Publications

The Louise-Nonny structure is one of the hydrocarbon prolific structures located in the Sanga-Sanga Field. The production interval is dominated by the deltaic multi reservoir-layers found in the B-C-D7 and D8-D25 Zone which are individually observed in the hydrostatic and overpressure regime. The challenge in developing this field is the possibility of encountering drilling operation hazards, such as mud losses and overpressure. Moreover, only minimum reserves are found in the overpressure regime. Thus, the current study aims to better understand and identify the characteristics of mud losses hazard and map its distribution. It will be used to formulate well placement strategy to minimize the risk of drilling hazards and maximize hydrocarbon production in order to support shallow-well drilling campaigns.

This study utilized triple combo logs, pressure data (pressure test and leak-off test), mud log, drilling parameters and drilling events from 42 representative key wells. The analysis was initiated with the calculation of pore and fracture pressures which were then calibrated with the pressure data. The calculated data were further used to map the mud loss distribution, primarily in the hydrostatic pressure regime.

This study found that mud losses hazard can be observed from the southern area to the northern area of Louise-Nonny structure. However, the specific total loss hazard were only found around the central area. Such mud losses occured in the B-C-D7 Zones. It was interpreted as due to the decreased fracture pressure within the depleted reservoir which is still contributing to hydrocarbon production until now.

The above understanding will aid the well placement strategy in supporting the shallow-well drilling campaign of the Louise-Nonny structure. A total of 20 wells are planned to be drilled in year 2025/2026. Those wells will be placed away from the central area with a focus to produce the remaining hydrocarbon in the B-C-D7 Zones.