ts deepwater basic awareness (training package)

 Vessel which features mooring/station keeping capability  Utilizes rig heave compensation system  Variable deck loading VDL considerations due to rig motion  BOPs are on the sea-

Deepwater Testing Basic Awareness

Training Material

Testing Services

© 2010 Schlumberger All rights reserved

An asterisk is used throughout this presentation to denote a mark of Schlumberger Other company, product, and service names are the

properties of their respective owners

Objectives: Deepwater Testing Basic Awareness

To provide basic understanding and awareness of common technical

subject matter related to deepwater exploration, appraisal and development activities This includes:

 What is Deepwater Testing?

 Deepwater Rigs

 Heave Compensation Systems

 Variable Deck Loading

 Station Keeping – Moored and DP

 Deepwater Risers and BOPs

 Basic Subsea Trees

 Basic Met Ocean

 Subsea Landing Strings

What is Deepwater Testing?

We define a deepwater operations as any Testing activity on a floating MODU (Modular Offshore Drilling Unit)

 Floating MODU:

● Moored vessel (e.g Semi-submersible)

● Dynamically Positioned vessel (e.g drillship)

 Testing activity:

● Operational activity executed on that vessel by one, some, or all of the Testing Sub-segments

What is Deepwater Testing?

Deepwater Deepwater Deepwater

What is Deepwater Testing: Subsea LS Definition

What is different in Deepwater?

 Increased water depth

 Increased operating pressures

and temperatures downhole

 Wellbore stability and/or quality

 Production and flow assurance

(e.g hydrates)

 Operating environment

(Met Ocean)

 Subsea equipment requirements

 Surface facility requirements

 New generation of drilling, testing, and completion challenges

 New generation of technical professionals required

The following differences may apply to deepwater well construction:

How is a Deepwater Rig Different

 It floats!

 Vessel which features mooring/station keeping capability

 Utilizes rig heave compensation system

 Variable deck loading (VDL) considerations due to rig motion

 BOPs are on the sea-bed

 Extended marine riser systems to access the sea-bed and well

 Significantly increased operating costs and client exposure

 Significantly increased impact of non-productive time

“Deepwater is Our Reputation”

 The associated cost of NPT in deepwater operations is severe

 The customer must minimize risk, despite increased operational costs

 Schlumberger must provide reliability through excellence in execution

in deepwater operations

 High costs = high exposure Service quality incidents will attract

considerable attention and have an increased impact on our

reputation

Deepwater Drilling Rigs

Two hull types:

Drillship Semi-submersible

Deepwater Drilling Rigs

Drillship advantages:

 Higher variable deck loads

 Faster transit speed (10-12 knot)

 Capable of high transit loads

Deepwater Drilling Rigs

Deepwater Drilling Rigs Typically Feature:

 Power to drill while maintaining position in rough weather

 Station keeping ability

 Stability and deck capacity characteristics

 Moonpool facilities for subsea tools and equipment

 Three of four 1600HHP triplex mud pumps (or alternatively 2 larger 2200HHP)

 Large variable deck load (minimum of 4000MT)

 Adequate mud pit and reserve pit capacity

 Heave compensator system

 Work areas for simultaneously handling subsea equipment

 Competent deepwater drilling teams

Generations of Deepwater Rigs

Heave Compensator Systems

 The “Heave Compensation System” isolates vertical motion of the drilling vessel from the drill-string:

● Prevents forces due to the movement of the vessel being transferred to the drill string and BHA

● Allows constant weight on bit

● Prevents constant movement of drill-string/tubing in the riser and BOPs (reduces wear)

 Effectively a giant spring between the rig and the drill string

 Two major types of compensators are:

● Drill string compensator between travelling block and hook

● Top mounted (crown mounted) heave compensator

 Compensation system can be passive (PHC) or active (AHC)

Heave Compensator Systems

Passive Heave Compensator Systems (PHC)

 Passive Heave Compensator is a reactive system – utilizing a large air cushion the PHC attempts to isolate the vessel heave

 Low frequency dampening systems (employing compressed air to

effect the dampening of vessel heave)

 Has to overcome the friction of seals each time the vessel heaves up

or down

 Traditional systems on older generation floaters

 Requires weight-on-bit (i.e weight set down on the drill-string) to

compensate for rig motion

 Reduced sensitivity, approximately 12% of drill-string load

Active Heave Compensator Systems (AHC)

 Active compensation systems developed for

rougher sea-state conditions and to land

subsea production trees

 Utilize a computerized feed-back system

The heave of the rig is measured, and the

block is lifted or lowered in response to the

measured heave to compensate and

maintain a constant weight on the string

 Used in conjunction with passive system

 Passive system compensates for the largest

part of the load and active system provides

sensitivity required for operations where

precise control is required

Variable Deck Loads (VDL)

The rig floats because:

 Buoyant forces act to push the rig out of

the water

 Displacement volume of the rig in lbs/64 =

Buoyant force in lbf

 There are 3 centers of buoyancy along

each axis of the vessel i.e vertical,

longitudinal, and transverse

 The corresponding mass of the rig (and

its load) acts down

 Provided rig mass is less than buoyancy

force, the rig floats

Variable Deck Loads (VDL)

Ballast Control:

 Ballast water is used in rig footings to

keep the rig submerged in “lightship” or

no additional load condition to maintain

operating “DRAFT”

 Additional load pushes down; rig sinks

deeper Replace ballast water with air

to keep the rig at constant draft

 Rig sinks down reflecting location of

load (e.g Starboard side) Remove

water from Starboard ballast tank to

maintain rig level or “TRIM”

Station Keeping: Mooring Systems

 A drilling vessel is “moored” if it is connected to the sea floor with a

multipoint spread of anchors and mooring lines

 The primary function of a mooring system is to hold the rig within a

specified tolerance of a “station” or well location

 As the rig tends to move off station due to external forces, tension lines

in the mooring system increase as required to restore or maintain

station keeping

 Conventional mooring systems can be used up to 5000ft water depth, beyond this depth specialized systems are required

Station Keeping: Mooring Systems

Station Keeping: Dynamic Position Systems

 Used on new generation vessels, station is maintained

by continuously acting thrusters to prevent tension

lines from having to be run to the sea-bed

 Enables operations in deeper water

 Major elements of a DP system include:

● Control system

● Sensor system

● Thruster system

 Redundancy built-in to all systems to ensure single

point failure does not result in the rig losing station

Station Keeping: Dynamic Position Systems

DP Control System

 Process environmental sensor

information

 Computes instantaneous

position of the vessel

 Calculates force and moment

required to counter

environmental forces

 Allocates thruster forces to

compensate and hold station

Station Keeping: Dynamic Position Systems

DP Sensor System

 Continuously measure the

position of the rig using;

GPS/DGPS, satellite surveys,

acoustic systems, and riser

angle systems

 Measure the “YAW” (or

heading), “PITCH” and “ROLL”

using; gyrocompass and vertical

referencing

Station Keeping: Dynamic Position Systems

Thruster System

 Typically powered by electric

motors

 Most common type are azimuth

controlled ducted thrusters with

controllable pitch

 Positioned around vessel to

optimize station keeping control

Deepwater Riser Systems

 The drilling riser and BOPs are attached

to the well and the seafloor by

connecting to the subsea wellhead

 Deepwater riser system consists of:

● Subsea BOPs (connected to the well

head via connector)

● Lower Marin Riser Package (LMRP) c/w

Flex joint

● Sections of subsea drilling riser

● Telescopic or slip joint

● Rig floor riser diverter

Deepwater Riser Systems: SS BOPs

The purpose of the subsea BOP system is:

 Shut in the well as needed

 Allow for rig movement

 Allow temporary suspension and re-entry

(in the event the rig must move of station

quickly)

 Provide an integral connection to the well

and sea floor (i.e subsea well-head)

 Provide multiple redundant methods of

shutting-in and isolating the well

Deepwater Riser Systems: SS BOPs

Features include:

 Increased capacity for increased variation in ram sizes

(multiple DP sizes) and multiple Variable Bore Rams

(VBRs)

 Sometimes two annular preventers feature in the BOP

stack often with increased closing force to account for

riser hydrostatic opening force

 Pipe rams feature the capability to support the weight of

the drill string so that it can be hung-off and the well

isolated in the event the rig must move off station

quickly

 Two sets of shearing rams – conventional blind shearing

rams (sealing) and casing shearing rams (non sealing)

Deepwater Riser Systems: SS LMRP

 The Lower Marine Riser Package:

● Located directly above the BOP stack

● Features the ability to disconnect from the BOPs

● Features a flex joint to allow some rig

movement without loading the BOPs directly

connected to the subsea wellhead on the seabed

 The Flex Joint:

● Can provide up to ten degrees of tilt in any direction

● Available in different working pressures and tensile

ratings

Deepwater Riser Systems: Drilling Riser

The Drilling Riser

 Is the “tube” between the LRMP and rig,

provides conduit for the drill-string and

drill fluids from the well and sea-bed back

to the rig

 Wall thickness and tubing grade depends

on water depth due to increasing collapse loads at deeper water depths

Increasing depth requires higher wall thickness and grade

 Most DW risers utilize flanged riser connections

 Significant weight, increasing with water depth, which must be supported by the rig Buoyancy units are attached to each riser section to reduce the weight of the string in water

Deepwater Riser Systems: Telescoping Riser Joint

The Telescopic Riser Joint

 Also known as the riser “slip-joint”

 Located in the top section of the drilling riser

 Permits relative movement between the

stationary section of the drilling riser (which is

attached to the sea-bed) and the upper section

which is attached to the moving drilling rig

 Consists of a hydraulic or pneumatic activated

Deepwater Riser Systems: Marine Riser Tensioner

The Marine Riser Tensioner

 Tensioning system which maintains positive pulling force on the

drilling riser independent of the movement of the rig This

counteracts high forces which can be transmitted to the riser due

to rig movement

 Consists of a number of riser tension lines attached from the rig to

the marine riser (at the load ring on the riser slip joint)

 Hydraulic system – a cylinder with sheaves at each end for the

tension line The wire rope tension line is fixed to the rig and

through the sheaves The other end is connected to the riser Line

tension is regulated by a cylinder and piston connected to high

pressure gas bottles and a low pressure accumulator

Deepwater Riser Systems: Diverter

The Diverter

 Located immediately below

the rig floor, above the riser

slip joint

 The diverter provides a means

of diverting an unexpected

release of well fluids (primarily

gas) to a location away from

the rig floor at the extremities

of the rig

Subsea Trees

There are two categories of subsea production trees:

Horizontal Trees Vertical Trees

Subsea Trees: Vertical

Vertical Subsea Trees

 Tubing hanger landed in the well-head before

deploying tree

 Tree valves stacked vertically on top of the tubing

hanger

 “Vertical” flow path of produced fluids through the TH

and SST with vertical master valve orientation

 Downhole functions for the completion via

hydraulic/electronic penetrations through the bottom

of the tree to the top of the tubing hanger

 The tree must be pulled in order to recover and

re-run completion strings

Subsea Trees: Horizontal

Horizontal Subsea Trees

 Tree deployed before the completion and tubing

hanger Completion is deployed through the

horizontal production tree Tree cap installed after

installation of completion is complete

 “Horizontal” flow path of produced fluid through tubing

hanger and tree Fluid flows through production port

in side of tubing hanger aligned with flow-line in tree

Horizontal orientation of master valve

 Downhole functions provided through radial

penetrators on the side of the tubing hanger

 Completion strings can be recovered without pulling

the tree

Met Ocean

 “Metocean”

● A combination of the words "Meteorology" and "Oceanography" The term is used to describe the offshore physical operating environment of a MODU or

offshore structure (platform)

 As water depth increases, environmental loading on a rig

increases (increased winds, higher seas, ocean currents etc)

 Environmental loads impacting a floating rig include:

● Wind – typically collinear with seas, highest load on a semi, drillships aim to

orientate bow into the wind usually

● Waves – can be highest environmental load in extreme locations, drillships

have increased sensitivity

● Currents – winds generate a shallow surface current, deeper currents

What happens if…

The rig loses station while testing or has to move quickly in the middle of a well-testing operation?

Subsea Landing Strings

Subsea Landing String (SenTREE) provides a fast acting and reliable means to:

 Isolate the landing string from the test string

 Prevent discharge of landing string content (retainer valve)

 Disconnect the landing string from the test string / completion

 Provide additional barriers in the flow path

 Pump through feature

 Cuts wire line & coil tubing

Schlumberger SSLS products

 Subsea safety systems

● SenTREE 3 (3.0” Bore – Exploration)

● SenTREE 7 (7.0” Bore – Development/Completions)

● SenTREE HP (High Pressure Operations)

 Subsea control Systems

● Direct Hydraulic Mid-water control System

● SenTREE 3 Electohydraulic deepwater control system

● SenTREE 7 Commander deep-water control system

● SenTREE 7 / HP SenTURIAN Deep-water control system