DeltaTek’s pioneering team is constantly striving to make technological improvements to provide our clients with greater value when deploying our systems. A recent improvement to our SeaCure® bottom hole assembly (BHA) involved offering DeltaTek’s weight set centraliser (WSC) as an alternative to our weight set sub (WSS).
Both the WSC and WSS provide the set down weight required for the SeaCure® latch in adapter’s collet function to engage into the shoe, with the main design change being the addition of solid centraliser blades on the WSC, in lieu of bow spring centralisers used on the WSS.
Weight set centraliser Weight set sub
This change has further improved operational efficiency, with a DeltaTek offshore supervisor no longer having to fit bow spring centralisers at the wellsite prior to running the SeaCure® BHA into the casing being cemented.
Although additional operational efficiencies and rig time savings are always welcomed, the main benefit being realised from the design comes from the pocket engineered into one of the solid centraliser blades, which can be fitted with a temperature probe.
This probe works in conjunction with DeltaTek’s QuikCure® technology, a post cement job seawater heat sweep, that rapidly cures cement and significantly improves compressive strength. The probe records frequent temperature readings whilst running in hole, circulating and cementing in order to provide data on the downhole temperature that the cement slurry is being subjected to, after the QuikCure® heat sweep is introduced.
Graph 1: Temperature logger, DeltaTek.
The above graph outlines the temperatures recorded by the probe in the WSC during the various stages in the SeaCure® cementing process. The graph clearly shows the elevation in temperature when the heat sweep is introduced, followed by a reduction in heat when circulation of the heated seawater sweep ceases.
Determining WOC time
The most interesting finding from the analysis of the downhole data is outlined in red on the temperature logger graph. A gradual elevation in temperature is observed as the exothermic reaction of cement takes place, giving a clear indication that the cement is beginning to cure.
Currently, the procedure to determine the wait on cement (WOC) by DeltaTek supervisor during QuikCure® operations involves imitating the downhole conditions by immersing a cement sample in seawater. The seawater is gradually heated up, followed by modelling a temperature profile using SimCure, software that is the product of collaboration between DeltaTek and the University of Aberdeen. When the cement sample is solid, it is presented to the Drilling Supervisor, who can then advise the offshore drilling team to begin slacking off weight in increments.
Improvements to cementing operations
The addition of the temperature probe can further improve the process used to determine WOC time during a batch drilling campaign. As operators continue to look for efficiencies in the drilling process, the batch drilling of topholes is often selected to save rig time and reduce costs.
The various topholes in a batch drilling campaign can be as little as 1.5m apart, and therefore well parameters such as depth, wellbore geometry, temperature and formation pressure may be similar in each well. When this is the case, the data recorded by the probe in the WSC can be analysed to determine when the exothermic reaction of cement begins. This data can then be used to further reduce the WOC time when the rig skids to the next well and begins operations.
The ~70% reduction in WOC time provided by our QuikCure® technology could therefore be increased, resulting in additional rig time savings for our clients on each well, significantly reducing costs over a multiple well batch campaign.
If you would like to discuss the benefits, including risk mitigation, operational efficiencies and rig time savings, that our SeaCure® and QuikCure® technology can provide on your batch drilling campaign, please contact us on firstname.lastname@example.org.