نوع مقاله : علمی - پژوهشی
1 زمین شناس نفت/ شرکت ملی حفاری NIDC
2 عضو هیئت علمی پژوهشگاه صنعت نفت تهران
عنوان مقاله [English]
Accurate detection of changes in geological layers and boundaries between them using petrophysical logs, is a fundamental problem in the petrophysical data processing. In this study, the boundaries of geological layers in a carbonate reservoir was determined in two different ways and petrophysical parameters and concentrations of minerals and fluid volume due to the boundaries specified for the interval studied were calculated layer by layer. In the first method, using blocking algorithm, effects of noise and shoulder beds of petrophysical logs readings were taken and sudden changes on these logs was used as the indication of boundary layer. In the second method, using a log clustering (MRGC method), the number of 9 electrofacies in the interval was determined and the facies boundary was defined as a geological boundary layer. The log entry contains both common method GR, RHOB, NPHI, DT and the PEF. In the next step, the petrophysical parameter and volumetric concentration of minerals and fluids in both methods were calculated set by applying the boundaries layer by layer and was compared with conventional petrophysical evaluation method. The calculations showed that, unlike commonly used petrophysical evaluation methods that calculate reservoir parameters in a mean and continuous manner across a reservoir, by specifying the boundaries of the layers in the sequence of a reservoir, petrophysical parameters can be calculated on a layer-by-layer basis with a much higher accuracy. As a result, with this method, the strongest and weakest layers in a reservoir can be identified precisely, and also a better view of the other layers can be obtained. The layer by layer study is more important in reservoirs with alternating and thin layers.