f The Role of Elastic Rock Properties Conditioning for Quantitative Interpretation of Seismic Amplitudes in the Sarawak Basin, Malaysia.

Data integration is very important for the success of quantitative interpretation project. Well logs, core measurements, reservoir fluid properties, existing geological model and pre-stack/post-stack seismic data need a close-up analysis before integrating for quantitative analysis. Any of the poor quality data set may limit the analysis/interpretation. Limitations of seismic data due to noise, frequency content and imaging issues are well known. In this paper we have discussed well log data issues with core measurements and fluid properties. In general, well log data is always considered very accurate. However, the precision required for quantitative seismic interpretation indicates that if possible, well log data should also be corrected for necessary corrections like poor borehole condition, well trajectory, mud-filtrate invasion and tools problem. Therefore, poor quality log data should be identified and edited using appropriate techniques like empirical relations and rock physics modeling. In this study, rock physics modeling has been used for identification, correction and to generate missing logs of any wells in the Sarawak basin, Malaysia. The main focus of log editing/modeling was on the elastic logs i.e. P-sonic, shear sonic and density. Thin laminated sands and shaly sands impose major challenges for rock physics modeling and log editing. Special emphasis has been given for modeling of thin laminated sands and shaly sands in the study area. Different fluid substitution methods and upscaling techniques have been tested and it has been found that an iterative editing and well seismic calibration is a must for correct rock physics model for laminated and shaly sands in Sarawak basin. The rock physics based well log condition workflow will be elaborated further in the paper. A rigorous quality check including iterations for petrophysical interpretation, depth dependent rock physic model parameters are very crucial to explain the recorded well logs and fluid substituted responses through integration with core measurements and seismic data. It has be established that pre-stack seismic gathers and synthetic CDP gather matching should be analyzed for insitu case before embarking on modeling other fluid responses in the reservoir. The rock physics model has been used to show the impact of well log conditioning for AVO modeling and reliable quantitative interpretation. Based on analysis of several wells in Sarawak Basin, it can be mentioned that data QC and conditioning is very important to understand amplitudes and to boost the confidence especially for thinly laminated sand-shale sequences.