The Deep Water Field Alpha Plug and Abandonment Campaign – An Integrated Approach to Optimize Operations and Costs

Abstract

After having been developed in the early 2000's and put on production since then, the deep water (700 M water depth) Field Alpha is now at the end of field life and in the plug and abandonment (P&A) process. Although this field-life phase does not make any money for an E&P operating company, it can be a liability and put the company's reputation at stake, if not done correctly. Therefore, like any other field-life phases, it requires a professional and multidisciplinary integrated approach to deliver it while reducing the company's exposure. P&A campaign involves many stake holders: the local authorities, its technical and operational representative / auditor, the operator's well engineering community, the subsurface team, e.g., petrophysics team, and the operator's management. Understanding all their expectations and KPIs is primordial to prepare and successfully deliver such operations. The P&A process relies on the placement of adequate "barriers" inside the well to guarantee blockade of any potential reservoir fluid communication either within separate reservoirs (to avoid any reservoir re-pressurization through cross flow) or with seabed / surface which could impact the environment. As part of the well barrier, annuli cement quality and efficiency must be checked by cement bond evaluation. The petrophysics team has the responsibility to both define, in collaboration with others team members, the cement quality criteria and then to evaluate the cement quality in timely and efficient manner. In this campaign, which is expected to run for more than a year, with several petrophysicists involved both in the preparation phase and in the operation phase, e.g., execution and results validation, consistency in the process is of utmost importance. This paper presents the workflow put in place by PETRONAS Carigali during the Field Alpha P&A campaign. It emphasizes on the petrophysicist role and responsibilities from the preparation phase, during the operations, and through the results validation. The learnings and experiences acquired during the Deep-Water Field Alpha P&A campaign are now going to be transpose to domestic and international assets by means of corporate guidelines and workflows.