Geosteering - The Key to Late Life Appraisal on a Giant Producing Field

The application of live geosteering on DWG resulted in the collection of a suite of data previously unobtainable with conventional high-angle wells. The data collected (i) bed parallel core, (ii) laterally extensive (>1000m) pressure measurements in a 42m TST bed and (iii) high resolution dip meter and azimuthal density data has allowed a step change in understanding and a fundamental re-working of the depletion plan for the structurally complex north flank of DWG. The data also confirmed that a simple model treating the whole of the north flank as a single structural zone is inappropriate given the different results in wells in a similar structural position but 4km apart. Although over 100 wells had been drilled on the structure prior to these geosteered wells, the data confirms that significant Km wide portions of the field can contain very high uncertainty even while a field is developed and on plateau. Geosteering bed parallel wells proved to be a very effective approach to reducing the remaining uncertainty on the field.