It empirical dating try more productive estimator for up to 20% weight % clay posts; the most popular state on sandstone reservoirs
It is also inferred out of this studies one to, the latest Shurijeh tank Creation was transferred throughout the marine ecosystem while the Th/You proportion ranged between step 1.8 and 23.2 in the fuel creating well and you will between step 1.2 and you can 5.6 in the non-producing well. Every research factors in both wells realize Th/You rates less than 10 demonstrating one, the fresh depositional ecosystem had a marine characteristics. The higher Th/You ratio from the energy producing well could be on account of much more oxidizing standards or to a top concentration of other radioactive nutrition such as for instance K-feldspar or heavier minerals on the sand proportions small fraction. The newest intermediate Th/You ratio from chappy mobile the dos–7 throughout the non-producing well shown a reduced levels off weathering and you may leaching regarding uranium, otherwise it can be inferred while the an indication of blends out-of content out of lowest and you may high proportion environment.
The get across-plots of land investigations made it clear that Shurijeh is not an excellent clean tank once the collection of party study points were not close to the origin inside not one of one’s cross-plots revealed throughout the Fig. 11; these people were all clustered regarding the all the way down remaining-hand area each and every get across area. Shorter differences contained in this wells in place of ranging from wells, recommended particular medical alter such as for example various other diagentic records between wells. The details activities of gasoline creating really have been smaller better discriminated however, the demonstrated seemingly average potassium and you will thorium to your get across plot marked An off Fig. 11. For both wells, the data situations into clay typing mix-plots dropped inside the a specific city that showed the general systems of your own clay vitamins in the area. But not, some study regarding each other wells was basically moved on out of the pattern. Even if, there is zero agreement towards clay designs put from the for every single cross-patch, however, in accordance with the abilities offered of them, the newest clay mineralogy in the development lower than studies is concluded because the simply out-of glauconite/smectite/muscovite/Illite models. Such overall performance just weren’t in the arrangement with this of one’s XRD research degree accomplished into key types of each other wells. The newest kaolinite, chlorite, and also the blended level clay nutrition was along with stayed unrecognized by that it petrophysical strategy.
In this paper, all previously proposed modifications of natural gamma ray log and its spectral components data were reviewed and a new calibration equation for reliable assessment of the clay content in the Shurijeh reservoir Formation was presented. The quantitative XRD results showed a low average percentage of clay minerals for the gas producing well and moderate amounts for the non-producing well. The differences between the varying amounts of clay minerals in wells were attributed to the changes in the diagentic histories. In both wells, all the previously proposed modifications overestimated the weight percent clay indicating it is critical to calibrate petrophysically-derived weight percent clay to the laboratory data to find better estimations. The results also showed by using natural Steiber modified gamma ray values, more reliable clay contents could be obtained rather than all other previous modifications in this area. On the basis of minimum average percent relative error, the natural gamma ray and thorium curves were powerful tools to recognize the clay zones in a sandstone reservoir rather than potassium curve. In summary, the comparison of core clay contents from quantitative XRD data, estimated values using the previously proposed modifications and the empirical calibration, demonstrates that a simple nonlinear regression using the XRD data and natural gamma ray index (IGR) allows for the quantification of clay content with the least percent relative errors, i.e., lower than 12%, which is comparable to the values of the methodological errors associated with the XRD analysis. The excellent agreement between the locally calibrated natural gamma ray index and the clay quantitative XRD data showed it was well suited to provide reliable quantitative clay content estimates. The application of the proposed approach in this paper, will significantly improve the weight percent clay estimations from the gamma ray log in the Gonbadli field. The depositional environment can be correctly recognized from the spectral gamma ray logging ratio, however the safest method of reservoir clay typing is still based on the laboratory analysis of core samples. Overall, the natural gamma ray log and its spectral components data proved to be dependable qualitative and quantitative tools to diagnose clay minerals in sub-surface formation studies. In this paper, the broad scope of problem-solving capability of them was illustrated in the reservoir formation evaluation.