PSI - Issue 14

Praveen Bhat et al. / Procedia Structural Integrity 14 (2019) 656–663 Praveen Bhat, S. Karunanithi/ Structural Integrity Procedia 00 (2018) 000 – 000

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Table 2. Salient details of platforms.

Sl. No.

Platform

A

B

C

1 2 3 4 5 6 7 8

Type

Well platform

Well platform

Well platform

Original water depth (m)

25.00

19.00

19.00

No. of conductors

2

4

9

No. of piles

4 Main Piles 60” (1.524m)

4 Main Piles 60” (1.524m)

4 Main Piles 60” (1.524m)

Diameter of Main piles

Boat landing No. of risers Riser Protector

1 (4 stage)-along Row-2

1 (4 stage)-along Row-2

1 (4 stage)-along Row-2

3 (1*8” + 2*12")

3 (1*8 ” + 2*12")

3 (1*22 ” + 2*12")

2 (one each on Row-A & Row-B)

2 (one each on Row-A & Row-B)

2 (one each on Row-A & Row-B)

4.1 Analysis results for ‘A’ Platform Platform ‘A’ has been considered for relocation to Y location which has similar water depths to its existing water depth. Hence, plinth platform is not required for re-location purpose. The water depth at Y location is 25.1m which is similar to its existing water depth. The proposed foundation system at the re-location consists of installing four insert piles (of 48 ” dia. up to 86.3m vertical penetration) and four clamp-on skirt piles (of 60 ” dia. up to 60m vertical penetration) at the relocation (Figure 2). The results of in-place analysis reveals that all the piles are found to be adequate with respect to both factor of safety in axial loading and pile material utilization.

Fig. 2. Relocation of platform A for Y site.

The member and joint strength assessment results reveals that few structural components would require strengthening in the form of grouting/metal clamps. Hence, the preliminary in-place analysis reveals that the jacket structure of platform A is re-locatable to Y location subject to providing adequate foundation system (in the form of 4 insert piles + 4 clamp-on skirt piles) and strengthening of few structural members. 4.2 Analysis results for ‘B’ Platf orm Platform ‘B’ has been considered for relocation to X location with water depth of 22.65m which is slightly higher to its existing water depth. Due to increase in water depth of around 3.5m, the appurtenances (boat landing, riser protector, etc.) may be required to be raised by some elevation for facilitate uninterrupted operations, considering