Novel Petrophysical Approach for Water Saturation Estimation

Summary Water saturation is a key parameter for petrophysical formation evaluation based on well logging measurements; it is derived normally from one of saturation models using wireline or LWD data such as Archie or non-Archie equations etc. As a classic water saturation model, Archie model is often used for sand or shaly-sand reservoirs. In fact, due to the effects above, the resistivity measurements may not respond to hydrocarbon variations. However, as one of inputs, the resistivity log may often cause under or over-estimated water saturation. On the basis of Equivalent Rock Element Model (EREM, Shang et al. 2004 ), a modification in our research has been proposed as a new saturation approach which called Pore Structure Saturation Model (PSSM). This method combined with the pore structures and hydrocarbon distributions in order to correct the EREM for influences removing. PSSM has been applied to water saturation calculation for petrophysical formation estimation based on our field data. Further to combine with Dean-Stark core analysis from SCAL and DST testing, which shows that the precision of saturation estimation in PSSM was improved in comparison of the original EREM. Application to the Huan-Jiang oil filed in China also shows satisfactory results that might be achieved.