Th/You ratio mix-area is produced into cored periods of each and every well to have a look at toward 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 step 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 insignificant contribution of the potassium-100 % free clay nutritional elements in the Shurijeh Formation, this new absolute gamma beam, potassium and you will thorium signing analysis were utilized confidently to get rates regarding Shurijeh clay blogs. There was a strong linear relationship involving the weight per cent clay together with pure gamma ray journal studies in line with the Pearson’s relationship coefficient. With regards to the XRD abilities, new low-creating really try way more shaly with a clay quantity of one . 5 buy of magnitude larger than which was for the the newest gas promoting really. The fresh new clay articles determined about altered pure gamma beam diary as well as spectral areas analysis, exceeded the real key-counted of factor, most likely because of the most other non-clay radioactive nutritional elements and/or perhaps the measurements of sampling.
It’s obvious the borehole signing device steps brand new natural radioactivity during the an enormous part of stone weighing of several kilograms, in contrast to the newest core decide to try hence is short for just a small portion of a kg. This is certainly referred to as size testing perception. With the density as opposed to gamma beam cross-plot (Fig. It had been investigated out-of Fig. According to the average percent relative error, among all the prior to now proposed adjustment on Shurijeh Creation, people brought by the Dewan, Bhuyan–Passey, and you may Larinov had the most commonly overestimations. Dewan formula brought the greatest quote errors, from the great value of 3 within the formulation, which had been a knowledgeable suppose and there is actually no measured research from the books to support they. Buhyan–Passey modification lovoo app produced seemingly erroneous estimations, as a result of the non-practical presumption out-of similar attributes for clay nutritional elements about clastic reservoirs in addition to surrounding shales.
Larinov formula with the extremely consolidated rocks provided overestimations too therefore the cause for which inapplicability you are going to sit throughout the standard assumption utilized in their formulation. It’s are created according to the undeniable fact that the new earlier rocks confronted with strong burial contain more illitic nutrition compared to the most other rocks due to the illitization out of smectite as a work out-of burial depth. Because there are of a lot exclusions to that particular generalization, in the event the clay content try chosen of Larinov earlier stone curve, such as for instance what is actually shown in Fig. The fresh modification advised from the Clavier are good give up involving the tertiary and you will older rock equations to own estimation of clay content material throughout the reservoirs; yet not, it appeared to a little overestimate the newest clay blogs of your Shurijeh tank Development (Fig.
Complete, it featured your generalization feature of your own empirical low-linear calibration relationship are a lot better than the earlier calibrations and you can the fresh new suitable mistake of one’s model was smaller
New contract between your XRD analysis therefore the Stieber rates are satisfactory; nevertheless the estimations provided by new empirical calibration increased the precision of your own estimations much better than that. On clay content estimation goal, the utilization of the fresh new empirical matchmaking is actually discovered far more reputable than simply the new before proposed improvement of sheer gamma ray journal, due to its signal philosophy and you will lower estimate errors. The fresh estimation errors of all the in the past advised variations had been depended towards the record types of (new gamma ray, potassium otherwise thorium logs), in lieu of the fresh new empirical non-linear calibration which in fact had approximately equal mistakes for all of the different varieties of logs.
