The Impact of Glauconite on Pay Zone Identification in T Member in X Block, Ecuador

Glauconite develops widely in T Member in Oriente Basin, Ecuador. The presence of Galuconite reveals the information that can help to determine the sediment environment. However, the distribution of glauconite also makes the pay zone identification of glauconitic sandstone difficult in oilfield operation in many ways. Detailed core data analysis of glauconitic sandstone, include core description, thin section observation, porosity and water saturation, has been performed. The core data indicates that sediment environment changed from coastal estuary to open shelf during the deposition of T Member. The PEF and RHOB data from conventional well logs have been selected to estimate the concentration of glauconite based on the correlation with observation of thin section of core. And porosity estimation can be improved by using various matrix density with consideration of concentration of glauconite, which shows better result than using regular uniform matrix density by comparison with core data. Further, water saturation of glauconitic sandstone can be improved. And gas log data from mud logging has been introduced in pay zone identification of glauconitic sandstone. The combination analysis of well log data and gas log data can improve the determination of pay zone of glauconitic sandstone. The practice in oilfield proves the effectiveness of this method.