API RP 17P:2019 pdf free download.Recommended Practice for Subsea Structures and Manifolds
4.4.2 Drilling and Completion Interface If wells will be drilled through the template, the template should provide guidance for drilling, landing/latching capability for the first casing string, and sufficient space for running and landing a BOP stack. If subsea trees will be installed on the template, the template should provide proper mechanical positioning and alignment for the trees and sufficient clearance for running operations. The design will also need to accommodate removal of drilling cuttings.
4.4.3 Structure Orientation
The template should provide an alignment capability to ensure proper orientation to physical interfaces, such as wellhead/tree, tree/manifold and manifold/flowlines.
4.4.4 Subsea Guidance
The template should provide for a guidance system to support operations through the life of the installation. If guidelines are used, the template should provide proper spacing and installation/maintenance capability for the guide posts. If guidelineless methods are used, the template should provide sufficient space and passive guidance capability to successfully install key equipment items. Detail Design
5.1 General
5.1.1 Number of Wells When wells are incorporated into the template or tied into a cluster manifold, the number of wells will vary depending on the site-specific application, and will greatly influence template size and manifold design. Spare well slots should be added for contingencies such as changes in reservoir depletion plan, dry holes, drilling problems, and other unforeseen production requirements, as agreed with the end user.
5.1.2 Well Slot Spacing Well slot spacing at the mudline or on the cluster manifold may be governed by the field architecture and the type and size of drilling and production equipment used. The following will need to be addressed during the design phase:
— For a template solution, the functional requirements of the manifold, flowline, and wellhead connections and their running tools and adjacent BOP and production tree clearances will determine the minimum well slot spacing. Access should be provided for inspection and maintenance tools.
— For a cluster manifold solution, the jumper design and well jumper connection system will determine the minimum well slot spacing.
5.1.3 Intervention Functionality Intervention is a key factor in system design, and the maintenance approach should be used in the design phase of a template or subsea structure system. Required maintenance should be minimized and limited to retrievable modules where possible. Specific guidance on intervention flushing and retrieval can be found in 11.2.1 and 11.2.2.
The following factors will influence intervention planning and functional requirements: — diver-assisted or remote maintenance methods;
— inclusion of reaction posts/securing points for diver-assisted lift rigging;
— clear definition of which components will be retrievable;
— clear access space for divers, subsea vehicles, or other intervention equipment;
— clear markings to allow distinguishing similar components;
— height above seabed for adequate visibility;
— system safety with components removed;
— fault detection to identify failed components.
5.1.4 Barrier Philosophy Refer to API 17A for additional information on barrier philosophy. Prior to any subsea operations which involve use or removal of an environmental barrier, a risk/safety assessment should be performed to ensure risks are identified and mitigated. Permanent isolation requirements against external leakage for pressurized systems should be provided by double, pressure-containing barriers in all external connection points.
The primary barrier intended for long-term service should be metal-to-metal sealing type. Individual barrier integrity should be confirmed by leak testing, and the final dual barrier integrity should be verified. For temporary, time-limited operations, it can be acceptable to use only one metal-to-metal sealing isolation valve for isolating pressurized piping towards the environment.
The primary barrier valve should be verified to ensure it is holding pressure prior to releasing the outboard barrier. An overall safety assessment should be performed for the activity prior to the start of operations.
NOTE If the primary barrier valve cannot be verified, depressurization of the pressurized piping to prevent flow to the environment may be an acceptable alternative to verifying the primary barrier valve.API RP 17P pdf download.API RP 17P:2019 pdf free download
