“Back to the Future”Inertial Navigation for

Precise Well Bore Survey

Ferranti Inertial Navigational Directional Surveyor Baker Hughes Inteq 1979

Advantages:1,000:1 accuracy - actual accuracy is operator dependent;

Disadvantages:Tool diameter 10 5/8”13-3/8" casing and larger;No downhole communications;Battery poweredTemperature limitedThe system only measures North, East and Vertical. Along hole depth, inclination and azimuth have to be back-calculated using a method which may introduce uncertainties

FINDS

RIGS Ring Laser Inertial Guidance Surveyor (RIGS)Baker Hughes INTEQ 1990’s

Inertial Technology

Strapdown inertial navigation systems constructed with:

Three angular rate sensors or gyros Three accelerometers

Sensor electronics and some sort of processor

An IMU is an Inertial Measurement Unit – outputs raw rate and accelerationAn INS is an Inertial Navigation System – outputs position, attitude, velocityAn INS is an IMU with more signal conditioning and processing

Inertial Metrology Components

RLG & IFOG

Rate & Integrating

Gyros

MEMS

Self-Aligning Strategic Missile

Consumer

RLG & IFOG

Autonomous Submarine Navigation

TacticalMissile

MidcourseGuidance

Cruise MissileAir/Land/SeaNavigationSurveying

AHRSTorpedoes

Flight Control, Smart

Munitions, Robotics

IFOG & Quartz

DTG

Bias Stability (˚/hr)

Scal

e Fa

ctor

Sta

bilit

y (p

pm)

1,000

100

10

1

0.10.000150.000015 0.0015 0.015 0.15 1.5 15 1500150 3600

Mechanical

RLG = Ring Laser GyroDTG = Dry Tuned GyroIFOG = Interferometric Fiber Optic GyroQuartz = Coriolis SensorMechanical = Spinning MassAHRS = Attitude Heading Reference SystemMEMS = Micro-Electro-Mechanical Sensors

Courtesy of Draper Labs

Earth rate1 nm/hr

Gyro Technologies

Mechanical, spinning mass or “rotor” gyro (DTG)(Northrop, Honeywell, Kearfott, Atlantic Inertial, many others)

Vibratory/Resonant (HRG)(Systron Donner, Sagem, Murata, Northrop, Atlantic Inertial)

More Gyro TechnologiesOptical - RLG and FOG(Honeywell, Northrop, Kearfott, iXsea, Sagem, etc.)

Pros Rapid reaction and turn on(<1s)Ideally suited for strapdown operationNo moving parts - very rugged

Cons Performance increases with baselineRLG is a high voltage deviceFOG can be temperature sensitive

Micro Electro Mech. Sensors (MEMS) (Draper/Honeywell, Northrop, JPL, BAe, AD, Bosch, etc.)

Pros Very smallNo moving partsVery low cost

Cons Higher precision still under developmentLimited performance range (only for a while) Bias stability – very difficult to model all errors across temp range.

MechanicalFloated

Instruments

Self-AligningStrategic Missile

Stellar-AidedStrategic Missile

AutonomousSubmarineNavigation

Cruise MissileLand Navigation

Aircraft Navigation

Stellar-Aided

Interceptor

Tactical MissileMidcourseGuidance

Quartz

Mechanical Pendulous Rebalance

Accelerometer

MEMS

1,000

100

10

1

0.10.1 1 10 100 1,000 10,000

Bias Stability (g)

Scal

e Fa

ctor

Sta

bilit

y (p

pm)

Consumer

Accelerometer Technologies

Courtesy of Draper Labs

Force Rebalance Accels - Honeywell Q-Flex, Northrop Grumman A4, Kearfott Mod Pros Highly reliable - relatively low cost

Wide bandwidthLow bias error

Cons Analog outputself heating under changing accelerationPower consumption

Pendulous Rebalance Accels.Pros Reliable, rugged, small

Well understood error modelPendulous Integrating Gyro Accel. (PIGA) as good as it gets used for ICBM and general missile guidance

Cons PIGA – Cost

Resonant Element Accel. Sundstrand, Allied Signal, AdkemPros Digital output

Low powerCons Not good in high shock environment

Detailed calibration required

Accelerometer Technologies

Critical photolithographic manufacturing process in silicon wafers.Noise is the challenge. Adding very high speed DSP processingaround the core sensor is allowingsignificant improvements

MEMS Technologies

The performance of an INS is usually rated in terms of itsposition error growth rate once the INS is navigating in freeinertial mode (no aiding).

The USAF defines INS in the following manner*:

Several vendors offer 1nm/day INS – these can be difficult to export *Following a standard ground alignment at 50 ° or lower latitude – USAF SNU84-1

What is the Performance of a “Good” INS

INS Classification Position Error Growth Rate Heading Errors

Low (Tactical) > 2nm/hr >0.2°Medium (Navigation) 0.5 to 2nm/hr 0.05 ° to 0.2 °Precision (Strategic) <0.5nm/hr <0.05 °

W-PINS Phase 1 TestsThe W-PINS project was developed intwo phases:Phase 1 was concept testing:The conclusion after testing in Phase 1was that we could reliably meet the targetset to position the “toe” of a SAG-D well towithin a tolerance of +/- 2m (R95) in thehorizontal and within +/- 2m (2 Sigma) inthe vertical.

The largest error seen in our horizontaldata over a 2.6km round trip was 0.64m(R95)

The largest error in the vertical data over a5km round trip was 1.365m (2σ).

Control for Phase 1

The concept is a core tube assembly containing all components, batterypowered for 16 hours continuous operations with data logging for multipleoperations. Housing is manufactured from DOM 4340. The end caps, nosecone and fishing neck are manufactured from 4340 bar stock.

W-PINS Phase 2 Tests

Align at a known control point – tumble to ensure system is fully aligned.

Update at well site. This should be the well center. If the rotary is well know this will work. If not we will have to provide a static sampled, post processed position for the rotary (+/- 5cm in x,y,z).

Disconnect from tool.

Run into, run out of the hole – motion 2mins, zupt 1min.

Recover to rotary, download data, process data.

W-PINS Operational Procedure

W-PINS Sample Data From Field Use

Northing Easting Orth HeightRun 1 Alignment 6150671.633 499582.411 669.824

Prior to update 6150670.910 499582.570 669.02Misclosure 0.723 -0.159 0.804Half 0.362 -0.079 0.402

Run 2 Alignment 6150671.639 499582.411 669.824Prior to update 6150672.441 499581.723 670.070Misclosure -0.802 0.688 -0.246Half -0.401 0.344 -0.123

Run 1 Toe Unprocessed 6151756.664 499582.737 186.84Compensated 6151757.026 499582.658 187.242

Run 2 Toe Unprocessed 6151757.005 499581.369 187.27Compensated 6151756.604 499581.713 187.147

Difference Uncompensated -0.341 1.368 -0.430Difference Compensated 0.421 0.945 0.095

W-PINS Data Plotted

Modification so far:The original tool had no access to allow forcommunications while on the well. A modified toolfishing neck does.

Centralizers - needed above and below the tool.Modified the nose cone to allow for a centralizer to beinstalled below the tool.

Tool handling was an issue. Had to modify handlinginterfaces, c-plates, etc.

Wireline tractors used – with issues.

Running in the field on coiled tubing this week for thefirst time

ConclusionsWe have learned a lot from a recent operational periods in the field. We willcontinue to learn. Things being worked on (so many)!

Improvements to post processing software

Wireline real time communications (Warrior PCB)Wireline powerReduce the diameterExtend the temp spec a little – BUT

The project was switched on Jan of this year, designed, machined, built andtested and operationally on site by mid April – a very short developmentwindow.

Three trips to the field so far – currently in the field today.

Re-statement of the “Shortcomings” of FINDS from 1980’s

No downhole communications

Battery powered

Temperature limited

The system only measures North, East and Vertical. Along hole depth, inclination and azimuth have to be back-calculated using a method which may introduce uncertainties

Conclusions

Does a Market Exist?The “Holy grail” for such a tool:

<2” dia - including a 20,000psi housingFully operational to 275°C~ 1,000:1 accuracySurvive or work in high shock, BHA environment

Why this tool does not exist:Baseline length is everything – 0.005°/hr single axis is~>1,000m FOG, >~20cm RLG, 3”?? dia DTG, *1.5”dia HRG

Smallest navigation grade (0.005°/hr) inertial components we are aware of defineour future potential ID close to 3.5”. For a 20,000psi pressure housing – with somesort of flask or heat shield – we will not be much smaller than we are today to thishigh pressure high temp.No MEMS or Cold Atom sensors exist anywhere close to this specification today!

Does a Market Exist?Some markets may exist?

SAG-DHigh Latitude, East/West wells, multiple wells in close proximity,large well bore casing to TD

Top hole prior to kick offCongested well planning, close approach drilling?

Relief well assistance

For the foreseeable future we believe that a 5” to 6” OD 20,000psi,100°C tool is as good as it gets for inertial navigation for well boresurveys.

Thank You

Zupt, LLC10963 Cutten Rd, A102Houston, TX 77066+1 832 295 7280

Keith Vickery kv@zupt.com Cell +1 (832) 465 4020President

www.zupt.com