Today, fractured basement is becoming an important contributor to the petroleum industry. However, drilling into the granitic basement reservoir is challenging because of the severe shocks and vibrations and the high requirement for accurate detection of productive fractures. Logging-while-drilling (LWD) technology has quickly adapted to respond to these challenges. The development of new LWD sonic and electric image tools supports an integrated methodology for reservoir characterization and fluid identification, which are critical for success.

The new methodology takes advantage of the latest technology of LWD resistivity image logs and LWD sonic acquisition; the processed high-resolution resistivity images enable the identification of borehole breakouts, natural or induced fractures, vugs, and dips, and Stoneley measurements from the LWD sonic tool enable analysis of the producibility of fracture system with the sonic fracture technique. The integrated methodology combines the strength of the two independent methods to give a comprehensive characterization of the fracture systems.

Analysis from LWD sonic and resistivity images provide location and characters of faults or fractures (open/closed). Results from the analysis are also important input for the production and perforation planning. The case history in this paper shows excellent results from the integrated fracture evaluation with LWD sonic and resistivity image logs. In this case study, fracture database for well design and field development is updated with the result obtained from the well.

It is the first time of combining latest generation of LWD sonic and LWD resistivity imaging logs in Vietnam, essentially this sets a benchmark in the fractured basement characterization. Numerous basement reservoirs are present in Vietnam and worldwide. This advanced technology opens opportunities for fracture evaluation in basement reservoirs using LWD technology.

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