This new wanting was at arrangement with cored periods of Shurijeh depositional ecosystem demonstrated from the Moussavi-Harami and you will Brenner

It empirical dating is one particular efficient estimator for 20% weight % clay blogs; the preferred problem about sandstone reservoirs

It’s also inferred using this data you to definitely, the fresh new Shurijeh reservoir Development try transferred on the marine ecosystem since Th/U proportion ranged ranging from 1.8 and you may 23.dos regarding the energy generating better and you will between step one.dos and 5.6 regarding non-creating really. All the research products in wells read Th/You percentages below 10 appearing one, brand new depositional ecosystem got an aquatic nature. The greater Th/You ratio in the gas creating really could be because of significantly more oxidizing conditions or even a top intensity of other radioactive nutritional elements eg K-feldspar otherwise heavy minerals on sand dimensions tiny fraction. Brand new advanced Th/You ratio regarding dos–7 on non-generating really presented a minimal level away from weathering and leaching away from uranium, or it could be inferred since an indication of mixtures from product off reasonable and large proportion surroundings.

The fresh new get across-plots of land assessment managed to get obvious the Shurijeh isn’t a good brush reservoir since the line of cluster study situations were not next to the origin inside the nothing of your own cross-plots found throughout the Fig. 11; they were all the clustered regarding all the way down leftover-give corner of each and every cross spot. Reduced distinctions within wells instead of between wells, advised some clinical change particularly other diagentic histories anywhere between wells. The information items of gas producing better was in fact smaller better discriminated but all presented apparently modest potassium and you will thorium for the get across spot noted An off Fig. 11. For wells, the content situations toward clay entering get across-plots dropped into the a particular area that showed the general designs of the clay vitamins in your community. However, particular investigation regarding each other wells was indeed shifted off the development. Though, there is certainly no agreement on the clay designs introduced by for each and blackplanet every cross-patch, but in line with the show given away from all of them, the brand new clay mineralogy throughout the creation not as much as investigation could well be concluded while the simply out of glauconite/smectite/muscovite/Illite versions. These types of results were not in agreement with this of your own XRD research knowledge accomplished for the center types of one another wells. Brand new kaolinite, chlorite, as well as the blended covering clay nutrients was in fact and stayed unrecognized of the that it petrophysical technique.


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.

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