Publications

One of the important pieces of information to estimate the remaining hydrocarbon reserves of the Peciko Field is the residual gas saturation. The residual gas saturation is commonly measured from a core sample by measuring the imbibition or the relative permeability. Whilst the above methods are effective, the processes are costly and time consuming. Moreover, to align with cost efficiency campaigns, there should only be an effective number of coring jobs performed, especially in a mature gas field such as the Peciko Field. Therefore, an alternative technique which utilizes the widely-available log data to compute the residual gas saturation is required. Within this study, the residual gas saturation was computed from the resistivity logs in wells in which core samples were also taken. The residual gas saturation is derived by integrating and comparing resistivity and computed water saturation in several wells with virgin gas zone, water-rise zone and virgin-water zone. The result of the study suggests that there is a good correlation between the residual gas saturation that was computed from the resistivity and the residual gas saturation data that was measured from the relative permeability. Among the several advantages of computing the residual gas saturation from the resistivity logs is the estimation of the displacement efficiency of a reservoir by adopting the Welge method in the reservoir with no core samples. The result is reasonable and acceptable when compared to the microscopic residual gas measurement from core data or the megascopic recovery factor from simulation which considers the reservoir heterogeneity. This paper details the method of this technique and its example in the Peciko Field from the Mahakam PSC, East Kalimantan, Indonesia.