Given some of the close-tolerance wells that are being drilled, a potential customer (in a Major Oil Co) has asked what the industry thinks about the following potential game-changer(s).
Challenge: Can we develop smart technology around the casing running and cement jobs, that could be integrated into the casing that could:
1. Measure and transmit surge pressure whilst lowering the casing
2. Measure the hole caliper (directly or by inference)
3. Measure Borehole breakout analysis
4. Measure annuli pressure build-up
5. Device that accurately determines the volume-to-bump BEFORE the cement job (i.e. whilst circulating to condition the mud).
We would love to hear what you think and especially from those who are working on solutions; we will lift our 'no sales pitch' rule (in this instance) as long as you provide meaningful information in your reply (not just redirecting us to your website).
to bump the plug
In order to determine the actual volume to bump the plug , came up with a method which involves pumped a cementing plug on he final casing circulation which utilises a pressure burst disc of variable rating.
The issue is that with a normal cement plug the pressure to rupture the plug diaphragm can vary from a few hundred psi to very little due to the friction of the plug in the casing causing pressure behind the plug to rise. It has also been noted that you may not see the pressure to burst the diaphragm in a normal bottom plug. That pressure to move the plug varies depending on the plug casing interference, mud etc. Also the plug will rupture with no or little differential pressure whereas when the cementing top plug lands the differential can be thousands of psi.
So by choosing a rupture disc a few hundred psi above the
calculated pressure to land the plug to
for this friction pressure it mimics the pressure to land the plug. Therefore by bumping the displacement
plug under the same pressure with the same fluid all we really need
is the pump strokes to land the sacrificial plug. We can then go
ahead with reasonable certainty with the cement job with knowing the
pump stokes to land the plug.
I was working for Halliburton at the time and it was patented by them. Some equipment was stocked at that time in Aberdeen.
I would also
recommend calipering a sample of the pipe ID's so that the ID range
covered by the plugs is checked prior to running. If the casing is
outwith the OD
of the plug it may be bypassed by mud and you would not accurate in
your pump stoke measurement. You may also want to consider utilising
non-rotating plugs to reduce the drill
out time of multiple plugs.
I hope that you find this information helpful and it answer one of your questions.
Direct measurement of surge pressures, caliper and caliper analysis are all already available via MWD for drilling but designed for repair and reuse rather than sacrifice as reflected by the cost and reliability. Since it is assumed the casing will not be rotated throughout the run a directional caliper (needed for breakout analysis) is probably limited to some form of orientated mechanical multi-arm caliper or multiple ultrasonic set up, with the likelihood of needing 8 directional arms / directions to gain the information required.This leads neatly onto the next point, whilst having ultimately a full gauge centraliser (caliper) may present a dimensionality concern at first sight, the required sensors, telemetry, power source, etc will have to be mounted on the OD of the casing if there is a requirement to drill out which will significantly increase the OD and thus the surge pressures, unless it can be built, say, into an acceptable solid body centraliser and data transmitted via EM or acoustic back to a central processing and transmission location (again impacting dimensionality of the casing). Alternatively, if there was no requirement to re-enter or drill out the casing then the sensor, telemetry, processing and power package could be placed in the shoetrack in a similar manner to a collar mounted MWD tool but would need access to the OD mounted sensors without impacting the design integrity of the casing string. Though there may be an option to make such a design retrievable (like a retrievable MWD tool) and give drill through capability though the retrieval would need to be performed prior to cementing or more precisely pumping any internal restriction into the casing.