, pressure and rate transient analysis

Abstract

An operational initiative for the initial completion and evaluation of reservoirs is presented. It uses the concepts of pressure and rate transient analysis to calculate well potential and rate request to the Ministry of Energy and Non-Renewable Natural Resources (MERNNR), without the need to perform a Build Up test and reducing the time to definitive well commissioning. The procedure is based on the use of automatic-release guns, BHA's with ESP equipment and pressure sensors with real-time transmission. Prior to the activation of the guns, the ESP is installed , the well fluid is evacuated to generate “Low Balance Conditions” and once the cannons are activated, the well enters to the emerging phase and by hydrostatic balance conditions, the well pressure is approaching to the static reservoir pressure. After 12h of the gunfire, the ESP equipment is turned on with constant surface parameters. The pressure and flow data allow to calculate the well potential. The use of automatic-release gun technologies and ESP equipment with "real time" pressure monitoring allows to design a different proposal for the initial evaluation of wells, prior to the request for maximum oil rate setting by MERNNR in Ecuador.  The traditional proposal included the use of BHA's jet pump evaluation and memory gauge for Build Up Test. Under this methodology it was possible to estimate the potential of the well before installing final completion (ESP in most cases). The average time elapsed between the cement log and the well commissioning was +/- 16 days assuming that the same drilling rig is used in the completion which is costly. In case of using a Workover Rig for the completion phase, the time associated increases (+/- 15 days. ENAP's goal since 2018 was to optimize completion times and determine the well potential to obtain maximum oil rate setting by MERNNR. The result was to reduce the time between the completion of the cement register and the definitive production to 7 days.