Uncertainty and Risk Analysis of 3D Geological Model for Syn Rift HP-HT Reservoir of Krishna –Godavari Basin, India

Abstract

Geo-cellular modelling has long been used to understand lithology extent and petrophysical property distribution within the geological body. In case of Syn rift HP-HT green field, uncertainty in modelling parameters, initial gas in place and risk related to well locations optimization within Geo-cellular model. The quality of 3D geological model strongly depend on the type of integration geological data ,their integration and associated uncertainty analysis in order to improve an exiting geological model and effectively plan further site of investigation.Therefore this paper aim to identify and quantify uncertainties and obtain more accurate geo-cellular model to be used in reservoir simulation.The methodology intends to evaluate geo-cellular model,GIIP and risk analysis.The study was divide into generation of flow stream line, S-curve, sensitivity analysis and uncertainty map. Uncertainty range was applied to variable of facies modelling, petrophysical modelling and input data series. Variables ranges from these data were used by Monte Carlo simulation method to generate random values to be input uncertainty in geo-cellular model.Total 500 models was generated by Monte Carlo simulation method. and it is cross plotted GIIP vs connected pore volume to find out the S-curves and array of variability approach to select P10, P50 and P90 cases of the model distribution.The Connected pore volume was estimated for each of the model using streamline simulation technique to further rank these models on basis of dynamic connectivity. Connectivity was qualitatively ascertained by visualizing streamlines & was quantified by estimating connected pore volume estimation. Based on ranking, model having better dynamic connectivity was simulated.In conclusion, all cases GIIP of P10, P50 and P90 not showing more variation to base model.It means input data and geo-cellular parameter has been taken for base case is robust.The uncertainty maps of mean and variance is showing well A position is falling in low risk area and well B is having very high risk. Key Words: Uncertainties, Risk, Syn rift HP-HT reservoir, Geo-cellular model, GIIP.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018