WELLOG                                 WIRELESS WIRELINE



Revised 11-07-2016

© WELLOG 2016

All Rights Reserved





Wireline logging has traditionally involved the use of wireline cable. A tool containing electronic instrumentation is lowered into a well or borehole. The tool is connected to a cable that has an outer armored steel sheath. Insulated conductors within the cable connect the necessary tool power and communication circuits to the surface electronics referred to as panels and data acquisition system.




Wireline cable is very complex.  The nature of the construction of wireline cable creates a list of problems associated with the use of this type of cable. Designers over the last century have attempted to meet the challenge of overcoming the problems.




Wireline cable must be able to withstand the rigors of field operation. In this case the cable must have an exterior armor sheath that has the strength of steel wire rope. The tools used on larger wireline tools must be able to support a tool string that can weight up to 1000 pounds. Because the cable has weight, the cable must also be strong enough to support the tool and the weight of the cable that is in the hole. The cable in the hole can add another 4000 pounds of weight. Lighter cables used with smaller tools and shallow wells must still be able to support as much as 1000 pounds. The internal conductors must be well insulated and capable of operation in water, oil, and similar chemicals that can attack the insulation. Finally, many wells can have temperatures that approach 300 degrees or more. All of these requirements contribute to the extreme cost of wireline cable. Only a few companies manufacture wireline cable. Limited competition is another factor that adds to the cost.




Wireline cable is similar to other cable in terms of electrical characteristics. The conductors are separated by insulating material that creates capacitance. As ac waveforms are applied to one end of the cable, they are reduced in size as they progress along the length of the cable. The reduction in size or amplitude is caused by attenuation due to capacitive reactance. Another form of attenuation occurs because of the inductance created by the conductors within the cable. A third form of attenuation occurs due to the inherent resistance of the copper conductors. When a voltage is applied to one end of the wireline cable and current flows through a conductor, a certain amount of the voltage is dropped across the resistance of the conductor. As current increases, the voltage drop also increases.  




Wireline cable is constructed with internal conductors that have limited voltage and current carrying capacity. Conductors are designed to carry a limited amount of current. If the current exceeds the capacity of a conductor to carry it, the conductor overheats and fails. In the process, the overheating of one conductor can cause the short circuiting of other conductors as insulation materials melt. If voltages exceed the design limits of the insulating materials used in a cable, the insulation will be subject to failure from arcing due to conduction through the insulating material.




Wireline cable has physical limitations. The cable has a limitation on the amount of stretch that may occur before internal conductors separate and become open-circuited. Wireline cable can only be bent around a minimum bend radius. I wireline cable is bent excessively or kinked, internal conductors may become damaged, shorted, or broken causing permanent or intermittent failure due to open circuits and shorted circuits.




Noise is defined as any unwanted or undesirable signal.  One type of noise is called cross-talk. Cross-talk is a form of noise that is caused by inductive coupling from one conductor to another. Winch noise can occur from the slip-ring assembly that is used to couple the rotating wireline winch to a stationary contact or contacts on the winch frame.




Electronics has evolved. Wireless isn’t new! Wireless has been around a long time! Many modern devices in use today are wireless. Wireless products like CB radio, Cellular Telephones, Blackberry computers, provide mobile communication without the limitations of wire connections.


Computer memory has also evolved into low cost, high capacity memory modules that are easy to obtain.




Recently, logging tools have been developed called memory logging tools. The memory logging tool contains sufficient memory that it can be lowered into a well, perform a logging function (collecting geophysical data) and upon retrieval at the surface the data is downloaded through a serial cable to a personal computer. The theory of operation is that the memory logging tool has a very stable internal clock. The tool stores the logged data and a time stamp that is associated with the data.  Simultaneous time keeping occurs on the surface as the tool is lowered in to the well. Depth of the tool is recorded with a time stamp. After the tool is retrieved and the data downloaded, the data and depth are correlated with time. Memory logging tools are battery powered. High capacity batteries may be used that allow logging tools to use more energy than a logging cable can supply.


The obvious benefit of a memory logging tool is that the limitations and other factors that reduce the quality of logging data are eliminated.




WELLOG has developed a completely wireless logging tool. This tool uses an internal radio modem to download data. The benefit is that the tool does not require disassembly in order to download data. Wireless communication is established with a laptop that has a compatible radio modem.




How does WELLOG charge the battery pack for its memory logging tools? WELLOG technology has evolved with the electric tooth brush!  The latest electric toothbrushes use the principle of Inductive Power Transfer (IPT). WELLOG is able to recharge its memory logging tools without having to connect to the tool electrically!


We call our system “WELLOG Wireless Wireline”.


Contact WELLOG at info@wellog.com for information on Wireless Wireline!