Autonomous Perforating Tool Works Without Umbilicals and Self-Destructs During Process
Authors: Wilson Adam 
Published: February 2015

This article, written by Editorial Manager Adam Wilson, contains highlights of paper SPE 147296, ’Autonomous Perforating System for Multizone Completions,’ by Pavlin B. Entchev, SPE, and Renzo Angeles, SPE, ExxonMobil Upstream Research Company; Krishnan Kumaran and Niranjan Subrahmanya, ExxonMobil Corporate Strategic Research; and Randy Tolman, SPE, RC Tolman, prepared for the 2011 SPE Annual Technical Conference and Exhibition, Denver, 30 October-2 November. The paper has not been peer reviewed.

Autonomous downhole tools offer a range of advantages over conventional tools controlled manually through umbilicals. For instance, perforating guns or bridge plugs could be dropped or pumped downhole without the use of wireline, coiled tubing, or tractors. Because umbilical intervention is no longer required, the tools may perform an action automatically (e.g., perforate a desired interval), with substantial cost reduction and enhanced safety. An autonomous perforating system currently being developed is based on using a self-destructing disposable perforating tool that is run without a wireline. To accomplish this, the tool has three frangible components: a logging device, an onboard navigation system, and friable perforating guns.

Introduction

The autonomous system presented here enables individual stimulation of each zone in a multizone completion interval without the use of wireline or other conventional umbilicals. Because of such critical step elimination, the proposed system eliminates much of the crane work and lubricator exposure within the drilling footprint. More important, no additional wireline trips are required to change perforating-tool assemblies and pumping rate is no longer limited to the breaking strength of the cable. Fracturing operations can be continuous, as with the case of ball-actuated openhole technology, but with the additional advantage of being able to complete and treat individual zones as opposed to an entire range of perforation clusters that can lead to suboptimal stimulations. In addition, safety is improved by the reduction of equipment at surface, which could enable simultaneous operations such as completion while drilling, where wells are completed while the drilling rig continues to operate on the same pad. Thus, the system presented here has the potential to accelerate the production startup in pad development and improve the economics of the project.

Objectives

The overarching goal was to develop a prototype autonomous perforating system that meets and exceeds the current industry safety standards and requirements while using industry standard hardware such as perforating charges. With this goal in mind, the design of the autonomous perforating system should satisfy a number of specific objectives. One of the main objectives was to have a disposable tool that destroys itself downhole without obstructing future operations of the well. In addition, the system should not require any changes during the well-construction phase and should be usable in both newly drilled and previously drilled wells. This requirement eliminated several design possibilities, such as putting tags or markers in specific casing points.