Hydrocarbon type detection using the synthetic logs: A case study, Baba member, Gulf of Suez, Egypt

Abstract

Lack of pressure data and/or one curve of the essential well logs such as density, neutron, sonic, resistivity and gamma ray curves in some reservoirs, is not preferred situation for the petrophysict, which will affect the petrophysical evaluation process and the reservoir characterization study.Four wells (A, B, C and D), in the area of interest, penetrated Baba sandstone zone in Badri field. The main challenge in the studied zone is the absence of pressure gradients and the density-neutron separation is not clear enough to judge the hydrocarbon type in all wells at the level of baba sandstone reservoir, where they are needed for the estimation of the hydrocarbon type (oil or gas). So it is preferred to use the three porosity logs to investigate the hydrocarbon type. The second challenge is constructing synthetic logs in the absence of the three main porosity logs.In this paper, all available data were used to estimate the hyocarbon type in two studied wells at the level of Baba sandstone zone, firstly by using well logging relationships between density and sonic in the wells which have sonic logs at the zone of interest, secondly by applying special petrophysical studies to help for estimation of hydrocarbon type.Crossplot technique was used to estimate the hydrocarbon type in the zone of interest using the synthetic sonic curve, original density curve, original neutron curve plus their derived porosity and variables values in the used well logging crossplots including some petrophysical crossplots, which can help in this situation.The results of this study revealed that, 1) the synthetic logs play a great role in solving of petrophysical and geological problems, 2) there is a good relationship between the density and sonic logs in the analogues (A and D) wells, and 3) the obtained synthetic sonic log makes a sense with lithology and other logs (neutron and gamma). Therefore, the synthetic sonic log, in corporation with the density and the neutron logs as well as the crossplots can detect the fluid type in the studied wells. The final result that the most likely hydrocarbon type in well (B) is oil while it has gas signature in well (C).