TGS-NOPEC Invest AS in March 2007 contracted TDI-Brooks Internationa Inc. to conduct a large surface geochemical exploration (SGE) coring and heat flow (HF) program offshore Indonesia as part of their integrated geophysical and geochemical survey in Indonesian waters during 2006 and 2007. The program objective is to evaluate the hydrocarbon prospectivity and present-day geologic/sedimentological/geomorphic environment of the survey areas. The survey areas are located across Indonesia, and include a total of sixteen (16) different sedimentary basins (Figure 1 ). Water depths range from 50 to 3500-meters, with most of the survey areas deeper than 500-meters.
Figure 1. Location of Indonesian basins that will be cored and where heat flow data will be collected starting in April 2007. (Indonesia Basins Overview.pdf)
As many as 1,500 cores and 250 heat flow sites will be acquired in the basins to be surveyed. TGS is undertaking the project in cooperation with the Directorate General of Oil and Gas (MIGAS). The surveys will acquire a variety of data to conduct a comprehensive prospectivity analysis over an area of around one million square kilometers.
TDI-Brooks will conduct the SGE/HF program with its research vessel, the R/V GEOEXPLORER. The
program will start in mid-April 2007 with the mobilization of the vessel in Bali. The first leg of the program will include the collection of approximately two hundred (~200) cores in the Makassar Straits. The SGE/HF components that TDI-Brooks is conducting will follow 2-D seismic and swath bathymetry acquisitions in these same areas by other contractors. The 2-D seismic data and swath bathymetry will be used to select the core and heat flow locations. It is expected that the total SGE/HF acquisition program will take eight (8) to ten (10) months.
The purpose of the piston coring and geochemical analysis is to provide a regional evaluation of the petroleum charge and oil types in the deep water basins offshore Indonesia. Cores will be acquired with a 2000 lb. piston corer with collapsible piston, 20 ft. (6-m) of pipe and core liner. Cores will be positioned using differential GPS and a Kongsberg HiPAP350 USBL navigation system. One kilometer (1-km) chirp subbottom lines will be run over each site prior to core acquisition to assist in placing core locations. A comprehensive suite of geochemical analyses will be provided on the cores. The cores will be analyzed for free-hydrocarbon gas and the higher molecular weight, migrated hydrocarbons (as determined by total scanning fluorescence and capillary gas chromatography). Three (3) sections per core will be analyzed. Biological marker analysis of selected high bitumen-containing sediments and carbon isotopes on interstitial gas hits will help to define the source of the microseepage in respect to regional oils in the area.
Regional heat flow measurements will be conducted in the basins to assist in contraining thermal maturity models. The heat flow will be measured by TDI-Brooks’ NRCAN Heat Flow Probe(s). The Heat Flow Probe is a completely integrated system designed to measure heat flow in water depths of at least 600 meters and up to 6,000 meters. It is capable of making multiple measurements over a single deployment period. The system measures both temperature gradient and thermal conductivity in situ over sub-bottom depth intervals of up to 5.5 metres. Data is digitally recorded on an internal data logger. Replicate heat flow meaurements are conducted on at least 10% (pogos) of the heat flow sites.
