Th/You proportion mix-area is made toward cored durations each and every better to take a look at into the depositional environment (Fig. 10).
The clay typing was later accomplished by a group of cross-plots (Fig. 11) with various combinations including thorium versus potassium, photoelectric (PEF) versus potassium, photoelectric versus Th/K ratio and thorium versus AldosOstep three/(Al2O3 + SiO2). For generating the last one , the XRF data were used. The presence of clay minerals like illite, montmorillonite and glauconite are evident from Fig. 11, however chlorite and kaolinte are not detected by this method.
The results of log-derived clay typing: a Th (vs) K, from Schlumberger ; b PEF (vs) K, from Schlumberger ; c PEF (vs) Th/K, from Schlumberger ; d Th (vs) Al2O3/(Al2O3 + SiO2) from . Black circle Gas producing well data points, and black up-pointing triangle non-producing well data points
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Due to the insignificant contribution of the potassium-totally free clay vitamins about Shurijeh Formation, this new pure gamma ray, potassium and you can thorium logging data were utilized with confidence to locate estimates off Shurijeh clay blogs. There was a robust linear correlation amongst the pounds percent clay as well as the sheer gamma ray log data based on the Pearson’s correlation coefficient. With regards to the XRD overall performance, new non-creating well try significantly more shaly with an excellent clay amount of that and a half order of magnitude bigger than that has been within the the fresh new energy promoting really. The latest clay blogs calculated from the altered natural gamma beam log and its particular spectral parts study, surpassed the actual center-mentioned in the parameter, probably because of the almost every other non-clay radioactive vitamins and/or perhaps the measurements of testing.
It is clear that the borehole logging device strategies the newest absolute radioactivity when you look at the a huge percentage of material weigh of many kilograms, weighed against the new core try and this is short for just a small percentage of a kg. This might be known as the dimensions sampling impact. To the occurrence in place of gamma beam get across-plot (Fig. It actually was examined off Fig. According to the average per cent relative mistake, certainly all the previously proposed changes on the Shurijeh Formation, those people put because of the Dewan, Bhuyan–Passey, and you may Larinov encountered the most extensively overestimations. Dewan formula delivered the biggest estimate errors, by great worth of step three within the formulation, that has been a knowledgeable assume there try zero measured investigation https://datingranking.net/pl/fastflirting-recenzja/ regarding the literary works to support they. Buhyan–Passey amendment produced seemingly incorrect estimations, as a result of the low-realistic expectation out-of similar attributes both for clay nutrition regarding clastic reservoirs additionally the adjoining shales.
Larinov equation into extremely consolidated stones given overestimations too plus the reason for so it inapplicability you will rest on general assumption utilized in their ingredients. It is getting devised according to the fact that brand new elderly rocks subjected to strong burial contain sigbificantly more illitic nutrients compared to the other stones as a result of the illitization off smectite once the a features away from burial depth. Since there are of numerous exceptions to this generalization, if the clay articles try selected regarding Larinov more mature rock curve, eg what is found within the Fig. This new amendment advised by the Clavier is actually a sacrifice involving the tertiary and you can earlier stone equations to possess quote of the clay content material regarding reservoirs; not, it seemed to a little overestimate this new clay articles of Shurijeh tank Formation (Fig.
Full, they looked the generalization ability of your own empirical low-linear calibration dating are better than the earlier calibrations and you can the fresh fitted error of your design are smaller
The fresh agreement involving the XRD investigation while the Stieber prices is actually satisfactory; although estimations supplied by the latest empirical calibration increased the accuracy of one’s estimations better than that. With the clay stuff estimate mission, using the fresh empirical dating is actually discover a great deal more reputable than simply this new previously suggested changes of your absolute gamma ray journal, simply because of its indicator thinking and you may lowest quote problems. The latest estimation errors of all in past times suggested variations was indeed depended to the diary sorts of (the gamma beam, potassium otherwise thorium logs), rather than new empirical non-linear calibration which in fact had approximately equal errors for everybody of one’s different varieties of logs.
