scholarly journals Determination of Shale Volume and Distribution Patterns and Effective Porosity from Well Log Data Based On Cross-Plot Approach for A Shaly Carbonate Gas Reservoir

Author(s):  
Siyamak Moradi ◽  
Mohammad Moeini ◽  
Mohammad Kamal Ghassem al-Askari ◽  
Elaheh Hamed Mahvelati
2018 ◽  
Vol 1 (1) ◽  

The evaluation of shaley formations has long been a difficult task. Presence of shale and shale types in some of the Iranian formations are one of the most important factors. Shale types have to be considered, because existence of shale reduces, porosity and permeability of the reservoir to some degree. Shale Distributed in formations in three basic types, Dispersed, Laminar and structural. Each of these shale types has different effect on porosity, permeability and saturation. Dispersed shale reduces porosity and permeability to a great degree, but, laminar shale and structural shale have little effect on petrophysical parameters. In this investigation, shale types, Shale volume and effective porosity of Kangan Formation have been determined from well log data and compared with crossplotting. In other words, a triangle Density-Neutron cross-plot is used to determine above parameters. The area of study lies in central oil fields of Iran, where one of the well is used (Tabnak Well C). Tabnak Well C selected to study Kangan Formation from Iranian oil field, in Pars onshore. This study illustrates that distribution of shale types in Kangan Formation is mainly dispersed shale with few of laminar shale, and percentage of effective porosity (φe) decreases with increasing depths for Kangan Formation.


2019 ◽  
Vol 7 (2) ◽  
pp. 142
Author(s):  
Ubong Essien

Well log data from two wells were evaluated for shale volume, total and effective porosity. Well log data were obtained from gamma ray, neutron-density log, resistivity, sonic and caliper log respectively. This study aimed at evaluating the effect of shale volume, total and effective porosity form two well log data. The results of the analysis depict the presence of sand, sand-shale and shale formations. Hydrocarbon accumulation were found to be high in sand, fair in sand-shale and low in shale, since existence of shale reduces total and effective porosity and water saturation of the reservoir. The thickness of the reservoir ranged from 66 – 248.5ft. The average values of volume of shale, total and effective porosity values ranged from 0.004 – 0.299dec, 0.178 – 0.207dec and 0.154 – 0.194dec. Similarly, the water saturation and permeability ranged from 0.277 – 0.447dec and 36.637 - 7808.519md respectively. These values of total and effective porosity are high in sand, fair in sand-shale and low in shale formations. The results for this study demonstrate: accuracy, applicability of these approaches and enhance the proper evaluation of petrophysical parameters from well log data.    


2021 ◽  
Vol 11 (5) ◽  
pp. 2075-2089
Author(s):  
Mohamed Mahmoud Elhossainy ◽  
Ahmed Kamal Basal ◽  
Hussein Tawfik ElBadrawy ◽  
Sobhy Abdel Salam ◽  
Mohammad Abdelfattah Sarhan

AbstractThis paper presents different well log data interpretation techniques for evaluating the reservoir quality for the sandstone reservoir of the Alam El-Bueib-3A Member in Safir-03 well, Shushan Basin, Egypt. The evaluation of the available well log data for the Alam El-Bueib-3A Member in this well indicated high quality as oil-producing reservoir between depths 8108–8133 ft (25 ft thick). The calculated reservoir parameters possess shale volume less than or equal to 9% indicating the clean nature of this sandstone interval, water saturation values range from 10 to 23%, and effective porosity varies between 19 and 23%. Bulk volume of water is less than 0.04, non-producing water (SWirr) saturation varies between 10 and 12%, and permeability ranges from 393 to 1339 MD reflecting excellent reservoir quality. The calculated BVW values are less than the minimum (BVWmin = 0.05) reflecting clean (no water) oil production, which was confirmed through the drill stem test (DST). The relative permeabilities to both water and oil are located between 0.01–0 and 1.0–0.5, respectively. The water cut is fairly low where it ranges between 0 and 20%. Additionally, the water saturation values are less than the critical water saturation (Scw = 29.5%) which reflects that the whole net pay will flow hydrocarbon, whereas the water phase will remain immobile. This was confirmed with reservoir engineering through the DST.


2021 ◽  
Vol 5 (2) ◽  
pp. 1-10
Author(s):  
Taheri K

Determination of petrophysical parameters is necessary for modeling hydrocarbon reservoir rock. The petrophysical properties of rocks influenced mainly by the presence of clay in sedimentary environments. Accurate determination of reservoir quality and other petrophysical parameters such as porosity, type, and distribution of reservoir fluid, and lithology are based on evaluation and determination of shale volume. If the effect of shale volume in the formation not calculated and considered, it will have an apparent impact on the results of calculating the porosity and saturation of the reservoir water. This study performed due to the importance of shale in petrophysical calculations of this gas reservoir. The shale volume and its effect on determining the petrophysical properties and ignoring it studied in gas well P19. This evaluation was performed in Formations A and B at depths of 3363.77 to 3738.98 m with a thickness of 375 m using a probabilistic calculation method. The results of evaluations of this well without considering shale showed that the total porosity was 0.1 percent, the complete water saturation was 31 percent, and the active water saturation was 29 percent, which led to a 1 percent increase in effective porosity. The difference between water saturation values in Archie and Indonesia methods and 3.3 percent shale volume in the zones show that despite the low shale volume in Formations A and B, its effect on petrophysical parameters has been significant. The results showed that if the shale effect not seen in the evaluation of this gas reservoir, it can lead to significant errors in calculations and correct determination of petrophysical parameters.


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