This document provides an overview of the history and development of directional drilling technology from the early oil industry in the late 19th century through modern applications. Key developments include the introduction of rotary drilling, downhole motors to enable steering while drilling, measurement-while-drilling tools for continuous well surveying, and rotary steerable systems that allow extended reach drilling up to 15-18km while continuously rotating drill pipe. These advancements have enabled greater access to reservoirs and reduced environmental impacts from offshore oil and gas development.

1. Directional Drilling – Technology,
Developments and Achievements
Martin Cox CEng FIMMM
Aberdeen Drilling Management (ADM)
8th
December 2016

2. Outline
• Early oil industry drilling (1885 – 1930’s)
• Early Survey practice
• Oil & gas drilling/surveying developments (up to late 1970’s)
• Improvements in drilling/surveying technology
• Oil & Gas industry developing deviated drilling (1980’s & 90’s)
• Refining deviated drilling technology for he 21st
Century:
Extended Reach Drilling (ERD)
Ultra Extended Reach Drilling/UERD

3. Early Oil Industry Drilling
• Small scale shallow drilling water/salt/oil
recorded for centuries.
• Oil from seepages – many areas mainly for
lamp fuel.
• 19th
Century whaling industry for lamp fuel.
Oil industry competes with and replaces by
end 19th
century).
• Oil industry begins 1859, Titusville,
Pennsylvania . USA.
•‘Colonel’ Edwin L Drake (former railroad
conductor).
• Attempts to mine near oil seeps – floods.
• Adapts technique for salt drilling using iron
‘drive pipes’ to drive through shale to oil
deposit.
• Discovers oil at 69 ½ ft – 400 gallons (approx
10 bbls)
• Oil boom in Western Pennsylvania –
production up to thousands of barrels a day
(oil price collapses)

4. Oil drilling expansion into
20th
Century
• Spindletop, Beaumont, Texas strikes
oil 10th
January 1901.
• Identified as an area with high oil
potential by sulphur springs &
bubbling gas
• Utilises rotary drilling & use of
drilling mud to drill deeper
(1,139ft/347m).
• 1st
well comes in at 100,000 bbl/day
(35 Imp gal/bbl 42 us gal/bbl)
•Spindletop boom results in 600
companies formed by 1902 with 285
wells in the field (Founding of Amoco,
Chevron, Exxon, Mobil, Texaco)
• US becomes world major oil producer
• Overcapacity in US market
- drinking water 5 cents/drink ($1/gal)
- Oil 3 cents/bbl (0.1 cents/gal)
• Peak production 1927 @ 21 million
bbls/day.
• Spindletop productive to 1956 and then
mined for sulphur to 1975.

5. Early Oil Industry drilling
• Early drilling in areas with history of seepage
• Percussive drilling initially utilised (e.g. Titusville 69 ½ ft)
• Deeper /more productive wells – rotary drilling establishes its
self (to present day) (Spindletop >1,000ft)
• Oil often found (in NA) when looking for water for agriculture
• Rotary drilling includes use of mud (fluid) in the well at all
times. Cutting removal/hole stability/cooling/formation fluid
containment
• Surveying – Limited to depth (Measured Depth)

6. Route to Directional Drilling - Surveying
1920’s to 70’s
• Several lawsuits allege wells may not all be vertical – deliberate or otherwise crossing
lease/reservoir boundary
• Small diameter tools developed to survey wells
• Survey requires: 3 components measured at a given point:
- Depth (Measured Depth)
- Inclination
- Magnetic Azimuth (problematic due to metal in well)
• Azimuth solution from (gyroscopic compass) creates first survey company ‘Sperry Sun’
- Sperry Corporation – aero navigation industry
- Sunoil – Involved in several lawsuits ‘Slant Drilling Scandal – East Texas Oilfield’.
(Deeper wells >3,000ft)
• Surveying
- Run during trip, later deployed by cable
- Continual innovation 1930 – 70’s
(acid etching / pendulum / photographic single and multi shot)

7. Route to Directional Drilling
1920’s to 70’s
• Rotary drilling establishes principles for equipment configuration of Bottom Hole
Assembly (BHA)
- Prone to dill a crooked hole from the vertical
- Prone to bring a crooked hole closer to the vertical
• 1934 John Eastman innovation to reliably ‘kick off’ from the vertical using a
whipstock.
• Combined BHA designs and ability to survey makes directional drilling possible but
considered arcane/specialist operation (e.g. Drilling relief well for a blow out)
• Industry prefers to find new areas to exploit with vertical/conventional wells
- 1950’s Industry exploratory rate 900 bbls/ft drilled where no previous oil/gas production
- 1960’s Industry exploratory rate 200 bbls/ft drilled where no previous oil/gas production

8. Directional Drilling Developments
1980’s & 1990’s
Drivers
• Need to increase recovery efficiency
Increase exposed section length
through reservoir by drilling at angle
through the reservoir.
• Need to access reservoir/area of
reservoir with limited or no vertical
access
Onshore – access limited by physical or
environmental constraint
Offshore – platform access to all areas
of reservoir or adjacent reservoir
• Reduce environmental impact and cost
of surface facilities to handle
production
• Requirements not limited to oil & gas
Innovations
• Downhole Motor
Development of turbo drill concept mud
flow moves turbine which rotates bit with
drill pipe stationary. (Frank Whittle – 1st
Directional well 1950’s Gainsborough).
Downhole Motor + Bent Sub enables Slide
Drilling. (Ability to change angle without
placing whipstock).
• MWD (Measurement While Drilling) +
Mud Pulse/EM Telemetry.
Continuous well survey measurements
taken downhole and transmitted to
surface.

9. • Straight Hole
Applications, e.g.
Freeze Hole Drilling
e.g. Selby project
To drill holes to tighter
tolerance
Directional Drilling - Where?
Freezing
Agent
Pumped
Down Each
Well
“Perfect”
Vertical
Wells
Equally
Spaced

10. 1970’s Directional Drilling BHA
Two modes of operation:
•Sliding (steering) -
Drillstring is non-rotating
and bend is oriented in
plane of directional change
Early 1970’s POOH and
change out to straight
rotary assembly once angle
built
•Drilling ahead - Drillstring
and motor body are
rotated by late 70’s
•Survey by cable deployed
wireline tool. Late 70’s
early survey transmission
by mud pulse.
•Trip out of well for
change of bend (angle)

11. 1980’s Directional Drilling BHA
80’s Directional Assembly:
Bent housing motor – changeout at surface
Major advancement - Could rotate or slide
MWD – for survey measurements
Could survey in minutes (Higher data
transmission rates – more information)
Tools powered by lithium batteries
Introduction of Evaluation Tools
-Gamma Ray
-Resistivity
-Early Porosity Tools (Density & Neutron)
-Acoustic Calipers

12. 1990’s DD BHA
• Bent Sub adjustable at surface (AKO).
• Can drill in rotary or sliding to change angle.
• Continuous MWD survey data stream.
• Higher accuracy survey measurements
Reduced survey ellipse of uncertainty.
• Full set of evaluation logs available
Multiple Resistivity, Porosity (Density, Neutron, Sonic), Acoustic Caliper,
fracture imaging pressures
• Ability to Geosteer in reservoir
• Continuous data stream to surface
Mud pulse or EM telemetry at up to 200 bps (theoretical), usually 30-70 bps range,
<10bps @10km
• Downhole Positive Displacement Motors/Turbines in BHA
Greater reliability
• New generation of bit technology for directional drilling activities
Design & Materials technology

14. Directional well design & surveying
Directional Survey
• Measured Depth (MD)
• Angle (from vertical)
• Azimuth
• True Vertical Depth (TVD)
• Vertical Section – displacement from
surface location
• Trajectory
• Directional Terms
• Build Rate – how fast angle is
increased
• Tangent – section of well where
angle is constant
• Drop Rate – how fast angle is
decreased
• Walk rate – natural turn in a well
path
• Dog Leg Severity – measure of rate of
change of angle
• Rotate Vs. Slide – drilling term
• Ellipse of uncertainty

15. Ellipse of Uncertainty
Potential location of the
wellbore when the
Accuracy of the survey
methods are applied
To the well path.
“Cone” represents range of wellbore
locations .If directional survey errors
are applied.

16. Brent Field
1970’s
4 platforms
NEIMME - Tyneside
NEIMME – N-U-T CS

17. 1980’s field development
Directional Drilling enables greater reservoir access

18. Extending the reach

19. BP Wytch Farm – South Coast UK (Dorset)

20. 1990’s Towards ERD
• Wytch farm near to shore development of 200mm bbl field
• World record well set late 90’s at 10.1km (now exceeded)
• Further development of Direction Drilling Technology
• Identification of future industry requirement for ERD/UERD
drilling
- Field development with less surface disturbance
- Cost & environmental impact reduction at acceptable risk
level
• Oil and gas industry sets out requirement to be able to
directionally drill in rotary – The Rotary Steerable System

21. ERD and on to Ultra Extended reach Drilling

22. Rotary Steerable – Push the Bit
Rotary Steerable – Point the Bit

23. Directional Drilling in the 21st
Century – Rotary
Steerable Systems
• Directional Drilling while rotating the pipe
• More time on bottom making hole
• Continuous survey data transmission
• Faster ROP / Better hole cleaning along reach
• Smoother wellbore (eases completion phase)
• Operational Cost $30K - $40K/day
• Cost around $3m per assembly
• Wells exceeding 15km have been drilled
• Wells of up to 18km are planned

24. How far can we go?
Reach limited by
• Torque – limited by
strength of tubulars and
tool joints and is directly
related to length of hole.
• Power to the bit – deeper
depths or longer step outs
require more power to
pump mud that distance
and remove cuttings from
the hole.
20km by 2015?