Directional Drilling

Directional Drilling Newsco | Paolo Herrera

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 Aplicación Perforación Direccional. •Sidetracking. •Inaccessible locations. •Salt Dome Drilling. •Fault Controlling. •Multiple Explorations wells from a single wellbore. •Onshore Drilling. •Offshore multiwell drilling. •Multiples Sands. •Relief wells.

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Drilling Tools Drill Collar (DC) Drill collars are heavy, stiff steel tubulars. They are used at the bottom of a BHA to provide weight on bit and rigidity. Flush or spiral drill collars are available. In directional drilling, spiral drill collars are preferable. The spiral grooves machined in the collar reduce the wall contact area by 40% for a reduction in weight of only 4%. The chances of differential sticking are greatly reduced. Spiral drill collars usually have slip and elevator recesses. Stress-relief groove pins and bore back boxes are optional. The drill collars (various sizes) are normally owned by the drilling contractor.

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Drilling Tools Short Drill Collar (SDC) Often called a pony collar, this is simply a shortened version of a steel drill collar. Short drill collars may be manufactured or a steel drill collar may be cut to make two or more short collars. For the DD, the SDC and the short non-magnetic drill collar (SNMDC) have their widest application in the make-up of locked BHAs. SDCs of various lengths are normally provided by the DD company. Non-Magnetic Drill Collar (NMDC) Non-magnetic drill collars are usually flush (non-spiral). They are manufactured from high-quality, corrosion-resistant, austenitic stainless steel. Magnetic survey instruments run in the hole need to be located in a non-magnetic drill collar of sufficient length to allow the measurement of the earth’s magnetic field without magnetic interference. Survey instruments are isolated from magnetic disturbance caused by steel components in the BHA and drillpipe. Short Non-Magnetic Drill Collar (SNMDC) A short version of the NMDC, SNMDCs are often made by cutting a full-length NMDC. The SNMDC may be used between a mud motor and an MWD collar to counteract magnetic interference from below. It is also used in locked BHAs, particularly where the borehole's inclination and direction give rise to high magnetic interference. Finally, BHAs for horizontal wells often use a SNMDC. Float Sub This is a PIN x BOX sub which is bored out to take a float valve. It is often run above a mud motor. In conventional rotary BHAs, a float valve is inserted either in the bit sub (in the case of a pendulum BHA) or in the bored-out near-bit stabilizer. Poppet and flapper designs of float valve are available. Note that some clients may not allow the use of a float valve (because of kick-control problems). The DD should check the client's regulations on arrival at the rig. The float sub is usually provided by the DD company. The float valve is usually provided by the drilling contractor.

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Drilling Tools Heavyweight Drill Pipe (HWDP) This is an intermediate-weight drill string member with drill pipe dimensions for easier handling. Its heavy wall tube is attached to special extra-length tool joints. These provide ample space for recutting the connections and reduce the rate of wear on the OD. The OD of the tube is also protected from abrasive wear by a centre wear pad. Tool joints and wear pad are hard-banded. Some HWDP have two wear pads.

HWDP is less rigid than DCs and has much less wall contact. Chances of differential sticking are reduced. Its three-point wall contact feature solves two serious problems in directional drilling. It permits high-RPM drilling with reduced torque. HWDP can be run through hole angle and direction changes with less connection and fatigue problems. Today, the trend in BHA design is to minimize the number of DCs in the BHA and use HWDP to comprise a major portion of available weight on bit HWDP is normally provided by the drilling contractor. However, it is the DD’s responsibility to ensure there are sufficient joints of HWDP on the rig. For normal directional jobs, 30 joints of HWDP should be sufficient. 5

Drilling Tools Stabilizer Stabilizers are an indispensable part of almost all rotary directional BHAs. Near-bit stabilizers have BOX x BOX connections. They are usually bored out to accept a float valve. String stabilizers have PIN x BOX connections. Most stabilizers have a right-hand spiral. For directional control, 360 wall coverage (in plan view) is recommended. Stabilizer blades are "dressed" with various possible types of hard-facing The leading edge of most stabilizer designs also has hard-facing applied. It is possible to order variations of stabilizer design. Stabilizers are used to:

· Control hole deviation. · Reduce the risk of differential sticking. · Ream out doglegs and keyseats.

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Drilling Tools Orienting Sub UBHO An orienting sub is commonly called a UBHO (Universal Bottom Hole Orientation) sub. It is a straight sub having PIN x BOX connections which are compatible with the bent sub and/or the NMDCs. It is bored out to accept a mule-shoe sleeve. After all intermediate connections have been torqued up fully, the key of the mule-shoe sleeve is aligned directly above the scribe-line of the bent sub. This key is the landing-point for the mule-shoe survey running gear. It gives the DD the tool-face position on his survey disc. The sleeve is locked in place using two hexagonal screws (3/8" allen key required) which are screwed in from the body of the sub. Figure shows the situation when the mule-shoe stinger is landed on the UBHO, with the mule-shoe slot sitting on the key of the UBHO sleeve. This is the situation when surveying during a singleshot kickoff/correction run sidetrack.

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Deflections Methods •Any number of directional tools can be used to deflect a wellbore or make the wellbore go where we want it to go. 1. Whipstock The primary use of a whipstock today is in sidetracking out of casing.

Watermelon Watermel Mill on Mill

Window Mill Window Mill 8

Deflections Methods 2. Jetting This technique is used to deviate the wellbore in soft and friable formations. The well can be kicked off and built up to maximum inclination using one BHA. Special jetting bits can be used or it’s possible to use a standard long-tooth bit, normally using one very large nozzle and two other blank (or very small) nozzles.

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Deflections Methods Steerable Positive Displacement Motor (PDM). The most common type of steerable motor is the single bent-housing design. The motor housing is not straight. One of the motor housing connections (usually the connecting rod housing) is machined at a certain precise offset angle. This is known as the bent housing angle. The bent housing angle is usually 1.5°. At offsets greater than this, it becomes difficult to rotate and motor life is shortened.

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Deflections Methods A steerable motor can be used to perform kickoffs, correction runs and sidetracks. However, the usual application of a steerable motor is as the major component of a BHA which can be used in oriented ("sliding") or rotary mode. I n sliding mode, the steerable motor changes the course of the well. The BHA is designed as a "locked" assembly in rotary mode. The ideal use of a steerable motor is to drill a complete hole section from casing point to casing point. In theory, provided the bit and BHA selection is good, a steerable motor can stay in the hole until the next casing point. The extra cost to the client of running the motor must be compensated for by significant savings in rig time - due to less round trips and/or faster ROP. A surface-adjustable bent housing is now available. The next technological advance will be a downhole-adjustable bent housing.

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Deflections Methods

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Deflections Methods There is a maximum recommended value of motor differential pressure. At this point, the optimum torque is produced by the motor. If the effective WOB is increased beyond this point, pump pressure increases further. Pmotor increases to a point where the lining of the stator is deformed. The rotor/stator seal is broken and the mud flows straight through without turning the bit. The pump pressure reading jumps sharply and does not vary as additional WOB is applied. This is known as stallout condition. Recent studies have shown that the power output curve is a parabola (Figure 7-9) and not a smooth upward curve, as originally thought. If the PDM is operated at 50%-60% of the maximum allowable motor differential pressure, the same performance should be achieved as when operating at 90% of differential. The former situation is much better, however. There is a much larger "cushion" vailable before stallout. This should result in significantly longer motor life. Stallout Pressure:

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BHA Theory The design of the rotary bottom hole assembly (BHA) is, together with orientation, the most critical part of the DD job. Minimizing trips for BHA changes is the objective of every client. They all want to "make hole" and drill a usable hole to TD as soon as possible. A DD’s reputation depends, to a large extent, on the judgment and "feel" he has for choosing the appropriate BHA for a given situation. This chapter is meant to be an introduction to BHA principles, concepts and design. It is not meant to be a theoretical approach to the subject. The objective is to give broad guide-lines in selecting BHAs. Deciding on the changes to be made to a BHA (e.g. not over-reacting to unexpected BHA tendencies) is often more difficult than in selecting the basic BHA. It is important that the DD keep an open mind about BHA design. A DD may think he’s got his BHAs all figured out until he moves to a new area. He may be baffled to find that few or none of his previous BHAs work as expected. This is understandable. As long as the "learning curve" is short, the client will not complain. Finally, keeping accurate, comprehensive records of BHA performance is vital. When a "new" DD arrives in an area, the only aid he has in selecting the BHAs is the performance of previous wells.

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BHA Theory Side Force All BHAs cause a side force at the bit that leads to an increase in hole inclination (positive side force - Fulcrum effect), no change in inclination (zero net side force Lockup BHA) or a drop in inclination (negative side force - Pendulum effect). In addition, changes in hole direction (bit walk) may be either minimized or increased by specific rotary BHAs and drilling parameters.

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Directional Drilling

Building Assemblies 90’

High

High 30’

60’

High

60’

30’

High to Medium 45’

Medium to Low 16

Directional Drilling

Dropping Assemblies 60’

30’

High

60’

High

45’ Medium

30’ Low 17

Directional Drilling

Holding Assemblies 30’, 60’ or 90’

30’

15’-20’ Medium

30’

30’

5’-15’ Medium

30’ or 60’

30’ or 60’

30’-40’ Low 18

Directional Drilling Reactive Torque Reactive torque is created by the drilling mud pushing against the stator. When drilling with a PDM, as weight-on-bit is increased, the drilling torque created by the motor increases. There is a corresponding counter-clockwise torque on the motor housing. This tries to twist the motor and, hence, the whole BHA counter-clockwise. This changes the facing of the bent sub, i.e., the tool face orientation. The big disadvantage of using a PDM/bent sub deflection method is that reactive torque makes it difficult to keep a steady tool face. Using single-shot surveys, the DD must estimate the magnitude of the reactive torque. He initially sets the tool face to the right of the desired tool face position by that angular distance, so that the reactive torque will allow the bit to drill off in the correct direction. This is one area where the "art" of the DD comes into play. On-bottom drilling parameters, especially pump pressure, should be kept constant when using a PDM. This should lead to constant reactive torque and a steady tool face (provided there are no formation changes). Reducing the flow rate leads to less reactive torque. Reducing WOB also leads to less reactive torque. Finally, use of a less aggressive bit means less reactive torque. With the jetting deflection method, reactive torque does not apply. However, there is a tendency for the bit to screw to the right during jetting. Usually this is no more than 20°. It can be easily compensated for when the tool face is set.

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Directional Drilling Magnetic and Gravity Tool Face From vertical until approximately 5° inclination, gravity forces are minimal. A borehole does not have a well-defined high side (or low side). Until this point, the tool face is set relative to North (e.g. N45W). This is called the Magnetic Tool Face (MTF) setting. Above 5° inclination, the tool face is set using the high si de of the hole as the reference. This is called High Side Tool Face or Gravity Tool Face (GTF) setting. Exactly the same convention applies whether we're using single-shot surveys, MWD or a Steering Tool. If a plumb-bob were suspended in the hole, gravity forces would force it to hang toward the low side of the hole. The high side of the hole is 180° away from the low side of the hole.

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Directional Drilling

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Directional Drilling

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Directional Drilling

 Survey/ Slide Sheet Calculator Job # Location Well Name Rig Dir. Driller Dir. Driller MWD Operator

Hole Size 1 Hole Size 2 KB Elevation Target Formation Target TVD BUR / Plan  VS Direction

#

FT

1 Tie-In

53

Survey Offset :

Enter info in yellow to start

BHA C.L.

Bit

Survey

Depth

Depth

Per / 100ft Inc.

Azm.

Tvd

DLS

Build

12 1/4 8 1/2 29,67 Salina 2230 4°Up/4°Dwn 63,45

BHA # 1 2

Motor 8007830 (NM20304) 6507830 (NM17109)

Bend 1.83° 1.83°

Bit (make, model) PDC(Baker, HCR605Z) PDC(Baker , DR605Z)

Rotary Comments/ Formation TVD / Tie In / KOP / BHA Change FT

47 FT

R.O.B. Calcu.

Turn

Seen   Per/FT

580,46

0,00

343,00

290,00

0,00

0,00

290,00

1   44,31   38 7, 31

3 34 ,3 1

0 ,7 0

2 57 ,2 0

3 34 ,3 1

1 ,5 8 1 ,5 8 

1   30,92   4 18 ,2 3

3 65 ,2 3

0 ,5 0

3 18 ,2 0

3 65 ,2 3

2 ,0 5 - 0, 65  197,28 0 ,0 0

1   47,55   465,78

412,78

0,90

50,30

412,77

2,20

1   31,21

4 96 ,9 9

4 43 ,9 9

1 ,5 0

4 7, 40

4 43 ,9 8

1   30,96

5 27 ,9 5

4 74 ,9 5

2 ,4 0

5 1, 50

4 74 ,9 2

1   30,93

5 58 ,8 8

5 05 ,8 8

3 ,5 0

5 5, 80

1   30,40

5 89 ,2 8

5 36 ,2 8

4 ,5 0

1   30,91

6 20 ,1 9

5 67 ,1 9

1   31,19

6 51 ,3 8

5 98 ,3 8

1   30,55

6 81 ,9 3

1   30,91

7 12 ,8 4

1   30,84 1   31,48 1   31,50

TF

Slide

Slide

From

To

# Of FT

Rotate

Rotate

From

To

343,00

0,00

rot

343,00

387,31 44,31

##

387,31

405,31

18,00 65M

405,31

418,23 12,92

1 08 R

4 18 ,2 3

4 36 ,2 3 18 ,0 0 6 5M

4 36 ,2 3

4 65 ,7 8 2 9, 55

0,84   -563,41 18,00 0,02

68 L

465,78

487,78 22,00 65M

487,78

496,99 9,21

1 ,9 3 1 ,9 2 - 9, 29 1 8, 00 0 ,0 3

6L

4 96 ,9 9

5 18 ,9 9 2 2, 00 70 M

5 18 ,9 9

5 27 ,9 5 8 ,9 6

2 ,9 4 2, 91 1 3, 24 9 ,1 7 0, 10

9R

5 27 ,9 5

5 52 ,9 5 25 ,0 0 7 0M

5 52 ,9 5

5 58 ,8 8 5 ,9 3

5 05 ,8 1

3 ,6 3 3 ,5 6 1 3, 90 2 1, 72 0 ,0 5

11 R

5 58 ,8 8

5 83 ,8 8 2 5, 00 3 5R

5 83 ,8 8

5 89 ,2 8 5 ,4 0

5 7, 90

5 36 ,1 3

3 ,3 2 3, 29 6 ,9 1 2 1, 44 0 ,0 5

8R

5 89 ,2 8

6 14 ,2 8 25 ,0 0 3 5R

6 14 ,2 8

6 20 ,1 9 5 ,9 1

6 ,0 0

6 3, 50

5 66 ,9 1

5 ,1 2 4 ,8 5 1 8, 12 2 4, 98 0 ,0 6

19 R

6 20 ,1 9

6 40 ,1 9 2 0, 00

HS

6 40 ,1 9

6 51 ,3 8 1 1, 19

7 ,5 0

6 6, 40

5 97 ,8 9

4 ,9 3 4 ,8 5 9 ,3 8 2 5, 79 0 ,0 6

10 R

6 51 ,3 8

6 71 ,3 8 2 0, 00

HS

6 71 ,3 8

6 81 ,9 3 1 0, 55

6 28 ,9 3

8 ,9 0

6 7, 30

6 28 ,1 3

4 ,6 0 4 ,4 9 2 ,8 9 2 4, 64 0 ,0 6

13 R

6 81 ,9 3

7 01 ,9 3 2 0, 00 3 0L

7 01 ,9 3

7 12 ,8 4 1 0, 91

6 59 ,8 4

1 0, 10

6 5, 80

6 58 ,6 1

3 ,9 6 3 ,9 3 - 4, 91 1 9, 72 0 ,0 6

8L

7 12 ,8 4

7 34 ,8 4 2 2, 00

7 34 ,8 4

7 43 ,6 8 8 ,8 4

7 43 ,6 8

6 90 ,6 8

1 1, 50

6 4, 90

6 88 ,9 1

4 ,5 7 4 ,5 3 -2 ,9 1 2 0, 29 0 ,0 7

8L

7 43 ,6 8

7 61 ,6 8 1 8, 00 1 0R

7 61 ,6 8

7 75 ,1 6 1 3, 48

7 75 ,1 6

7 22 ,1 6

1 2, 90

6 5, 00

7 19 ,6 7

4 ,4 5 4, 54 0 ,3 2 2 0, 57 0 ,0 7 ##

7 75 ,1 6

7 93 ,1 6 18 ,0 0 HS

7 93 ,1 6

8 06 ,6 6 1 3, 50

8 06 ,6 6

7 53 ,6 6

1 4, 30

6 4, 20

7 50 ,2 9

4 ,4 8 4 ,4 5 - 2, 54 2 2, 66 0 ,0 6

8 06 ,6 6

8 24 ,6 6 1 8, 00

8 24 ,6 6

8 38 ,1 6 1 3, 50

7L

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0,00

TF Set @

HS

HS

Tie-In csg. Shoe @ 290ft.

Rotate jars down

Switched to GTF

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