Compartment Analysis Using Fault Seal Prediction In Miocene Carbonate Reservoir of Banggai Basin And Its Implication To Field Development

Abstract

Research area is located in colision zone between Banggai-Sula microcontinent and Sulawesi Ophiolite Belt with Miocene carbonates deposited during to post colision. In this structure, hydrocarbon entrapment is controlled by fault dominated resulted from compressional event. Fault capacity may act as a conduit or a barrier for hydrocarbon flow. The objective of this reserach is to analyze compartments in producing field in order to optimize development scenarios.
Due to the rarely presence of impermeable layer in carbonate platform reservoir, fault seal analysis method that being used in this research was generating shale gouge ratio, which were confirmed by cut offs of porosity-vshale, porosity-permeability, and permeability-SGR. These cut offs were made to determine the minimum limit of hydrocarbon flow through faults in carbonate reservoir. To confirm connectivity of the compartments, pressure test analysis was performed on wells separated by faults. The pressure difference may confirm compartmentalization in reservoir.
The results are showing different characteristics of each fault. Porosity with 2% cut off and vshale with 0.8% cut off becomes the minimum value for flowing hydrocarbon in reservoir. Then the value of porosity cut off was associated in porosity-permeability relationship to obtain the minimum limit of permeability for flowing hydrocarbon, which is 4.6mD. Then this permeability value is used in permeability-SGR crossplot. From the generated crossplot, the minimum SGR value is 0.045. based on the analysis, the faults were categorized as sealing faults, partial sealing faults, and leaking faults. These results also confirmed by RFT pressure analysis which performed in wells separated by faults.
This Research highlights the possibility for carbonate reservoir compartments in adjacent fault blocks to be hydrocarbon bearing, water bearing zone or connectivity of the reservoir itself. Thus it is important for developing oil and gas fields with faulted reservoir.