Paradigm Shift in Well Economics thru Robotic Well Interventions
Jyoti Prakash Nayak, Sales Director - APAC Welltec

In the back of low crude prices, new oil & gas projects have been delayed or indefinitely postponed so production targets are now being met from existing wells and fields. While fields maturing, it is imperative for all offshore assets to have an efficient and reliable solution to enable increased oil production while minimising investment cost and ensuring profitability. In last two decades, e-line based Robotic Intervention has evolved as future methodology or practices of Well Engineering to enable recovery rates higher than 50 per cent in offshore assets. The article discusses paradigm shift in ‘Well Intervention’ that allows future smart robotic intervention to minimise intervention cost along with increasing life of the well.

We are in the third quarter of 2016 and Oil & Gas E & P business has adapted itself to the new low price regime. Objectives and outlooks have evolved to enable increased oil production while minimising investment cost and ensuring profitability. New projects have been delayed or indefinitely postponed so production targets are now being met from existing wells and fields. With fields maturing, the need of the hour for all offshore assets is to have an efficient and reliable solution which will reduce the cost of production. For last two decades, e-line based Robotic Intervention has evolved to reach the moment when it defines future methodology or practices of Well Engineering to enable recovery rates higher than 50 percent in offshore assets. There are three paradigm shift in Well Intervention - firstly, adopting intervention as methodology of increasing life of well; secondly, when wells are designed to enable future smart robotic intervention' and thirdly, adoption of robotic intervention to enable low cost intervention - to recovery higher rate in minimum cost of production for the companies operating mature fields.

Adopting Intervention as Methodology of Increasing Life of Well
As wells are being designed, a universal design criterion is the capability to keep production flowing as long as possible without having to intervene in the well. This is why, typically, interventions are only done when something 'breaks' i.e. production becomes restricted, or stops or an unwanted production type begins. But this conventional strategy often forces operators into a position where they must cope with unnecessary levels of uncertainty, leading to inefficient responses . No other industry works on the principle of 'fix it when it breaks' approach and yet in the oil and gas industry billions of dollars are invested into putting wells in the ground only to squander the potential performance of the well and reservoir development through gross inefficiencies.

Similar to a vehicle or other expensive asset, regularly performed maintenance will increase the current performance and extend the overall life of the asset. Operators can prolong production and achieve the highest ROI possible while simultaneously increasing recovery factor and reservoir drainage. This is point number one, illustrated in Figure 1 .

Figure 1 shows the theoretically understanding of higher recovery or increased life of well thru regular intervention and the data on the right courtesy Norwegian Petroleum Directorate shows the example of four fields in the North Sea which shows increased recovery thru management of wells thru Well.

What happens when Operator Designs Completion based on Intervention
Operators around the world design and complete wells based on production estimates and not based on future intervention plans. Planning wells with future intervention enables operators to extend live of well rather than only plan for side tracks or drilling new wells.

An operator in Offshore India had to design well based on new found production zone in well which meant zonal isolation was required to enable production from different production zone. Operator planned the well with 4.5" tubing in combination with 2.313" SSDs. Prior to running completion, operator contacted Welltec to plan future intervention; and it was determined, intervention on e-line was not feasible due to well completion restrictions. Well completion was redesigned with 3.5” production string which could be intervened in future with e-line robotic Intervention. Well intervention was carried out with Well Stroker, and 3 SSDs were opened to enable production of the well. New Well Completion design enabled saving of OPEX reduction of USD 750,000 per intervention as no barge and CT was required for intervention. This has enabled the operator to complete the well with multi zonal completion enabling extending the life of well and increased ROI for single well CAPEX cost.

Adoption of Robotic Intervention to Enable Low Cost Intervention
Intervention is generally defined by three generic parameters which amazingly have no clear definition across the industry: efficiency, Reliability and Innovation. Welltec believes in defining efficiency as the ability to quickly mobilise, rigup, run in and out of the well, rig -down and demobilise off location, it's clear that a WO rig is the lowest while slickline and e-line score the highest. Reliability is defined as the ability to solve the problem once on location

Here the WO rig scores the highest as it can generally overcome even the most severe of challenges. On the definition of innovation, this is the ability to understand what the problem is, adapt to the challenge and bring the appropriate technology to bear quickly, minimising downtime and restoring production as quickly as possible. With real time, surface controllable features enabled by e-line versus the mechanical solutions offered by the others, it scores the highest in this category, offering a 40 percent advantage over the WO rig.

While a workover rig has the highest chance of success to rectify the problem, what about the trade-off on efficiency and innovation? Slickline may be efficient as per our definition, but what is the confidence level on its reliability and innovation to overcome and fix the unknown challenge? Overall, e-line stands out as the overall winner for these key elements of success.

Another important factor which has not been addressed or scored, but should be considered as part of the innovation content is the ability to accomplish the work in the safest, most sustainable and cost effective way possible. A quick comparison of a CT unit to an e-line crew with regards to some simple metrics: total footprint, size, number of people, number and weight of lifts, sustainability, complexity of operations and carbon footprint, demonstrates that there is significant additional value to be gained from deploying e-line.If a WO rig were to be compared the contrasts become even greater.

When you consider these additional benefits it becomes even more clear that an e-line solution offers significant advantages, especially if you've got the right portfolio of tools. That's point number three.

A few examples to highlight that approach are provided below:

94% Time Savings, Increased Safety and Cash Flow
Offshore Mexico, subsurface safety valves (SSSV) require periodic function testing to ensure reliable operation when needed. Typically, they are tested and if they fail, a workover rig is scheduled to shut in the well and replace them.

A new technique has successfully been implemented which precludes the requirement to shut in the production or even to mobilize a workover rig . Using the Well Cleaner Wishbone Honer (WBH), the operator has been able to repair the valve insitu with the well flowing.

Analysis determined that often the SSSV failed to close completely due to debris which limited its ability to hold pressure during the testing. After careful planning, a Well Tractor® and Well Cleaner® WBH were mobilized and run on e-line to the desired depth. There the WBH was activated and cleaning of the SSSV and surrounding tubing was performed. Following the cleaning the SSSV was successfully tested.

The entire operation was completed in only 18 hours compared to ~1 week for the rig operation to pull the SSSV. And the well remained on production throughout, demonstrating the benefits that e-line interventions can provide.

Production Restored, USD 2 million Saved
Onshore Nigeria, a retrievable safety valve assembly failed to seat properly in the tubing and flowed up hole with the production to get stuck somewhere near the tubing hanger; precise position unknown.

More than 1,000 slickline jar attempts were made to free the fish. Indicators showed that the lock mandrel fishing neck was partially open, suggesting that its keys were jammed in a slightly inclined position, below the lower ID of the tubing hanger profile.

Based on this problem description, Welltec engineered a solution. Using the Well Tractor and Well Miller plus a custom nipple milling bit in combination with the Well Stroker the team succeeded in milling out the safety valve which fell to the bottom of the well as desired, restoring access and production.

This successful milling operation enabled the operator to avoid having to pull the entire completion string and saved more than USD 2 million compared to the alternatives. The operator was very pleased to be able to regain the well in a shorter time frame and estimated that the milling solution was twice as efficient as the other options.

90% Cost Reduction while Restoring Injec tion on a Limited Space Platform
Offshore India, limited crane height, space and daylight operations posed challenges on a small platform to an operator trying to restore injection on a converted producer.

A thorough risk assessment was conducted and equipment mobilized offshore to rectify the problem. The first run revealed that the GS profile couldn't latch onto the lock mandrel completely. A Well Cleaner Power Suction Tool (PST) was then run to remove debris which had settled on top of the lock mandrel. The Well Cleaner PST uses a venturi system to create a powerful vacuum which agitates and mobilizes the debris, trapping it inside bailers and removing it from the wellbore.

Once the Well Cleaner PST was recovered, the Well Stroker with GS pulling tool was run. It latched the lock mandrel and with one stroke pulled the reluctant lock mandrel (and attached T TSS) free. The entire assembly was removed from the well and injection established at 22,000 bwpd.

The operation was carried out in only three days and provided significant savings, approximately 90%, versus a barge-based, coiled tubing operation.