In the name of Allah An Introduction to Directional Drilling (Advanced Drilling Engineering course)
Instructor: Dr. Tabatabaei nejad Lecturer: Mojtaba Owrangi - 87333102 Master of Petroleum Drilling & Production engineering Sahand University of Technology
Introduction Definition & Reasons for D.D 2. Reference Systems and Coordinates 1.
Types of Directional well trajectories 4. Calculation of a well trajectory 3.
Directional Drilling Measurements 6. Deflection Tools 5.
7.
Principles of BHA
Definition & Reasons for D.D
D efinition : Definition
Kick off point (KOP):
The science of directing a well bore along a predetermined predetermin ed trajectory to intersect a designated subsurface target. The kick off point is defined as the point below surface location where the well is deflected from the vertical.
Target: Target
A predetermined point in the reservoir that D.D should reaches to it.
Well classification Vertical Well
Wells with less than 10º deviation
High Inclination Well
Wells between 60 and 85º deviation
Horizontal Well
Wells with more than 85º deviation
Extended Reach Well
Horizontal/TVD displacement greater than 2.5
Designer Well
Wells with significant turn in the horizontal plane of 30 to 180 degrees, and turn not restricted by inclination
Directional wells Radius Classification
Build Rate
Radius
( degrees/30 meter )
(meter)
Long Radius
1- 6
1719 – 286
Medium Radius
7 – 30
285 – 57
Intermediate Radius
30 - 70
56 – 24
Short Radius
71 - 150
23 - 11.5
Reasons for D.D
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
Side-tracking existing well (because of hole problems or fish or reaching new targets) Restricted surface locations (inaccessible locations) To reach multiple targets To reduce number of offshore platforms Horizontal Drilling To reach thin reservoirs (using horizontal wells) Salt dome drilling (directing the well from the salt dome to avoid casing collapse problems) To avoid gas or water coning c oning For intersecting fractures Relief wells For controlling vertical wells Shoreline drilling
D.D applications
D.D applications (multiple targets)
D.D applications (relief well)
D.D applications (side-tracking)
D.D applications (inaccessible locations)
D.D applications (shoreline drilling)
D.D applications (salt dome drilling)
D.D applications (fault drilling)
D.D applications (horizontal well)
Horizontal well
Horizontal wells
The Incl. Incl. reaches reaches to to 90° thro through ugh reservo reservoir ir section section
ﺑﻴﺸﺘﺮﻳﻦ ﻛﺎرﺑﺮد در اﻓﺰاﻳﺶ ﺑﻬﺮه ﺑﺮداري و در ﻣﺨﺎزن ﺧﺎص ﻣﺜﻞ
:
Fracture Limestone & Low permeabili permeability ty zone
Horizontal drain holes:
ﻓﻮﺗﻲ30 ﺧﺎص ﺑﺮاي اﻳﺠﺎد زاوﻳﻪ ﺧﻴﻠﻲ ﺳﺮﻳﻊ و در ﻳﻚ ﺷﻌﺎعBHA
2° per ft Deep Kickoff and Build :ﺷﺒﻴﻪ ﻧﻮع
Drilling Fluid Selection
Virtually all of the considerations for choosing a fluid for drilling a vertical hole apply to choosing a fluid for a directional hole:
Formation protection
Hole cleaning
Lubricity
Inhibition
Fluid weight required
Economics
Environmental impact
Reference Systems and Coordinates
Depth references
Measured Depth (MD)
True Vertical Depth (TVD)
Pipe tally, wire line depth counter, or mud loggers depth counter calculated from the deviation survey data
Inclination references
is the angle (in degrees) between the vertical and the well bore axis at a particular point.
TVD & MD
Reference Systems and Coordinates
Reference Systems and Coordinates
Azimuth references
Magnetic North (measured by MWD)
True (Geographic) North
Grid North
Horizontal departure or displacement •
Horizontal distance between rig location & the target.
Note:
True north = magnetic north ± (declination)
Reference Systems and Coordinates
Reference Systems and Coordinates
Types of Directional well trajectories
1.
Build and hold
2.
Build-hole-drop (S type)
3.
Build-hold-drop-hold Build-hold-drop -hold (modified S type)
4.
Continuous build
5.
Deep Kickoff and Build
Types of Directional well trajectories
Build and hold
Features:
Shallow kick-off point (KOP) Build-up section Tangent section Penetrate target at an angle equal to the Max buildup angle No major changes in incl. & azimuth After build up section Incl: 15 – 55 deg or may may be more more
Applications:
Deep wells with large horizontal displacements Moderately deep wells with moderate horizontal displacement, where intermediate casing is not required
Build-hole-drop (S type) & Build -hold-drop-hold (modified S type)
Modified S type
S type
Build-hole-drop (S type) & Build -hold-drop-hold (modified S type)
Features:
Shallow KOP Build-up section Tangent section Drop-off section
Applications:
There are several variations:
Build, hold &drop back to vertical (illustrated above) Build, hold, drop & hold (illustrated above) Build, hold & continuous drop through reservoir
Multiple pay zones Reduces final angle in reservoir Lease or target limitations Well spacing requirements Deep wells with small horizontal displacements
Disadvantages:
Increased torque & drag Risk of key seating Logging problems due to inclination
Continuous build
Features:
Decrease in torque & drag
Lowest risk of key seating
Continuous build rate
KOP
Build Section
Applications:
This type occurs when using down-hole motors with bent sub.
Target
Deep Kickoff and Build
Features:
Applications:
Deep KOP Build-up section Short tangent section (optional)
Salt dome drilling Sidetracking Appraisal wells to assess the extent of a newly discovered reservoir
Disadvantages:
Formations are harder so the initial deflection may be more difficult to achieve Harder to achieve desired tool face orientation with down hole motor deflection assemblies (more reactive torque) Longer trip time for any BHA changes required Build up rate is more difficult to control
Calculation of a well trajectory (build-hold where X3 < r 1)
Radius of curvature: r 1 =
180
π
×
1
q
q= build rate (deg/100 ft)
Maximum inclination angle,
ɵ ,
when
X 3
⎤ ⎛ r − X 3 ⎞ ⎟⎟ ⎥ − arc tan ⎜⎜ 1 ⎢⎣ ( r 1 − X 3 ) 2 + ( D 3 − D1 ) 2 ⎥⎦ ⎝ D 3 − D1 ⎠ r 1
θ = arc sin ⎢
The length of arc, section DC: L DC =
π 180
× r 1 × θ Or
L DC =
θ q
Horizontal departure departure at the t he end of build section:
X 2 = r 1 (1 − cos θ )
Calculation of a well trajectory (build-hold where X3 < r 1)
The total measured depth:
D M = D1 +
θ q
+
r 1 tan Ω
TVD at the end of build section:
D 2 = D 1 + r 1 ⋅ sin θ
Measured depth at CP section: CP =
C P ′
C P′ = ( D′ − D1 − r 1 ⋅ sinθ )
cos θ
Another way of expressin expressing g maximum inclination angle, angle, in term of r 1, D1, D3 and X3 for X3
⎧⎪ r ⎡ ⎛ D3 − D1 ⎞ ⎤ ⎫⎪ ⎟⎟ ⎥ ⎬ arc cos ⎨( D − D )× sin ⎢ arc tan ⎜⎜ ⎪⎩ ⎝ r 1 − X 3 ⎠ ⎦ ⎪⎭ ⎣ 1
3
1
Calculation of a well trajectory (build-hold where X3 > r 1)
The maximum inclination angle, ɵ can be calculated by: ⎛ D 3 − D1 ⎞ ⎟⎟ − θ = 180 − arc tan ⎜⎜ ⎝ X 3 − r 1 ⎠
⎧⎪ ⎛ r 1 ⎞ ⎡ ⎛ D 3 − D1 ⎞ ⎤ ⎫⎪ ⎟⎟ × sin ⎢ arc tan ⎜⎜ ⎟⎟ ⎥ ⎬ arc cos ⎨ ⎜⎜ ⎪⎩ ⎝ D 3 − D1 ⎠ ⎝ X 3 − r 1 ⎠ ⎦ ⎪⎭ ⎣
Calculation of a well trajectory (S type) r 1
θ = arc tan(
D4 − D1 r 1 + r 2 − X 4
)−
⎧⎪ r +r ⎡ ⎛ D4 − D1 ⎞⎤ ⎫⎪ ⎟⎟⎥ ⎬ arc cos⎨( D − D )× sin ⎢arc tan⎜⎜ + − r r X ⎪⎩ 4 ⎠⎦ ⎪ ⎝ 1 2 ⎣ ⎭ 1
4
2
1
r 1X4
⎛ D4 − D1 ⎞ ⎟⎟ − θ = 180 − arc tan⎜⎜ ( ) X r r − − 1 2 ⎠ ⎝ 4 ⎧⎪⎛ r 1 + r 2 ⎞ ⎡ ⎛ D4 − D1 ⎞⎤ ⎫⎪ ⎟⎟ × sin ⎢arc tan⎜⎜ ⎟⎟⎥ ⎬ ( ) − + X r r ⎪⎩⎝ D4 − D1 ⎠ 1 2 ⎠ ⎦ ⎪ ⎝ 4 ⎣ ⎭
arc cos⎨⎜⎜
Example 1- Design of D.D Design a directional well with the following restrictions:
Total horizontal departure= 4500 ft
True vertical depth (TVD)= 12500 ft
Depth of KOP= 2500 ft
Rate of build of inclination angle= 1.5 deg/100ft
Type 1 well (build-hold)
A.
Determine the maximum hole angle?
B.
What is the total measured depth?
Example 1- Design of D.D
Ans.
r 1=(180/Л)*(1/q)=(180/Л)*(100/1.5)= 3820 ft
Because r1
⎧⎪⎛ r 1 ⎞ ⎡ ⎛ D − D1 ⎞ ⎤ ⎫⎪ ⎟⎟ × sin ⎢ arc tan ⎜⎜ 4 ⎟⎟ ⎥ ⎬ arc cos ⎨⎜⎜ − X r ⎪⎩⎝ D 4 − D1 ⎠ 4 1 ⎝ ⎠ ⎣ ⎦ ⎪⎭
⇒
=26.29 deg
D1=2500 ft , D3=12500 ft , X3=4500 ft, r1=3820 ft
Total measured depth:
D M = D1 +
θ q
+
r 1 tan Ω
DM=2500+1753+9264=13517 ft
Survey Calculation Methods •
Various procedures h ave been developed to have estimate the t he w ell bore trajectory traje ctory as it is being drilled. Eighteen Eightee n methods are kn ow Eighte en kno w n for computing surveys, but the 3 most mo st w idely used methods are the tangential , angel -averaging a n d minimum curvature methods.
•
The normal method for determining the w ell path pat h is to ascertain ascertai n the coordinates by using som e type of surveying instrument to measure the inclination a n d direction at various depths (station s) and then to calculate the trajectory.
Survey Calculation Methods Below is a list of the most used methods: 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Acceleration method Average angle method Angle-averaging method Backward station method Balanced tangential method Circular arc method Compensated acceleration method Mercury method Minimum curvature method Quadrant method Radius of curvature method Secant method Tangential method Terminal angle method Trapezoidal method Vector averaging method
Survey Calculation Methods
Survey Calculation Methods
Tangential method: method
(Backward station method) or (Terminal angle method)
the tangential method uses only the inclination and direction angles at lower end of the course length. length. n ⎧ It is inaccurate among other methods: L = L
⎪ n ∑ i i =1 ⎪ Li = D Mi . sin(α i ). cos(ε i ) ⎫ n ⎪ ⎪ M i = D Mi . sin(α i ). sin(ε i )⎬ ⇒ ⎨ M n = ∑ M i i =1 ⎪ ⎪ Di = D Mi . cos(α i ) ⎭ ⎪ n Li= latitude north/south = D D ⎪ ∑ n i Mi= latitude east/west i =1 ⎩ αi= inclination angle Di= TVD segment
DMi= course length
εi=
direction angle
Example 2- tangential method Use the following survey data to determine det ermine the trajectory coordinates for tangential method? Measured depth, ft 3000 3300 3600 3900 5000 6000 7000 8000 9000 10000
Hole angle, deg 2 4 8 12 15 16 17 17 17 17
Azimuth N 28 E N 10 E N 35 E N 25 E N 30 E N 28 E N 50 E N 20 E N 30 E N 25 E
Survey Calculation Methods Average angle Or Angle Averaging Method: •
the angle averaging method is the simple average of the angles at the top and bottom of course length.
n ⎧ α i + α i −1 ε i + ε i −1 ⎫ Li = D Mi . sin( ). cos( )⎪ ⎪ Ln = ∑ Li i =1 2 2 ⎪ ⎪ n ⎪ α i + α i −1 ε i + ε i −1 ⎪ M i = D Mi . sin( ). sin( ) ⎬ ⇒ ⎨ M n = ∑ M i 2 2 i =1 ⎪ ⎪ n α i + α i −1 ⎪ ⎪ Di = D Mi . cos( ) Dn = ∑ Di ⎪ ⎪ 2 ⎭ ⎩ i =1
Example 3- Average angle method
Determine the trajectory coordinates for the corrected survey points given below: Measured depth (ft) 7100 7200 7300 7400 7500
inclination angle (deg) 0 10.1 13.4 16.3 19.6
direction angle 0 S68W S65W S57W S61W
Note:: Note For the first point the direction should not be averaged, it means that at MD= 7200 we use dir. = 248 instead of 124. For the first point the inclination should be averaged, so for MD=7200 the incl. = 5.05.
Survey Calculation Methods Min imum Minim um curvature method and Radius of curvature method: The minimum curvature method uses the angles at A1 and A2 and assumes a curved well bore over the course length not a straight line.
Survey Calculation Methods
β is in [radian] and if it is less than 0.25 radian, it is reasonable to set F=1.0
⎫ cos β i = cos (α i − α i −1 ) − {sin α i −1 . sin α i (1 − cos (ε i − ε i −1 ))}⎪ ⎪ ⎞ ⎛ β ⎞ ⎪ F = ⎛ ⎜ 2 β ⎟. tan ⎜ i 2 ⎟ ⎪ ⎝ i ⎠ ⎝ ⎠ ⎪ ⎪ D Mi ⎞ ⎛ .(sin( α i −1 ). sin (ε i −1 ) + sin α i . sin ε i ).F i M i = ⎜ ⎟ ⎬⇒ 2 ⎝ ⎠ ⎪ ⎪ D Mi ⎞ Li = ⎛ ( ( ) ) F + . sin( ). cos sin . cos . α ε α ε ⎜ i −1 i −1 i i i ⎪ 2 ⎠⎟ ⎝ ⎪ D ⎪ ⎞ Di = ⎛ ⎜ Mi 2 ⎟.(cos( α i −1 ) + cos α i ).F i ⎪⎭ ⎝ ⎠
n ⎧ ⎪ Ln = ∑ Li i =1 ⎪ n ⎪ ⎨ M n = ∑ M i i =1 ⎪ n ⎪ ⎪ D n = ∑ Di i =1 ⎩
Comparison of accuracy of various calculation methods
Calculation method
Total vertical depth & North displacement & differences from actual (ft) differences from actual (ft)
Tangential
1628.61
-25.38
998.02
+43.09
Balanced tan
1653.61
-0.38
954.72
-0.21
Angle-ave.
1654.18
+0.19
955.04
+0.11
Radius of curvature
1653.99
0.0
954.93
0.0
Minimum curvature
1653.99
0.0
954.93
0.0
Mercury
1653.63
-0.37
954.89
0.04
Dogleg Severity
Large angle changes occurring over a short course length can place high bending stresses on the pipe. In addition, these doglegs can cause key seating problems. Most operators place a limit on the amount of angle change allowable over a 100 -ft segment. The limit is 4-6 deg per 100 ft.
DL =
100
L[(sin I 1 sin I 2 )(sin A1 sin A2 + cos A1 cos A2 ) + cos I 1 cos I 2 ]
DL: dogleg, deg/100ft L: course length I1, I2 : Inclination at upper & lower survey, survey, deg deg A1, A2 : direction at upper & lower survey, survey, deg deg
Directional Drilling Measurements
Magnetic single shot instruments Magnetic multi shot instruments
Measurement while drilling (MWD)
Electromagnetic Acoustic
Pressure pulse Pressure pulse modulation
Cable & DP
Directional Drilling Measurements
Directional Sensor Hardware The figure above shows the basic configuration of the Directional Sensor probe. The directional probe is mounted to the MWD assembly and keyed into a Non-Magnetic Drill Collar. Collar. The nominal nominal length of the sub is 30 feet. The nonmagnetic collar is usually referred to as Monel.
Directional Drilling Measurements
Records –inclination –direction –tool face position
on sensitized paper or photograph photographic ic film
Inclination may be determined by –a float on a liquid –a pendulum
Directional Drilling Measurements (Single shot)
Procedure: –load film into instrument –activate timer (activate stopwatch) –make up the tool –drop the tool –retrieve tool (wire line or drill pipe)
Magnetic Multi shot Instruments
Are capable of taking numerous survey records in one run.
May be dropped down the drill pipe or run on wire line in open hole.
The unit contains a watch that is spring wound and uses the power of the spring to operate a timer cam.
The multishot tool is usually dropped down the drill pipe and landed in the nonmagnetic drill collar.
During the trip out, a survey is taken every 90 ft, i.e. every stand.
More closely spaced stations could be obtained by stopping the pipe more often, and waiting for a picture.
A stopwatch at the surface is synchronized with the instrument watch.
Magnetic Multi shot Instruments
MWD (Measurement While Drilling)
While drilling it is possible to transmit to the surface down hole information on: Inclination Direction tool-face gamma ray Resistivity
temperature weight on bit angle torque on bit sonic velocity
Inclination, direction, and tool -face angle are of particular interest in directional directional drilling. A lower lower cost MWD tool tool can be used if only directional drilling information information is required.
Information is typically transmitted through the mud column by: +ve or - ve pressure pulses, or pressure pulse modulation
Deflection Tools
Hole angles are usually kicked off by jetting, whip stocks or some type of bent sub, down hole motor tools.
Geology affects the decision as well as the desire to use a steering tool.
Jetting: It was a widely used technique several years ago. It involved the use of a large bit jet and two smaller jets. After washing 6-8 ft rotary was used to drill the rest of the joint 1.
Whip stock is a very simple device used to kick off the well. 2.
Separated into 2 categories: i. ii.
Open hole whip stocks Casing whip stocks
Bent subs: are used with down hole motors. The sub has 1/2 -5/2 degree of bend in it that will deflect the motor in the desired direction. 3.
Deflection tools (Jetting)
Jetting
A standard soft formation tricone bit, with one very large nozzle and two smaller ones.
Important parameter:
Geology:
S.S & oolitic limestone (best) Unconsolidated S.S & very soft rock (good) Very soft rocks erode too much (bad) As a rough rule of thumb, ROP>24m/hr using normal drilling parameters
Hydraulic energy
A rule of thumb: mud velocity through the large jet should be at least 500 ft/sec.
Deflection tools (Jetting)
Advantages & Disadvantages Of Jetting
Advantages Same BHA to change trajectory & drilling ahead Simple and cheap method in soft formations. Dogleg severity can be partly controlled from surface by varying the number of feet “ jetted” each time. The survey tool is not far behind the bit. Orientation of tool face is fairly easy
Disadvantages Only works in soft formation and therefore at shallow depths. high dogleg severities are often produced. Deviation is produced in a series of sudden changes, rather than a smooth continuous change. For this reason, it is normal practice to jet an under gauge hole and then open it out to full gauge, which smoothes off the worst of the doglegs.
Deflection tools (Whip stock)
Some movies about D.D:
1.
Movie 1 (bottom trip W.S)
2.
Movie 2 (section milling)
3.
Movie 3 (section milling)
4.
Movie 4 (retrieving a W.S)
5.
Movie 5 (cement type W.S)
6.
Movie 6 (Casing W.S)
Deflection tools (Whip stock)
Deflection tools (Whip stock)
Whip stocks
Standard removable Whip stock used to kick off wells Sidetracking Disadvantage If the whip stock is set on the fill, then whip stock rotate when drilling starts Fill tend to wash away, causing the bit to slide down the side of the well bore and entire whip stock assembly to rotate Critical: when bit leaves the end of W. wedge, if the rock too soft & circulation too high, bit can lose curvature and continue straight number numb er of of “trips” “trips” invo involved lved.. whip stock produced a sudden, sharp deflection Advantages It is a fairly simple piece of equipment which requires requires relatively little maintenance and has no temperature limitations.
Deflection tools (Whip stock) • Circulating Whip stock – the drilling mud initially flows through a passage to the bottom of the whip stock which permits more efficient cleaning of the bottom of the hole and ensures a clean seat for the tool.
– It is most efficient for washing out bottom hole fills.
Permanent Casing Whip stock used where where a “window” “window” is to be cut in casing casing for a sidetrack sidetrack advantage
operation usually takes less time.
disadvantage
gives a sharp dogleg Casing window is too short. Numerous trips & long hours of rotation can wear or damage the casing, difficult to trip out the BHA through the casing window
Deflection tools (Whip stock)
Down hole motors
Was developed in 1966, and 2 years later the PDM began to be used in the US PDM & turbine + Bent Sub + Bent Housing or eccentric stabilizers
turbine motor (left) and positive displacement motor (right) designs.
PDM s vs. Turbines
PDM:
The directional driller can use pump pressure as a weight indicator long lo nger er bi bitt lilife fe
because of the slower rotary speed.
Use a small bend at the U-joint housing instead of bent sub
Turbine:
operate at higher temperatures DO NOT have a dump valve.
Factors Affecting directional behavior of rotary assemblies
Gauge and placement of stabilizers Diameter and length of drill collars Weight -on-bit Rotary speed Bit type Formation anisotropy and dip angle of the bedding planes Formation hardness Flow rate Rate of penetration
PDM accessories
PDM accessories
PDM accessories
PDM accessories
Turbine accessories
Principles of BHA (Fulcrum)
The Fulcrum principle is used to build angle (increase borehole inclination)
Full gauge near bit stabilizer, followed by 40 to 120ft DC, before the first string stabilizer, or no string st ring stabilizer
Principles of BHA (Fulcrum) The rate of build will be INCREASED by the following: • Increasing the distance from the near-bit stabilizer to the first string stabilizer • Increase in hole inclination • Reduction of drill collar diameter • Increase in weight on bit • Reduction in rotary speed • Reduction in flow rate (in soft formations)
Principles of BHA (Stabilization)
The Stabilization (Packed Hole) Principle:
hold angle and direction three stabilizers in quick succession behind the bit separated by short, stiff drill collar sections, then the three stabilizers will resist going around a curve and force the bit to drill a reasonably straight path
Principles of BHA (Stabilization)
Principles of BHA (Pendulum) Drop angle
References
“Applied drilling engineering engineering”” Adam T.bourgoyne, T.bourgoyne, spe text book,vol book,vol 2.
“Oil well drilling engineering” engineering” H. Rabia, univ. of newcastle,1985.
“Advanced directional drilling” drilling services, computalog, computalog, Texas.
“Drilling engineering” N.J Adams, Adams, pennwell pennwell books, Tulsa, Oklahoma. Oklahoma.
“Drilling engineering workbook” baker huges INTEQ,80270H rev. B, Dec 1995.
“IADC Drilling manual”, e-book version(11),2000.
“Well engineering engineering & construction” construction” Hussein Rabia, Rabia, e-book e-book version. version.
“Introduction to directional directional drilling” drilling” schlumberger hand out, out, 1998
“Directional drilling training manual”, schlumberger handbook, 1996
Attachment- review of 6 calculation methods
Attachment- review of 6 calculation methods
Attachment- review of 6 calculation methods
Attachment- review of 6 calculation methods
Attachment- review of 6 calculation methods
Attachment- review of 6 calculation methods
That was all I knew about D.D Thanks for your attention
