Abstract

In the TUNU field, Mahakam delta area, the reservoir is made up of a multitude of thin sands, deposited in a distal deltaic environment (mostly channel mouth bars). The evaluation of the gas in place, based on statistical methods, is considered as reliable. However, the main task, when designing the development plan, is to optimize the well spacing for a given production profile. The corresponding number of wells is a key figure for the development plan.

Due to the expected lack of continuity, at field scale, of the sand bodies, no detailed mapping of each individual sand can be achieved. Thus, a statistical model of the field was first used. This method evolved into a geostatistical model, using the HERESIM software. The field images obtained were calibrated by some additional field work performed in the mean time.

Additional software had to be developed, including the taking into account of the structural position of fluids in the reservoirs, and the direct computation of the gas connected to a given set of development wells.

As the field has been put into production, the first production data were also used to calibrate the geostatistical results. So far, all the available information fall in good agreement with each other. However, longer production history is needed before firm conclusions can be drawn.