A Technical Revolution

The right sesame to be called was intervention on electric wireline, today regarded as a break-through in the application of new technology. With tools running on electrical wireline, the door also opened for accessing even highly deviated wells where conventional methods earlier had to throw in the towel. The tool to master this feat was the Well Tractor, a 6-meter long and slender wheel-driven conveyance device designed by Welltec.

The Challenge
Before the invention of the Well Tractor, methods like drill pipe, snubbing and coiled tubing were considered the only feasible ways to get down into the horizontal well bore. The drill pipe method consists of a steel pipe in approximately 9 meters lengths, screwed together to form one long pipe going back from the drilling bit at the bottom of the well to the surface of the drilling rig. When the drill pipe and bit rotate, they cause the bit to bore through the rock.

Snubbing, on the other hand, is a method where the drill string has to be pushed (‘snubbed’) in and out of the well bore repeatedly and under pressure. Potential hazards imply falling from heights or being burned by a fire as well as explosions.

Another traditional method is coiled tubing, a fluid-driven solution, where cable is replaced by heavy but small diameter tubes deployed from a large truck-mounted roll or coil at surface. Coiled tubing is used to replace jointed pipe in certain types of drilling and completion operations. This method also exposes personnel to risks of falling from heights or getting injured by falling objects.

Common for all three methods is that they require heavy equipment, are extensive to rig up and/or require the use of a work-over rig. In other words, they are expensive solutions and cannot always reach the targeted point in the well.

The Solution
Always being up for a challenge, Welltec decided to develop a wireline alternative, although parts of the industry deemed it impossible. Backed by a leading North Sea operator and a founder who’s motto seems to be “anything is possible”, the wireline Well Tractor was designed and the operator ended up returning their investment manifold. Working closely with the industry to develop new solutions to specific challenges has since become a Welltec hallmark.

Replacing conventional methods with a solution that runs on electrical wireline has meant a revolution within the oil and gas industry. Welltec has eliminated the constraints of traditional wireline by extending the reach of the wireline into the horizontal part. With tractoring it is possible to run operations on wireline in the entire length of the well, and in contrast to the methods mentioned above, the entire operation can be run in a rig-less environment. A unique feature of the Well Tractor is that it is surface controlled, thus eliminating the need for an expensive rig.

An additional benefit of being surface controlled is the fact that this also eliminates the need for mobilising heavy equipment, which means engaging a smaller number of personnel and reduced operational hazards. Furthermore, the required equipment is logistically easier to handle and the rig-up time is reduced considerably compared to competitive technologies.
Areas of operations are multiple, such as providing important data about the well conditions, performing repairs such as opening and closing of valves or cleaning the well bore of sand or other materials, just to mention a few. The Well Tractor can convey Welltec’s other tools or that of 3rd party companies. Altogether, this makes the Well Tractor a highly versatile tool for running operations in even hostile environments.

Value Creating Solutions
This cutting edge technology has established Welltec as a world leader in the development of cost-effective and value-creating conveyance solutions. What seemed impossible 20 years ago now forms part of several leading oil companies’ standard equipment for intervention in horizontal and deviated wells.

As outlined above, the advantages are many, but the most important one is probably substantial cost savings achieved through reduced expenses for personnel and work hours. In an industry where time indeed is money, operators always seek after ways to save their pennies. A North Sea operator has calculated that they save approximately 50% on operations where the Well Tractor is utilised instead of conventional equipment.

Benefits as Seen by the Operator
To illustrate the effectiveness of the Well Tractor, a major North Sea operator experienced a build-up of scale in two gas wells. Traditionally this would have been removed by a method such as coiled tubing (CT), but in the case of these two wells, the costs were prohibitive.

The well manager says: “The development of this technology enabled us to complete the project at a fraction of the cost of CT and in considerably less time. To give you an idea of the advantages of this new technology, the scale was removed from both well bores in just 12 days – the same time it would have taken just to rig up/down the CT equipment offshore.“

To be exact, the operation took half the number of people that a CT intervention would have required and reduced the total operation costs by 60% (£300,000). Further benefits were reduced human exposure to risks offshore and the fact that the field was able to export an additional 4 million cubic feet of gas a day.

Having proven the effectiveness of the tool, the operator expects that the Well Tractor has a great potential to unlock areas of production, which so far have proved uneconomic due to the high operation costs or impracticality of conventional methods.

In the future, Welltec will continue to convey their way into the business as a full-scale well service provider. The promise is to keep on designing more tools to compliment the Welltec family of revolutionary tools.