The subsea well cementing status quo currently involves the use of the poor boy inner string method and SSR plug method. The standard poor boy inner string cement job involves running an inner string to within a pre-designed distance of the float shoe and making this up to the running tool. The cement job is then pumped and displaced, leaving a designed shoetrack length to try and guarantee quality cement at the shoe. Alternatively, a landing collar is run at the top of the casing shoetrack, with SSR plugs and darts loaded into the wellhead assembly and cement head respectively. The cement job is then pumped and displaced, and a casing pressure test can be carried out upon plug bump in the landing collar.

      Poor boy inner string                                                                            SSR Plug method

The challenge          

Although these methods are considered the status quo and have been part of countless successful operations, they are not without challenges. Dedicated clean out trips to drill out shoetracks, high TOC inside casing and SSR plugs spinning on drill out, to name but a few.

These conventional methods create another potential problem which may not get the consideration it deserves – the risk of damage to drill bit and casing ID when drilling out shoetracks.

Photo: The damage that can be done to PDC drill bits when drilling out shoetracks.

As the PDC drill bits can potentially be damaged, often beyond repair, when drilling out shoetracks, the process not only can result in high costs for the operator but also may prevent the bit from reaching section TD. Similarly, vibration of the drill out can cause damage to  the expensive directional drilling or logging tools in the BHA.

Damage to the ID of the casing is a further risk posed during the shoetrack drill out. The below example showcases images captured by an operator who had to pull the casing back to surface after a cement job went wrong. The operator witnessed significant gouges out of the casing ID, so much so, that only 34% of the casing wall thickness remained when measured with callipers.

Consequently, this missing 66% of wall thickness manifests itself in the form of swarf in the wellbore, providing additional risks and challenges in the drilling programme. With the average shoetrack drill out time being 4-6 hours, a large window exists for either drill bit or casing ID damage to occur.

Changing the status quo

Through the use of DeltaTek’s award winning SeaCure® system, this zero shoetrack solution significantly mitigates the risk of drill bit or casing ID damage occurring. SeaCure®’s  latch-in adapter sealed into the float shoe allows for a conduit to exist, through which the cement job can be pumped and displaced.

With no shoetrack of cement above the float shoe, SeaCure®  shoes drill out in an average time of 25 minutes, with the fastest drill out seen to date at only 6 minutes. This drastically reduces the time spent drilling inside casing, closing the window of opportunity for damage to occur.

On a recent DeltaTek deployment, our SeaCure®  system enabled the drill out of a 13-3/8” shoe in just 15 minutes utilising 8-1/2” bit, which then drilled over 7000ft to TD in one run without any BHA failures.

If you would like to find out more about what the zero shoetrack solution SeaCure® has to offer, please email us on enquiries@deltatekglobal.com and a member of our technical team would be delighted to assist you.