Hole Problems

8/10/2019 Hole Problems

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1

PETE 405Well Dri l l ing

Lesson 5

Hole Problems



2

Depths of historically important boreholes

in Germany and around the world (left)

and deepest three wells world wide (right)

31440

40223

29859

0

2000

4000

6000

8000

10000

12000

14000

1974 Bertha Rogers, USA gas exploration 1985 Kola SG3, USSR gas exploration

1994 KTB Oberpfalz HB, Germany,

scientific drilling

D e p t h [ m ]

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

D e p t h [ f t ]

Source: oil f ield review, January 1995



3

Lesson 5 - Hole Problems

Lost Circulation

Stuck Pipe

• Keyseat- Crooked Hole

• Differential Sticking

• Mechanical Sticking

Junk in Hole

Kicks and Blowouts

Crooked Hole



4

Read:

* Applied Drilling Engineering, Ch. 1* Definitions

HW #2 ADE 1.12, 1.13, 1.14

due Monday, Sept. 11, 2006

Homework



5

Hole Problems - Lost Circulation

Flow out < Flow in (e.g 400 < 500)

Drop in Mud Pit Volume

Blowout

Indication:



6

Hole Problems- Lost Circulation

Poor Drilling Fluid Characteristics

Induced Fracturing of Formation

From Rapid Pipe Movement

Causes:

High Formation Permeability (e.g. fractures)

Low Formation Pore Pressure



7


Costly Mud Makeup Loss of Production

Fire

Loss of Permit to Drill

Results:



8


Preventive Measures:

Crew Education Good Mud Program

Study Wells in Area

…to be prepared



9


Use Lost Circulation Material

as Mud Additive (fibrous or granular)

Drill Through Troublesome

Interval and Case Off

Decrease Mud Weight

Decrease Circulation Rate

Remedial Measures:



10

Hole Problems - Stuck Pipe

(drill pipe, drill collars, casing)

Indication:

Cannot Pick Up Pipe (Venezuela case)

Causes:

Cave - ins

Keyseat - Crooked Hole



11


Differential Pressure Sticking Filter Cake

Deposited AFTER Circulation Stops

- While Still on Bottom

Causes, cont’d:



12


Results:

Fishing OperationsBack off, POH, RIG w/fishing string

Loss of Hole

or at least part of the hole



13


Use Minimum Mud Weight Required

to Control Formation Pressures.

Use Special Drill Collars (spiral)

Use Centralizers on Casing

Periodically Establish Circulation

while Running Casing or Drillpipe

in Deep Hole




14


Erode Mud Filter Cake - at High Fluid

Velocity (speed up pumps)

Spot Special Fluid; Oil, Acid

Reduce Mud Weight as Far as Possible

Rotate Pipe - Keep Moving Pipe

Remedial Measures:

If Circulation Can Be Established:



15


If Circulation Cannot BeEstablished:

Cut Pipe or Unscrew Joint

- and Fish

Remedial Measures:



16

KEY

SEAT



17

P1

P2

P1>>

P

2



18

Thick Filter Cake

Thin Filter Cake

F = mN

N = P A

F = m P A

How is filter cake formed?

Pipe Stuck in Wall Cake



19

Outer filter cake Inner filter cake

Filter

Cake

Bridging the pores

F l o w

F l o w D

r i l l P i p e A

n n

u l u s



20

Hole Problems - Junk in Hole

Bit Parts Missing

Items from Surface Droppedinto Hole

Erratic Torque

Indication:



21


Cause:

Negligence of Crew

Result:

Fishing Operation



22


Crew Education

Preventive Measure:

Remedial Measures:

Run Junk Basket

Run Basket with Collapsible Teeth(“Poor Boy” Basket)

Run Magnet



23

Hole Problems – Kick, Blowout

(oil, gas or water)

Returns to Surface after Circulation isStopped (KICK!)

Well Out of Control - Big Problem!

Lost Circulation . . .

Indication:



24


(oil, gas or water)

[surface or underground]

Causes:

Loss of Hydrostatic Headdue to Lost Circulation

Poor drilling Fluid

Swabbing Effect while Pulling Drillpipe

Insufficient Mud Weight



25

Hole Problems - Blowout

Results:

Possible Loss of Life and Property Legal and Financial Problems



26


Crew Education

Be Alert

Blowout Control Equipment on RIGincluding Pit Volume Indicators




27


Remedial Action:

If on Bottom:

Use proper Mud Weight (increase)

Add Lost Circulation Materials

In Extreme Case of Blowout:

May Have to Directionally

Drill a Relief Well



28

Hole Problems- Blowout

Dynamic Killfrom a Relief

Well



29

Hole Problems - Crooked Hole

Periodic Directional Surveys

Stuck Drill String

Casing Problems

Indication:



30


Causes:

Too much Weight on Bit

Dipping Formation

Anisotropic Formation

Too Small Drill Collars

No Stabilizers



31


Results:

Uneven Spacing (on bottom)

Legal Problems

Production Problems

Cementing Problems



32


Avoid Buckling of Drill Pipe by

using sufficient number of drill

collars

Use “Oversize” Drill Collars

Use Reamers and Stabilizers

Start the Hole Vertically

Preventive Action:



33


Plug Back and Sidetrack

Use Whipstock (wedge)

Use Reamers in 3 Locations

Remedial Action:



34

Lost Circulation Example

This Example shows how to determine the mud weightthat can be supported by the formation and also the mud

weight that will control the subsurface pressure.

Well depth = 16,000 ft Protective casing seat = 12,500 ft

Mud Weight = 17.0 lb/gal

Drillpipe size = 4.5 in.

Hole size, casing I.D. = 8.5 in.

Annulus volume = 0.05 bbl/ft

Water required to fill hole = 20 bbl

B f W t Aft W t



35

Before Water After Water

Water - 20 bbls

400 ft

12,500 ft

BHP = 13,963 psig

Mud - 17.0 lb/gal

16,000 ft

BHP = ?



36

Example - Solution

Determine: The effective hydrostatic headand mud weight in lb/gal.

Solution:

water of ft400ft/bbl05.0

bbl20

Water gradient = 0.052 * 8.33 = 0.433 psi/ft

Mud gradient = 0.052 * 17 = 0.884 psi/ft



37

Example 3.1

Pressure imposed at total depth:

400 ft of water x 0.433 psi/ft = 173 psi

15,600 ft of mud x 0.884 psi/ft = 13,790 psi

Total pressure at 16,000 ft = 13,963 psi

lb/gal78.16.052)(16,000)(0

13,963 weightmudEffective



38

Example 3.1

Pressure imposed at the casing seat:

400 ft of water x 0.433 psi/ft = 173 psi12,100 ft of mud x 0.884 psi/ft = 10,696 psi

Total pressure at 12,500 ft = 10,869 psi

lb/gal72.16.052)(12,500)(0

10,869 weightmudEffective

B f W t After Water



39

Before Water After Water

Water - 20 bbls

400 ft

12,500 ft

EMW = 16.72 lb/gal

BHP 13 963 i

Mud - 17.0 lb/gal

16,000 ft

EMW = 16.78 lb/gal

10,869 psig

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Hole Problems

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