Fishing Technology (8)

MILLING OPERATIONS

Overview

Junk mills are the surest way to eliminate junk in the hole. There are various
mills that can be used in different circumstances. For example, the insert
type of mill is best suited for milling pipe or tools anchored securely in the
well bore; however, chatter, vibration or loose junk are detrimental to the
inserts.

صورة 15

Types of Mills

1- Insert Type

Can be used for:
• pipe/tools anchored securely in the wellbore.
Caution: Chatter, vibration, or loose junk are detrimental to the
inserts.

2- Crushed Tungsten Carbide Mills

Can be used for:
• almost anything, except in hard abrasive formations.

3- Skirted Flat Bottom Or Concave Type Mill 

Can be used for:
• flared or burred top of fish prior to engagement with an
overshot. Because the skirted mill is stabilized and the
fish is contained within the skirt, it cannot slip off

4- Blade Type Mill

Can be used for:
• junk or cast iron material which will break up.
Features:
• Rugged, durable construction
• Concave, convex, and flat-bottom designs available
• Dressed with tungsten carbide inserts for stationary fish
or junk
• Dressed with crushed tungsten carbide for loose fish or
junk
• Improved cooling during milling
• Increased milling efficiency

5- Pilot Mill/Diamond Point

The Pilot Mill/Diamond Point is used for milling tubing, casing,
liner hangers, liners, drill pipe, drill collars, wash pipe, or
perforated liners.
Using Pilot Mills:
• Select a pilot mill with a blade O.D. ¼ inch larger than
the O.D. of the tool joint or coupling of the fish milled.
The pilot O.D. should be the same as the drift I.D. of the
fish.
• Determine the best rotary speed and weight to run a pilot
mill for each job. Conditions may change from one pilot
milling job to the next in the same well. The change may
require different rotary speeds and weights at different times. In the absence of experience, start with a speed of
between 80 and 100 RPM’s and a tool weight of 2,000
to 6,000 lbs. Vary the speed and weight to obtain the
best results.
• If milling a liner or casing that is gun-perforated,
damaged with a spear, or collapsed, use 60 RPM’s and
2,000 lbs. of weight or less.
• A sudden drop in the milling rate while milling swaged
casing may be caused by a loose ring of steel formed at
a joint or weld, which turns with the pilot mill. Spud the
mill gently to break up the ring and position it for
milling.
• If the milling rate stops or drastically slows down in the
milling of wash pipe, casing or liner without a
noticeable increase in torque, the fish may be turning.
• If so, pull the mill, and retrieve the fish with a spear.

6- Tapered Mills

The Weatherford Standard Tapered Mill is designed for milling
through restrictions. The spiral blades and pointed nose dressed
with crushed tungsten carbide make the mill ideal for reaming
collapsed casing and liners, cleaning permanent whipstock
windows, milling through jagged or split guide shies, and
enlarging restrictions through retainers and adapters. The torque
encountered governs the tapered mill rotary speeds.
• To overcome torque challenges, do not exceed 75
RPM’s.
• Do not rotate a tapered mill resting on a fish. Enter the
fish with a rotary speed of 75 RPM’s ort less.
• Use less weight when running a tapered mill than a junk
or pilot mill. After entering the fish, increase the tool
weight to slowly to 1,000 to 2,000 lbs. Watch for any
torque increase.

7- Watermelon/String Mills

The Weatherford string mill is dressed with tungsten carbide
spiral blades tapered from top to bottom to enable reaming both
up and down in collapsed casing and liners. The lower
connection enables a stinger to be run below the tool to prevent
sidetracking. The mill can also be placed anywhere in a drill or
fishing string. The mill features crushed tungsten carbidedressed
reamer blades.
Can be used for:
• Smooth or rough OD
• Milling out collapsed areas in casing and liners
• Eliminating key seats and doglegs in open hole
• Extending whip stock windows

8- Flat Bottom Cone Buster
Mill

This flat bottom cone buster mill is dressed with crushed
tungsten carbide and is a very aggressive mill used to mill up bit
cones or other pieces of junk. The mill is sturdy enough for
light spudding on the junk to break it up into smaller pieces.
Large circulation ports improve mud circulation for cooling and
for the removal of cuttings. Field reports show these long
lasting mills are safer than using a rock bit because you can’t
lose any bit cones in the hole. Weatherford’s junk mills work
well when milling drillable packers, bridge plugs, retainers, and
cement.
Note: Important characteristics of cone buster mills include that
they can be furnished with:

•  large circulation ports which improve mud circulation for

cooling and cutting removal.

•  smooth outside diameter along with stabilizer pads designed

to be run inside casing.

9- Cement Mills

Can be used for:
• Milling cement

       

  

 

Fishing Technology (7)

Using a Boot Basket

Description

Boot Baskets are used to trap cuttings which are too large to circulate out of
the hole during drilling, milling or junk fishing operations. The boot basket
should be run as close as possible to the mill, bit or junk basket, etc.

Figure 2-4: Boot Basket

Table 2-3:
Weatherford Type P Boot Basket

Function

The boot basket design traps junk by producing a sudden decrease in
annular velocity when cuttings pass the larger OD of the boot and reach the
smaller OD of the mandrel and top connection of the basket.

Loading up the boot basket

Using a Globe Type Basket

Description

The Globe type junk basket is used to recover any type of small object that
may be in the well bore. The successful operation of the tool requires that a
core be cut from the formation. Any junk will be recovered above the core.

Figure 2-5: Globe and Boot Baskets

Use

The Globe Type Junk Basket is recommended when performing fishing
operations in soft to medium formations (with a drilling rate above 15 feet
per hour).

Types of globe baskets

Two commonly used globe type baskets are:
1- Bowen Itco/Globe basket
2- Weatherford Globe Type Junk Basket
The Bowen Itco/Globe basket consists of a top sub, barrel, and tungsten
carbide milling shoe. Inside are two manganese bronze catchers that are
free to rotate.
Specifications for the Weatherford and Bowen Itco Globe junk baskets are
listed in Table 2-4 and Table 2-5.

Table 2-4:
Weatherford
Globe Type Junk Basket Specifications

Table 2-5: Bowen Itco Globe Type Junk
Basket Specifications

Requirements for the shoe

The crown on the shoe should be about 1/8" to ¼" less than the hole size.
ould ssed with sten carbide to about 1/8" less than the
catche
The ID sh be dre tung
ID of the rs.

Running the globe basket

Fishing Technology (6)

Using Magnets for Fishing

Purpose

Fishing magnets are primarily used to pick up bit cones, but they can pick
up all types of small objects with magnetic properties.

Guidelines for using magnets

Magnets should be run on pipe instead of wire line so that you can circulate
and rotate. Fishing magnets run on wire line are usually made inside the
casing with clear fluid in the hole. There are adapters available to run
magnets on a wire line.
Note: Most, but not all tungsten carbide bit inserts are non-magnetic.

Checking magnet capacity

Check to see if the magnet is charged properly by attaching a 20-lb.
sledgehammer to the face of it. If the magnet will support the weight of the
sledgehammer, it will likely hold any small pieces of junk in the well bore.
The lifting capacity of the magnet is a function of its size, area, and charge.

Verifying size

The OD of the magnet should be ¼" to ½" less than the hole size.

Figure 2-1:
Fishing Magnet with a Cripple Type Guide Attached

Using a Junk Mill

Description

Junk mills mill up and break up large junk into smaller pieces that can be
recovered in a boot basket. Junk mills provide the surest method for
eliminating junk in the hole.

Types of mills

The following are examples of types of mills that are used for eliminating
junk:
1- insert type mill
2- crushed tungsten carbide mill
3- skirted flat bottom or concave type mill
4- blade type mill
5- cone buster mill
6- cement mill.

 

Figure 2-2: Cone Buster and P Mill

Figure 2-3:  Packer or Cement Mill

Milling guidelines

Some important guidelines for milling with junk mills include:
1- Provide adequate circulation to flush the cuttings and cool the mill.
2- A boot basket must be run directly above the mill to catch the metal
cuttings.
3- Always mill by torque and not by weight. If the mill is producing torque
and making progress, then the weight applied to the mill is sufficient.
Most people run too much weight on mills. A standard rule of thumb is
not to exceed 1,000 pounds per OD inch of the mill.
Note: Mills with stabilizer pads should be used inside the casing.
IF you are milling pipe that causes the drill string to bounce and vibrate,
THEN consider using a Bowen Shock Sub to cut down on vibration.

Calculating milling rates

The milling rates for the carbide mills are specified by the manufacturer in
Surface Feet Per Minute (SFPM). The surface feet per minute must be
converted to revolutions per minute (RPM) because the operator does not
have a way to measure surface feet per minute.
The rpm may be derived from the SFPM by multiplying the mill diameter
by the milling RPM. This result is then multiplied by a constant, 0.262. For
example, a certain mill’s diameter is 4.5" and the milling rate in RPM is
120. You would calculate the SFPM in this way:
4.5 x 120 x 0.262 = 142 SFPM.
Table 2-2 lists some standard milling rates. Other rates may be computed
by converting the milling rates in revolutions per minute to surface feet per
minute.

Collecting the junk

Mills and boot baskets go hand-in-hand. Boot baskets are always run with
mills because they collect the pieces of the junk that the mill grinds up.

Fishing Technology (5)

FISHING FOR JUNK

Overview

Any undesirable object that is stuck or accidentally dropped in a well is
referred to as “junk.” Junk may include bit cones, tong dies, broken slips,
reamer parts or debris created by a fishing or milling operation, or any other
small debris that could impede normal drilling operations. Because of the
wide variety of junk that can be in the hole and the likelihood that the
customer may not know what the junk is, you will have to be fairly creative
in planning a junk fishing operation. However, because of the time and
money spent on fishing operations, you will need to devise a method for
fishing the junk that involves the fewest trips and equipment as possible.

Deciding How to Fish Junk

Evaluating the junk

Any debris or junk in the borehole must be thoroughly evaluated before any
successful fishing attempt can be made. Depending on the properties of the
junk, it can either be milled up, recovered, or pushed back (walled-off) into
the formation.
Consider the following questions before proceeding with a fishing job:

•  What is the size, weight, and condition of the junk?
•  Is the junk magnetic?
•  Can the junk be picked up?
•  What are the dimensions of the bit cone or cones?

The company man would ideally know exactly what the junk in the hole
consists of. When the nature of the junk is unknown, you must be creative
in your approach to fishing the junk.

 Impact of the junk size, weight, and condition

Try to determine the size, weight, and condition of the junk. This
information will help you determine the best method for fishing the junk.
For example, if you have junk that is:

•  large and/or irregularly shaped, you might try a poor boy basket
•  smaller, you might try a magnet, core type, or reverse circulating basket.

For very large pieces of junk, you may need to use a junk shot to break it
into smaller pieces before attempting to fish.

Determining if the junk is magnetic

Try to find out what the junk is made of. If it has a high ferrous content, it
is probably magnetic. The easiest method for fishing magnetic junk is using
a magnet.

Determining is the junk can be picked up

If the OD of the junk is significantly smaller than the ID of the hole, than
there is a good chance that it can be picked up. However, if the OD of the
junk is fairly large, it will be harder to get a fishing tool over it. In this case,
you will probably have to mill the junk to break it up and collect the pieces
in a boot basket.

Determining cone dimensions

If you know the junk is a bit cone, the dimensions of the cone must be
known before deciding which tool to run. Find out the size of the bit from
which the cone was lost, and verify the maximum OD of the cone. Select a
tool that has an ID at least 1/8" larger than the OD of the cone.
For example, a 7 7/8" bit cone is 5 15/64" OD. A 7 1/8" OD Bowen Itco
Type Junk Basket has an ID size of 5 28/64". This tool will get over the bit
cone.
Standard rock bit cone dimensions are shown in Table 2-1. Note: This
information can also be found in the Bowen user manuals.

Fishing Technology (4)

Maintaining the Tally Book

Purpose of record keeping

Record keeping is especially helpful when there is a shift change before a
job has been completed. Additionally, records from previous jobs form a
base of information that can be used as a resource when planning fishing
jobs. Record keeping is also important for ensuring that the customer is
billed for the correct equipment and services.

The tally book

The tally book is a short and abbreviated notation of each trip made in the
hole and the tools that were used. The tally book provides important
documentation of the job that is useful for job analysis after the job has been
completed. Additionally, the tally book provides the specifications of the
tools used and services rendered for billing purposes. The tally book should
be kept in such a manner that a relief man could carry on the job with the
information contained in the book.

Rules for keeping the tally book

The tally book must be accurate, legible, and current.
The tally book should include:

•  a complete description of the fish and all well data
•  the time, date, number, and brief description of each trip
•  all parameters, if a milling job is performed. These parameters include:

1.  depth
2.  RPM
3.  strokes per minute (SPM)
4.  weight on bit (WOB)
5.  torque
6.  time
7.  rate of penetration.

•  the size and footage along with all auxiliary equipment and daily charges,

if wash pipe is run

•  a record of any accidents.

Guidelines for the format of the tally book include:

•  only one trip should be recorded on each page
•  use one line for each tool description with the OD, ID, length, fishing

neck, and serial number.
The tally book should be kept for future reference.
An example of a tally book 

Fishing resume

The resume is a narrative of the fishing operations and tools that were used
each day. Each trip will be noted along with the outcome of the operation.
The resume is very important because it is the documentation for what the
customer is charged. The billing department will not know what to charge
the customer and the customer will not agree to any charges unless they
have been documented in the resume.
Anything that will be billed to the customer, including estimated repairs or
sold grapples, must be recorded on the resume and signed by the company
man

Signing off on the resume

The company man must sign the job resume when it is completed. We
leave ourselves open to legal action if the company man does not
acknowledge the tools and services that were utilized during the job.

Post-Job Procedures

Completing documentation

The job is not complete until all paperwork, including the resume, and tools
use sheet is completed and signed for.

Breaking down tools

Account for all Weatherford tools. Insure they are loaded in the tool baskets
or loaded on the trucks prior to leaving the job site.
If possible, use the rig tongs to break down all tools that come through the
rotary. Most Weatherford stores do not have the facilities to perform this
operation and vendors charge $100.00 per joint to break down the tools.
However, note that rig time on some offshore rigs is prohibitively expensive
for this operation. For example, when fishing on an offshore rig, especially
in the North Sea, it is cheaper for the customer to be charged for breaking
down the tools at the shop facility.

Transporting equipment

Ensure that all protectors are installed on the tools before transporting them
back to the Weatherford store location. This is important to prevent damage
to exposed threads.
Ensure that only Weatherford property is transported back to the
Weatherford store location. It is difficult to arrange a return trip to bring
equipment that is not the property of Weatherford back to the well site.

Fishing Technology (3)

Fishing Technology Manual

Determining the Amount DOK Required to Reach the Fish

Overview

You will need to determine the amount down on the kelly (DOK) required
to reach the fish in order to design your fishing string. Because you can’t
always rely on the string figures furnished by the customer, it is best to
personally check the figures before beginning operations.

The In and Out Method

The “In” and “Out” method is a good way of checking the string figures for
possible mistakes. The formulas used to calculate the total out and total in
and then the amount DOK required to reach the fish are shown below.

Note: The total “out” must always exceed the total “in” to use this formula.

Example

The following is an example using the “In” and “Out” method for
calculating the depth of the top of the fish.
The customer twisted off while drilling at 4,000 ft. They recovered
3,895.73 feet, including the length DOK. The customer then made a bit trip
and tagged the fish with 37 feet. DOK. To calculate the difference between
the bit run and the following overshot run, subtract the (in) from the (out).
The difference will be the length DOK with overshot run.
See the calculation of the depth of the top of the fish for this example in
Table 1-2

Determining the Kelly Bushing (KB) Measurement

Calculating the original elevation

The standard oilfield measurement to any depth downhole is recorded from
the wellhead, plus the distance to the kelly bushing (KB) on the rig that
drilled the well. This is called the original elevation and is recorded in the
well file.
It is important for everyone to be talking about the same depth. That is why
the total depth is always reported from the original rig elevation. If the
original rig has been replaced by a smaller workover rig, you will need to
account for the difference in this rig’s elevation from the original elevation.

Determining the true well depth

The difference between the original rig elevation and the current rig
elevation is added to or subtracted from the current pipe tally in order to
establish the true well depth. This is called the kelly bushing (KB)
measurement.
For example, assume that the original elevation of a well is 30 feet. The
current elevation is 6 feet. If you start running pipe from the current
elevation, you are already 24 feet into the well. Therefore, in order to reach
a fish that is at a depth of 4,500 feet, you will need to run pipe 24 feet
shorter than 4,500 feet because the depth is measured from the original
elevation (24 feet higher).

Fishing Technology (2)

Fishing Technology Manual

Scheduling Personnel and Equipment

Requirements of the job

When determining the personnel and equipment requirements of the job,
consider previous jobs and possible complications of the job. You may
decide to obtain standby commitments for assets that might be required to
successfully complete the job if the operation does not proceed as initially
planned.

Contact information

The phone number of a contact person on the rig should be secured in case
of any delay or problem lining up the tools. Get good directions to the rig
or boat dock and give the company man a reasonable ETA.

Scheduling required equipment

step:

1-Submit the equipment requirements for the job to the customer’s
operator.

 2-Determine whether or not the rig has sufficient tools.
IF the rig does not have sufficient tools, THEN consider:
- modifying the program and re-submitting the equipment
requirements
- whether Weatherford tools are compatible with the fish and
fishing plan and are available for rental
- special ordering or designing tools.
Note: Consider the time required to design and/or order special
tools and deliver them to the job site.

3-Schedule the delivery of all required tools for the date when
fishing will begin.

Management on Location

Your responsibilities

When you arrive on the rig for a fishing job, you should:

1.  verify all the pertinent information with the company man and/or tool
   pusher
2.  check the rig’s equipment
3.  check the string figures
   During fishing operations, you will need to:
4.  maintain an accurate fish location
5.  maintain the tally book
6.  call in a daily report to the fishing supervisor.

Verifying information

Introduce yourself to the company man and verify all pertinent information
concerning the fish, well, and local conditions. Record the BHA and pipe in
the hole with the company man.
Note: The fishing tool coordinator should be consulted if the company man
does not agree with the Weatherford fishing supervisor’s suggested course
of action. Additionally, the company man must sign the resume when
Weatherford’s suggested course of action is refused.

Checking equipment

Follow the steps below when checking equipment before a fishing
operation.

steps : 

1-The fishing supervisor should personally caliper all tools upon
arrival on location. It is very important to be precise when
callipering tools.

2- Count all pipe on the location and compare with the company
man’s records.

3- Clean out the V door and mark the first joint of pipe on the rack.

4- Count and tie off all pipe in the derrick. The count on the surface
subtracted from the total on location should equal what is in the
hole.

Fishing Technology (1)

Fishing Technology Manual

JOB PLANNING AND RECORD KEEPING

Overview

In fishing jobs, the customer is looking to you to provide an assessment of
the problem and a plan for resolving the problem. They will need you to
respond as quickly and as efficiently as possible so that they can resume
productive operations. You will earn their confidence by being
professional, thorough, and precise in your planning, coordination, and
execution of fishing operations.
At the end of the job, the customer will expect to be charged a fair price for
fishing services. In order to satisfy this need, you will need to plan an
efficient operation and keep accurate records of equipment used and
services performed.

Job Planning

Description

Successful fishing jobs start with excellent job planning. You will need to
do extensive research about the fish and hole conditions before the job is
even started. Appropriate paperwork must be maintained throughout all
phases of the job, including the planning stage.

Purpose

Proper preparation ensures that:

1. the best option for fishing is determined
2. time and money are not wasted on an unfishable job
3. equipment, personnel, and other assets are available when needed.

Components

In planning for a job, you will need to:

1. gather important information about the job
2. determine the dimensions of the fish
3. develop a fishing plan
4. obtain approval for the fishing plan
5. schedule personnel and equipment for the operation.

Gathering important information

Several important details should be obtained about the company, job
location, well parameters, work string, fish, and the operation at the time of
the incident. Important questions to ask include:

1. What are the hole size, angle, and depth?
2. What are the size, weight, and depth of all casings and liners?
3.  What are the connections on the work string and drill collars?
4.  What is the depth and condition of the top of the fish?
5.  Does the job require jars? Are there jars in the hole? If so, are they working?

Additionally, you should request that a copy of the bottom hole assembly
(BHA) be faxed to you. This document will list everything that is included
in the BHA along with the specifications for each part. This will be
especially important for you to be familiar with because it is often what you
will be fishing out.
When you have gathered all of the job information, research previous
fishing jobs with similar characteristics. The documentation from these jobs
may help you to anticipate problems that may be encountered and learn
about some of the best practices that have been used.

Determining fish dimensions

It is very important to determine all possible dimensions of the fish. This
can be done by obtaining a complete well profile, if one is available.
The following information should be included in the well profile:

1.  OD, ID, and length of the fish
2.  OD, ID, and length of the fishing tool assembly
3.  OD, ID, and length of the work string
4.  location of the top of the fish
5.  tensile and torsional strengths of everything that is run into the hole. The strength of the fish must be either memorized or noted in a readily accessible location. You may need to pull this information quickly and not have the time to calculate or research maximum pull values. Remember that pull strength is 80% of the tensile strength.

Other resources for information about the fish include the composite
catalog, technical manuals, and manufacturer’s drawings. These resources
can provide you with the critical points of recovering, burning over, or
milling up the fish. One of the first steps in planning a fishing operation is
studying how the manufacturer recommends releasing or picking up the
specific tool.
Important: You should have an exact replica of the fish (e.g., same type
packer, etc.) delivered to the location. It is far more valuable than drawings,
specification sheets, or photos.

Table 1-1:
Maximum OD of Tools to Run in Casing Excluding Overshots