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Analog Angle Blog

Sophisticated Sensors, Extreme Conditioning, Advanced Algorithms Yield Amazing Geolocation Results

Drilling for oil is not easy; you already know that. It's a harsh and unforgiving operation even under benign circumstances, and unimaginably worse when the climate is bitterly cold, or the platform is in deep water with high waves and storms as a regular occurrence. Drilling even a “simple” hole straight down brings enormous instrumentation challenges, beginning with the obvious: How do you know the drilled hole really is perfectly vertical? Even a tiny deviation or drift in the angle means you could be way off when you are go down a few thousand feet or deeper. Differential GPS with its centimeter-range accuracy, or ground-penetrating radar are not options here, of course.

The basic instrumentation incurs downhole temperatures of 200°C or more — not an easy place to get reliable electronics or consistent data, especially when you are looking for accuracy to a fraction of a degree. Techniques previously used included dropping a weighted line to punch a target disk at the drill tip site, and using a glass container filled with sulfuric acid to etch a horizontal axis. These techniques and others worked to a certain point, but required costly, time-consuming halts to the drilling process and were not compatible with the desire for constant feedback and corrective action.

Now add to this challenge the fact that many new drilling sites aren't just those basic vertical holes, but go horizontally as well, often with multiple downholes and their branches, all starting at a single top-side pad. How you get a drilling bit and its pipe to make such a right-angle turn at all, let alone so far down — that's an amazing story itself, but not the issue here. How do you make sure each downhole is true and, even more difficult, that the horizontal boring is also on track, where you have to worry about angular errors and deviations in both horizontal and vertical extensions?

Fortunately, you can read a well-written and very illuminating piece about previous approaches as well the most advanced ones in the Autumn 2013 issue of Oilfield Review (thanks to Rick DeMeis for bringing this article to my attention). The lengthy article Geomagnetic Referencing — The Real-Time Compass for Directional Drillers is well worth reading: It describes how advanced accelerometers, gyroscopes, and magnetometers, combined with near-real-time three-dimensional geomagnetic mapping at multiple layers of the Earth's ever-changing magnetic field, are used to provide highly accurate results.

(Source: Oilfield Review, Schlumberger)

(Source: Oilfield Review , Schlumberger)

It's an amazing combination of drill-head sensors and electronics, site and pad instrumentation, local geomagnetic measurement, and extremely sophisticated data-analysis and predictive algorithms, and it is all fully field-tested.

Just as impressive as the results themselves is that all this is accomplished while drilling without the need to stop; appropriately, it's called Measurement While Drilling. Thus, the new approach of integrating sensors and local-area information with calculation- and algorithm-intensive processing has solved three problems: the downhole vertical problem, the horizontal drilling problem, and the halt-while-measuring problem.

Too often, people who casually talk as if they are knowledgeable about advanced technologies either downplay or are just ignorant about what's really involved. In short, “what's the big deal?” is the attitude. (Believe me, I also have the highest regard for those crew who can remotely pour concrete at the sea floor, 2000+ feet underwater!)

It seems to me that a large part if the problem is not only their willful ignorance, but is also an unintended consequence of our success. The fact that the scientists, engineers, technicians and on-site workers routinely perform what are, frankly, near-miraculous missions on a regular basis makes it all look routine and easy, when they are anything but that.

I view this “extreme design” as one of the least-appreciated, least-discussed aspects of engineering and technology, though you will sometimes see them in special TV shows on niche channels. If these types of stories interest you — and I hope they do — check out the list here of such stories which EE Times and EDN have done in the past years. They make clear that much of what I'll broadly call “engineering” is pretty hard in practice, even if it is straightforward in concept.

Just think about the Voyager 1 (and soon, Voyager 2) space probe, and the incredibly minuscule power levels and accounted SNR of the signals coming back from it as it leaves the outer boundaries of our solar system (see NASA link here as well as the book Voyager: Seeking Newer Worlds in the Third Great Age of Discovery by Stephen J. Pyne). And how do they drill those very long rail/auto tunnels through mountains, starting at both ends, and meet perfectly midway?

Have you ever been involved with an especially “extreme” test and measurement or analog-signal problem? Did you and your team anticipate it reasonably well, or not?

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6 comments on “Sophisticated Sensors, Extreme Conditioning, Advanced Algorithms Yield Amazing Geolocation Results

  1. eafpres
    January 7, 2014

    Hi Bill–I agree with you that many people have become insensitive to the technologies all around us, without which our world would be vastly different.  As engineers many of us have lived our lives believing that technology and engineering would provide the solutions society needed and wanted.  I still think that is true.  Living in Boulder, CO I'm surrounded by people who are beneficiaries of these extreme engineering feats yet have deep rooted mistrust of technology (you can still spot a few “Split Wood Not Atoms” bumper stickers).

    I can recall a few projects that embodied “a lot more than meets the eye”.  I worked for a company called Sievers Instruments (now part of Ionics).  The key product line were Total Organic Carbon analyzers with sensitivity in the part per million range (carbon concentration in water).  They were used in both pharmaceutical manufacturing and semiconductor fabs to monitor process water.  The systems were quite complex.  A sensor was made by inserting metal electrodes into a plastic body through which a small channel of sample water flowed after it had passed through a small UV reactor along with inorganic reagents to react all available carbon to CO2.  Just this cell embodied significant engineering, from material selection (not all engineering plastics are impermeable to CO2 at very low concentrations), to implementing the nonlinear equations describing conductivity of water with small amounts of CO2 present, to temperature compensation, figuring out calibration, etc.  All this led ultimately to a system that provided a linear response over more than 2 orders of magnitude.  Of course there were analog electronics supporting all of this, plus microprocessor control.

  2. etnapowers
    January 9, 2014

    I think that big progresses have been done to create integrated electronics circuits for applications requiring gyroscopic sensors, the market is requiring further products with these functionalities.

  3. etnapowers
    January 9, 2014

    The combination of Differential GPS having a  centimeter-range accuracy and  ground-penetrating radar could be integrated in a unique automatic System in macro-package to automatically detect the right angle of penetration and the presence of hurdles in the penetration direction. An Iot approach might help.

  4. RedDerek
    January 11, 2014

    This question in your blog, Bill, is the key. Many people do take a casual view of things – look at the modern car and all the electronic gadgets as compared to those vehicles 15, 20 years ago. As engineers, we look at all possibilities during a design in order to make it, in the end, “not a big deal”. However, there is a lot of thought process to get there. Think of all the thought that went into the beginnings of the space program (through Apollo). Then at the end of Apollo, viewing dropped because it all became a “daily” thing – “not a big deal”. I view these folks as the ones that were true engineers. Todays engineers may not look at all the possibilites as if someone's life is on the line.

  5. Davidled
    January 11, 2014

    A dual polarized wide bandwidth, 200 MHz could be used for detecting two or three dimensional structure of area. Antenna would supplements GPS. The problem is how it could be mounted due to the harsh environment and device package. I image that this could be located behind of drill.

  6. etnapowers
    February 11, 2014
    @DaeJ: I agree with you,  the harsh environment allows only to position the
    combination of GPS and radar behind of drill or otherwise in a position
    that is adjusted as the drilling goes on.

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