Horizontal Directional Drilling

Erin BoylePipeline Engineering – EIT, Union Gas Ltd.

Eric MacDonaldGeneral Manager, Aecon Utilities

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Agenda• Introduction• Code Requirements

– CSA Z662-07 – Oil and Gas Pipeline Systems• General Design and Construction Considerations• Case Studies

– 10” Komoka Project – London, ON– 12” EWCC Project – Windsor, ON

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Introduction• Horizontal Directional Drilling (HDD)

– A trenchless method of installing pipe in the ground at variable angles using a guidable drill head

• Used when trenching or excavation is not feasible/practical– Water crossings, road and railway crossings, sensitive wildlife

habitats, etc.• Suitable for variety of soil conditions and pipe diameters

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Horizontal Directional Drilling• HDD process:

1) Pilot hole – initial bore drilled along designed drill path2) Reaming pass(es) - increasing the diameter of the pilot

hole to allow pipe pullback; may not be necessary for smaller diameter pipelines

3) Pipe string pull back – pull back of pre-fabricated pipe

• Drilling fluids pumped through drill head during pilot bore, reaming passes, and pipe pull back

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Drilling Fluids• Drilling fluids = water + additives (bentonite, polymers,

surfactants, etc.)• Aid drilling process

– Suspend and remove drill cuttings– Cool and lubricate drill stem and bit– Stabilize bore hole– Reduce friction between drill/pipe and bore wall

• Drill fluid cleanup and control plan for containment, removal, and disposal

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Drilling the Pilot Hole

Source: CAPP Publication 2004-0022

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Reaming of the Pilot Hole

Source: CAPP Publication 2004-0022

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Pipe String Pullback

Source: CAPP Publication 2004-0022

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CSA Z662-07 Requirements• 4.22 Requirements for pipelines installed by horizontal

directional drilling– Pipelines may be installed by directional drilling provided that

• (a) A feasibility assessment is made to assess the suitability of subsurface conditions.

• (b) The drill path is designed with due consideration given to the location and type of all subsurface features influencing installation operations.

• (c) An assessment is made to determine the risk of accidental release of drilling fluids from the drilling annulus and an appropriate mitigation plan is prepared.

• (d) For steel pipe, longitudinal stresses during installation do not exceed the specified minimum yield strength of the pipe.

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CSA Z662-07 Requirements• 6.2.12 Horizontal directional drilling (HDD)

– 6.2.12.1– Prior to commencement of horizontal directional drilling, designed in accordance

with Clause 4.22, a written drilling execution plan shall be developed that outlines the procedures to be used in the completion of such drilling. The plan shall include, as a minimum,• (a) use of drill bit directing and tracking equipment to confirm the drill path

while avoiding the no-drill zone and providing acceptable “as-built” information;

• (b) workspace requirements for equipment at entry and exit points;• (c) workspace requirements to construct and lay out the pipe drag section;• (d) drilling mud and water requirements;• (e) environmental protection and monitoring plan;• (f) drilling fluid management plans (trucking, pits, or tanks);• (g) spill or fluid loss contingency, response, cleanup, and mitigation plans;• (h) equipment specifications, condition, and integrity; and• (i) mitigation of potential detrimental effects of geological formations.

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CSA Z662-07 Requirements– 6.2.12.2– HDD personnel shall be trained and experienced to implement the execution plan.

– 6.2.12.3– Pipe handling and installation procedures shall be developed to minimize damage to the

coating and prevent damage to and overstressing of the pipe during installation. The procedures shall include suitably sized equipment to lift and support the pipe during installation into the drill exit point.

– 6.2.12.4– Evaluation of pipe and coating integrity shall include

• (a) prior to pull back, visual and nondestructive inspection of all girth welds as specified in Clause 7.10;

• (b) visual inspection of the pipe and coating for damage where it exits the drill hole upon completion of the pull back; and

• (c) post-installation pressure test of the drag section as specified in Clause 8.• Note: Consideration should be given to

– (a) pre-test of the drag section;– (b) post-installation coating survey; and– (c) in-line inspection.

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CSA Z662-07 Requirements• 12.6.13 Trenchless installations

– Note: It is intended that the requirements of Clause 12.6.13 supersede the requirements of Clause 6.2.12.

– 12.6.13.1– Prior to trenchless installations, underground structures shall be identified and

located in order to enable the required clearance to be maintained.– Notes:

• (1) The drill head, reamer location, or both, should be periodically monitored to determine that the clearance requirements are being met.

• (2) Where the field conditions indicate that the required clearance might be difficult to achieve, the drill head or reamer location should be monitored by exposing some structures to determine that the clearance requirements are being met.

– 12.6.13.2– Personnel shall be protected against electrical hazards.

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CSA Z662-07 Requirements– 12.6.13.3– Polyethylene pipe shall not be bent to a radius less than the minimum

recommended by the manufacturer.

– 12.6.13.4– The longitudinal force applied on the pipe shall not exceed the limit

recommended by the pipe manufacturer.

– 12.6.13.5– Drilling fluids and associated waste material shall be disposed of in a manner

that minimizes adverse environmental effects.

– 12.6.13.6– After the installation is completed, the exposed end of the pipe that was pulled

through the bore shall be inspected for scratches and other imperfections on the coating or the pipe itself. Where imperfections are found, they shall be evaluated and, if found to be defects, pulling or reaming shall continue until defects are not observed.

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General Design Considerations• Location of underground utilities or structures• Geotechnical and hydrogeological considerations

– Feasibility of HDD– Drill rig, bit, and reamer; drilling fluids

• Pipe specifications– Length and diameter of pipe– Longitudinal stresses encountered during installation

• Type of coating– Flexible and abrasion resistant

• Recommended No Drill Zone– Typically defined in terms of minimum recommended depth of cover

• Connection requirements

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Drill Path Design• Limits of Curvature

– Radius of the curvature in the drill path (minimum in meters)• Steel pipe - 1200 x OD• Plastic pipe- 40 x OD

– Entry angle – 8-18 degrees– Exit angle – 5-10 degrees

• Reaming Diameter– Recommended 1.5 x pipe OD to maximum of 300 mm beyond

pipe OD (OPSS 450 )– Reduce friction and allow circulation of fluids

• Changes in direction, depth, or elevation made smoothly and gradually

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Longitudinal Stresses• Tensile stress in pipe during pullback

– Frictional drag between pipe and borehole or slurry– Frictional drag on ground surface– Capstan effect around drill-path bends (increased frictional drag)– Tensile bending stress due to pipe curvatures

• Monitor pulling force and use “weak link” mechanical breakaway connector to prevent overstressing pipe

• Slow pullback to minimize stresses and not “outrun” drilling fluid

• Longitudinal stresses in pipe reviewed for both designed drill path and as-constructed drill path

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Testing and Inspection• Non-destructive inspection

– Radiography • Pressure testing

– Hydrostatic pre-test prior to pull back– Post-installation test (air or nitrogen preferred)

• Inspection of pipe and coating– Pre-installation

• Inspection of coating (visual inspection, holiday detection)– Post-installation

• Inspect leading joints for coating or surface damage• In situ electrical method - field cathodic protection measurements

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Contingency Planning• Hydraulic fracture

– Annular pressure induces fracture or opens up existing fracture in the formation during drilling process

• Inadvertent return– Drilling fluid and cuttings migrate from drilled hole to surface, along

a joint, fracture, or other path of least resistance• Unexpected geotechnical conditions• Failed crossings• Alternative crossing arrangements

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Reference Documents• Design aspect of HDD projects and pipelines

– Ontario Provincial Standard Specification (OPSS) 450– Planning Horizontal Directional Drilling or Pipeline Construction –

Canadian Association of Petroleum Producers (CAPP) Publication 2004-0022

– NASTT HDD Good Practice Guidelines• Standards

– CSA Z662-07 – Oil and Gas Pipeline Systems

10” Komoka Project

London, Ontario

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Project Overview• 1.8 km of 10” ST YJ• 500 psig MOP• Replacement of 1936 pipe• 35% HDD, 2 Bores

– Thames River Crossing– Small Ravine Crossing

• Construction Took Place October – November 2008• $960,000 Budget ($120,000 Contractor Bore Cost)

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Running Line

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Thames River Bore• Approx. 350 m bore• Abrasion Coated Pipe (Min 35 mm of SPC 2888, Shop

Applied)• Aztec DD8 Boring Machine• Geotechnical study conducted to determine feasibility of

HDD• Contingency plan was to perform a wet open cut crossing• Estimated 1 week to complete• Critical to try to eliminate frac outs• 18” Reamer Used

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Geotechnical Study

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Pictures

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Pictures

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Obstacles Encountered• Entry and Exit for drill very slow

going due to amount of gravel near ground level– First and Last 20 m of bore

took 15X longer than expected• To prevent frac outs it was

determined that vent points would be used to relieve the pressure inside of the bore hole

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Obstacles Continued• Pull head used did not fit to the reamer so a transition fitting was used

– When pipe was 2/3 of the way through there was some resistance and the operator had to back the pull up slightly

– The pins on the transition fitting snapped and reamer was disconnected from the pull head

– Quickly floated in a DD7 to pull the pipe back out of the hole– Reamer was machined to fit directly to the pull head

• Drive Carriage was worn down and eventually gave out – Parts needed to be shipped in from Toronto– Pull back was approximately half way through when machine broke and

had to be left in over weekend while machine was repaired– Machine was repaired and was luckily able to start pulling again

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Pictures

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Pictures

• Mud Reclaimer was used to minimize the amount of excess drilling mud waste (95% of mud able to be reused)

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Final Bore Profile

• Bore was completed in 2 weeks (1 week over schedule)• Pipe was pulled in safely and effectively• Current test was performed on pipe to check the condition of the

coating (Excellent)

12” EWCC Project

Windsor, Ontario

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Project Overview• 5 km of 12” ST FBE• 600 psig MOP• Purpose to feed a new 84 MW cogeneration plant• 60% HDD, 12 Bores (Longest 653m)

– 3 Railway Crossings– 4 Major Road Crossings– 1 Creek Crossing

• Construction Took Place April – June 2008• $5.3 Million Budget ($1.5 Million Contractor Bore Cost)

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Running Line

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Drilling Mud Disposal• Due to the recent uproar from the MOE with regards to drilling mud

being classified as a liquid industrial waste, a pilot program was conducted to solidify the fluid

• Pilot program was chosen for a specific bore due to the risk of there being contaminants in the soil (which test of samples from the bore hole later revealed to be clean at that depth)

• Company called Surface to Surface was used• 2 large holding tanks were brought in and all waste mud was dumped

into them with a hydro vac truck• Additive was applied to the mud and solidified within 15 min• Result was solid clay like material which was trucked to the local

dump site

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Pictures

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Chandler St. Bores• Residential street was chosen because the city did not allow

construction down the only commercial/industrial street in the area• Pipe was to be installed into the boulevards• City was unable to provide any data with regards to the location and

depth of the sewer and sanitary laterals• A subsurface utility engineering (SUE) company was hired for the

entire job to provide “B-level” data, but they were only able to pick up a few of the laterals

• Rather than hydro vac out each individual service lateral, a local plumbing company was hired to go into each individual house and snake a camera down the lateral at a cost of $30,000

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Chandler St. Bores Continued• A total of 96 houses were scoped and x,y,z data was provided (2

houses were unable to be completed because residents were not home during the study)

• Design was to run pipe at 1.2 m below ground level but laterals ranged from 4 - 9 ft so there wasn’t a window to shoot through

• Decision was made to bore under all of the laterals at a depth of 12 - 16 ft

• A total of 4 bores were required to complete the street with the longest of them being 653 m

• Only one storm lateral was hit on the entry of the last bore (1 of the 2 houses we were unable to scope)

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Pictures

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Chandler St. Bores Continued• Blocking driveways

– In order to install long bores, there needs to be enough space to set up the pipe for the bore

– The bores were laid out to minimize disturbance to the residents along the street (tried to keep each driveway blocked for no more than 3 days)

• Waiting for coating to dry– In order to keep side streets open, pipe was

welded into sections– Liquid epoxy was used to coat the welds which

takes a minimum of 1 hour to cure– Tape coat could not be used due to the risk of it

shearing off in the bore pull– Boring operation had to shut down for a

minimum of 2 hours while each section was welded together

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Thank You