Abstract

This paper presents the Petroleum Development of Oman (PDO) Rigless plug and abandonment (P&A) methodology, technologies & practices which resulted from the corporate goal to find a cost effective means to P&A obsolete oil wells. As the main Omani Oil Exploration & Development company, PDO is abandoning aging wells and fields and they must balance environmental and financial objectives. Technically sound abandonment practices are essential for long-term environmental protection. Many operators are revising their P&A procedures to ensure that abandoned reservoirs remain permanently sealed. During this 60 well pilot project PDO optimized their P&A practices by employing a rigless methodology as well as new technologies to minimize the cost of abandonment while still ensuring long term environmental protection from once prolific oil wells. Using a Coiled Tubing unit and eliminating the need for a rig can help speed up operations and reduce costs, while at the same time safeguarding environmental concerns. Typical savings of 30% over previous abandonment campaigns with a drilling rig have been achieved by PDO. This constituted a total saving of over $5M for this 60 well campaign.

Introduction

The Oil and gas industry worldwide faces growing activity in well abandonment operations using Coiled Tubing units and eliminating the need for a rig. Technically sound abandonment practices are essential for long-term environmental protection, especially as operating within more stringent regulations becomes more complex. Although advanced technologies and techniques bring new meaning to the "Rigless" aspects of abandonment work, operators seek to minimize abandonment and decommissioning costs because these investments are not recouped1.

The life of a well comprises of numerous stages. The discovery of a new accumulation of oil or gas after months or years of exploration and drilling typically invigorates the responsible technical team. Achieving first production is another uplifting milestone. Successful enhanced recovery operations can make the waning stages of production financially and technically rewarding. The stage that no one enjoys facing is abandonment of wells and production facilities, yet the effects of abandonment practices are felt for many more years than the relatively brief producing life of the average well. Well abandonments are becoming increasingly frequent as aging fields reach their productive and economic limits. From 2000 to 2010, offshore abandonments will encompass 27,000 wells on 4900 platforms worldwide. Onshore, tens of thousands of wells will need to be abandoned some day. In Oman alone about 2000 wells will need to be permanently P&A-ed in the next 8 years.

Environmental Objectives

Responsible operators now seek to balance their environmental objectives with the profit demands of company shareholders. Shoddy plugging and abandonment (P&A) operations exact a toll on both the environment and the reputation of the company. With those issues in mind, many operators are upgrading their well- and field-abandonment procedures to ensure that abandoned reservoirs are permanently sealed and that facilities are properly decommissioned. In this paper, we will review PDO's P&A practices, explain how sound abandonment practices protect the environment and discuss new technologies that bring new meaning to the Rigless Coiled Tubing part of abandonment work.

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