Th/You proportion cross-area are generated with the cored periods of each better so you’re able to read the on 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
As a result of the insignificant share of your potassium-free clay nutrients throughout the Shurijeh Creation, the fresh sheer gamma beam, potassium and you will thorium logging research were utilized with confidence discover rates out-of Shurijeh clay posts. There is an effective linear correlation between your weight percent clay together with natural gamma beam journal study according to the Pearson’s correlation coefficient. According to XRD abilities, the brand new non-creating better try even more shaly that have an excellent clay quantity of you to definitely . 5 acquisition of magnitude bigger than which had been into the brand new gasoline creating well. The newest clay blogs determined on changed pure gamma beam log as well as spectral section research, surpassed the true core-mentioned with the parameter, probably from the other low-clay radioactive nutrition and you will/or perhaps the measurements of sampling.
It’s clear that the borehole logging device actions brand new absolute radioactivity during the a big percentage of rock weighing of numerous kilograms, compared with the latest core sample which is short for merely a tiny portion of a kilogram. This can be referred to as dimensions testing effect. To the thickness versus gamma ray get across-plot (Fig. It actually was examined out-of Fig. On the basis of the average percent cousin mistake, certainly one of all the in earlier times recommended changes regarding Shurijeh Formation, those people put from the Dewan, Bhuyan–Passey, and you may Larinov met with the really widely overestimations. Dewan picture put the greatest quote mistakes, because of the rapid property value 3 within its elements, which had been an informed suppose and there try no mentioned data regarding the literary works to support it. Buhyan–Passey amendment made relatively erroneous estimations, as a result of the low-realistic assumption away from identical qualities for clay nutritional elements regarding the clastic reservoirs and the adjacent shales.
Larinov equation to your extremely consolidated rocks given overestimations as well plus the reason behind it inapplicability might rest in the standard assumption included in their ingredients. It’s being conceived based on the fact that the fresh new old stones exposed to strong burial contain much more illitic nutrition compared to the most other rocks due to the illitization regarding smectite as a function from burial depth. Because there are of several exclusions to that particular generalization, in the event that clay content is picked off Larinov old rock bend, particularly what is shown for the Fig. This new amendment proposed because of the Clavier try a beneficial sacrifice within tertiary and you will earlier rock equations for quote of clay articles throughout the reservoirs; but not, it seemed to somewhat overestimate this new clay stuff of your Shurijeh reservoir Formation (Fig.
The latest contract between your XRD studies in addition to Stieber rates is actually satisfactory; however the estimations provided by this new empirical calibration enhanced the precision of your estimations much better than you to. Into clay articles estimation purpose, the employment of brand new empirical relationships try located alot more reliable than simply the new in earlier times proposed changes of your own sheer gamma beam record, because of its sign viewpoints and lower estimation mistakes. This new estimate errors of all of the previously advised improvement was basically depended for the record sorts of (the brand new gamma ray, potassium or thorium logs), instead of the new empirical low-linear calibration which had up to equal errors for everybody of your different varieties of logs.