Attempting to calibrate the fresh new key so you can diary research, a straightforward low-linear regression relationship are run-in Matlab seven

Table 4 summarizes the pertinent well data used for calculation of the gamma ray, potassium, and the thorium indexes. Their comparison with the actual measured clay content from the XRD analysis (Fig. 5) showed that the unmodified gamma ray, potassium, thorium indexes calculated from the linear Eq. (1) provided wide overestimation of the Shurijeh clay content, which leads eventually to the misestimating of the original hydrocarbon in place and reserves. According to the Shurijeh age (Early Cretaceous), Larinov calibration for highly consolidated formations was used and based on the data in Fig. 6, ? _sh in Dewan equation which is corresponding to the highest gamma ray reading considered to be 2.75 g/cc units. The C factor in the Bhuyan–Passey modification was considered to be 60 for the Shurijeh Formation after measuring the clay contents of reference adjacent shale in many surface samples. The estimated clay content from modified gamma ray, potassium, and thorium indexes are given in Table 5.

The testing ranging from unmodified ray indexes and you may key-counted clay information. Black colored network http://www.datingranking.net/pl/collarspace-recenzja/ Fuel producing better analysis products, black right up-leading triangle low-generating really research circumstances

Density against GR on key examples of the fresh new Shurijeh Development. Black circle Gasoline creating really studies circumstances, and you will black colored upwards-pointing triangle low promoting better studies situations

Ergo, the costs from linear gamma ray, potassium, and you may thorium indexes were changed, playing with each one of the empirically derived low-linear transform equations delivered of the Larinov , Clavier , Steiber , Dewan , otherwise Bhuyan and you can Passey (all the relationship are listed in Desk step one) to track down a faster incorrect estimation regarding Shurijeh clay posts

As the errors associated with the prior variations made a fairly higher difference towards the abilities, you should obtain an enthusiastic empirical dating on the clay stuff estimations within this creation. 11.0 application. Revealed less than ‘s the acquired low-linear calibration dating into the Shurijeh Development when it comes to an intellectual mode anywhere between pure gamma beam directory because the independent variable and also the lab-derived weight per cent clay based on the X-ray diffraction study since based changeable:

Contour 8 reveals the relationship off lbs percent clay regarding XRD sized each other wells and modified pure gamma beam directory using more equations plus highly consolidated Larionov alter, Clavier ainsi que al

The natural gamma ray index was chosen for running the regression analysis due to the stronger correlation coefficient in compare to the potassium or thorium indexes, with the core clay contents in both wells. The unique feature of new equation is to calculate the clay content of less than 100% with a given I_GR of 1.0, while all other previous modifications give clay content of 100% for such I_GR value. The assumption used in developing the non-linear relationships was based on the fact that the entire radioactivity is not due to the clay minerals only. The goodness of agreement and the reliability of the regression equation were then both verified by a correlation coefficient of 0.992 upon application on some other core samples from another wells drilled in the Shurijeh Formation. It is clear from the data in Fig. 7 that the core data, verify both the very low and the medium range of clay contents, estimated from the non-linear empirical relationship. The average percent relative error was also minimized to 11.4%. Due to the statistical bias of comparing data samples with very different sizes and variances (76 samples versus 11 samples), the error cannot be reduced further. , Steiber, Dewan, Bhuyan–Passey and the empirical transforms. The clay content was also estimated from the potassium and thorium indexes using the empirical non-linear calibration (Table 5) and a comparison of average percent relative errors for different equations has been shown in Fig. 9.