ANALISA SEKAT PADA SISTIM SESAR LALANG-MENGKAPAN PADA FORMASI CIHAPAS DI LAPANGAN LALANG, CEKUNGAN SUAMTRA TENGAH

• Main Author: ODAKAR ARDJAKUSUMAH, WITAN
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69661
• Institution: Institut Teknologi Bandung

Lalang Field structure shows typical compressional features. It is intersected by right lateral north trending strike-slip fault into several compartments. Lalang accumulation is mainly controlled by the faulted anticlinal trap. An additional controlling factor is the sealing potential of the fault. The effectiveness of the seal depend on juxtaposition of layers between the fault plane, magnitude of the fault throw and volume of shale. The fault seal capacities varies with the strike-slip displacement. Thus, the study of the fault sealing competence is significant in defining undrained fault compartments and to locate the new development wells. This study focuses on the sealing behavior of the E4 fault, a segment of the main fault in Lalang-Mengkapan fault system. Data being used include 3D seismic, gamma ray log, resistivity log, and reservoir pressure, while methods being applied consist Allan mapping of reservoir juxtaposition and Shale Gouge Ratio algorithm. The challenge is using the SGR techniques in strike-slip regime where the actual dip slip magnitude is unknown and hence its actual throw. Assuming there is no significant stratigraphic variations within the Lower Sihapas Formation the calculated apparent throw is similar or more than the actual throw. The result shows that fault seal juxtaposition only occurred in the zone where the throw is greater than the thickness of the sand. The E4 fault is also sealing on juxtaposition between sands layers in Lower Sihapas Formation with SGR value greater than the threshold value of 15-20%. The leak potential is located in the area adjacent to the axis of the oblique fault where the throw is small or zero. In the absence of RFT data the calculated SGR values compare with the compilation result of fault seal observation in Brent, North Sea instead. In addition the differences in water-oil contact (100 ft) and well pressure (100 psi) between the fault compartment support the conclusion.