HTHP coating for downhole sensor system

Hi Chemprof,

Depending on the coating, the time for the heat of the surrounding environment to reach the chip will vary. The chip WILL ALWAYS reach the heat of the environment at some point. This being said, the chip modules will have a limited lifetime, depending on the temperature characteristics of the chip and the properties of the (heat-insulative) coating.

I'm assuming these sensors are sending data wirelessly to a receiver for datalogging. You need to make sure that the coating(s) you use will be sufficient to give enough time for the sensors to reach the desired location and send the telemetry data back.

We are devising miniature sensor systems (a few mm in diameter)

That seems very, very small for a sensor to be able to do what you desire! How many is "a few"? I know that there are uControllers in SOT-23 packages, but the associated sensors and circuitry must increase the size considerably.

As far as coatings are concerned, I would look into ceramic-type coatings, similar to the materials used on the space shuttle reentry "bricks".

Hopefully, this information will help. If it doesn't, please disregard.

Best Regards,

Mike

I appreciate all feedback and I found your comments to be interesting and helpful!

You are correct, the sensors will send data wirelessly to a receiver after they reach the surface. We anticipate some level of attrition of the "chips" for a number of reasons and therefore plan to send a large number of them downhole. Before we get to that stage, which is far down the road, we will test them on our own experimental drilling facility as well as research drill sites to which we we have access through industry partners.

The protypes will be about 5-mm in diameter, with a target size of 2-3 mm. Yes, we have looked into ceramic coatings. I have some concerns about possible difficulties associated with application of ceramic coatings, such as chemical vapor deposition and physical vapor depostion.

We are in the beginning stages of this research project and haven't ruled out anything. We are also looking at dip and coat and other techniques. I have contacted Dow Corning and will contact coatings specialty companies that I found through GlobalSpec.

Thanks again for your comments.

I assume (I know, I know) that you are not associated with Rice University in Houston Texas.

I heard that Rice were working on a wireless wellbore while drilling telemetry system using a multitude of trancievers which would be circulated continuously. I'm guessing they ran into the same problem that you are looking at and may have a solution.

Alternately talk to Reed Hycalog. They developed a small pressure, temperature and vibration measurement device for downhole well dynamics some years ago although nothing on the scale you are looking at.

What sort of temperature survivability are you looking at? Unless it's geothermal work you probably don't need to go much above 120C.

That's interesting about Rice. No, I am not associated with Rice and was not aware of the wireless system you mentioned. We will look into it. I assume (heh) that Rice has industry contacts for testing their device.

Speaking of industry contacts, thanks for the tip about Reed Hycalog. They are one of our industry sponsors. I will ask our contact there.

We don't have a fixed temperature in mind for a maxiumum. Yes, we probably won't need to go much over 120C.

Oh and by the way high temp industry standard is 175c but for proof of concept go low to 120c as it's vastly cheaper.

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Thanks for the info. As mentioned, we are in still in the exporatory stage and willing to look into all possibilities. Also mentioned, ease of coating application is a major consideration. We would prefer something that we could do ourselves, if possible.

Hi,

what is maximum temperature and pressure and time for a loop?

Is the data stored in some RAM or the like?

How do you transmit in a conductive (salty groundwater) fluid?

Do you like the housing of the device to be the antenna or contacts for readout?

If there is a radio transmitter inside what frequency is it? (to match the antenna).

The small size you are talking about can easily survive 300 bar but 300 °C is not so easy for the electronics and battery.

I would think about high temperature stainless steel and zirconia (matching in TCE) or molybdenum and alumina, also titanium and alumina-zirconia mixture.

May be also INVAR and cordierite or quartz-glass. (Lowest thermal conductivity may be longest survival time.

I do not think that thin film coating is an easy job as the elastic deformation is likely to be high. And there is no need, brazing to ceramics is not a big problem.

So please be a bit more precise in your specs.

RHABE

You ask good and relevant questions. However, I don't have answers or cannot share them due to the proprietary nature of the work. I know this makes it difficult to offer suggestions, but I am only looking for things to try and possible industry contacts at this point, given the general parameters mentioned in the opening post.

I'm not sure about the other materials you suggested, but brazing to ceramic is something we will definitely consider. Thank you.