Riser Recoil Analysis Report for Acme Drillship

GEI-RRA1100 June 8, 2010 Page 1 of 21

Riser Recoil Analysis Report for Acme Drillship

Revision 00 Prepared by Groves Engineering, Inc.

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Document Information

Prepared For: Acme Corp. 123 Main Street, Suite 1 City, State, Zip Prepared By: Groves Engineering, Inc. 2755 NW Crossing Drive, #233 Bend, Oregon, 97701 Document Title: Riser Recoil Analysis for Acme Drillship Document Description: Emergency disconnect, parted riser, and recoil control algorithm analysis for the Acme Drillship in 7150 ft. and 1000 ft of water. Initial Document Date: Revision Date: Revision Number: May 25, 2010 May 25, 2010 00 GEI Document Number: GEI-RRA1100 Project Engineer: Supervising Engineer: Josh Groves Frank Groves Engineering Manager, GEI President, GEI

Revision Notes

Revision Number: Revised By: Notes:

About Groves Engineering, Inc.

Frank Groves has almost four decades of advanced offshore engineering experience, having focused on the hydraulic and mechanical design of riser anti-recoil systems. Josh Groves has over 10 years of experience in control system engineering, specializing in hardware and software development. GEI is based out of Bend, Oregon and can be found on the web at www.grovesengineering.com.




Table of Contents

1 INTRODUCTION ..................................................................................................................................................................... 4

2 OBJECTIVE ............................................................................................................................................................................. 5

3 SCOPE OF REPORT NOTIFICATION .......................................................................................................................................... 6

4 ANALYSIS, RESULTS AND DISCUSSION .................................................................................................................................... 7

4.1 PLANNED, EMERGENCY DEEPWATER DISCONNECT IN 7,150 FT OF SEAWATER .......................................................................................... 8 4.1.1 Predicted Sea States (Emergency Disconnect, 7,150 ft) ....................................................................................................... 8 4.1.2 Telescoping Joint Travel and Cylinder Stroke (Emergency Disconnect, 7,150 ft) ................................................................. 9 4.1.3 Riser Configuration and Top Tension per API RP 16Q (Emergency Disconnect, 7,150 ft) .................................................. 10 4.1.4 Tensioner System Design and Setting (Emergency Disconnect, 7,150 ft) ........................................................................... 12 4.1.5 Anti-Recoil Control Algorithm (Emergency Disconnect, 7,150 ft) ....................................................................................... 13 4.1.6 Simulation Results (Emergency Disconnect, 7,150 ft) ........................................................................................................ 15

5 CONCLUSIONS ..................................................................................................................................................................... 19

6 APPENDIX - RISER CONFIGURATION AND TENSIONS PER API RP 16Q (7,150 FT) ................................................................... 21




1 Introduction

This document presents analyses and discussions based upon the emergency disconnects simulated by Groves

Engineering, Inc. (GEI) for Acme Corp. involving the drilling riser and tensioning system of the Acme Drillship.

Section 4 of this document presents and discusses the analyses and results for the following Acme Drillship scenario: a

planned emergency disconnect occurring in 7,150 ft of seawater. Other items covered in Section 4 include calculated

riser top tension, telescoping joint vs. tensioner rod relationship, as well as tensioner system design and setup.

Section 5 discusses conclusions of the analysis as well as possible improvements to the existing anti-recoil valves and to

their control algorithms.

The disconnects have been simulated using the GEI proprietary software, GRASIM (Groves Riser Anti-Recoil Simulation).

GRASIM adheres to the guidelines of API RP 16Q wherever applicable. Dividing the riser into constituent parts, GRASIM

analyzes the riser from the load ring and outer barrel of the TJ down to the LMRP. The analysis accounts for complex

effects such as the viscous drag of the seawater external to the riser and LMRP and the viscous drag of the mud internal

to the riser, the spring rates and buoyancies of the riser sections and the interaction of the load ring with the TJ outer

barrel.

For the Acme Drillship, the tensioning system consists of the load ring, tensioner cylinders, control valve, local

accumulators (high and low pressure sides), piping between the cylinder and control valve and between the control

valve and accumulator, compressibility of the compensator fluid, length and diameter of the air line connecting the

local, high pressure accumulator to the air banks and volume of the air banks.

As the LMRP clearance over bottom and telescoping joint clashing are key considerations in riser recoil analysis, both the

rig’s heave amplitude and period of motion are critical. The nature of the recoil is affected by the event’s occurrence

point in the heave cycle. Therefore, the disconnect analysis is performed at eight, evenly distributed points throughout

one heave cycle of the rig. The vessel motion is simulated as a sinusoidal heave wave with the period and amplitude of

the heave wave derived from the vessel RAOs and significant heave information provided by the rig owner/operator.

The emergency disconnect is examined for the event occurrence at various points along the heave cycle. Forces,

pressures, flows, accelerations, velocities, positions, etc., are calculated for very small time intervals and, thus, the

program proceeds in time in an iterative manner.




2 Objective

The primary goals of the analyses presented herein are:

A. Determine the top tension requirements per API RP 16Q for the Acme Drillship given various operational

scenarios

B. Determine acceptable control criteria to be used with the Acme Drillship’s riser anti-recoil control

system with consideration for clashing of the telescoping joint (TJ), jump-out of the outer barrel from

the load ring, as well as the lower marine riser package’s (LMRP) clearance over the lower blow-out

preventer (BOP) stack. The customer has prescribed that GEI optimize the anti-recoil control algorithm

for an emergency disconnect event for the heaviest riser weight scenario. Then, this same algorithm will

be applied to the lightest riser weight scenario and the disconnect event will again be analyzed. GEI

shall assess whether multiple anti-recoil control curves are required by the Acme Drillship.




3 Scope of Report Notification

The results and recommendations of this report apply solely to the test cases as described in specific detail in this

document. Groves Engineering, Inc. has relied upon the accuracy of information provided by the customer to generate

this report and shall not be held responsible for inaccuracies in this information.

The results and recommendations of this report exclude any consideration for the yielding of materials, failure modes of

the riser and riser tensioning system, and regional or international laws that may be applicable to the design or

operation of the drilling equipment.

Groves Engineering, Inc. does not intend to imply any guarantee or warranty with the contents of this report, and the

results and recommendations contained herein are only to be viewed as academic and informational in nature.




4 Analysis, Results and Discussion

In this section, summaries will be presented for the following recoil events that were modeled by GEI:

• Planned, emergency deepwater disconnect, 7,150 ft of seawater

For the test case above, the following information will be discussed:

• Predicted sea states

• Telescoping joint travel and cylinder stroke

• Riser configuration, mud attributes, and top tension requirements per API RP 16Q

• Tensioner system design and setting

• Key output from simulation, including LMRP and telescoping joint clearances




4.1 Planned, Emergency Deepwater Disconnect in 7,150 ft of Seawater

This section discusses the riser and tensioning system arrangement, along with the GRASIM simulation results, for a

planned, emergency deepwater disconnect in 7,150 ft of seawater for the Acme Drillship. This disconnect occurs by way

of a planned disconnect of the LMRP from the lower BOP.

4.1.1 Predicted Sea States (Emergency Disconnect, 7,150 ft)

The owner/operator of the Acme Drilling Rig provided the following information regarding the rig heave amplitude and

period to be used for the emergency disconnect analyses. The following values have been used in this simulation:

WAVE PERIOD HEAVE AMPLITUDE HEAVE PERIOD 11.2 seconds 47 inches 11.7 seconds

Table 1 Customer-Supplied Rig Heave Values Used in Analyses




4.1.2 Telescoping Joint Travel and Cylinder Stroke (Emergency Disconnect, 7,150 ft)

Figure 1 Telescoping Joint vs. Cylinder Stroke (7,150 ft)

540 in(Fully

Extended)

531 in177 in

168 in9 in

(Fully Collapsed)

Full Cylinder Stroke Nominal Space-Out Clashing of TJ

Tele

scop

ing

Join

t Str

oke

Cylin

der S

trok

e

09

119

177

250

444

540

0

110

168

241

435

531

696

Over-stroke of tensioner cylinder (9 in)

Riser recoil control region (110 in)

Rig heave amplitude for typical operational conditions (58 in)

Tidal variations, stretch in riser and other variations (73 in)

Allowable increase in tensioner stroke due to offset (194 in)

Rig heave amplitude for severe operational conditions (96 in)

Excess telescoping joint stroke (165 in)

Tensioner Cylinder vs. Telescoping Joint Stroke




4.1.3 Riser Configuration and Top Tension per API RP 16Q (Emergency Disconnect, 7,150 ft)

It should be noted that the minimum tension (Tmin) as calculated by way of API RP 16Q and referred to in this document

represents the sum of the upward forces exerted by all tensioner pistons on the load ring, measured parallel to the

stoke path of each piston, with the weight of load ring then subtracted from this sum.

Tmin = ( Fpiston * N ) – Wload ring

Minimum top tension as calculated per API RP 16Q:

Tmin = Minimum Top Tension = TSRmin * N / [ Rf * ( N - n ) ]

TSRmin = Minimum Load Ring Tension = Ws * fwt - Bn * fbt + Ai * [ dm * Hm - dw * Hw ]

Ws = Submerged Riser Weight Hm = Drilling Fluid Column

fwt = Submerged Weight Tolerance Factor

dw = Sea Water Weight Density

Bn = Net Lift of Buoyancy Material Hw = Sea Water Column

fbt = Buoyancy Loss and Tolerance Factor

N = Number of Tensioners Supporting Riser

Ai = Internal Cross-Sectional Area of Riser including fluid lines

n = Number of Tensioners Subject to Sudden Failure

dm = Drilling Fluid Weight Density Rf = Reduction Factor Relating Vertical Tension at Load Ring to Tensioners

A detailed account of the API 16Q calculations for minimum top tension requirements can be found in the Appendix,

Section 6. The below summary tables capture key results of the calculations.

Since inaccuracies in riser and LMRP weights significantly affect the results of the recoil analysis, all recoil scenarios were

simulated for both upper and lower limit weight estimates.

Utilizing the convention of API RP 16Q, the upper limit was derived by applying a factor of 0.98 to the nominal lift on the

riser and LMRP, and a factor of 1.05 was applied to the nominal steel weight. The lower limit was then calculated, per

the customer’s recommendation, by applying a factor of 1.00 to the nominal lift on the riser and LMRP, and a factor of




1.00 was applied to the nominal steel weight (i.e. the lower weight limit equals the nominal weight and buoyancy). Table

2 through Table 3 below show the weights that were used in the riser recoil analysis.

Table 2 Nominal/Low Limit Riser and LMRP Weights (7,150 ft)

Table 3 High Limit Riser and LMRP Weights (7,150 ft)

11

LENGTH PER

SECTION

GROUP DRY WEIGHT, W/O

BUOY MODULES

GROUP WET-WEIGHT, W/O

BUOY MODULES

GROUP LIFT FORCE OF SUBMERGED BUOY MODULES

GROUP WEIGHT

(ft) (lbs) (lbs) (lbs) (lbs)35.4 1 50874 50874 0 5087442.0 1 29986 26070 0 2607030.0 3 58971 51269 2130 49139

5.0 2 11374 9889 202 968780.0 5 164065 142638 10965 13167380.0 50 1681400 1461809 1394750 6705980.0 27 907956 789377 716796 7258180.0 0 0 0 0 080.0 5 149320 129819 10890 11892912.6 1 13589 11814 0 1181443.3 1 262300 228044 0 228044

95 3329835 2901603 2135733 765870

Riser Adaptor

TOTALSLMRP

Steel Weight Penalty FactorBuoyancy Module Penalty Factor

RISER AND LMRP WEIGHTS

Pup Joint 5ftSlick Joint (0.875" wall)Bouyancy Joint 5,000ftBouyancy Joint 7,500ftBouyancy Joint 9,500ftSlick Joint (0.75" wall)

SECTION GROUP DESCRIPTIONQUANTITY

OF SECTIONS IN GROUP

Telescoping Joint, Above WaterTelescoping Joint, Below WaterPup Joint 30ft

1.050.98

LENGTH PER

SECTION

GROUP DRY WEIGHT, W/O

BUOY MODULES

GROUP WET-WEIGHT, W/O

BUOY MODULES


GROUP WEIGHT

(ft) (lbs) (lbs) (lbs) (lbs)35.4 1 53418 53418 0 5341842.0 1 31485 27373 0 2737330.0 3 61920 53833 2087 51745

5.0 2 11943 10383 198 1018580.0 5 172268 149770 10746 13902480.0 50 1765470 1534900 1366855 16804580.0 27 953354 828846 702460 12638680.0 0 0 0 0 080.0 5 156786 136310 10672 12563812.6 1 14268 12405 0 1240543.3 1 275415 239446 0 239446

95 3496327 3046683 2093018 953664

Riser Adaptor

TOTALSLMRP

Steel Weight Penalty FactorBuoyancy Module Penalty Factor

RISER AND LMRP WEIGHTS

Pup Joint 5ftSlick Joint (0.875" wall)Bouyancy Joint 5,000ftBouyancy Joint 7,500ftBouyancy Joint 9,500ftSlick Joint (0.75" wall)

SECTION GROUP DESCRIPTIONQUANTITY

OF SECTIONS IN GROUP

Telescoping Joint, Above WaterTelescoping Joint, Below WaterPup Joint 30ft




4.1.4 Tensioner System Design and Setting (Emergency Disconnect, 7,150 ft)

For the Acme Drillship riser tensioning system, one tensioner consists of a direct-acting tensioner rod and cylinder

applying an upward force on the load ring. The hydraulic fluid in the cylinder is pressurized by an accumulator that, in

turn, is pressurized by a common air bottle bank. An Olmsted Co. anti-recoil control valve lies in the fluid pathway

between the accumulator and the tensioner cylinder. See Figure 2 below for a qualitative depiction of the tensioning

system layout.

Figure 2 Qualitative Layout of Riser Tensioning System

The required top tension as discussed in Section 4.1.3 determines the necessary pressure settings for the riser

tensioning system. The relationship of the cylinder to telescoping joint stroke is depicted in Figure 1. Based upon these

values and the information provided by the rig owner/operator regarding the characteristics of tensioning system, the

following values have been used for this analysis. Note, the values in Table 4 correspond to a nominal, calm sea state.

Common Air Bottle Bank

(Qty 1)

Olmsted Anti-Recoil Valve

(Qty 6)

Accumulator(Qty 6)

Direct Tensioner

(Qty 6)




Description Units Value Description Units Value

Ambient Temperature rankine 540 Area of Line, Cyl to Accum In^2 7.07

Number of Tensioners (no units) 6 CV of Valve (Fully Open) (no units) 305

Bulk Modulus of Hydraulic Fluid psi 250,000 Total Accumulator Volume In^3 102,942

Total Rod Stroke inches 540 Initial Pressure in Accum psi 2,119

Rod Weight lbs 6357 Initial Air Volume in Accum ft^3 41.1

Rod-Side Cylinder Area In^2 181 Length of Line, Accum to Bank inches 167

Initial Pressure in Cylinder psi 2,119 Area of Line, Accum to Bank In^2 7.07

Initial Rod Stroke-Out inches 168 Total Volume of Air Bank ft^3 2079

Length of Line, Cyl to Accum inches 167 Initial Pressure in Air Bank psi 2119

Table 4 Tensioning System Characteristics (7,150 ft, 17.2 ppg)

4.1.5 Anti-Recoil Control Algorithm (Emergency Disconnect, 7,150 ft)

A primary objective of this analysis is the determination of the control algorithm for the rig’s riser anti-recoil system. Based upon the customer’s direction, an anti-recoil control algorithm shall be optimized to minimize telescoping joint clashing as well as outer barrel/load ring jump-out. The scenario that results in the closest proximity for telescoping joint clashing, referred to Test Case 1, occurs when the top tension is at its maximum and the riser and LMRP weights are at their low weight extreme.

Based upon the customer’s description of the anti-recoil control system aboard the Acme Drillship, GEI is providing coefficients for a 5th-order polynomial that dictates the relationship of the valve CV to the tensioner position, along with boundary conditions for the control curve. The polynomial is of the structure:

CV = A * CYLPOSITION ^ 5 + B * CYLPOSITION ^ 4 + C * CYLPOSITION ^ 3 + D * CYLPOSITION ^ 2 + E * CYLPOSITION + F

It has been assumed that one second before the disconnect event, the control system will begin shifting the anti-recoil valve to the position as calculated by the polynomial and its boundary conditions. Thus, when the disconnect event occurs, the control valve will be fully throttled to the CV as dictated by the curve.

The control curve recommended below has been optimized to minimize telescoping joint clashing and outer barrel/load ring jump-out, while maximizing LMRP clearance, for Test Case 1 as explored by GEI.




Coefficient A -1.19E-10 Coefficient B 8.71E-08 Coefficient C -2.07E-05 Coefficient D 4.05E-03 Coefficient E -7.35E-02 Coefficient F -3.31E-10

Cylinder Stroke-Out for CV=0 20 Cylinder Stoke-Out for Full CV 400

Table 5 5th-Order Polynomial Coefficients and Boundary Conditions for Anti-Recoil Valve Control Curve

Table 6 Anti-Recoil Valve Control Curve




4.1.6 Simulation Results (Emergency Disconnect, 7,150 ft)

There are two primary concerns for emergency disconnect event which occurs at the LMRP/BOP interface: the LMRP’s clearance over the BOP during subsequent downward heave cycles of the rig and the clashing that can occur if the telescoping joint runs out of travel. A secondary point of interest is the jump-out which can occur at the outer barrel/load ring interface when the upward rate of travel of the riser exceeds that of the tensioner pistons.

Though GEI has analyzed the disconnect event for varying riser weights, top tensions, mud weights, and telescoping joint space-outs, the two most extreme scenarios present the greatest opportunity for unfavorable outcomes.

The scenario that results in the closest proximity for telescoping joint clashing, referred to Test Case 1, occurs when the top tension is at its maximum and the riser and LMRP weights are at their low weight extremes. Also, the rig is considered to be off location, exposed to larger significant waves, and the telescoping joint is at its minimum allowable nominal space-out. Table 6 below summarizes the key settings for Test Case 1.

Item Description Units Value Nominal Top Tension lbs 2,259,000 Riser and LMRP Total Wet Weight lbs 775,103 Mud Weight ppg 17.2 Rig Heave Range inches 94.0 Rig Heave Period seconds 11.7 Nominal Telescoping Joint Space-Out inches 168.0

Table 7 Key Settings for Test Case 1: Testing Exposure to Telescoping Joint Clashing

The affect of the disconnect event on the ACME Drillship’s riser and LMRP was analyzed at eight points evenly spaced over one rig heave cycle. Table 8 below presents key results of the analyses while Figure 3 shows the outcome in graphical form.

It should be observed that no modification of the control curve could fully remove the potential for jump-out, the slight parting of the load ring from the telescoping joint outer barrel. Though the jump-out is small (1.6 inches at its maximum), GEI is not prepared to make any comments on how this jump-out will influence the anti-recoil control system overall and what will occur when the riser goes into compression.




Item Description Units Value Closest Proximity of Telescoping Joint to Clashing inches 16.1 Closest Proximity of LMRP to BOP Clashing inches 97.2 Maximum Jump-Out from Load Ring inches 1.6 Average 95%-Full-Recoil Time seconds 17.8

Table 8 Key Results of Test Case 1: Testing Exposure to Telescoping Joint Clashing

Figure 3 Test Case 1 Results: Testing Exposure to Telescoping Joint Clashing




The scenario that corresponds to the closest proximity for LMRP/BOP clashing, referred to Test Case 2, occurs when the top tension is at its minimum and the riser and LMRP weights are at their high weight extremes. Also, the rig is considered to be off location, exposed to larger significant waves, and the telescoping joint is at its minimum allowable nominal space-out. Table 7 below summarizes the key settings for Test Case 2. Recall, per the customer’s recommendation, GEI has applied the anti-recoil control algorithm developed for Test Case 1 to Test Case 2.

Item Description Units Value Nominal Top Tension lbs 1,096,958 Riser and LMRP Total Wet Weight lbs 953,664 Mud Weight ppg 8.55 Rig Heave Range inches 94.0 Rig Heave Period seconds 11.7 Nominal Telescoping Joint Space-Out inches 168.0

Table 9 Key Settings for Test Case 2: Testing Exposure to LMRP/BOP Clashing

The affect of the disconnect event on the ACME Drillship’s riser and LMRP was analyzed at eight points evenly spaced over one rig heave cycle. Table 10 below presents key results of the analyses while Figure 4 shows the outcome in graphical form.

Item Description Units Value Closest Proximity of Telescoping Joint to Clashing inches 52.1 Closest Proximity of LMRP to BOP Clashing inches 0 Maximum Jump-Out from Load Ring inches 0 Average 95%-Full-Recoil Time seconds 24.6

Table 10 Key Results for Test Case 2: Testing Exposure to LMRP/BOP Clashing




Figure 4 Test Case 2 Results: Testing Exposure to LMRP/BOP Clashing




5 Conclusions

It is the recommendation of GEI that, in order to account for different mud weights and, thus, top tensions, the Acme

Drillship employ more than one anti-recoil control algorithm.

An optimized anti-recoil valve control curve was derived by GEI for the 17.2 ppg mud weight scenario, where the only

undesirable effect was a small amount of jump-out (1.6 inches) between the outer barrel and the load ring. This same

control curve, however, when applied to the 8.55 ppg mud weight scenario resulted in potential LMRP/BOP clashing at

significant velocities.

GEI recommends that at least two additional anti-recoil valve control curves by used by the Acme Drillship’s control

system to accommodate different ranges of mud weights and top tensions. These recommended additional control

curves have not been analyzed in this report.




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6 APPENDIX - Riser Configuration and Tensions per API RP 16Q (7,150 ft)

The calculations below are based upon detailed equipment information as provided by the rig owner/operator. The minimum riser top tension calculations have been performed with strict adherence to API RP 16Q, however, high and low top tension limits have been imposed based upon the characteristics of the riser and LMRP.

It should be noted that the minimum tension (Tmin) as calculated by way of API RP 16Q and referred to in this document represents the sum of the upward forces exerted by all tensioner pistons on the load ring, measured parallel to the stoke path of each piston, with the weight of load ring then subtracted from this sum.

Information Last Submitted: 6-7-2100

Information Submitted By: John Doe, Acme Drilling and Exploration Co.

Information Submitted To: Josh Groves, Groves Engineering, Inc.

Tmin dm

TSRmin Hm

Ws dw

fwt Hw

Bn Nfbt nAi Rf

Steel Wet-Weight Factor 0.8694 6 262300 1.990Submerged Weight Tol Factor (fwt) 1.05 1 228044 0.271Buoyancy Loss and Tol Factor (fbt) 0.98 0.9 43.25 2.261Sea Water Density (lbs/ft^3) (dw) 63.65 29000000 120939

LENGTH PER SECTION

DEPTH AT BASE OF GROUP

SECTION DRY WEIGHT, W/O

BUOY MODULES

SECTION DRY WEIGHT, W/

BUOY MODULES

SECTION WET-WEIGHT, W/O

BUOY MODULES

SECTION LIFT FORCE OF SUBMERGED BUOY

MODULESGROUP LENGTH

GROUP DRY WEIGHT, W/O BUOY MODULES

GROUP DRY WEIGHT, W/ BUOY

MODULES

GROUP WET-WEIGHT, W/O BUOY

MODULES


(ft) (ft) (lbs) (lbs) (lbs) (lbs) (ft) (lbs) (lbs) (lbs) (lbs)35.4 1 0.0 50874 50874 50874 0 35.4 50874 50874 50874 042.0 1 42.0 29986 29986 26070 0 42.0 29986 29986 26070 030.0 3 132.0 19657 21978 17090 710 90.0 58971 65934 51269 2130

5.0 2 142.0 5687 6124 4944 101 10.0 11374 12248 9889 20280.0 5 542.0 32813 41549 28528 2193 400.0 164065 207745 142638 1096580.0 50 4542.0 33628 59318 29236 27895 4000.0 1681400 2965900 1461809 139475080.0 27 6702.0 33628 60052 29236 26548 2160.0 907956 1621404 789377 71679680.0 0 6702.0 0 0 0 0 0.0 0 0 0 080.0 5 7102.0 29864 38778 25964 2178 400.0 149320 193890 129819 1089012.6 1 7114.6 13589 13589 11814 0 12.6 13589 13589 11814 0

95 7114.6 7150.0 3067535 5161570 2673559 2135733

26735592135733

714219(ppg) (lbs)

MINIMUM TENSION LOW LIMIT 8.55 109695845000 2510000 10.50 1280263

987262 2950000 15.00 20058961096958 2259000 17.20 2259000

Tensioner System Limit (lbs)Max Tensioners Setting, Tmin (lbs)

Min LMRP Overpull, LMRPmin (lbs)Min Load Ring Tension, TSRmin (lbs)Min Tensioners Setting, Tmin (lbs)

MINIMUM TENSION HIGH LIMITRiser Coupling Rating (lbs)

724366960197

15044221770488

965821128026320058962360651

(lbs)

MIN TENSIONERS SETTING, Tmin

(lbs)TSRmin * N / [ Rf * ( N - n ) ]

Tmin W/ LIMITS IMPOSED

MIN TENSION AT LOAD RING, TSRmin

Ws * fwt - Bn * fbt + Ai * [ dm * Hm - dw * Hw ]

MUD UNIT WEIGHTSubmerged Riser Weight (Ws)Net Lift of Buoyancy Material (Bn)Penalized Riser Weight (Ws * fwt - Bn * fbt)

Riser AdaptorTOTALS

RISER SECTIONS

TENSION CALCULATIONS

Slick Joint (0.875" wall)Bouyancy Joint 5,000ftBouyancy Joint 7,500ftBouyancy Joint 9,500ftSlick Joint (0.75" wall)

SECTION GROUP DESCRIPTION

Telescoping Joint, Above WaterTelescoping Joint, Below WaterPup Joint 30ftPup Joint 5ft

QUANTITY OF SECTIONS IN

GROUP

LMRP Wet-Weight (lbs)LMRP Height Off Sea Floor (ft)

RISER CROSS-SECTIONMain Riser ID Area (ft^2)Choke, Kill, Boost, Hydro ID Area (ft^2)Total Cross-Sectional Area (ft^2)Total Mud Volume in Riser Column (gal)

LMRP INFORMATIONLMRP Dry Weight (lbs)

= Sea Water Column = Number of Tensioners Supporting Riser = Number of Tensioners Subject to Sudden Failure = Reduction Factor Relating Vertical Tension at Load Ring to Tensioners

TENSION REQUIREMENTS, PER API RP 16Q

= Submerged Weight Tolerance Factor = Net Lift of Bouyancy Material = Bouyancy Loss and Tolerance Factor = Internal Cross-Sectional Area of Riser including fluid lines

= TSRmin * N / [ Rf * ( N - n ) ] = Ws * fwt - Bn * fbt + Ai * [ dm * Hm - dw * Hw ]

= Minimum Top Tension = Minimum Load Ring Tension = Submerged Riser Weight

= Drilling Fluid Weight Density = Drilling Fluid Column = Sea Water Weight Density

Number of Tensioners (N)

Tension Reduction Factor (Rf)Tensioners Subject to Failure (n)

Elasticity of Steel (psi)

FACTORS AND CONSTANTS

Documents

Riser Recoil Analysis Report for Acme Drillship