Coiled Tubing Sets Packers Precisely During Offshore Well Abandonment
Authors: Carpenter Chris 
Published: June 2020

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 29839, “Successful Offshore Coiled-Tubing Permanent Well-Abandonment Operation Uses Downhole Real-Time Parameters To Set Inflatable Packers With Surgical Precision in Cost-Effective Manner,” by Cassiano Guimaraes, Eduardo Delgado, SPE, and Lucio Galvao, Halliburton, et al., prepared for the 2019 Offshore Technology Conference Brasil, Rio de Janeiro, 29-31 October. The paper has not been peer reviewed. Copyright 2019 Offshore Technology Conference. Reproduced by permission.

The complete paper discusses the systematic approach adopted by a service company to achieve the goal of safely abandoning wells offshore southwest Brazil with different completion types using light workover vessels. Having determined the abandonment methodology, service company personnel developed processes and procedures to reach the objective that included advances in coiled-tubing (CT) rigup procedures and use of a real-time telemetry system.

Introduction

The use of a CT real-time telemetry sys-tem enables accurate setting of a through-tubing inflatable device system (T-TIDS) by monitoring the necessary downhole parameters in real time. The paper presents a case study wherein sensors [such as a casing collar locator (CCL) to perform depth correlation before setting the T-TIDS and placing cement plugs, a pressure sensor to monitor the T-TIDS setting, and a CT internal pressure sensor to help ensure all cement was pumped out of the CT] were used in real time to verify that well barriers were set in place, contributing to successful well abandonment. Real-time data collection proved to be the most-effective methodology for running critical equipment, thereby saving overall time and cost.

General Abandonment Requirements

The decision for permanent abandonment of a well is not always easy. In Brazil, the National Agency of Petroleum, Natural Gas, and Biofuels (ANP) has established a compendium of rules for oil companies that extract and produce oil, gas, and derivatives. This involves a group of barriers known as CSB, which is a set of one or more elements with the objective of preventing the unintentional flow of fluids from the formation to the external environment and between intervals in the well considering all possible paths. The CSB’s aim is to guarantee the isolation of intervals with current and future flow potential. Cement or other material with similar performance must be used as barrier elements.

Achieving a unique solution is dependent on having up-to-date information regarding the wellbore diagram, reservoir, history, well location, CT-performance capability, surface equipment, well-control equipment, and proposed layout. Fig. 1 illustrates the design of the 3D wellbore graph generated with modeling software.

Solution Described

The well discussed in this work contains deposits of asphaltene and sand-accumulation debris. For the operator to perform a plug-and-abandon (P&A) intervention, an effective solution to provide reliability safely is necessary to avoid worsening the well condition and delaying the intervention. The service company offered experienced personnel and engineering capabilities, a customized program for job-specific requirements, the CT package, and reliable processes and advantages compared with heavy workover units. Included as part of those advantages is a variety of bottomhole-assembly (BHA) tools that can be deployed in the well with the capability to be customized, working together with wireline operations and the robust management safety system.