This paper presents Petroleum Development of Oman's (PDO's) rigless plug and abandonment (P&A) technologies and practices resulting from a corporate goal to find a costeffective means to abandon its oil wells. PDO is abandoning aging wells and must balance environmental and financial objectives. Technically sound abandonment practices are essential for long-term environmental protection. Many operators are revising procedures to ensure that depleted reservoirs remain permanently sealed. During a 60-well pilot project in Oman, PDO optimized its practices by employing new cementing and plugging technologies to minimize the cost of abandonment while ensuring long-term environmental protection from once-prolific oil wells.

PDO used a new expanding, flexible sealant system on the P&A project, conveying the flexible sealant with a coiled tubing (CT) unit. The new sealant has improved elastic and expansion properties to meet PDO's requirement for a longterm mechanical durability and zonal isolation. The presence of expanding material leads to an optimum configuration to prevent loss of zonal isolation resulting from changes in downhole conditions over time. The presence of flexible and expanding materials increases the elasticity and decreases compressibility and permeability of the set cement while retaining good compressive strength.

Use of a CT unit eliminated the need for a rig, which reduced the time and cost of operations. The novel flexible sealant system provided the long-term isolation necessary to meet environmental standards. This paper presents case histories on the use of this new flexible, expanding sealant and its influence on the P&A project.

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