So it empirical matchmaking are probably the most productive estimator for as much as 20% lbs % clay stuff; typically the most popular situation about sandstone reservoirs
It edarling visitors can be inferred from this studies you to definitely, the newest Shurijeh reservoir Development are deposited from the marine ecosystem given that Th/U proportion ranged ranging from step one.8 and 23.dos throughout the energy generating better and anywhere between 1.2 and 5.six about low-promoting well. All the analysis items both in wells see Th/U percentages less than 10 appearing that, the fresh depositional ecosystem had a marine character. The better Th/U ratio from the fuel producing better might possibly be due to so much more oxidizing requirements or even to increased concentration of other radioactive nutrition instance K-feldspar otherwise heavy nutritional elements on the mud proportions small fraction. This new intermediate Th/U ratio throughout the dos–eight about non-creating better demonstrated a minimal grade out-of weathering and leaching away from uranium, otherwise it could be inferred just like the an indication of combinations off material regarding lowest and you may large proportion environment.
The fresh new get across-plots review caused it to be obvious the Shurijeh isn’t a brush reservoir because type of people research circumstances weren’t next to the foundation within the nothing of your mix-plots revealed throughout the Fig. 11; these people were every clustered regarding the lower kept-hand spot of every mix area. Less differences contained in this wells rather than between wells, recommended particular systematic transform particularly various other diagentic records anywhere between wells. The information and knowledge points of the gasoline promoting really was less really discriminated however, every displayed seemingly reasonable potassium and you can thorium to your cross spot marked An off Fig. eleven. Both for wells, the content factors towards clay entering get across-plots fell inside the a certain town one showed the entire models of one’s clay nutrients in the area. Although not, particular data from both wells was indeed moved on from the pattern. Even though, there is certainly zero agreement on the clay models lead by the for each and every cross-patch, however, according to the efficiency offered regarding all of them, the fresh clay mineralogy on formation under research will be finished once the just out-of glauconite/smectite/muscovite/Illite products. These abilities just weren’t for the arrangement with that of XRD laboratory studies achieved on core samples of each other wells. The fresh kaolinite, chlorite, while the blended coating clay nutrients had been including remained unrecognized by which petrophysical method.
Conclusions
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.
