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Acquiring data to assist with difficult cement jobs
12 February 2019

Dear members

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).




6 answer(s)
Insight GeoMechanics
Total Posts: 2
Join Date: 03/08/18

The question about cement volumes is driven by the expectation that some form of hole enlargement could or has occurred in previous wells. I'm assuming the rocks are young and not well-cemented yet. 

In the absence of any downhole caliper measurement, a 'liquid caliper' make sense. But do it more than once. There might me a time-dependent process happening whereby hole enlargement increases with time. 

Not sure what LWD tools are available in a 17" hole. It is possible to telemetry the data in real-time (even image data) but this will only give you a snap-shot shortly after the bit drilled that interval. Pay attention to high-torque, overpull, tight hole, etc.

When POOH, do a deliberate repeat pass to document any changes in hole condition, especially where any high-torque, overpull, or tight hole event might have occurred.

Depending on what LWD tool you have access to, you might get an average caliper with no azimuthal control or you might find from an image log the true character of the hole; breakout vs washout since both failure types might influence cement volumes.

 Let's say you come with with a volume number. Multiple that by pi/3 to make it scientific.  Just kidding!

Good luck
Drilling Superintendent
Total Posts: 22
Join Date: 31/10/07
Morning Dave

On your item nr 5 the following info is available: 
  • Weatherford already have a sub to determine accurate volume to bump the plug. Looks like the easiest system without the need for special wires etc.
  • It is basically a sub placed some pre-determined distance above the float collar with a restriction on the ID. When the top plug passes this sub a pressure spike on surface tells exactly how many more bbls to displace to bump the plug. 
I have not used it myself.

I can see a small downside in that the sub uses aluminum for the restriction later to be drilled by the next bit. Similar to drilling other plugs containing drillable metal they sometimes form big enough debris causing difficulties. Either the debris can't come out from below the bit or debris jamming between BHA and the casng ID.

I attached the brochure from Weatherford fyi.
Documents uploaded by user:
RR _ Plug Indicator.pdf
SPREAD Associates
Total Posts: 7
Join Date: 21/09/10

Volume 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 allow 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 range 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.

Total Posts: 112
Join Date: 10/04/08

As you know I work in this area of well cementing operational effectiveness and have done so for a number of years.

 I doubt that the device required could be developed quickly nor economically enough for it to have commercial applications, especially in tight tolerance casing regimes. There are number of low cost tools and methods that can already provide some of the information before or during running/circulating casing/liners and they are not often justified commercially in the eyes of many well engineers today.

Figuring out the correct and accurate displacement volume of the casing or liner for plug bump does not need to be done whilst running pipe nor once in the well, but can already be figured out without the need for an expensive telemetry tool. There are already tools and methods to mitigate surge pressure during casing running/liners.

 I suppose much of what the client is asking for can be done today during directional drilling casing/liner drilling when a conventional directional drilling/MWD BHA is hanging out of the bottom of the casing and do they collect this information and use it during their subsequent cementation operations, of course their casing or liner is already at TD when they finish drilling? Am not sure............

.In summary I don't think the technical benefit gained would be justified by the cost/time to develop and then the cost to use it to get a commercial return on that significant investment. not when many engineers don't use existing low cost methods to gain some of this information already.
Documents uploaded by user:
CasingIDTOOL Information Sheet Rev 1.pdf
SPREAD Associates
Total Posts: 146
Join Date: 05/03/08
Hi Dave,

Well the easy answer is of course you can - if you want to throw enough money at it...

My thought is you'd need a special sub to run in the shoe track, installed below a modified float collar.

The sensors would obviously be based on already available on MWD / LWD technology for annular pressure and caliper measurements.

These could be either embedded in the body of the sub itself, externally mounted, or in the form of a solid body centraliser of some sort - to minimise the equipment actually inside the casing which could then need drilling out.

That would take care of the first two requirements.

If you wanted to get fancy, then it could be split into two separate subs, as I'm guessing the annular pressure sub would only be used a few times to calibrate swab/surge computer models already in use.

I would question the need for breakout analysis during casing running, as what would you do with the information at that point in the operation?

Surely you'd have the required data for geomechanics analysis from the LWD, or E-Line logs?

This requirement would also significantly affect the design and running of the tool, as you now not only bring into the complication of needing to know the azimuth of the caliper measurements (so rotating the casing would probably be possible) and a huge increase in the amount of data that would need to be sent back.

To minimise complexity, any sensors and processing equipment would have to be battery powered - again, these would have to be mounted on the outside of the casing.

Data transmission is another issue altogether.

My thoughts on that are that electro-magnetic or acoustic transmission of the data are unlikely to work, especially since I'm presuming the focus of this would be for deepwater operations.

That leaves either the data being downloaded into a wireline retrievable memory cartridge on the inside, or hydraulic transmission.

Since you'd obviously want the data real time, it has to be hydraulic transmission.

My thought on that is to use a modified float collar.

Instead of having a conventional spring loaded poppet valve, use it as the equivalent of a pulser sub in an MWD / LWD to transmit the data back through the fluid column.

The data and power (again battery) would be provided by a hard wire link through the skin of the float collar - again to minimise the equipment inside the casing that may have to be drilled out.

The materials used in the manufacture of the pulser sub and it's control / drive system would obviously need to be drillable, so maybe ceramic or aluminium, with embedded soft metal filings so it can be driven electro-magnetically?

With respect to the fourth requirement, never used them myself, but I know that battery powered annulus pressure monitoring guages are commercially available already.

The final requirement is the easiest.

In the good old days when casing manufacturers used to have much larger tolerances with respect to wall thickness and ID / OD, on critical jobs we'd drop an additional bottom plug during circulation and look for the pressure spike when it landed, to work out the actual displacement volume required.

So it's all possible - just depends on how much money you want to throw at the project and how cheap (i.e. cost-effective) you can make the downhole equipment since it cannot be recovered.

All the best!

Consultant Driling Engineer / ERD Advisor
Stanfield-Hayes Consulting
Total Posts: 45
Join Date: 25/03/11

I see this list as three independent problems, thought I'd share my thoughts below

1) Annular pressure

Annular sensors have been run on subsea casing for the purposes of annular pressure build up monitoring without penetrations being required in the wellhead. This has been done by a number of operators but has limited duration monitoring governed by battery life (see, for example OTC paper 19286) though I’ve had over a year of data out of metrol gauges permanently installed in B & C annuli. On surface wellheads with penetrations monitoring of APB with remote sensors is already an available solution.

2) Downhole Sensors (Surge Pressure and Caliper w/Breakout)

This is significantly more complicated. even before considering the sensors, the data transmission presents a challenge since conventionally data transmission is performed via wire, hydraulically or in retrieved memory and the last of these would be of little use for real time management of surge pressure. To solve the problem something like the XACT (BHGE) acoustic transmission could be modified, and with the requirements for repeater nodes these would provide a chassis for sensors through the string, but I believe it would need contact with the string at surface to receive the signal. As an alternative I’m not convinced EM transmission would be possible without impacting the casing integrity requirements, but this provides a potential means of not needing to contact the string as it’s run. EM would be primarily a land based option, I’m only aware of a couple of offshore jobs where EM MWD has been run offshore (Precision had a run with Shell in the UK SNS from memory) and it presents some well design challenges in the offshore environment.

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.

3) Internal Caliper (Volume to Pump)

the only effective solution I can think of off the top of my head is some form of fluid caliper, since the most common issue isn’t necessarily actual volume to bump but strokes / actual pumped volume to bump. Downhole instrumentation could help to identify when the fluid caliper reached a specific sensor location but a better knowledge of rigs true pump outputs with the displacement fluid may be the preferred and much cheaper starting points.

In conclusion it is interesting to see these requests, though see a lot of the requirement as a potentially very costly band aid for good quality engineering modelling calibrated by previous measurements, possibly taking more measurements than would usually be taken. For example when requesting surge pressures in real time for casing, is there monitoring of drill string tripping swab and surge pressures with comparison and calibration of (real-time) engineering models? For example in the annular pressure example I gave above the Metrol gauges were run to monitor APB to confirm the accuracy of the WellCat models generated for a deepwater field development and whether (the installed, and costly) mitigation measures were required. What is really interesting is the need for Breakout analysis from the casing, which though useful from a geomechanics perspective, from an delivery perspective would seem a little late once the shoe has entered the breakout zone?
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