Moving tools and equipment up and down the casing is important for locating and repairing problems in the well, as well as monitoring conditions downhole. When tools need to be run in the well, or the tubing or other equipment pulled out of it, it will be done using a wire line. Wire lines might be used to pull tubing or rods, cut paraffin, swab fluids, conduct surveys, and a number of other things.

Wire line is available in a few different types, each with their own advantages and disadvantages. They might be laid up wire, solid wire, or wire that can conduct an electrical current into the well. In oil and gas wireline work, picking the wrong line for the job costs you a trip, a tool, or a fishing job.

Which wire line do you need for the job in your well?

It depends on the job. Hoisting tubing and rods on a servicing unit takes rotation-resistant wire rope from drum to blocks. Swabbing, bailing sand, cutting paraffin or fishing a parted rod takes the sand line. Temperature and pressure surveys, setting valves or dropping a pressure bomb call for slickline, a solid wire. Logs, perforating and any powered tool need electric line. Guy lines never go downhole. They hold the unit steady. Match the line to the job and inspect it before every use.

What is wireline in oil and gas?

Wireline in oil and gas is any cable used to lower tools, gauges or equipment into a well and pull them back out. The term covers three families of line. Slickline is a single solid wire with no conductor. Braided line is laid up wire rope, the kind found on a sand line. Electric line, often called e-line, is armored cable with one or more conductors inside, so it can carry power and data to tools downhole.

Production wireline is the work done on wells that are already producing: setting and pulling plugs, running gauges, swapping valves, cutting paraffin and checking for leaks. Drilling and completion wireline covers open hole logs, cased hole logs after the drilling wire line has run casing into the hole, and perforating. Wire line work is one part of servicing an oil and gas production well, and it often comes up when you are troubleshooting problems on the lease.

This guide is written for the producing company and the pumpers and supervisors who call out wireline crews. It is not a training manual for running a wireline unit. That training comes from the service company.

Slickline vs. wireline: what is the difference?

People in the field use “wireline” two ways. Some mean any line run into the well. Others mean electric line only, and call the solid wire “slickline.” Either way, the difference that matters is power. Slickline has no conductor, so it runs mechanical tools and memory gauges that record data and get read back at the surface. Electric line carries current, so it can fire a perforating gun, run a real-time log or power a tool while you watch the readings come up the cable.

Slickline is cheaper, lighter and faster to rig up. Electric line costs more but does jobs slickline cannot do.

The Basics Of Wire Rope

As mentioned above, wire lines may be of a few different types. The style most often encountered is wire rope, which consists of smaller, solid strands of wire that are woven together, more technically referred to as laid up. This is similar to twine or fiber rope. Wire rope might have a central core around which the individual, smaller stands are braided. Figure 2 shows the different parts of the rope.

Shapes of wire rope. (courtesy of Williamsport Wirerope Works, Inc.)

Figure 1. Shapes of wire rope. (courtesy of Williamsport Wirerope Works, Inc.)

A diagram of a basic wire rope. (courtesy of Williamsport Wirerope Works, Inc.)

Figure 2. A diagram of a basic wire rope. (courtesy of Williamsport Wirerope Works, Inc.)

The rope can be laid up in different ways, usually left or right hand lay. This has some implications for how the wire line should be handled and possibly some other considerations. In Figure 3, you can see several different styles of laid up wire rope. Right hand lay is much more common.

Examples of wire rope. (courtesy of Williamsport Wirerope Works, Inc.)

**Figure 3. Examples of wire rope. (courtesy of Williamsport Wirerope Works, Inc.) **

It’s important to measure rope using the correct method, so that you can identify the correct tool and equipment size to use with that wire. Always measure the rope across it’s widest dimension, as it’s the total diameter of the rope that’s important.

Correct and incorrect ways to measure wire rope diameter. (courtesy of Williamsport Wirerope Works, Inc.)

**Figure 4. Correct and incorrect ways to measure wire rope diameter. (courtesy of Williamsport Wirerope Works, Inc.) **

While wire rope is fairly sturdy stuff, it can be damaged if handled or used incorrectly. Damage is essentially permanent and will have a long term impact on the rope’s strength and use. Wire rope, wherever it is used, should be protected and inspected before each use.

Examples of damaged wire rope. (courtesy of Williamsport Wirerope Works, Inc.)

**Figure 5. Examples of damaged wire rope. (courtesy of Williamsport Wirerope Works, Inc.) **

Types of Wire Line

Wire can be used for a few different purposes. Some uses will require a specific type of wire line, while some types of line are multi-purpose.

Line From Drum To Blocks

These lines will run from a reel drum on a servicing unit or derrick to the blocks. The blocks are the pulleys used with that equipment to provide mechanical advantage. The wire rope used with a servicing unit, is different from that used with a drilling rig in a few important respects.

Wire line used with a servicing unit will be resistant to rotation so that elevators don’t turn on their way up through the derrick. This is a particular consideration when only using a single line. This line is also designed to be used on the surface only, and don’t have the same protection against corrosion and other downhole problems.

This line will need to be at least 500 feet long, though it will usually need to be quite a bit longer. The wire is run back and forth between the blocks many times, and it’s important that there is enough wire to lower the traveling block all the way to the floor. There should be some reserve on the drum when that’s done. Also, a length of the worn line should be cut off according to the ton mile schedule. There should be enough reserve line that the blocks can be re-threaded, which will extend the useful life of the line.

Sand Lines

While wire lines may be used in various places around the lease, the lines that are run down into the well are going to get most of your attention. The sand line is a wire line with a high tensile strength and which is used to run tools and equipment down into the well. The line is placed on the second drum of the pulling or servicing unit, or on the drum closer to the cab. This line should be long enough to reach the bottom of the hole.

Sand lines are basically utility lines that can be used for a wide range of purposes, depending on the tool or piece of equipment that is being run on it. For example, by using the sand line with a swab, fluid can be lifted out of the hole. This might be done for a variety of reasons, but it is usually done to clean up the wellbore and matrix area. It may also be done to remove pressure from the tubing so that fluid can flow into the lines and tanks.

The sand line can also be used for bailing sand. Sand may migrate to the bottom of the hole during pumping operations, carried by the flow of fluid through the formation. When the tubing is pulled for service, this sand can be bailed out. The sand line can also be used to cut paraffin and remove scale. In Figure 6, you can see an example of a paraffin cutting tool.

An example of a paraffin cutter.

Figure 6. An example of a paraffin cutter.

When a rod parts, it needs to be fished out of the hole so it can be replaced. Unfortunately, because the rod parted it may be difficult to fish it using standard equipment. When a loose rod string is troublesome to fish, an impression block or tool can be sent down into the hole. This is a flat bottom tool made of soft lead. When run down onto the parted rod, the end of the rod will leave an impression in the block. A custom tool designed to hook that rod can then be made. Fishing jobs like this one are covered in more depth in our guide to unusual operations on the lease.

The sand line may also be used to pull a standing valve out of the tubing. Standing valves may be dropped into the tubing for a few reasons, primarily to check for leaks. The valve is dropped into the string. Once the valve is in place, the tubing string is filled with water and then pulled. The water will drain from the leak, so that the level of water in the tubing will show where the leak is. When this point is reached, the standing valve can be retrieved without having to pull the entire rest of the string.

Solid Wire (Slicklines)

As the name implies, solid wire lines are a single strand of solid wire. In the field, this is what most crews call slickline. It’s used in special circumstances, generally for running tests, placing valves, or dropping a pressure measurement device called a bomb. Some of the common tests and uses that may require a solid line include:

  • Temperature surveys. These are used to detect leaks in the tubing string. Gas will often escape through leaks and expand, causing a detectable drop in temperature. These surveys are usually run a regular basis, as frequently as every 6 months or as infrequently as once a year.
  • Pressure surveys. These are also run on a regular schedule, usually once a year. These surveys measure the pressure at the bottom of the hole. By comparing these readings to previous years’ measurements, the drop in reservoir pressure can be determined. This is useful information that can help to determine things like the amount of fluid remaining in the reservoir and gauging the effectiveness of pressure maintenance operations. It’s also possible to predict when a naturally flowing well will need to add artificial lift.
  • Directional surveys. When drilling a well, a direction survey may be run on a solid wire line. A clock is set within the survey bomb before it’s lowered into the hole. When the timer runs out, the bomb takes a 180 degree impression.
  • Other uses. Solid wire can be used to place valves, scrape paraffin and scale, and a few other specialized uses.

If you want to see how bottomhole pressure readings fit into the bigger picture, read our guide to special tests on flowing wells.

Electric Lines

Electric lines are used for many tasks that require powered tools or equipment be lowered into the well. A well that is being drilled will need open hole survey logs to determine whether the well is worth completing. Cased hole logs may be required once casing has been run into the well, and will be followed by the cement bond log after the casing has been cemented. Electrical lines will also be used to create perforations, for measuring depth and other surveys, and for a variety of other reasons.

Oil and gas wireline logging. A logging run sends sensors down on electric line and records the formation, the cement or the casing as the tool comes back up. Open hole logs tell you what the rock holds. Cased hole logs check cement bond, find holes in casing and locate fluid entry points on an older well.

Wireline explosives. Perforating guns carry shaped charges that punch holes through casing and cement into the formation. They run on electric line because the crew fires them with a current from the surface. Only a licensed service company handles the explosives. Expect the crew to ask everyone on location to turn off radios and cell phones near the wellhead while the gun is armed, and listen when they do.

Wireline cable and specifications. Electric line cable comes in different diameters, conductor counts, breaking strengths and temperature ratings. If you are looking for Schlumberger wireline cable specifications, or any other vendor’s, we don’t publish them here. Ask the service company for the cable data sheet on the exact line they plan to run, and check that its breaking strength and temperature rating fit your well’s depth and bottomhole temperature.

Guy Lines

Guy lines are essentially structural supports. Unlike most of the other wire line described here, guy lines do not run down into the well. They are instead wire lines that run from a tall structure, like a derrick or servicing unit, to the ground to provide stability. Guy lines are most often the standard right hand lay. Wire used for this purpose will usually have a smaller diameter than wire on the drum. You should be sure that the correct size line with the correct strength is used, as it’s possible that guy lines may be put under a fair strain.

What does a wireline worker do?

A wireline crew rigs up a truck or skid unit at the well, picks the right line and tool for the job, runs it in the hole, does the work and rigs back down. On a slickline job that might mean pulling a plug, setting a gauge or cutting paraffin. On an electric line job it might mean running a log, setting a bridge plug or firing a perforating gun. The operator runs the winch and watches depth and tension. The helper or hand rigs up the lubricator and pressure control, makes up the tools and keeps the location safe.

Most wireline services are hired out by the producing company. The company man or production supervisor calls the job, and the pumper is often the one on location who knows what the well has been doing.

Is wireline operator a hard job?

Yes, for most people. The hours are long and you are on call, often driving to a location before sunup and working in heat, cold and mud. The gear is heavy, the well is under pressure, and electric line crews handle explosives. It also takes focus. One wrong depth or too much pull on the line can leave a tool in the hole. The upside is steady work in the oil patch and a skill that carries from one basin to the next.

How do I get into wireline?

Most people who ask how to become a wireline operator start as a helper or trainee with a service company and learn the trade on the job. Companies usually look for a clean driving record, the ability to get a commercial driver’s license, a passed drug screen and basic safety training such as H2S awareness. A head for mechanics and electronics helps, especially on electric line. Engineers with a degree often come in as field engineers on logging crews. Ask local service companies what they require before you apply.

Keeping wireline work in the well history

Every wireline job tells you something about the well: where the leak was, what the bottomhole pressure read, how much paraffin came out. That record is only useful if it lands somewhere the office can find it next year. GreaseBook gets production data from your pumper’s phone to your screen, instantly, including comments and photos tied to each well. GreaseBook is trusted by 600+ production companies, with 10,000+ pumpers in the field, 15 years in the oil patch and 220 million+ barrels tracked across 22 oil-producing states. Pumpers get an 8-minute learning curve. It comes with a 200% money-back guarantee. TinyPumper, GreaseBook’s sister product, is 24/7 well monitoring that installs in 8 minutes.

Wireline FAQ

What is wireline in oil and gas? Wireline is the cable used to lower tools and gauges into a well and pull them back out. It comes in three main kinds. Slickline is a single solid wire for mechanical jobs and memory gauges. Braided line, like a sand line, handles swabbing, bailing and fishing. Electric line carries power and data for logs, perforating and powered tools.

What is the difference between slickline and electric line? Slickline has no conductor, so it runs mechanical tools and gauges that store their data for reading at the surface. Electric line has conductors inside an armored cable, so it can power tools and send readings up in real time. Slickline is lighter and cheaper to run. Electric line is needed for logging and firing perforating guns.

Is wireline operator a hard job? For most people, yes. Crews work long hours on call, drive to remote locations and work in every kind of weather. The gear is heavy, wells are under pressure and electric line crews handle explosives. The work also demands focus, because a mistake can leave a tool stuck downhole. In return, it is steady oilfield work with skills that travel.

How do I get into wireline? Most operators start as helpers or trainees with a wireline service company and learn on the job. Expect to need a clean driving record, a commercial driver’s license or the ability to get one, a passed drug screen and safety training like H2S awareness. Engineering graduates often start as field engineers on logging crews. Ask local service companies what they require.

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