Trying to calibrate brand new center in order to log studies, an easy non-linear regression matchmaking was 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 blk online 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 latest investigations ranging from unmodified ray indexes and core-measured clay articles. Black community Fuel generating well analysis affairs, black right up-directing triangle non-creating really analysis items

Density against GR on the center examples of the new Shurijeh Formation. Black colored network Gas creating really data things, and you may black right up-leading triangle low creating well study circumstances

Thus, the prices away from linear gamma beam, potassium, and you can thorium spiders was in fact altered, having fun with each of the empirically derived low-linear changes equations delivered of the Larinov , Clavier , Steiber , Dewan , otherwise Bhuyan and you will Passey (the dating are placed in Table step 1) to track down a faster erroneous estimate off Shurijeh clay blogs

While the errors of earlier in the day adjustment made a somewhat higher variation to the show, you will need to obtain an enthusiastic empirical relationships towards clay articles estimations within this formation. 11.0 software. Revealed less than is the gotten non-linear calibration relationships into the Shurijeh Formation when it comes to a mental means anywhere between pure gamma ray list given that separate variable plus the laboratory-derived weight per cent clay based on the X-beam diffraction analysis since mainly based changeable:

Profile 8 shows the relationship regarding lbs per cent clay throughout the XRD sized one another wells and you will altered absolute gamma beam index playing with additional equations also very consolidated Larionov change, Clavier mais aussi 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.