Th/You proportion mix-spot is actually generated toward cored intervals each and every really in order to look at the on the depositional ecosystem (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 AldosO3/(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 share of one’s potassium-100 % free clay vitamins on the Shurijeh Development, the fresh new natural gamma beam, potassium and you can thorium signing research were used with full confidence locate prices away from Shurijeh clay content. There can be an effective linear correlation involving the weight percent clay and also the sheer gamma ray diary analysis according to the Pearson’s relationship coefficient. With regards to the XRD overall performance, brand new low-producing really try way more shaly having a beneficial clay number of one to and a half acquisition off magnitude bigger than which was during the the newest gasoline generating better. New clay posts determined about altered pure gamma beam log and its own spectral components investigation, exceeded the true key-counted regarding the factor, most likely of the almost every other low-clay radioactive minerals and/or the sized sampling.
It is clear that borehole logging device steps the brand new pure radioactivity for the a massive part of rock consider of numerous kilograms, in contrast to the fresh key take to and that means merely a small part of a kg. This might be known as the size testing impact. To the density as opposed to gamma beam cross-plot (Fig. It actually was investigated out-of Fig. In line with the jak dziaЕ‚a beetalk mediocre percent cousin error, certainly one of all the in the past suggested variations regarding the Shurijeh Development, people lead of the Dewan, Bhuyan–Passey, and Larinov met with the extremely generally overestimations. Dewan picture brought the most significant quote mistakes, because of the rapid worth of step 3 with its materials, that has been an educated guess and there are no counted investigation on literature to help with they. Buhyan–Passey amendment produced seemingly erroneous estimations, due to the non-reasonable presumption out of similar features for both clay nutritional elements from the clastic reservoirs as well as the adjoining shales.
Larinov picture into very consolidated stones given overestimations also in addition to factor in that it inapplicability you are going to lie throughout the standard expectation used in their elements. It’s are created in line with the simple fact that the brand new older stones subjected to deep burial contain sigbificantly more illitic minerals compared to most other rocks as a result of the illitization away from smectite because a function of burial depth. Since there are of several exclusions to that particular generalization, in the event the clay information is actually chosen regarding Larinov old material bend, particularly what exactly is revealed when you look at the Fig. The fresh modification recommended by Clavier is actually an effective sacrifice between the tertiary and you can more mature rock equations having estimate of one’s clay content material on the reservoirs; but not, they appeared to slightly overestimate the fresh new clay posts of your own Shurijeh reservoir Creation (Fig.
Complete, they looked your generalization feature of your own empirical low-linear calibration matchmaking was better than the last calibrations and you may new installing mistake of one’s design is quicker
The brand new arrangement amongst the XRD study and the Stieber prices is actually satisfactory; nevertheless estimations offered by the new empirical calibration increased the accuracy of one’s estimations better than that. To your clay articles estimate objective, the aid of the new empirical matchmaking are discover a lot more legitimate than simply the fresh in past times proposed changes of pure gamma beam diary, because of its signal values and you can reasonable quote errors. This new quote errors of the many before advised improvement was indeed relied to your journal type of (the latest gamma beam, potassium otherwise thorium logs), instead of the new empirical non-linear calibration which had whenever equivalent errors for everyone of the different kinds of logs.