ABSTRACT: Using High Resolution Logs to find Gas in Bangladesh

Ashraf, Dr. Humayun¹, Engr. Shamsul Aziz¹, Peter Lloyd², Kasem Vathanavit³
(1) Sylhet Gas Fields Ltd, Dhaka, Bangladesh
(2) Schlumberger Sdn. Bhd, Kuala Lumpur, Malaysia
(3) Schlumberger, Bangkok, Thailand

This paper is a case study illustrating the application of high resolution logging and imaging techniques in discovering gas sands in the Rashdipur structure in Bangladesh.

The Rashdipur structure lies in the south central part of the Surma Geological Basin (part of the Greater Bengal Basin), which is a Miocene gas-bearing province in the northeast of Bangladesh. Basin subsidence continued from the Oligocene to Pliocene with the deposition clastic fluvio-deltaic sediments, with minor marine incursions.

The Rashdipur #5 well was the fifth appraisal/development well. The objectives were to delineate the southern extent of the two main reservoir sections, to evaluate them and to complete as producing horizons. It reached its target depth of 2984m BRT. This paper will show examples across these very thinly interbedded reservoirs, and compare gas bearing zones with adjacent water bearing intervals. Production tests have since validated the log analysis.

High resolution sensors and sampling rates, plus the use of real time environmental (including speed) corrections, have proven successful in Bangladesh. They have allowed a very fast turn-around time for the log analysis, so decisions could be made quickly and accurately in this remote location (despite additional complications such as poor borehole conditions with stickiness and standoffs caused by washouts).

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia