Title: Definition
1DRILLING ENGINEERING
CHAPTER 8
Directional Drilling and Deviation Control
2Definition
- Directional Drilling
- The process of directing the wellbore along some
trajectory to a predetermined target. - Deviation Control
- The process of keeping the wellbore contained
within some prescribed limits, relative to
inclination angle, horizontal excursion from the
vertical or both. - X-Y Plane
- X Plane direction plane
- Y Plane inclination plane
3- Angles
- X-Y Plane X angle direction angle
- Y-Z Plane Y angle inclination angle
- Purpose of Directional Drilling
- Res. Under lake (economics, environmental
reasons) - Offshore drilling.
- Res. beneath population centers.
- Res. beneath natural obstruction (mountains) Or
severe topographical features. - Sidetracking out of an existing wellbore to
bypass an obstruction (fish) or explore
additional producing horizons in adjacent
sectors. - Relief well to plug a blow out.
4Inclination and direction planes as a wellbore
proceeds in the depth plane.
5Plan view of a typical oil and gas structure
under a lake
6Typical offshore development platform with
directional wells
7Developing a field under a city using
directionally drilled wells
8Drilling of directional wells where the reservoir
is beneath a major surface obstruction
9Sidetracking around a fish
10Using an old well to explore for new oil by
sidetracking out of the casing and drilling
occasionally
117.1 Planning The Directional Well Trajectory
- Trajectory
- Well path that will intersect given target.
- First design propose the various types of paths
that can be drilled economically. - Second includes effects of geology on the
bottomhole assemblies (BHA) and other factors
that could influence the final wellbore
trajectory.
12Types of Trajectories
- Build and hold trajectory penetrates target at
max. build-up angle. - Build-hole and drop (s-shape) penetrate angle
vertically - Build-hold drop and/or hold (modified s-shape)
penetrates target at angle less than max.
inclination angle in the hold section. - Continuous build trajectory inclination angle is
increasing. - q1 lt q3 lt q2 lt q4
13- X3 horizontal departure
- g1 radius of curvature
- D3 TVD true vertical depth
- D1 kick off point TVD
- q rate of inclination angle build up
14Geometry of build-and-hold type well
157.2 Build and Hold Trajectory
- Circumference 2pr
- Srq
- q in radians max. inclination angle
- 1 radian 180 o/p 57.29578 o
- 1o p/180 radians
- q degrees per unit length q/L
- inclination angle build up rate
- q 1o/100ft
- r S /q
- r radius of curvature
16(8.1)
17(8.2)
- q W - T
- To find angle T look at triangle OBA
(8.3a)
(8.3b)
To find angle W consider triangle OBC
(8.4)
18(8.5)
q W - T
19(8.6)
Length of the arc section DC (buildup section)
(8.7)
20- Length of CB (Trajectory Path)
- Straight at constant inclination angle can be
determined from BCO
Total measured depth DM for TVD of D3 is
(8.8)
21- Horizontal departure at end of build up
(8.9)
True Vertical depth at end of build up section
(8.12)
22Geometry for the build section
23- Measure depth and Horizontal departure before
reaching maximum angle along any part of build
up. - Consider ? intermediate inclination angle ?
- XNHorizontal Departure at C
- DNVertical depth
- Consider ?DOC
(8.10)
(8.11)
24- New measured depth for any part of the build up
(8.13)
New measured depth at TVD of (Dlt D3)(D2ltDlt D3)
(8.16)
Horizontal Departure X (X2ltXlt X3)
(8.18)
25(8.20)
26Build-hold-and-drop and hold (modified-S)
27Directional quadrants and compass measurements
28Vertical calculation
29Horizontal calculation
30Three-dimensional view of a wellbore showing
components that comprise the X, Y and Z parts of
the trajectory
31Techniques for making a positive direction change
327.3 Directional Drilling Tools
- Stabilizing Tools
- The Stiff Hook-Up
- The Pendulum Hook-Up
- Angle Building Hook-Ups
- The Lock-in Hook-Ups
- Angle Losing Hook-Ups
33Directional drilling applications
34Stabilizing tool
35The use of stabilizers in directional drilling
36Other Application of Stabilizing Tools
- Key seat Guide
- Avoidance of Pressure Differential Sticking
- Whip stock
- Knuckle Joint
37Whip stocks
38Knuckle joint
39(No Transcript)
40Using a section mill to prepare for a kick-off
41Jetting bit
42Jetting a trajectory change
43Fig 8.95 A typical positive-displacement mud
motor (PDM)