This new depositional environment and also the clay typing according to research by the spectral gamma beam percentages

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This new depositional environment and also the clay typing according to research by the spectral gamma beam percentages

Th/U proportion get across-patch try generated towards the cored times each and every really so you’re able to look at the to your 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 Al2O3/(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


As a result of the insignificant contribution of your potassium-totally free clay nutrition regarding the Shurijeh Formation, the fresh natural gamma beam, potassium and you may thorium logging investigation were used confidently to locate rates of Shurijeh clay stuff. There can be a robust linear relationship amongst the lbs % clay additionally the pure gamma beam diary data in accordance with the Pearson’s relationship coefficient. According to XRD overall performance, the fresh non-producing better try much more shaly that have a great clay number of one and a half order off magnitude bigger than that was when you look at the the new gas creating better. The new clay stuff determined from the altered absolute gamma beam log and its own spectral section analysis, surpassed the true key-mentioned for the parameter, probably by the almost every other low-clay radioactive minerals and you can/or the measurements of sampling.

It’s obvious your borehole logging appliance tips the latest natural radioactivity inside a big percentage of material consider many kilograms, compared to the fresh new core try and that stands for simply a small part of a kilogram. This might be referred to as size sampling perception. To your occurrence as opposed to gamma ray mix-plot (Fig. It absolutely was examined off Fig. Using the mediocre percent relative error, among all of the in the past advised modifications in the Shurijeh Formation, those individuals brought of the Dewan, Bhuyan–Passey, and you may Larinov met with the very generally overestimations. Dewan picture delivered the most significant estimate mistakes, from the exponential property value step three within the materials, which was an informed imagine there try zero measured data regarding literature to help with they. Buhyan–Passey amendment generated relatively incorrect estimations, as a result of the low-practical assumption out of the same qualities both for clay nutrients on clastic reservoirs in addition to adjoining shales.

Larinov formula to your very consolidated stones considering overestimations too and the cause of it inapplicability might lay about standard expectation utilized in the materials. It is getting created in line with the undeniable fact that the new earlier rocks exposed to strong burial contain sigbificantly more illitic nutrition as compared to other stones because of the illitization off smectite due to the fact a function away from burial breadth. Since there are of many exclusions to this generalization, when the clay content material is selected from Larinov older stone contour, including what is found for the Fig. The fresh new modification recommended of the Clavier are an effective compromise between your tertiary and you may old stone equations having quote of one’s clay content material from the reservoirs; yet not, it did actually some overestimate the fresh clay blogs of your Shurijeh tank Creation (Fig.

Full, they searched that generalization function of the empirical non-linear calibration matchmaking try better than the earlier calibrations and the fresh new fitted error of the design is shorter

Brand new arrangement involving the XRD data in addition to Stieber prices try satisfactory; but the estimations given by the newest empirical calibration improved the precision of the estimations much better than you to. To the clay blogs estimate goal, the utilization of new empirical dating was discover much more reputable than just the new in past times advised modifications of your own absolute gamma beam record, due to the indicator beliefs and you will reasonable quote mistakes. The fresh estimation errors of all before advised modifications was basically depended for the journal sorts of (the fresh gamma ray, potassium otherwise thorium logs), rather than brand new empirical non-linear calibration which had just as much as equal errors for all of the different kinds of logs.

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