Th/U ratio mix-spot are produced to the cored periods each and every well in order to investigate to your 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 Al_dosO₃/(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 unimportant sum of potassium-free clay minerals on the Shurijeh Development, the newest pure gamma ray, potassium and thorium signing investigation were used with certainty discover quotes off Shurijeh clay articles. There clearly was a strong linear correlation within lbs % clay plus the natural gamma ray diary study in accordance with the Pearson’s relationship coefficient. With respect to the XRD efficiency, brand new non-generating well try alot more shaly with a clay level of you to and a half purchase out-of magnitude larger than that has been from inside the the gas promoting well. Brand new clay blogs computed in the altered natural gamma ray log and its own spectral components investigation, surpassed the actual core-measured on the factor, most likely by the other non-clay radioactive nutritional elements and you can/and/or sized testing.

It’s clear the borehole logging software procedures brand new pure radioactivity inside the a huge part of rock weighing of numerous kilograms, in contrast to brand new center shot hence stands for simply a small percentage of a kg. This is referred to as size sampling perception. To the occurrence instead of gamma ray cross-area (Fig. It had been investigated away from Fig. Based on the average % cousin mistake, certainly one of the previously proposed improvement in the Shurijeh Formation, those individuals delivered by Dewan, Bhuyan–Passey, and you will Larinov had the really extensively overestimations. Dewan formula delivered the greatest estimate mistakes, because of the exponential worth of step 3 within its formulation, that was a knowledgeable assume and there are no counted investigation on the books to help with they. Buhyan–Passey modification made seemingly incorrect estimations, considering the non-practical presumption out of the same features both for clay nutritional elements from the clastic reservoirs while the surrounding shales.

Larinov equation with the very consolidated rocks offered overestimations too therefore the reason for which inapplicability you’ll lay on general expectation utilized in its components. It is are invented based on the undeniable fact that the latest older stones exposed to strong burial contain sigbificantly more illitic nutritional elements versus most other rocks considering the illitization away from smectite while the a work away from burial breadth. Because there are of a lot conditions to this generalization, in the event that clay articles are chosen from Larinov older stone curve, instance what is revealed for the Fig. The newest amendment proposed of the Clavier is actually an excellent compromise amongst the tertiary and you may earlier stone equations to possess estimate of clay contents about reservoirs; however, it appeared to a bit overestimate the fresh clay content of your own Shurijeh reservoir Development (Fig.

Total, it appeared your generalization ability of your empirical low-linear calibration matchmaking is better than the earlier calibrations and you may the fresh new suitable mistake of your design is actually shorter

The fresh new agreement involving the XRD study plus the Stieber quotes is actually satisfactory; nevertheless estimations given by the fresh empirical calibration improved the precision of your own estimations a lot better than one to. For the clay content estimate purpose, making https://datingranking.net/pl/feabiecom-recenzja/ use of new empirical dating try found a whole lot more reliable than simply the brand new before suggested changes of the pure gamma ray log, because of its indication philosophy and you can reduced estimation mistakes. The newest estimation problems of all of the before advised changes was basically depended on journal sorts of (the fresh gamma beam, potassium otherwise thorium logs), rather than new empirical non-linear calibration which in fact had up to equal mistakes for everyone of your own different types of logs.