Enhanced Petrophysics Analysis to Identify By-passed Zone in Gas Field - A Badak Field Success Story

Wibowo, Ari Ari (VICO Indonesia) | Suhendar, Ade Diar (VICO Indonesia)

OnePetro 

The Badak Field, operated by VICO Indonesia, is one of the world's giant gas fields. Located in East Kalimantan, the field lies in the northern part of the Badak - Handil giant anticline. Discovered in January 1972, production started in October 1976 and reached a peak of 1,1 BCFD in December 1990. Up until now, cumulative production has exceeded 6 TCF.

Today, Badak is a very mature gas field which produces 80 MMscfd. The drilling of new wells and the well intervention activities continue to be the main way to maintain production in the field. Most of the reservoirs units, especially the larger ones, have been intensively drained over the life of the field. Only a few of them are producing, but at relatively low rates, due to their significant depletion. Finding zones with remaining production potential has become a much more difficult task, especially if some of these zones have incomplete suites of logs.

In VICO, the improvement in the subsurface analytical methods has proven successful in helping identify additional reservoir opportunities. Recently, a method has been developed to identify "bypassed gas zones?? in shallow reservoirs. This method uses the sonic log as the main tool for analysis. It also incorporates all of the subsurface data that has been acquired through time. The method has proven very successful in the Badak field in areas where no Density-Neutron log has been acquired.

Theoretically, the sonic log can be used as a complimentary tool to identify gas in the reservoirs. The problem arises when trying to differentiate between the event of gas and the effect of poor or under-compacted shallow reservoirs, as in many cases these events will present a similar feature across the sonic log. The development and implementation of these methods have helped significantly to maintain production in the Badak field.

Introduction

Badak is a giant gas field consisting of more than 180 production layers with more than 530 reservoirs. The cumulative production has reached more than 6 TCF since start up in October 1976. Today, the field is already in very mature production stage, and it has become very difficult to find high deliverability zones to be produced. The location of Badak field with respect to the Mahakam Delta in East Kalimantan is shown in Figure 1.