It empirical matchmaking try the most productive estimator for up to 20% weight per cent clay articles; the most popular problem in the sandstone reservoirs
It can be inferred using this data you to definitely, the fresh Shurijeh tank Development are deposited on the aquatic environment because the Th/You proportion ranged between step one.8 and you may 23.dos in the fuel creating better and you may anywhere between 1.2 and you may 5.6 on the low-generating really. All the investigation situations in both wells see Th/You percentages less than 10 appearing you to, new depositional environment had an aquatic nature. The better Th/You ratio on gasoline promoting better was due to a lot more oxidizing criteria or perhaps to a high concentration of most other radioactive nutritional elements such K-feldspar or heavier nutrition on sand proportions fraction. The fresh advanced Th/U proportion from the 2–seven from the low-generating well displayed a minimal levels regarding weathering and you will leaching out-of uranium, or it may be inferred since a sign of combinations away from material from lower and you may higher proportion surroundings.
The fresh cross-plots of land assessment managed to get clear the Shurijeh isn’t a good clean reservoir as line of party analysis circumstances were not next to the foundation for the nothing of the get across-plots of land revealed on Fig. 11; these people were the clustered regarding down leftover-give spot of each cross area. Shorter distinctions inside wells in place of ranging from wells, suggested certain health-related alter such as for instance different diagentic records between wells. The info situations of the gasoline promoting really was indeed quicker really discriminated but all demonstrated seemingly modest potassium and thorium to your get across area designated A from Fig. 11. Both for wells, the content points on clay entering cross-plots of land decrease into the a specific urban area one showed the overall versions of clay nutritional elements in your neighborhood. However, particular study out of both wells had been moved on off the pattern. Even though, discover no contract on the clay designs put from the each cross-patch, however, based on the abilities offered out-of them, the brand new clay mineralogy on creation less than analysis could be concluded due to the fact just off glauconite/smectite/muscovite/Illite items. Such abilities just weren’t inside the contract with this of the XRD research education carried out towards the center examples of each other wells. This new kaolinite, chlorite, and combined coating clay vitamins had been plus remained unrecognized of the which petrophysical method.
Findings
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 fcn chat bezpЕ‚atna aplikacja 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.
