THE GEOMORPHOLOGY OF BINTUNI BAY, EASTERN INDONESIA

摘要

Bintuni Bay is a shallow estuary with high tidal range and currents in the Bird's head region of Papua Barat province in eastern Indonesia. BP operates the Tangguh LNG plant on the south shore of the bay, with gas piped from the giant Vorwata field under the Bay. Several surrounding gas fields are due to be developed with additional wells, platforms and pipelines. The scale of the project warranted the acquisition of a regional site survey, covering all planned development activities. A variety of shallow geophysical tools and seabed profilers was acquired to image the complex shallow geology, understand the seabed morphology and integrate with geotechnical boreholes. A. geomorphology map was generated from the high resolution (1m x lm) bathymetry data. Distinct 1~(st) order zones (such as sharp, undulating or smooth bathymetry) can be strongly related to the subcropping geology. These are locally modified by 2~(nd) order features including channel cuts, scours, mega ripples and sand waves. The sandwaves are gently sinuous features with an amplitude typically up to 20 ft. Mega ripples have a smaller amplitude and shorter wavelength. Both features can be automatically mapped using seabed attributes such as maximum positive curvature. The sandwaves usually form in large fields associated with recent fill recording the lateral migration of the modern seabed channel. Access to several smaller heritage bathymetry surveys in the area shows that the sandwaves are laterally migrating, which has a major impact on pipeline routing and platform location. The geomorphology and other features are captured in a GIS-environment, which allows user-friendly access to a huge variety of geospatial data. This has proved an essential integration tool with the Project and Operations teams at Tangguh.