AUSTRACT This paper presents an oveIView of how the Completion performance on Rawnspurn North Development (RND) hilS heen dranliltically improved resulting in significant savings in well costs. With rcl'erence to performance statistics. four KL' Y aspects are reviL'wed. These arc the Completions Team, the Design Optimisation. the l'rocedural Optimisation and the Performance Optimisation.

Cemented completion provides an excellent opportunity for low cost drilling techniques and simple well designs to reduce well delivery costs without impact on safety or well integrity. In this concept, the completion is run straight into the open hole and cemented in place. There is no need to run a liner and perform a traditional clean-up. The cement effectively replaces the production packer. Achieving a good cement job is essential to a successful operation. A failed cement job would require cutting and pulling of the completion before running a conventional completion and packer, unless there was a high confidence in the outcome of a remedial cement job. Therefore good conditions for cementing are a definite requirement. Gas production and gas storage wells are particularly demanding on the cement sheaths. A failure of the sheath through de-bonding, cracking or plastic deformation results in formation fluids to enter the annulus, which pressurises the well and makes it unsafe to operate, the consequences are either losing the well altogether or, at best, an expensive intervention. Advanced cement technology combined with state of the art software are used today to ensure a complete long-term zonal isolation of the cemented completion. The software can model the stresses in a particular well over its entire life, including changes to the formation properties, well completion parameters, formation in-situ stresses, and operating envelope and can compare the properties of different available cements to enable the optimum cement to be selected (hole size, cement sheath thickness). The following paper will describe the process and the engineered cement used to ensure integrity of the cemented completion and lists case histories of the 3 cemented completions successfully cemented Onshore Netherlands. Introduction The cemented completion concept is a fundamentally simple one whereby the reservoir open hole section is drilled to the required depth. Following electric logging (if required), the completion tubing is run into the open hole and cemented back inside the previous casing shoe or window. The Christmas tree is then installed and the well perforated in the normal manner. Cemented completions have already been used in low cost operating areas around the world. Well CA-28S2 drilled from the Cormorant Alpha platform in June 1999 marked the first cemented completion to be performed in the North Sea by Shell. CA-28S2 was selected as the ideal candidate for evaluating the method due to it's short 6" open hole length of 708 ft [215.79m] and near vertical inclination. Since then open hole lengths have been progressively increased, culminating in CN-28S1 which was successfully completed with 6500ft of 8 1/2" open hole at 67 degrees. In 2003, 79 cemented completions were installed by Shell globally yielding a considerable saving. In the Netherlands, the land asset have after an initial trial with 5" completion 2003, adopted 3 ½" cemented completions as a base case to the slim well low cost land drilling campaign that commenced in 2005 Fig.1. By end 2006 this has been applied successfully to eight gas wells. Cemented Completion Benefits The advantage of cemented over conventional completions is commercial in that it saves 5 to 6 days rig time during installation by eliminating such operations as running and cementing liner, wellbore clean up and packer setting procedures. In addition, the amount of liner and completion accessories required such as packers, liner hangers, Polished Bore Receptacles (PBR), nipples are greatly reduced. Savings depend on the completion and well design.

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