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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.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis 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.

fax 01-972-952-9435. AbstractUnderbalanced directional drilling with coiled tubing is emerging as an instrumental technique for accessing new and bypassed reserves while enhancing overall reservoir recovery since, unlike jointed-pipe operations, circulation does not have to be interrupted every 30 feet to make connections. Coiled tubing drilling (CTD) thus offers the potential to achieve genuine steady state underbalanced conditions resulting in the elimination of formation damage, lost circulation and differential sticking. One of the enabling technologies assisting the growth of underbalanced directional CTD is the wireline-steerable bottom hole assembly (BHA). In contrast to conventional mud pulse telemetry systems, these purposebuilt wired BHAs have been designed to accommodate efficient, continuously underbalanced drilling operations while also providing an opportunity for reservoir evaluation while drilling.The paper details the operational results for several underbalanced and low-head CTD projects involving an integrated wireline-steerable BHA. The most recent wells were completed in the North Sea, Canada and United States in 1999. Topics discussed include equipment performance, nitrified fluids, wellbore stability, well results and learning points. An analysis of time-based underbalanced CTD data is also presented.

This paper discusses novel approaches that resulted in the successful drilling, completion, and production from shallow and unconsolidated clastic reservoirs, offshore Brunei. As a result of these new approaches, detailed planning, continuous and open communication throughout the development project, the candidate well was drilled successfully, with the directional, well placement, and completion requirements being achieved. In addition, the application of new sand control technologies coupled with specifically engineered procedural solutions assured sand-free production at a rate above expectations. Introduction The Champion oil and gas field, offshore Brunei, is a multibillion barrel field that was discovered in 1970. Because of the thin-bedded nature of the clastic reservoirs, the field is subdivided into multiple stratigraphic units and fault blocks. Some of the least developed parts of the field are located in shallow [less then 400 m true vertical depth, subsea (TVDSS)] and unconsolidated reservoirs. Previous production from these reservoirs, from near vertical wells, resulted in poor flow rates. A development project was initiated to overcome the challenge of optimizing flow rates from these shallow reservoirs within strict and tight project timelines. This paper discusses the results from one well in the project. Horizontal openhole gravel packing (OHGP) methods have been accepted as a proven standard of completion for maximizing hydrocarbon productivity and minimizing formation drawdown in the petroleum industry for many years (Price-Smith et al. 2003; Law et al. 2005). Implementing sand-control measures in unconsolidated formations without impairing well productivity has been a challenging task from both a technical and an economical perspective (Price-Smith et al., 1998; Parlar and Albino 2000; Law et al. 2005). Gravel packing of long horizontal intervals using conventional gravel-pack tools presents a moderately complex fluid mechanics problem. The most commonly encountered problems in horizontal gravel packing are premature sandout and/or formation breakdown. These problems lead to incomplete placement of the gravel pack, with undesirable consequences ranging from higher completion costs to sand in surface facilities and long-term completion reliability problems (Vliet et al. 2001). Until recently it has not been possible, technically or economically, to drill and complete horizontal wells in certain parts of the Champion field because of the challenging nature of the formation and the proposed well profiles. To enhance production from these reservoirs, challenging well designs were required to allow landing the well by approximately 400 m TVDSS and have in excess of 500 m of drain section. Dog-leg severities (DLS) of around 6°/30 m would be required, in a field which is notorious for soft and unconsolidated formations, making directional control using conventional mud motors unpredictable. Due to the soft nature of the formations, the drilling rate of penetration (ROP) was expected to be very high. This added to the challenge of being able to land the well in the 7 m true vertical depth (TVD) best quality layer within the reservoir by using logging while drilling (LWD) technologies.