lec 7 oct iii tripping and trajectory.pdf

Tripping and Trajectory Control

Lecture 7

PET 356

Q 1 2015-2016

Abu Dhabi Polytechnic

Normal Drilling Operations Practices

Tripping

Tripping is the act of pulling pipe out of or running pipe into a well

- To change bits

- At the end of a hole section

- Mechanical problems

- Change bottom hole assembly (BHA)


Tripping

- The kelly is removed from the drill string before tripping

- The kelly and swivel are stored in the rathole


Tripping

The pipe is pulled or run using the elevators attached to the hook


Tripping practices

-Determine initial overpull limit prior to tripping out of hole (0.5 of BHA Wt.).

•If the tight spot at the same depth (WB G-Back ream).•If the tight spot moved up (Hole cleaning problem)

-Determine initial set down limit (0.25 of the drill string overpull limit).* 0.25 of (ST tension limit – ST Wt. – Up drag).


Recording off BTM torque & Rotating weight

1- Position the bit off BTM about 20 ft.2- Stop the pump.3- Slowly increase the RPM to a preselected standard RPM.4- Record rotating weight & off BTM torque after stabilization.


Recording Up weight

1- Stop rotation.2- Stop the pump.3- Raise the string with a preselected standard Speed.4- Record up weight after stabilization.


Recording Down weight

1- Stop rotation.2- Stop the pump.3- Lower the string with a preselected standard Speed.4- Record down weight after stabilization.


Effect of circulating pressure

Recording string weights without circulation provides actual string drag information.

Stop circulation when recording string weight data


Basic Rotary Assembly Types

Dropping Assembly (Pendulum)

Building Assembly (Fulcrum)

Holding Assembly (Packed Hole)

Normal Drilling Operations PracticesAngle Dropping Assembly

wellbore contact

tangency length

negative side force

To increase drop rate :

•Increase stiffness

•Increase bit/DC size ratio

•Increase DC weight

•Decrease WOB

•Increase rotary speed


The Pendulum Principle

Pendulum assemblies drop angle as a pendulum

creates negative side force

Fs = Wc x BF x TL x sin IN

Fs Side force on bit (lbs)

Wc Weight below tangency point (lbs/ft)

TL Length of pendulum (ft)

IN Inclination at tangency point (deg)

BF Buoyancy factor (-)

Fs

tangency point


Generic Angle Dropping (Pendulum) Assembly

Bit

Drill collar, 30-90ft

String stabilizer, full gauge

Drill collar, 30ft


Drill collar,90ft

HWDP, 90ft min.

Drill pipe


The Fulcrum PrincipleThe fulcrum uses a near-bit stabilizer

WOB (if sufficient) will cause the bottom DC to bend

In holes with inclination > 5°, DC will bend towards the low

side of the hole

This bend will cause bit to exert a side force against the

high side of the hole, resulting in a build-up of angle as

drilling progresses

WOB


Generic Angle Building (Fulcrum) Assembly

Bit

Near-bit Stabilizer, full gauge





Drill collar,90ft

HWDP, 90ft min.

Drill pipe, as required

a b


Packed Hole Assembly

The packed hole assembly is used to maintain

angle

or build/drop at mild rates

3 or more stabilizers are placed at specified

points to

control the deflection of the drill collar string

The increased straightness of the drill collars

reduces

or eliminates the bit tilt


Generic Packed Hole Assembly

Bit

Near-bit Stabilizer, full

gauge

Short Drill collar, 6-20ft


Drill collar, 30ft


Drill collar,90ft

HWDP, 90ft min.

Drill pipe, as required


Typical Configurations - Summary

30 – 90 ft

9 – 27 m

30 ft

9 m

dropping pendulum

30 – 90 ft

9 – 27 m

30 ft

9 m

as close as

possible

building fulcrum

30 - 60 ft

9 - 18 m

30 ft

9 m

5-20 ft

1.5 – 6 m

holding packed hole

Operations Management• Basic Organization

lec 7 oct iii tripping and trajectory.pdf

Documents

gaugedrill collar

actual string

drill string overpull

ftstring stabilizer

record rotating weight

lbswc weight

initial overpull limit

preselected standard