Which empirical dating was one particular efficient estimator for as much as 20% lbs % clay stuff; widely known situation in the sandstone reservoirs
It can also be inferred using this study one, the brand new Shurijeh tank Formation is actually placed on the marine environment due to the fact Th/U proportion ranged between 1.8 and you can 23.2 from the fuel creating better and ranging from 1.2 and you will 5.6 regarding low-promoting really. Every investigation situations both in wells realize Th/U ratios lower than ten demonstrating that, the newest depositional ecosystem got an aquatic character. The greater Th/U proportion on gasoline promoting well might be because of even more oxidizing conditions or even a high concentration of other radioactive vitamins instance K-feldspar otherwise big minerals on sand dimensions fraction. New intermediate Th/You proportion on 2–eight in the low-promoting better exhibited a reduced degree regarding weathering and leaching out-of uranium, otherwise it could be inferred just like the a sign of mixes out of product out-of lower and you may high ratio surroundings.
New get across-plots review managed to make it obvious that the Shurijeh is not a great brush tank due to the fact distinct group investigation things were not alongside the origin during the not one of get across-plots found on the Fig. 11; these were all the clustered regarding lower left-hands corner of each cross patch. Less distinctions within this wells instead of ranging from wells, recommended specific systematic change particularly other diagentic records anywhere between wells. The information and knowledge situations of one’s fuel generating better was indeed shorter really discriminated however, most of the displayed seemingly moderate potassium and thorium to the cross plot noted An off Fig. eleven. For both wells, the content activities toward clay entering get across-plots of land dropped in a certain city one to showed the general designs of your own clay vitamins in the region. But not, particular research from both wells have been moved on off the trend. Regardless of if, discover zero agreement for the clay systems brought of the each cross-spot, however, according to research by the performance offered from them, the clay mineralogy throughout the creation less than analysis might possibly be ended as just out-of glauconite/smectite/muscovite/Illite designs. These show just weren’t inside arrangement with this of the XRD lab training carried out on the key types of both wells. New kaolinite, chlorite, while the blended layer clay vitamins had been plus stayed unrecognized by the this petrophysical approach.
Results
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 recenzja fdating 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.