The words you are searching are inside this book. To get more targeted content, please make full-text search by clicking here.
Discover the best professional documents and content resources in AnyFlip Document Base.
Search
Published by jasrudin, 2019-08-13 03:21:26

stuck pipe

stuck pipe

Chapter Handbook

Exit Table of Index Table of Topic Page Menu

Contents Contents

12 CHAPTER

Stuck pipe

Contents

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-2

Differential sticking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-2
ENVIRO-SPOT spotting fluid . . . . . . . . . . . . . . . . . . . . . . . . 12-4
DUAL PHASE spotting fluid . . . . . . . . . . . . . . . . . . . . . . . . . 12-5
Determining depth to stuck zone . . . . . . . . . . . . . . . . . . . . . . . 12-9

Packing off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-9

Undergauge hole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-11
Plastic flowing formations . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-11
Wall-cake buildup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-11

Keyseating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-12

Freeing stuck pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12-16

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

Overview

In drilling operations, the drillpipe is considered stuck
when it cannot be raised, lowered, or rotated. Stuck
pipe can be caused by several different mechanisms.
Typical stuck pipe situations are:

C Differential-pressure effects
C Packing off
C Undergauge hole
C Keyseating

Differential sticking

Most incidents of stuck pipe are caused by differential-
pressure effects. Excessive differential pressures across
lower-pressure permeable zones can cause the
drillstring to push into the wellbore wall where it
becomes stuck. See Figure 12-1.

Differential sticking may be identified by the following
characteristics:

C Pipe sticks after remaining motionless for a period
of time

C Pipe cannot be rotated or moved when circulation is
maintained

12-2

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

At moment of sticking

Drill Mud cake
collar

Isolated area

After short time lapse

Original cake
thickness

Slightly Isolated area
thickened
mud cake
and fillet

Figure 12-1: Differential-pressure effect. The difference in pressure between the hydrostatic
head pressure and the formation pore pressure forces the drillpipe into the wallcake and sticks
the pipe.

To avoid or minimize the risk of differential sticking,

follow these guidelines:

C Drill with the lowest practical mud weight.
C Maintain a low filtration rate.
C Keep low-gravity solids to a minimum.
C Never allow the drillpipe to remain motionless for any

period of time.
C Ream any undergauge section.
C Add appropriate bridging agents.
C Change to an oil/synthetic-based mud.

Revised August 1, 1997 12-3

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

ENVIRO-SPOT When differential sticking occurs, spotting fluid can
spotting fluid sometimes free the drillpipe.

Note: It is critical to have a spotting fluid readily
available and apply it within six hours of the stuck pipe
occurrence.

Spotting fluids are designed to penetrate and break up
the filter cake. To mix the ENVIRO-SPOT spotting
fluid, start with the required volume of oil and add
ENVIRO-SPOT, water, and BAROID in that order.

Base fluids can be diesel, mineral oil, water, etc. See
Table 12-1.

ENVIRO-SPOT spotting fluid formulation for 100 bbl

7.3 10.0 12.0 14.0 16.0 18.0
Weight, lb/gal (sg) (0.87) (1.20) (1.44) (1.68) (1.92) (2.16)

Oil, bbl (m3) 64 (10.3) 58 (9.2) 54 (8.6) 49 (7.8) 51 (8.1) 44 (7.0)

ENVIRO-SPOT, 6 (.98) 6 (.98) 6 (.98) 6 (.98) 6 (.98) 6 (.98)
55 gal drum 28 (4.5) 26 (4.1) 22 (3.5) 21 (3.3) 11 (1.7) 10 (1.6)

Water, bbl (m3)

BAROID, lb (kg) n/a 14,000 25,000 35,000 46,500 57,000
(6,350) (11,340) (15,876) (21,092) (25,855)

Table 12-1: ENVIRO-SPOT formulation. ENVIRO-SPOT is a good all-purpose spotting
fluid suitable for use in many different drilling regions.

12-4

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

DUAL PHASE Density
spotting fluid
Make the spotting fluid density equal to the mud weight
in use. PHASE ONE has a starting density of 14.2
lb/gal (1.70 sg) and can be increased with calcium
chloride to as high as 15.1 lb/gal (1.81 sg). PHASE
ONE can be reduced with seawater/drill water to the
desired density. PHASE TWO has a starting density of
8.6 lb/gal (1.03 sg). Adjust the density of PHASE
TWO, as needed, by additions of weight material.

Volumes Needed

PHASE ONE - 50 bbl minimum

PHASE TWO - 100 bbl minimum

Note: Larger volumes may be required to ensure that
the stuck point is covered by the spotting fluid.

Displacement

1. PHASE ONE should be mixed in the slugging pit.
Adjust the weight to the drilling fluid density. Pump
PHASE ONE into the drill string at the normal
pump rates.

2. PHASE TWO should be mixed in the slugging pit.
Adjust the weight to the drilling fluid density. Pump
PHASE TWO into the drill string at the normal
pump rates.

3. Pump the PHASE ONE through the bit leaving 10
barrels of PHASE ONE inside the drill string (If the
drill string capacity is greater than the volumes of
both PHASE ONE and PHASE TWO pills), mud
should be pumped to complete the spotting
procedure.12-4

Revised August 1, 1997 12-5

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

Soak Time

1. Break circulation once per hour pumping one barrel
of fluid. PHASE ONE should have a minimum
soak/exposure time of nine (9) hours.

2. After nine hours of soak time, pump PHASE TWO
into the annulus at a slow pump rate. Leave 15
barrels of PHASE TWO inside the drill string.

3. Break circulation every hour pumping one barrel of
fluid.

4. When the pipe becomes free, pump all of the DUAL
PHASE out of the hole and discard the DUAL
PHASE and interface.

5. Once the DUAL PHASE has been discarded, the
mud should be conditioned with deflocculating and
fluid loss control additives.

12-6

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

DUAL PHASE WORKSHEET

Date ________________ Pipe OD ID Capacity/ft

Operator ________________ DC ____________________

Offshore Area ________________ HWDp ____________________

Block ________________ Dp 1 ____________________

Last Casing Shoe ______ MD/ft Dp 2 ____________________

Total Depth ______ MD/ft Dp 3 ____________________

Bit Location ______ MD/ft _____________________________

Bit Size ______ inches Hole Data

BHA Length ______ feet Annular Vol. DC/OH ____bbl

Drill Collar Length ______ feet Annular Vol. HW/OH ____bbl

HW Pipe Length ______ feet Annular Vol. Dp 1 ____bbl

Drill Pipe Length ______ feet Annular Vol. Dp 2 ____bbl

Drill Pipe Length ______ feet Annular Vol. Dp 3 ____bbl

Drill Pipe Length ______ feet Annular Vol. Dp 4 ____bbl

Total String ______ feet Annular Vol. bit-shoe ____bbl
Length

Pump Data PHASE ONE Volume

Pump ______ bbl/stroke

Stroke to bit ______ strokes Feet of coverage DC/OH ____ bbl

Feet of coverage HW/OH ____ bbl

Placing PHASE ONE & TWO Feet of coverage Dp/OH ____ bbl

Vol. Strokes to Feet of coverage Dp/OH ____ bbl
Spot

PHASE ONE____ bbl ______ Feet of coverage Dp/OH ____ bbl

PHASE TWO ____ bbl ______ Footage Covered - ____ bbl
PHASE ONE

Table 12-2: DUAL PHASE worksheet. This worksheet can be used to calculate the
volumes required to be pumped and a pump schedule.

Revised August 1, 1997 12-7

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

PHASE ONE 50 bbl PHASE TWO 100 bbl

Desired PHASE CaCl2 Water Desired PHASE Water Barite
Density, ONE 80 lb bbl Density, TWO bbl sacks
lb/gal bbl lb/gal bbl
Sacks

15.1 43 79 15.5 53 20 332

15.0 43 71 15.0 53 22 370

14.9 44 62 14.3 58 20 332

14.8 45 54 14.2 56 22 325

Note: At 14.8-15.1 lb/gal-TCT is 63E F 14.0 57 22 315

14.7 46 43 13.5 65 15 300

14.6 47 32 13.0 68 15 255

14.5 48 24 12.5 73 12 222

14.4 49 15 12.0 75 12 193

14.3 49 9 11.0 80 10 147

14.2 50 0.0 10.5 82 10 120

14.0 48 2 10.0 83 10 100

13.5 44 6 9.5 95 0 74

13.0 40 10 9.2 98 0 35

12.5 35 15 8.6 100 0 0

12.0 31 19

11.5 27 23

11.0 22 28

10.5 18 32

10.0 14 36

9.5 10 41

9.0 5 44

Table 12-3: DUAL PHASE density table. This table can be used to calculate the required
amounts of materials to achieve the desired density.

12-8

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

Determining Measure the drillstring stretch to estimate the depth that
depth to stuck pipe is stuck. The following formula locates the depth at
zone which the pipe is stuck. The length of free pipe is based
on the drillstring dimensions and the measured amount
of stretch.

L ' EeW
40.8 P

Where

C L is the length of free pipe (ft)
C E is the modulus of elasticity (30 x 106) (psi)
C e is the stretch (in)
C W is the weight of pipe (per ft)
C P is the amount of tension applied (lb/ft)

Packing off

Drilling-fluid systems with poor suspension
characteristics exhibit strong packing-off tendencies
(see Figure 12-2). Factors that can lead to caving of the
formation include:

C Pressure imbalance
C Shale hydration
C Bottomhole assembly striking the wall

Revised August 1, 1997 12-9

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

Packing off

Figure 12-2: Packing off. Massive particle caving sticks the drillbit.
12-10

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

Undergauge hole

Undergauge hole is a condition where the borehole is
smaller than the bit diameter used to drill the section.
Undergauge hole can result from any of the following
causes:

C Plastic flowing formations
C Wall-cake buildup in a permeable formation
C Swelling shales

Plastic flowing A plastic flowing formation is a formation that is plastic
formations (easily deformable when stressed) and can flow into the
borehole. When these types of formations are
penetrated by the bit, the hole is at gauge. However,
when the hydrostatic pressure exerted by the column of
drilling fluid is less than the hydrostatic pressure of the
formation, underbalance results, the formation flows,
and hole diameter decreases.

Undergauge hole is a common problem when drilling a
thick salt section with an oil mud. The salt can flow into
the borehole and make the section undergauge. When
plastic salt formations exist, they are usually below
5,000 feet. Spotting fresh water is the best way to free
the pipe from a plastic salt formation.

Wall-cake Wall-cake buildup occurs when the drilling fluid has
buildup poor filtration control across a permeable zone.
Excessive wall-cake buildup can also be caused by:

C High percentage of low-gravity solids
C High differential pressures (excessive mud weights)

Revised August 1, 1997 12-11

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

Keyseating

Keyseating is a situation frequently encountered in
deviated or crooked holes when the drillpipe wears into
the wall. The normal drilling rotation of the drillstring
cuts into the formation wall in deviated areas where the
drillpipe tension creates pressure against the sides of the
hole.

Keyseating is diagnosed when the drillpipe can be
reciprocated within the range of tool joint distances or
until collar reaches the keyseat, while pipe rotation and
circulation remain normal. See Figure 12-3 for an
example of a keyseat effect in a crooked hole.

12-12

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

Keyseating

AA
Section A-A

Position of the pipe Position of the pipe
before keyseating after keyseating

Figure 12-3: Keyseating. The friction generated by drillpipe rotation against the borewall
cuts a narrow channel, or keyseat, into the formation.

Revised August 1, 1997 12-13

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

A preventive measure is to carefully control upper hole
deviation and dogleg severity throughout the well path.
This action will eliminate the force that leads to keyseat
creation.

Once a keyseat is formed, the best solution is to ream
out the small-diameter portions of the hole with reaming
tools. See the example of reaming action in Figure 12-4.
This action will solve the immediate stuck-pipe
problem, but the keyseat can be formed again unless
preventive steps are taken.

12-14

Chapter Handbook

Exit Table of Index Table of Topic Page Baroid fluids handbook

Contents Contents

Reaming the Key

BB
Section B-B

Drill collar in Reamer action in
keyseat enlarging keyseat

Figure 12-4: Reaming action. Attach a reamer to the drill assembly to widen the keyseat.

Revised August 1, 1997 12-15

Chapter Handbook

Exit Table of Index Table of Topic Page Stuck pipe

Contents Contents

Freeing stuck pipe

The following guidelines can be used to free stuck pipe:

Cause... Steps to free...
Differential sticking
Reduce mud weight.
Packing off Use spotting fluid.
Undergauge hole
Back off and wash over.
Keyseating
Increase mud weight.
Underream.

Ream the keyseat.

12-16


Click to View FlipBook Version