In any hydrocarbon explorations, there are many uncertainties in estimating the petroleum prospects, sealing capacity is considered as the most common uncertainty occurred. Fault coefficient is such a fundamental thing in influencing the sealing of hydrocarbons accumulation. Despite of fault ability to seal, the thickness ratio of low permeable rock is also considered in determining the sealing capacity either the fault is sealing or not. This observation takes focus on outcrop data assessment in analyzing the fault sealing risk located in Piyungan, Gunung Kidul, DIY. Generally, this area has an interbedded sandstone-siltstone and volcanic breccia facies, known as Semilir Formation members. Faults found in the area has a SE-NW trend shown in the normal fault and thrust fault. In analyzing the fault sealing capacity with outcrop data, we use algorithm calculation in determining the influence of the shale to increase sealing capacity. It consists of SGR (Shale Gouge Ratio), SSF (Shale Smear Factor), and CSP (Clay Smear Potential) (Yielding, 1997).The data required to calculate it are lithology logging, including shale thickness, fault identification, and the distance of the source bed. The XRD analysis provides the type of clay minerals in sealing ability and the origin of the clay. Based on the algorithm calculation, it can be concluded that the area has a moderate-poor sealing capacity which means increasing the risk for hydrocarbons accumulations leaking.
Keywords: Fault seal risk capacity, semilir, hydrocarbons exploration,sueface data
Authors : A. Andaru, A. H. Shamlan, E. Mulyaningsih