Publications

Understanding reservoir fluid characteristic has been one of the major contributing factors towards successful appraisal and development of any oil / gas field. Gas While Drilling (GWD) data and its analysis are very vital in evaluating hydrocarbon potential of the formations. However, this common practice is rarely used due to the presumption of it is unreliable and unrepresentative. Recent advances in gas detection technology has improved data acquisition and provided better-quality data. This paper aims to develop understanding in acceptable GWD interpretation method using real-time chromatographic analysis of hydrocarbons in order to provide effective reservoir fluid characterization. Our study incorporates six offshore wells from Timor Sea Area in Eastern Indonesia, focusing on Plover Formation which serves as primary target formation for hydrocarbon. The datasets consist of drilling parameters, mud log and wireline log, well test, laboratory tests, and conventional/side wall core. Total gas and chromatograph components reading were synchronized with depth and corresponding lithology. All data were verified for any potential errors, which may be caused by drilling mud properties and additives, borehole condition, nature of formation, etc. Gas-data Quality Ratio (GQR) was calculated in order to determine any contamination in the data, whereas gas ratio analysis was conducted to interpret gas readings using the following methods: wetness, balance, character ratio, pixler ratio, fluid saturation, reserval ratio, and additional light gas ratio plot. Gas analysis results were compared with production test data and suggesting that this method is reliable and capable of helping to justify decision for further drilling action. Our study demonstrates that integrated GWD analysis can be a powerful method for fluid characterization within minutes after the reservoir was drilled using real-time gas data. In addition, our interpretation suggests that this method is useful to identify fluid characterization and contacts, assisting pressure test (permeability), picking pay zone, and distinguish between productive and non-productive hydrocarbon.