SES STEERING GUIDANCE
DIRECTIONAL STEERING GUIDANCE & MONITORING
SES contains directional steering technology called FDDC steering guidance. The technology is based on a
U.S. Patent granted in 2000. FDDC is an abbreviation for Fuzzy Logic Drilling Direction Controller.
FDDC takes THD as input and uses Fuzzy Logic and steering rules to
calculate changes to directional drilling tool setting adjustments/modes.
FDDC output is available in SES to assist directional
drillers, and to help monitor directional steering decision-making and oversight.
FDDC STEERING GUIDANCE
FDDC steering guidance is calculated at each survey station with sufficient respective well plan inclination. A technical paper
about FDDC steering guidance was
published in 2003
and a similar paper is
A 2007 presentation about FDDC use and geosteering is
U.S. patent is also a reference to interested parties.
FDDC steering guidance is relative and how to "change". For example, "Towards DROP 40%" could mean to continue
drilling high side, but Less with respect to what occurred during the last survey station interval and with respect to what in general
is considered to be a Very Large steering adjustment
with the current bottom hole assembly in the current sized hole.
To very briefly explain general concepts, two
different example FDDC rules are
pictured below. On the left, the actual path is below the plan ([VD] is <LOW>) and not progressing
much ([RCVD] is <ZERO>) so <BUILD_SOFT> is fired.
On the right is a different scenario in which the actual path is above the plan ([VD] is
<VERY_HIGH>) and ([RCVD is <NEGATIVE_BIG>) so <LEAVE
ALONE> is fired.
There's nothing fuzzy about the
logic as the two preceding example rules match common
sense. There are 100s of rules in FDDC and each can
be isolated to basic fundamental steering concepts
that humans apply each day without hesitation. Input and
output terms are described with Fuzzy Sets and Fuzzy
Logic is used to calculate resulting steering
below picture from SES, FDDC steering guidance at MD
(9306 ft) from THD VD (8.43 ft high of plan) and
RCVD (-79 ft/1000ft) and ID (5.51 deg low of planned
inclination) and RCID (-6.1 deg/100ft) is..."Towards BUILD 60%"; in other words significantly more
steering towards high-side is being advised at MD
9306 ft even
though the wellbore is currently 8.43 high of the
well plan. That's not intuitive, and ID isn't
discernable from a vertical section view.
Again, "D High/Low Side" FDDC
output is a % value with respect to what's
considered to be an absolute large respective change. For
example, if the last "Kelly-down"—or more-precisely
the last measured depth distance between two
successive directional survey stations—the wellbore
was largely drilled in rotary mode and if steering
guidance was then "Towards BUILD
100%", this could be interpreted as suggesting that
the next Kelly-down be drilled predominantly in a
high-side manner, whether that be via PDM TFO
high-side sliding, or by rotary-steerable means. For
another example, if the last Kelly-down was largely
drilled low-side and steering guidance was then
advised to be "Towards BUILD 100%", this could be
interpreted as suggesting that the next Kelly-down
be drilled predominantly in a rotary or
non-oriented/non-sliding manner (i.e., a large
change from drilling entirely low-side prior). Thus,
FDDC steering guidance is contextual with recent directional
If an SES user is using
FDDC steering guidance to generally monitor directional
control performance while drilling, then successive
directional survey stations with repeated "Towards XXX 100%" may instigate communications with the
directional driller to determine the root cause,
especially if still drilling the curve before the
horizontal landing. Even when drilling a horizontal
wellbore that will be geosteered, the geometric well
plan is usually honored until 50-75 degrees
wellbore inclination is achieved. If repeated "Towards XXX 100%" is occurring while the live
drilling wellbore is in the curve, there could be
multiple explanations ranging from a break-down in
well plan communications and steering desires or
simply a bottom hole assembly that is not currently
performing; or even a personnel problem.
SIMULATED WELL PATH TRAJECTORIES AND FDDC
Rewind to the 1990s...A
directional drilling simulator was originally
created with which to design FDDC. The
simulator was a 3D finite element model incorporated with a drill-ahead model.
The finite element model was a static analysis of a rotary-steerable
bottom hole assembly. The drill-ahead model was based on laboratory data and a
simulation model proposed by Millheim and Warren in
1978 and Brett et al. in 1986.
Progress was slow. In the
beginning the design efforts experienced all of the common problems associated with complex
controllers: well path instability and
THD and FDDC were
being invented simultaneously.
FDDC eventually produced simulated results with seriously noteworthy characteristics. Consider the following two
vertical section views that were created with the
simulator and FDDC. The first graph presents six TVD corrections for a horizontal well
where initial vertical deviations varied from 3 feet to 8 feet and initial wellbore inclination was 90 degrees. The second
vertical section view presents three entire horizontal wells
modeled from KOP through the horizontal section.
Section View for six TVD Corrections
Section View for three Horizontal Wells
smooth well bores were "drilled" with the
same FDDC. FDDC parameters were kept constant in all cases, while initial
conditions, well plans, and formation parameters were significantly varied.
The performance suggests generality and the right
overall design structure.
Every controller has parameters that directly affect the computed
output and those parameters must
be tuned. Classical controllers (e.g., P, PI, PID) typically have a very small
number of parameters, therefore, "choosing" or tuning to find the
"right ones" usually does not result in a general controller. In other
words, take a tuned classical controller and simply change the initial
conditions and directional control performance becomes heavily degraded. FDDC has more than one hundred control parameters but common-sense
human intelligence gets most of them "close-enough" and the remaining few are tuned.
That's the power of Fuzzy Logic rule-based systems.
COMMERCIAL APPLICATIONS THAT USE FUZZY LOGIC
10000s of documents have been published about Fuzzy Logic theory and applications.
Searching on "Fuzzy Sets" at Amazon.com returns over
1000 books. Even decades ago several
industries had successfully applied Fuzzy technology to solve real problems for
benefit. See the
dated table below that lists commercial applications that employ Fuzzy
Logic. The sources are:
1) Kosko, Bart. 1993. Fuzzy Thinking: The New Science of Fuzzy Logic. New York, New York: Hyperion.
2) McNeill, Daniel, and Paul Freiberger. 1994. Fuzzy Logic. The Revolutionary Computer Technology That Is Changing Our
World. New York, New York: Simon & Schuster Inc.
||Hitachi, Matsushita, Mitsubishi, Sharp
||Honda, Mitsubishi, Nissan, Saturn, Subaru
|cement kiln control
||Isuzu, Nissan, Mitsubishi
||Fujitec, Mitsubishi Electric, Toshiba
|golf diagnostic system
|health management system
|iron mill control
||Hitachi, Matsushita, Sanyo, Sharp, Toshiba
|space shuttle docking
|subway control system
||Goldstar, Hitachi, Samsung, Sony
|traffic control system
||Hitachi, Matsushita, Toshiba
||Canon, Matsushita, Sanyo
||Goldstar, Hitachi, Matsushita, Samsung, Sanyo, Sharp
Fuzzy set theory was invented by
Dr. Lotfi Zadeh in 1965. The first commercial applications of Fuzzy Logic
addressed control problems (e.g., controller for a cement kiln; controller for a high-speed train).
Fuzzy systems debuted within the Petroleum Industry as fuzzy expert systems (e.g., fluid selection for stimulation).