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.