Abstract

Tambora is a gas field located in the Mahakam Delta in East Kalimantan and operated by TOTAL Indonesie.

A part of the gas-in-place is situated between 3800 and 4200 m below sea level (mss), in deep multilayered, fluvio-deltaic sands, with relatively poor reservoir properties.

The initial policy was to produce these reservoirs by comingling with shallower and better quality sands, through multi-packer well completions. The result to date is that these tight sands have been largely underproduced.

Following advances in drilling technology, the redevelopment of these reservoirs has become possible by means of horizontal drains.

This paper presents a new drilling strategy with the first horizontal well, which was drilled in 1997 to a record-depth of 3900 mss, with a conventional drilling rig. Successful production performances are presented with the reservoir simulation studies that guided the well design. This paper also summarises the specific problems faced and techniques used when drilling this well. Historical data, test results and both numerical and analytical interpretations are presented.

A brief section summarises why horizontal drains are a better development option than hydraulic fracture jobs for Tambora deep sands.

The paper concludes by a discussion of future plans focusing on multi-drain side-tracks, drilled through the completion string of existing wells with a coiled tubing unit.