Abstract

Mobil Cepu Ltd., (an ExxonMobil subsidiary) hereinafter referred to as MCL, plans to develop the Banyu Urip Oil Field located onshore in Cepu Block. The planned activity will cover the area of two districts, namely Bojonegoro and Tuban regencies in the Province of East Java, Indonesia. Banyu Urip Oil Field will consist of oil production clusters, a Central Processing Facility, onshore and offshore pipelines, a coastal facility, and a floating storage and offloading (FSO) facility. Besides those main facilities, Banyu Urip field development will also have other supporting facilities, such as housing, warehouses, an airstrip and a water reservoir lake.

To support the development of the Banyu Urip Oil Field Environmental Impact Assessment (AMDAL) and Oil Spill Contingency Plan, an oil spill modeling study was conducted for the offshore location and pipeline river crossing. This paper will focus solely on oil spill modeling for the offshore operations activities.

Oil spill modeling was conducted using Surface-water Modeling System (SMS) version 8.0 for a comprehensive environmental hydrodynamic analysis, and OILMAP version 4.2 for oil trajectory and fate modeling. Two specific oil spill scenarios were considered in this study:

• 27,000 bbl instantaneous spill of crude oil due to failure of an offshore pipeline.

• 1,100 bbl instantaneous spill of crude oil due to a loading hose failure.

The stochastic modeling of the oil spill at the coastal area shows that the critical time for a spill is during the seasonal transition periods (March - May and September - November). This applies for both the 27,000 bbl and 1,100 bbl oil spill. The oil spills are estimated to reach the Tuban Coast in seven days under typical conditions during the seasonal transition periods. Under squall conditions, trajectory simulations estimated that the spills would reach the Tuban Coast in six hours.