|
Introduction
Terms
Specifications
Cable
Construction
Portable
Marking
Unit
Stationary
Drum
1 Capstan
Stationary
Drum
2 Capstan
Steps
to Good
Cable Care
Calculating
Pull-Out Point
Rehead
Strenght
Calculations
Specific
Gravity
Weight
and Pressure
Table
Calculating
Stuck Point
When
Tool or
Cable is Stuck
Steps to Find
Stuck Point
Eliminating
Errors
Things
to check
Back to Manual Menu
|
CABLE CARE
Cable Specifications and Terms:
There are a number of things we
must know about wireline, such as
specifications and terms, how to check for leakage and how to find a short in the
inner conductor.
Here
are some specifications and terms that you need to
know to be more informed about the limitations of your cable.
- A. Cable
diameter:
-
Knowing the correct diameter of your cable
will help you evaluate the accuracy of
the measuring system, and determine the correct grease flow tube I.D. This will be covered more in depth later
- B. Weight per 1000 feet:
-
Knowing the correct weight per 1000 feet of your
line will help you evaluate the accuracy and sensitivity of the weight
indicator system
- C. Breaking strength -
total:
-
Knowing the breaking strength of
the cable
can help you determine the maximum loads that can be applied to the cable
- D. Individual wire strand
breaking strength:
-
Knowing this can help you to calculate
the strength of the cable clamp or to modify the strength of the cable clamp
when using some types of reheads
- E. Elongation per 1000 feet at
various tensions:
-
Knowing this factor you can calculate the stuck
point. You can also verify which, either cable or tool, is stuck and where it is stuck
- F. Conductor
direct current (D.C.) resistance per 1000 feet:
-
This factor can be used to calculate the length
of the cable on a unit. It is useful in evaluating electrical
problems.
It can be
used
to calculate the amount of current available at the end of the
cable to operate
equipment
or fire explosive devices
- G. Conductor total
D.C. resistance:
-
Knowing the total D.C. resistance of your cable
will help in troubleshooting cable problems. It also is needed to determine
the total length of the cable
H. Elastic stretch:-
Elastic
stretch is cable stretch, or elongation, that occurs each and every time the
cable is run in the well. Elastic stretch is a reasonably constant factor
and must be compensated for in depth measurements
I. Permanent stretch:
-
During the "break
in period" of the cable, which is the first 20 - 25 runs. The
cable will be physically pulled out, or stretched to a longer total length.
The cable will remain at this longer length for the rest of its life.
Remember "Permanent stretch" occurs only during the first
20 - 25 runs of the cable's life, and then
remains for the rest of the life of the cable. Permanent stretch
cannot be compensated for in depth measurements
J. Elastic limit:-
Elastic limit is the maximum amount of strain
(tension) that a cable can withstand without suffering permanent,
irreparable damage. The elastic
limit of a
cable can be calculated from the cables total breaking strength. The elastic
limit of the cable can be calculated by using a percentage (e.g. 60%) of the
cable total breaking strength
K. Maximum temperature rating:The maximum temperature that a cable can be
operated at is determined by the type of insulating material used.
Polypropylene has the lowest rating (300° F).
The wellbore temperature also has a definite
effect on the conductor(s). As the wellbore temperature increases the
resistance, of the conductors will increase
Previous
Page | Print Page
|
