It would appear that I have a new admirer. Imitation being the sincerest form of flattery, I consider myself very flattered that Professor Smythe has created a blog in my honour, going so far as to name it "Frackland" in reflection of my own small contribution to the national shale gas debate.
Prof Smythe has featured previously on this blog, firstly when I pointed out errors in his critique of Cuadrilla's Balcombe operations, and subsequently to document his contretemps with the Geol. Soc. and Glasgow University.
In his original critique of Cuadrilla's operations at Balcombe, Prof Smythe proved himself to be ignorant of modern drilling technologies. Sadly, it seems that Prof Smythe has doubled down on his errors in a new presentation, which, in a comment on his blog, he claims "show[s] that it is James Verdon, not I, who misunderstands the technology of drilling".
In his latest piece, Prof Smythe admits to learning about geosteering and LWD at the Dart Airth CBM planning inquiry, and grudgingly concedes that one of my principal criticisms was, in fact, accurate: "It is correct that I did not at that time know about the gamma-ray geosteering technique." I would add that listening to a submission at a planning inquiry does not make anyone an expert in anything.
It is interesting that Prof Smythe refers to a "gamma ray" geosteering technique. I don't actually refer specifically to gamma-ray logging at any point in my original comments. There is a reason for this: there is a huge range of LWD measurements that can be made to measure the properties of the rocks through which a well is being drilled.
The motivation for this is severalfold - in addition to the real-time aspect of LWD, in horizontal wells a "well tractor" is required to pull wireline logging tools (the traditional method of well logging, done once the well had been drilled) along the horizontal section of the well, which can be time consuming and expensive. LWD obviates this need, so as a result in the last 20 years much effort has been put into developing LWD tools that can match traditional wireline tools both in terms of the different petrophysical measurement techniques, and the quality of the measurements.
If Prof Smythe thinks that LWD is limited to a non-directional gamma-ray measurement then he is still spectacularly uninformed as to the state of modern drilling technology.
Almost every traditional wireline logging tool is now available as a LWD equivalent. This might include measuring the electrical resistivity (which is particularly sensitive to whether the rock is full of oil/gas (high resistivity) or salt water (low resistivity)), the porosity, the bulk density, and the acoustic properties of the formation, in addition to its gamma-ray levels. The latest technologies can even tell you the colour of the rock you are drilling through (organic-rich rocks tend to have a dark colour), and microimaging even takes images of the rock as you go!
Equally importantly, these measurements are not taken uni-directionally. Modern LWD tools take measurements at many angles to the well bore. This enables an operator to identify the dip of the beds through which he is drilling, as demonstrated in the image below, taken from a Schlumberger Oilfield Review paper. Note that this SOR is from 1996, which gives an indication of how out-of-date Prof Smythe's comments are. Prof Smythe (and the interested reader, of course) would do well to peruse the latest offerings from the various oilfield service providers, such as this from Weatherford or this from Schlumberger.
So, how does all this tech help an operator stay in zone while drilling a horizontal well. In most cases, an operator will have prior geological data from logs run in vertical wells (such as Cuadrilla will have had from Conoco's drilling of the first Balcombe well in 1986). They will have identified marker beds from this log data, characterising the petrophysical properties of each different layer (the resistivity, porosity, density, acoustic properties, the microimages etc.). These marker beds, along with the dip information, are then used to guide the horizontal wellbore and stay in formation. If a fault is intersected, the well will find itself in a different geological layer. The operator can determine which layer this is by comparing the LWD data with pre-existing logs and, in combination with the dip data, determine where the well must be steered in order to return to the formation.
Now, if a fault is encountered that has substantial offset, it may not be possible (or economic) to steer the well back to the target formation, and the well must be abandoned. And of course it's better if an operator has 3D seismic data to help plan their wells, and to ensure that their LWD matches the 3D seismic data. I make this point in my original post, and I expect that as operators move from exploratory to production phases, we will see more 3D seismic data collected. However, LWD data alone is usually sufficient to keep a well on target, even if faults are encountered.
Importantly, however, the proof is in the pudding.
One of Prof Smythe's principal conclusions was that keeping the well within the 30m thick target layer would be a "near impossibility", "all-but impossible", and "the drilling will therefore almost certainly transgress into the Kimmeridge Clay, either above and/or below the micrite (the target layer)." Indeed, Prof Smythe goes so far as to claim that Cuadrilla will intentionally drill out of formation in order to collect samples of Kimmeridge Clay with a mind to future fracking at Balcombe, and makes the claim that Cuadrilla's activities at Balcombe were little more than a "cover story" for future unconventional work.
Prof Smythe maintains that "[his] criticism of Cuadrilla in 2013 was and remains substantially correct". However, in September 2013, Cuadrilla announced the results of their Balcombe well, and that "using geo-steering technology, the entire 1700ft was successfully drilled within the target limestone".
Now, Prof Smythe might claim that Cuadrilla are still deceiving us. If they are, it would be a odd thing to do, given that all well log data becomes publicly available after a short confidentiality period, so they'd know that they'd soon be found out.
He also makes the unsubstantiated accusation that Cuadrilla may actually have encountered a fault, and that they had been forced to stop drilling as a result:
"We do not know why the horizontal well stopped at 518 m (1700 ft). For all we know, Cuadrilla may have encountered a fault."This seems very unlikely. If Prof Smythe were more familiar with the full history of the Balcombe site, he would have been aware that Cuadrilla's planning consent for the site expired on the 30th September 2013. By this date they were required to have removed all of their drilling and other kit from the site. The two images below show the drilling equipment on site, and the condition to which Cuadrilla had to return the site by the 30th September.
In his original criticism, Prof Smythe made strong conclusions ("near-impossibility", "all-but impossible") , and accused an operator of intentional deceit, which should not be done lightly. I would suggest that when an "expert" claims that something is a "near-impossibility" and "all-but impossible", but then that thing happens, then those claims do not "remain substantially correct", as Prof Smythe claims. In fact, I'd think it would be considered rather embarrassing, and would draw the status of said "expert" into question. Perhaps this is why the Geol Soc asked Prof Smythe to cease referring to himself as a Chartered Geologist.