Th/You proportion mix-spot try generated with the cored periods of each really to have a look at to 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 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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Considering the unimportant sum of your potassium-totally free clay minerals regarding Shurijeh Formation, the new absolute gamma ray, potassium and you can thorium logging studies were utilized with certainty to get estimates regarding Shurijeh clay posts. There is certainly an effective linear relationship between the lbs percent clay together with natural gamma ray diary research according to research by the Pearson’s correlation coefficient. With regards to the XRD overall performance, the non-producing well is actually a lot more shaly that have an excellent clay amount of one and a half acquisition out-of magnitude larger than that has been from inside the new energy promoting better. The new clay content determined regarding the modified sheer gamma beam journal and its spectral components research, exceeded the actual center-counted from the factor, probably from the almost every other non-clay radioactive nutrients and you may/or even the measurements of sampling.
It’s clear the borehole signing device steps the fresh new sheer radioactivity inside the a big part of material consider of several kilograms, compared with brand new key sample and therefore stands for simply a little portion of a kilogram. This is referred to as size testing effect. Towards the occurrence rather than gamma ray get across-area (Fig. It was examined out-of Fig. Based on the average percent relative error, certainly all of the prior to now proposed changes on Shurijeh Formation, those individuals brought from the Dewan, Bhuyan–Passey, and you will Larinov encountered the extremely generally overestimations. Dewan equation produced the most significant quote mistakes, from the rapid worth of step 3 within the formulation, that has been an informed imagine so there is actually zero mentioned data from the books to support it. Buhyan–Passey modification made seemingly erroneous estimations, considering the low-reasonable assumption out of identical features both for clay nutrition from the clastic reservoirs and the adjoining shales.
Larinov equation toward highly consolidated stones offered overestimations too and reason behind that it inapplicability you are going to sit throughout the standard expectation used in their elements. It’s being formulated based on the fact that new earlier stones exposed to strong burial contain much more illitic nutritional elements compared to other rocks as a result of the illitization regarding smectite due to the fact a work out of burial depth. Since there are of a lot conditions compared to that generalization, in the event the clay content was chose of Larinov old material bend, for example what is actually shown within the Fig. New amendment suggested because of the Clavier is actually a give up within tertiary and you may earlier stone equations having estimate of your clay content on reservoirs; although not, they did actually slightly overestimate the fresh clay blogs of Shurijeh tank Formation (Fig.
Full, they appeared the generalization function of empirical low-linear calibration matchmaking are a lot better than the last calibrations and you will the installing error of one’s design is smaller
The new agreement within XRD study and the Stieber estimates is actually satisfactory; nevertheless estimations provided by new empirical calibration enhanced the accuracy of your estimations much better than you to definitely. Into clay stuff quote objective, the usage of brand new empirical relationship was discover much more legitimate than just the latest in the past recommended changes of your own absolute gamma ray log, simply because of its indication values and you will lower estimate errors. The fresh estimate problems of the many previously suggested variations was in fact depended with the journal variety of (the kupon minder fresh gamma ray, potassium or thorium logs), unlike the fresh empirical non-linear calibration which in fact had approximately equivalent problems for everybody of your different types of logs.