The D1D3 gas field in Krishna Godavari basin has deep water Subsea structures namely well, manifold, Subsea Distribution Assembly (SDA), Deep Water Pipeline end manifold (DWPLEM). These structures will be monitored and controlled by a Subsea Control Module (SCM) installed on each particular structure and the top side Subsea control system "iconSCU" supplied by Aker Kvaerner Subsea, Aberdeen. All SCMs have redundant Subsea Electronic modules (SEMs) with Fiber Optic communications (FO) & back up combined power signal (CPS) links connected to the top side monitoring system. SCM is a critical part of each subsea structure and if required may need to be replaced as and when failures are evident. For changing the Manifold SCM the associated flowing well to the specific manifold requires to be shut-in because the power supply to the associated well SCM is through manifold SCM via Electrical Distribution Box and hence causing production loss. To avoid this production loss, an innovative approach has been developed. The highlight of this approach is SCM change-out without taking any shutdown of the flowing wells or interrupting the production by using redundancy of communication and power to the manifold and well SCM in real time. While design was such that shut in of all wells for each associated manifold would be required to replace a manifold SCM, the approach described in this paper will illustrate how use of redundant power paths are used to keep all production online, while changing the manifold SCM. This necessitates designing and subsea installation of electrical distribution box/EFLs on a Deep Water Manifold while maintaining production.

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