TIGHT GAS EXPLOITATION: A STOCHASTIC MODELING STUDY OF A LOW SINUOSITY RIVER SYSTEM

The overall objective of this research was to develop reservoir models using published petrophysical and geological data, representative of the Kenai Group of tight gas sands in Cook Inlet, Alaska, in order to simulate tight gas exploitation using viable technologies. We initially analyzed the eighteen parameters influencing the porosity and permeability (P&P) of tight gas sands of the region to develop suitable correlations, based on published petrographic data. The data from 33 available sandstone samples were first divided into cemented and non‑cemented rock categories. The non‑cemented samples provided better representation of P&P. Analysis of the data revealed that there was a moderate correlation (R2=0.455) when depth(ft) and rigid (%) was used to predict porosity. However, macropore %, mean grain size (mm) and quartz % to predict permeability revealed relatively high correlation (R2= 0.796). It was evident that P&P of the non‑cemented sandstone was directly controlled by mechanical compaction and a useful regressional relationship was developed for petrophysical modeling. Next we used published geological data (Flores et al. 1997 and AOGCC 2008) for simplified channel facies modeling. The parameters used to build the channel facies models were sand volume fractions, channel width, sinuosity, orientation and azimuth. Twenty one different scenarios were developed based a range of sand volume fractions and channel sinuosity. Each scenario was used to generate ~20 realizations to capture the antecedent uncertainty. Effective sand body connectivity was analyzed for each model by streamline simulation technique. This channel facies modeling in conjunction with petrophysical modeling may assist in predicting the factors controlling sand body connectivity of tight gas reservoirs of Kenai group of sands. Further, this work may help to determine the required well spacing , well type, orientation and completion technique to enhance recovery efficiency in Cook Inlet tight gas sands.