Shifting your intervention strategy towards lighter interventions

The oil and gas industry has witnessed a boom in the development and deployment of new technologies in response to the ever increasing operational challenges of having to drill deeper, longer, horizontal wells in even more complex environments. The strategy to drill horizontal and highly deviated wells has been widely recognized by the industry and these well types are now quite common. Unfortunately, the intervention techniques for accessing these types of wells did not evolve as quickly. Historically, methods such as snubbing, slickline and coiled tubing units were needed to access these wells and for many years have provided feasible strategies for operators. These techniques today, however, are proving to be more costly and time consuming and are creating additional challenges for operators in the financial, personnel and HSE sectors of their businesses.

The size of these older intervention techniques are massive and involve transporting heavy equipment that could provide the required force to push the equipment into these well types. These methods of access also require carefully-coordinated logistics and supply chain management involving very heavy equipment and a significant workforce before operations could be performed. Mobilizing a full coiled tubing spread, for instance, was not (and is not) done without considering personnel, logistics and the HSE aspects carefully.

Apart from being costly, the use of this heavy equipment increases personnel safety issues and associated environmental risks; an aspect that the industry, currently, is working hard to minimize. As wells increasingly have been drilled in environmentally-sensitive areas, production has become even more demanding and financially challenging.

Introducing a New Intervention Technique
The international oil field service provider, Welltec ®, was built around a desire to optimize well interventions in difficult to reach wells. The mission was to move away from heavy methods and move towards lighter intervention techniques for horizontal and highly deviated wells. To Welltec, “Lighter interventions”, means: eliminating all of the unnecessary heavy equipment, reducing manpower requirements, decreasing the “environmental footprint” and increasing deployment speed with simplified logistical requirements. These light intervention techniques would be deployed on electric wireline. Backed by one of the biggest operators in the North Sea, who provided valuable operational knowledge, Welltec ® developed and manufactured the technology that pioneered “light intervention” services and has revolutionized the access and service capabilities for these well types for the entire oil and gas industry: the Well Tractor ®. This tool was developed both as a wireline and a coiled tubing version for extended reach wells.

The Well Tractor ® was designed to meet the demand for new technology that would enable the oil and gas industry to achieve maximum well performance even from hard to reach wells and to comply with the always existing need to bring down costs and rig time requirements. Introducing the Well Tractor ® has actually caused operators to plan and manage their fields differently and prominent oil companies all over the world have incorporated this technology into their intervention and completion strategies.

HSE Benefits
Apart from being a very financially appealing alternative, Welltec’s technologies represent a paradigm shift within the mobilization time and weight of interventions. Whereas traditional intervention techniques involve tons of equipment and many people on deck to operate it, Welltec’s equipment can be operated by a crew of 2 people and be mobilized in a matter of hours. This rapid mobilization makes proactive maintenance of the well site attractive and avoids the cost of mobilizing a full coiled-tubing (CT) spread with bottom hole assembly drill bit.

For further operational efficiency, the intervention can be performed in a rig-less environment; a crane or mast unit is all that is required to operate the equipment, which means that it is operational from even the smallest platforms (Please see picture below).

Tools are deployed via helicopter

Technological advancements have enabled Welltec to develop tools with increased strength and capabilities equivalent to the older, heavy intervention tool sets, in a much more manageable scale. The working environment is improved considerably as heavy lifting requirements are eliminated from operations. Safety on board the platforms are also improved due to reduced personnel requirements.

As this technology is remote-controlled, it has the advantage of being operated miles away from the actual point of intervention, which means that the environment is not affected by the interventions. Additionally, the equipment can be flown to the platform in a helicopter, which reduces fuel consumption, emissions and discharges caused by transporting and operating traditional intervention methods such as coiled tubing. For this reason, Welltec ® is the operator of choice in e.g. the Alaskan tundra where rolling in heavy equipment could have catastrophic consequences for the environment.

Another benefit is that interventions can be executed with such precision that they do not affect the rest of the reservoir or risk damaging the well or the surrounding environment – in sheer contrast to the very large equipment weighing up to many tons required by traditional intervention methods.

Enabling an Increased Operational Scope
As illustrated by the graph below (the green color bar), the first jobs ever performed with the Well Tractor ® were conducted in 1996. Due to this new intervention technique, the operator was able to increase the operational scope because more types of interventions could be performed more often. This is also apparent from the graph where the total amount of operations increased from approximately 75 in 1996 to roughly 145 ten years later - or almost twice as many operations per year.

Today, the operator uses Welltec’s technology for 80 per cent of their intervention jobs and coiled tubing intervention has become a last resort for them. Contemplating the benefits they have gained from changing intervention strategy, the choice seems evident. On one platform alone they saved US$ 10m in intervention costs in one year by using the Well Tractor ® compared to coiled tubing methods.

Huge Value-Creations

The optimized intervention strategy turned out to be an amazingly cost-efficient alternative for the North Sea operator. According to their own estimates, they have saved US$ 10 million in intervention costs on one platform alone in one year by using the Well Tractor ® on wireline compared to coiled tubing methods.

Furthermore, they have received huge value creations as a consequence of changing their intervention strategy. Well Tractor ® services required approximately US$ 50 million on one offshore platform – this returned to the operator approximately US$ 599 million from the improved production on the initiative. On another field, US$ 43 million was leveraged on the Well Tractor ® services which returned US$ 460 million of value creation - more than tenfold rate of return. This is also illustrated in the graph below:

Case story: Efficient Open Hole Logging

A logging job was performed at one of the oldest producing fields on the Norwegian Continental Shelf and the largest oil discovery in the North Sea. The well path was S-shaped above the reservoir section with a maximum inclination of 70º, which dropped to about 20º in the reservoir section.

The Well Tractor ® was chosen as the best solution. It was configured for open hole and rigged up for a Modular Dynamics Tester (MDT) log­ging job and run in hole to approximately 2,600 ft. At this point, the well had reached an inclination of 70° so the Well Tractor ® was powered up and tractored to around 10,760 ft across the part of the well where the inclination reached 70º. When the angle dropped, the Well Tractor ® was turned off and logging was completed on wireline.

Because the operator decided to deploy Welltec’s technology, two days were saved compared to a TLC logging job; one day due to less time spent on the job and one day saved because the “wiper trip” after logging step was eliminated.

Case Story: Isolating Water without a Rig

Offshore India, a gas well was displaying signs of increased water production in 2007. The operator decided to isolate the water producing zone with a plug run on the Well Tractor ® and to open a sliding side door with the Well Stroker ® and Well Key ®. This was executed from a platform and did not require a rig.

The operation took 3 runs. Due to previous experience, there was a concern that sand had entered the well, so a drift run was performed, which established that there was no sand. Then, the Well Tractor ® was used to set a plug at 85° in order to isolate the water producing zone. The third run opened the sliding side door by running the intelligent shifting tool in hole which allowed access to a new producing interval.

Total time for performing the intervention was less than 26 hours, by far outperforming traditional intervention techniques. Compared to coiled tubing, the operator saved 75% off the cost of traditional “heavy intervention” methods, while increasing gas production from 4 to 18-20 mmcft.

Case Story: Milling on Wireline

The world’s first job performed with the Well Miller ® took place in the North Sea in 2003. The operation was to mill a 0.78” thick flapper valve with a 3.15” diameter hole that had become stuck in the closed position. After 7 minutes of milling, the flapper valve was drilled through, which returned the well to production below budget. If coiled tubing had been chosen for the job, it would have taken an estimated 4-5 days to mobilize, rig up and run.

For the operator, when time, money and HSE matter, shifting heavy intervention strategies towards lighter intervention strategies have proven to be effective.