Publications

Oil and Gas differentiation is quite challenging on Bekapai field with shaly sand reservoir characteristics. Analysis of Gas Chromatograph data is essential to support fluid identification from well electric logs interpretation, particularly between oil and gas reservoirs. Interpretation using gas data usually always face normalization problems. To overcome this issue, utilizing ratios such as Wetness and Balance Ratios are proposed. The “Dynamic Baseline” from each ratio is used to separate between oil and gas over hydrocarbon intervals in Bekapai field. This paper wants to draw attention to the fact that mud logging gas data contains a vast amount of information that is often not exploited. The Gas Chromatograph data is verified for any contamination using Gas Quality Ratio (GQR). If the GQR is in the range of 0.8-1.2, the gas data is considered appropriate to carry out gas analysis. The reliable quality data is used to calculate various ratios and is then compared with its dynamic baseline to differentiate between oil and gas. Gas ratios used in analysis are Wetness, Balance, Gas Oil Water Ratio, C3/C1, and C2/C1. The Dynamic baseline is generated from each gas ratio as a moving average for a given window. Contrast difference between oil and gas is captured with dynamic baseline used as a cut off definition to differentiate between oil and gas reservoir. The fluid types indicated by these analyses have been ratified by fluid identification through downhole fluid analysis tools. Dynamic baseline of Chromatographic Gas Ratio Analysis has successfully differentiated oil and gas with more than ~80% success ratio confirmed with fluid analysis results. Dynamic Baseline is an alternative technique for oil and gas differentiation by using Gas Chromatograph data which is independent from clay content.