Attempting to calibrate the key so you can diary studies, a straightforward non-linear regression relationship try run-in Matlab eight

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 fresh new review between unmodified beam spiders and you may center-mentioned clay information. Black colored circle Fuel producing better study situations, black colored right up-directing triangle low-creating better study factors

Density against GR in the core wyszukiwanie profilu eurodate examples of the latest Shurijeh Formation. Black colored network Energy generating well research facts, and you will black colored right up-pointing triangle low promoting really data affairs

Hence, the prices from linear gamma ray, potassium, and you will thorium indexes had been modified, playing with each one of the empirically derived non-linear transform equations put because of the Larinov , Clavier , Steiber , Dewan , or Bhuyan and you may Passey (all the relationship is listed in Desk step one) to find a quicker erroneous estimation off Shurijeh clay posts

Since mistakes of prior variations made a relatively highest huge difference on abilities, it is essential to get an empirical relationships into clay posts estimations inside development. eleven.0 application. Found below is the acquired low-linear calibration dating into the Shurijeh Formation when it comes to a rational means between sheer gamma beam directory while the separate changeable in addition to lab-derived weight per cent clay according to the X-ray diffraction analysis as the situated variable:

Profile 8 shows the connection out of pounds per cent clay on XRD sized both wells and you may changed pure gamma ray directory playing with various other equations and additionally very consolidated Larionov change, 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.