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Lecture
6:
DIRECTIONAL
DRILLINGDirectional Drilling Fundamentals &Directional Trajectories
Arun S Chandel
Assistant [email protected]
09997200339
1
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Segments of Deviated Well
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Major Directional Well Profiles
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Directional Drilling Terminologies
KICK-OFF POINTThe kick off point is defined as the point below the surface locationwhere the well is deflected from the vertical. The osition of the kick
off depends on several parameters including: geologicalconsiderations, geometry of well and proximity of other wells.
The maximum permissible build up /drop off rate is normally
determined by one or more of the following: The total depth of the well Maximum torque and drag limitations Mechanical limitations of the drill string or casing Mechanical limitations of logging tools and production strings.
T h e o p t i m u m b u i l d u p a n d d r o p o f f r a t e s i n c o n v e n t i o n a l
d i r e c t i o n a l w e l l s a r e i n t h e r a n g e o f 1 . 5 0 t o 30 p e r 1 0 0 f t ,
a l t h o u g h m u c h h i g h e r b u i l d u p r a t e s a r e u s e d f o r h o r i z o n t a l a n d
m u l t i l a t e r a l w e l l s .
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INCLINATION ANGLE
The inclination angle of a well at any point is the angle the wellboreforms between its axis and the vertical, see Figure 11.11.
MEASURED DEPTH
from one reference point to the survey point. Measured depth isalso known as Along Hole Depth and is measured with the pipetally or by a wireline.
True vertical depth (TVD) is the vertical distance measured from
a reference point to the survey point. TVD is usually referenced to
Northing: Horizontal distance between one survey point and theRKB, measured to the North. A distance to the South is generally
eno e as e ng nega ve.
Easting: Horizontal distance between one survey point and theRKB measured to the East. A distance to the West is eneralldenoted as being negative.
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Azimuth & Departure
The azimuth of a wellbore at any point is defined as the direction of thewellbore on a horizontal plane measured clockwise form a northreference. Azimuths are usually expressed in angles from 0-360 ,measure rom zero nor .
Azimuths can also be expressed in a quadrant system from 0-90measured from north in the northern quadrants and from south in thesouthern quadrants. The azimuth reading of 135 equates to S45 E inquadrant readings.
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Azimuth and departure
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Azimuth and departure
N
AB
C OEW
84
tD
n
D
1852
S
AZIMUTH = 272.6 de rees
0
.
eD
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HorizontalDeparture:
2 2
t e nD D D= +
Azimuthof
the
well ( )= 1tan eD
n
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Azimuth and departure
Given the following grid coordinates, determine the departureand azimuth of the target from the surface location.
Grid Coordinates: Target6,334,400.00 N (m)200 600.00 E m
Grid Coordinates: Surface
6,335,000.00 N (m), .
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Circular Functions
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Circular Functions
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Radius of curvature
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Radius of curvature
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Build-up Rate Formula
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Determining End of Build
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J-Profile (departure >R)
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J-Profile (departure < R)
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S-Profile (R1+R2 < total target displacement)
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S-Profile (R1+R2 > total target displacement)
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Whats Best?
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ManualDesign:Build&HoldTrajectory(JProfile)
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ManualDesign:Build&HoldTrajectory(JProfile)
To carry out the geometric planning for a Type Iwell, Figure 11.13, the following information isrequired:
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Target Co-ordinates
TVD of target
TVD to KOP
Build-u rate
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Base Equations
Using the detailed trigonometry shown in Figure 11.13, themaximum inclination angle max for type I trajectory can becalculated for two cases:
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Base Equations
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Base Equations
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Problem:Build&HoldTrajectory(JProfile)
Following data is given for a directional offshore
we r e as -pro e:
Kick-off point (K) = 1000
Build Rate BUR = 2.50 100
Target data
True vertical depth (V3) = 9500Northings (Dn) = +3507
Eastings De = -1752
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Find the following:
1.Horizontal Departure (D2)
2.Azimuth of the well ( )
.
4.End of build at TVD (V2)
5.End of build at departure (D1)
6.Measured depth at end of build (OE)
.
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O
CK
A
v1
R
B
Rv2
E
v3
xy
T
D2
1