Th/U proportion get across-patch was generated into the cored periods each and every better to help you browse the into 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 3/(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 sum of one’s potassium-free clay nutrients regarding Shurijeh Formation, the brand new pure gamma beam, potassium and thorium logging research were used with full confidence to get rates out of Shurijeh clay articles.
You will find a strong linear correlation involving the pounds % clay together with sheer gamma beam record investigation in accordance with the Pearson’s correlation coefficient. With respect to the XRD overall performance, the low-promoting well are alot more shaly having an effective clay quantity of you to definitely and a half acquisition from magnitude larger than that has been for the the fresh gas creating really. The latest clay blogs calculated in the modified pure gamma ray journal as well as spectral areas study, exceeded the true center-measured for the parameter, probably because of the other low-clay radioactive minerals and you will/or the measurements of testing.It is obvious that borehole logging means actions the brand new natural radioactivity when you look at the a huge part of material weigh of several kilograms, compared with brand new center decide to try hence represents just a little percentage of a kilogram. This really is referred to as size testing feeling. On thickness in the place of gamma beam mix-spot (Fig. It actually was investigated out of Fig. Based on the mediocre percent relative mistake, certainly one of most of the in past times suggested adjustment regarding the Shurijeh Development, those produced because of the Dewan, Bhuyan–Passey, and you can Larinov encountered the very generally overestimations. Dewan equation brought the most significant estimate mistakes, of the exponential worth of step three within the components, which was the best assume there are zero counted investigation about books to support they. Buhyan–Passey modification produced seemingly incorrect estimations, considering the low-reasonable assumption away from identical properties for both clay nutritional elements from the clastic reservoirs as well as the adjoining shales.
Larinov equation towards very consolidated rocks given overestimations as well while the cause of that it inapplicability you are going to sit throughout the standard presumption used in their formulation. It’s being devised in line with the fact that the fresh new more mature stones confronted with deep burial contain sigbificantly more illitic nutrition compared to the other rocks due to the illitization away from smectite because the a purpose regarding burial breadth. Since there are many exclusions to this generalization, if clay material is chose away from Larinov earlier stone bend, like what is actually shown in Fig. The fresh modification suggested of the Clavier try a great lose involving the tertiary and more mature stone equations to possess estimation of the clay content material throughout the reservoirs; however, it did actually slightly overestimate the clay content https://www.datingranking.net/pl/lavalife-recenzja/ of the Shurijeh tank Development (Fig.
This new contract between your XRD studies therefore the Stieber estimates are satisfactory; but the estimations provided by new empirical calibration enhanced the precision of the estimations much better than you to definitely. Into clay blogs quote goal, the usage the latest empirical relationships is located way more credible than simply brand new in past times recommended modifications of the natural gamma beam record, simply because of its sign opinions and you may reduced estimation problems. The latest estimation problems of all the prior to now advised variations had been relied on the log sort of (the fresh new gamma beam, potassium otherwise thorium logs), unlike the newest empirical low-linear calibration which in fact had approximately equal problems for everyone of one’s different types of logs.
