Offshore drilling companies with a strong contract backlog have seen their cash flow largely unaffected by the drop in dayrates over the past few years. However, what these companies are gaining in security during a downturn they lose in upside when dayrates start rising again. With that in mind, here are some companies that have the most upside to rising dayrates.

1. Transocean (NYSE:RIG)
Transocean has the largest offshore drilling fleet in the world with 77 rigs as of its most recent fleet report. It also has one of the strongest contract backlogs that currently stands at $19.9 billion. However, despite that strong backlog the company has a lot of available capacity starting as early as next year as the following slide points out.

Source: Transocean Ltd Investor Presentation 

As that slides points out Transocean's fleet is more than 65% contracted for 2015. However, that drops well below 50% next year and even further in 2017. While that's a concern in a falling dayrate environment, it's quite the opposite in a rising dayrate environment as Transocean can capture the upside of those higher rates.

2. Ensco plc (NYSE:ESV)
Ensco has the next largest fleet in the industry with 68 offshore drilling rigs. However, its contract backlog is much weaker as the company only has $8.4 billion in contracted revenue in its backlog. Because its backlog is weaker it leaves the company much more exposed to the downside of falling dayrates in the near term. However, it's also much more open to the upside of rising dayrates.

Where Ensco is particularly open to rising dayrates is in this uncontracted newbuild fleet. As the following slide shows the company has one drillship and three premium jackups that are under construction, but uncontracted.

Sources: Ensco Investor Presentation 

Because these rigs don't have contracts they could potentially benefit from rising dayrates in the future should those rates rise before the company signs up a customer to a long-term contract. Likewise, as that slide shows, the company has four additional rigs currently under contract that could benefit if dayrates rise before these rigs are up for renewal.

3. Noble Corp plc (NYSE:NE)
While its fleet is much smaller at 32 rigs, Noble also has upside to rising dayrates in the future. That's because like Transocean and Ensco it has a largely uncontracted fleet after this year. Though at $10.1 billion its backlog is stronger than Ensco's over the longer term. Still, as we see on the following slide almost half of Noble's fleet is without a contract in 2016.

Source: Noble Corp plc Investor Presentation 

While this fact does leave Noble's fleet at risk to persistently weak dayrates, the fact that its fleet is largely available starting next year also leaves it very open should dayrates begin to rise. That being said, unlike its peers Noble doesn't have any speculative newbuild drilling rigs on the way. That means it will have to get by with its current fleet, unless of course it makes an acquisition.

Investor takeaway
At the moment the offshore drilling industry is going through a rough patch. Not only is it currently oversupplied with drilling rigs, but offshore oil and gas activity plunged along with oil prices. However, at some point activity will pick up and with it dayrates. When that happens Transocean, Ensco and Noble will be among the biggest beneficiaries.