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Typically, deepwater subsea completions are characterized by significant production rates which require large completion hardware. Slim-hole designs (defined as 5½" production casing and smaller) are usually avoided due to increased risk and production concerns. However, as the deepwater Gulf of Mexico basins grow more mature, sidetracks and challenging new drills become frequent. Sidetracks out of 7¾" to 7" production casing are being performed, ending with 5½" or 5" casing at TD. Additionally, many new drills either have to penetrate multiple depleted intervals or require more aggressive directional plans to reach smaller targets. Both scenarios can result in slim-hole designs. Historically, the two (2) riskiest phases of the completion are wellbore displacement and sand control. This paper presents the design, the risk assessment, the installation and the actual results for three (3) subsea slim-hole deepwater completions. A summary of the completions are as follows:5" Frac Pack (FP) at 74 degrees deviation5" FP with > 40000 md-ft kH sand5½" High Rate Water Pack (HRWP) at 25000 ft TVD As a result of proper planning, the Case Histories were successfully executed in Gulf of Mexico deepwater. However, performance expectations from these type wells must be risked and managed. Completion Challenges Completion operations in deepwater are very challenging and are even more challenging in a slim-hole design. Slim-hole completion challenges include:Small completion tools which result in limited injection rate, sand volume, and treatment lengthsSmall workstrings create high treating pressures due to friction during wellbore displacement and sand control operations.Small tubulars limit production due to erosional velocities.Small completion tools limit the options available for "positive" mechanical fluid loss devices. With high spread rate costs, any non-productive time (NPT) is magnified. Planning is critical for success. Mitigating Risk Complete the Well on Paper (CWOP). One of the best ways to mitigate risk is to review the plan with as much knowledge and experience as possible. A CWOP provides a very effective way to achieve this goal. CWOP meetings are usually conducted for two (2) days with the rig crew and the responsible contractors. The completion procedure is reviewd in phases with small breakout groups. Operational recommendations are captured, and a technical limit curve is established. A CWOP was performed for all three of the Case Histories discussed in this paper. Case Histories The data presented are from three (3) deepwater Gulf of Mexico field Case Histories. A general well information summary table is included in each section. Wellbore Displacements As identified earlier, the first critical phase of slim-hole completion operations is wellbore displacement. Each Case History had similar issues including the following:High differential pressure (Mud in hole / seawater)Limited standpipe pressure (SPP) rating: 4500 psiTapered workstrings (High friction)Large completion fluid volumesLimited pit capacityTwo (2) exposed liner tops

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