Caisson Inspection Record Assignment Help
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Answer both questions
Question 1. Caisson Question
Preamble:
The Swordfish platform is located in the central North Sea. It comprises a 4 legged structure installed in 72m water depth in 1992. See figure 1.

Caisson Inspection Record Assignment HelpThe platform has a number of caissons including two firewater caissons. Firewater caisson C10 is of particular concern as it is located vertically above the main gas export line which traverses the seabed.

If the caisson C10 failed it would likely fall vertically onto the 16” gas export line.

Deliverables:

1. Complete significant research into the various remedial options that might be available to mitigate or prevent the caisson from hitting and damaging the gas export line.

1. Write a 500 to 1000 word Technical Note (suitably structured and referenced) initially summarising the facts about the caisson, then giving the likely failure scenarios based on the inspection record available and the proposed remedial measures that may be taken (engineering argument) to stop this failure happening. Determine, based on the caisson data (See table 3), where failure might occur and calculate the deadweight of the failed caisson for each occurrence. Present remedial/risk mitigation scenarios for cessation of platform operations in 2020 (Option A) then again for 2035 (Option B). Define any assumptions made e.g. estimated costs, time periods, etc. and where appropriate attempt quantitative estimates in support of your scenarios.

Table 1. Supplemental Data:

16” Gas Export Line
Material	API 5L X60
Outer diameter	406mm
Wall thickness	16.7mm
Yield Strength (N/mm2)	415

Table 2. Cost Factors:

Saturation Diving Support Vessel (DSV):	£100,000 per day
Cost of a combined Air Diving/ROV Support Vessel:	£50,000 per day
ROV Support Vessel (ROVSV):	£20,000 per day
Swage-lining (5m length):	£300,000 lump sum
Concrete mattresses (6m x 3m size):	£500 each
Caisson fall-arrest clamp (half shell design):	£50,000
Rope access team (3 persons):	£1,000 per day
Scaffolding gang c/w scaffolding equipment:	£5,000 day
Cost of 41-inch diameter steel pipe:	$4 (US Dollars) per kg
Lost production if gas export line fails:	$500,000 (US dollars) per day

Table 3.  Caisson Inspection Record
CAISSON INSPECTION RECORD	Asset:	Swordfish
	Caisson:	C10
			Use:	Firewater Pump
	Installation Date:	1992

Summary Design Data

Minimum

Diam.

Length

Term.

Term.

Delivery

Termination

Contents

Pump

thick

(mm)

(m)

El. (m)

El.

Requirements

Grill

(m)

Type

(mm)

barg

m3/hr

Firewater

1040

46.3

-23

-21

13.5

2100

3 stage

20

Yes

Diesel

Construction Details

The caisson was transported with the jacket using a temporary support

Installation status:

located at El+8m. Once the jacket was installed on the seafloor the caisson

was pulled up to the cellar deck (pump room floor) rotated onto a

supporting frame, hung, and welded secure topside.

Structural supports:

Dead weight support located at El+23m. Guides at El+8m and El-15m.

Inspection History Topsides

2013 – MPI

• Inspection of the Caisson C10 dead weight support welds including deck plate welds indicated multiple crack indications. Combined length 950mm.

• Caisson wall was found to be in fair condition with light coating breakdown and associated corrosion. Evaluated as Ri4 to Ri5.

• Fretting corrosion was noted at EL+8m level between guide and caisson wall with estimated 5mm wall loss.

2009 – GVI

• The coating system was generally intact with no areas of significant breakdown or 
corrosion noted.

• The dead weight support was free from any gross defects or visible cracks. The coating 
system was generally intact.

2005 – CVI

• Due to restricted access of the fire pump, only 75% of the caisson dead weight support could be visually inspected.

• The dead weight support was found to be of average condition with 40% coating breakdown and light to medium surface corrosion noted.

• All structural welds appeared to be in good condition

2001 – CVI

- No surface breaking cracks found. 
Caisson in good condition.

Inspection History Splashzone

No record of internal inspection or externally mounted tool systems to inspect the wall of the caisson through the splash zone (El-4m to El+3m).

Inspection History Subsea

2013 – ROV Inspection

• Caisson generally in reasonable condition though inspection obscured by 70% marine growth cover comprising tubeworm, soft corals and sponges. 
Unable to determine whether holed around the pump location. Contact CP ranged from -875mV to -915mV.

• Confirm relative movement in the El-15m guide, possibly increased to 40mm.

• Caisson grill checked and confirmed secured though fouled with 50% marine growth.

2010 – ROV Inspection

• Relative movement of approximately 20-30mm seen between caisson C10 and guide at El-15m.

• Bare metal area (200mm x 50mm) seen just above El-15m guide. Possible cause could be the previously installed strop which is now missing, presumably fallen off.

• The minimum contact CP reading was taken on the caisson was -890mV.

• Wall thickness readings were taken as per table below; note nominal wall thickness 20mm. During the ROV inspection of the pump location no signs of corrosion were found. 
Pump actually located between El-20.4m and El-21.4m.

Elevation	Wall Thickness Measurements (mm)
(El)	12o/c	3o/c	6o/c	9o/c
-20.3m	11.6	8.2	9.2	7.8
-20.5m	12.0	15.3	14.8	12.3
-20.7m	5.5	16.5	11.7	7.3
-20.9m	12.1	12.9	6.9	8.5
-21.1m	9.4	3.2	12.1	13.7
-21.3m	13.2	9.7	7.6	12.6
-21.5m	15.5	11.6	13.2	17.9

2007 – ROV Inspection

• Restraining strop prevents full access for ROV at El-15m guide but caisson noted to be moving about 40mm laterally in guide. Effectiveness of strops queried.

• Caisson reported to be in good condition, CP readings -910mV to -950mV..

2002 – Diver Inspection

• Restraining strop installed around caisson just above El-15m guide to arrest caisson should it fail above the El-15m level and to prevent it falling onto the 400mm diameter steel gas export line located at sea bed level (El-72m).

• MPI conducted on guide support welds (El-15m); no defects reported.

• Contact CP on caisson ranged from -990mV to -950mV.

• Termination grill cleaned of marine growth.

Pre-2000 – No data available.

Caisson C10

El+8m

Mean Sea Level

 El-15m

El-42m El-70m

Figure 1. Jacket Elevation

Question 2.  Oil price changes, risks and opportunities.

Preamble

Oil prices have fluctuated over the last 60 or so years in response to various drivers. The current low price looks set to continue for a few years yet at least. The sector is responding in different ways to the resulting business pressures. Some are taking a long view of this part of the regular cycle having “seen it all before”. Others are making knee-jerk reactions laying off a lot of skilled labour in some cases with no choice because their business model relied on sustained high prices. Still others are seeing this as a new form of the phenomenon and reviewing their approach in order to develop a sustainable business model.

This exercise is deliberately open-ended and allows you to demonstrate your own analysis supported by good research.

2015. Research the fluctuations in oil prices and the key milestone events over the last 50 years that have impacted on them. By combining reputable sources create the most up to date chart that you can of the fluctuations to include data from 2015. 

2017. Study the brief consideration by BP of what they think should be the response to sustained low oil prices, which look likely to continue at $50-$70 per barrel till at least 2017. [See attached] 

1. Complete a 500 to 1000 word review of the strategic risks, opportunities and threats facing each of the following players in the sector and include some suggested strategies for maintaining business continuity. Present this as a technical briefing document for a senior manager. 

• Large integrated multi-national

• Independent oil producer focussed on North Sea
• An oil services company; e.g. one supplying equipment and personnel for working-over / stimulating wells using coiled tubing

N.B. Both of the above questions require research in support of your answers. In assembling your submission it is essential that you reference your sources properly using a consistent style.

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