Estimation of geological data using assisted history matching in the pilot-scale CO2 injection site, Iwanohara, Japan

Assisted history matching using real field data from the Iwanohara project of CO2 storage was conducted. About one tonnes of CO2 was injected into a saline aquifer by one vertical well and observed by three vertical wells in the Iwanohara project. We developed the suitable optimization method for assisted reservoir history matching and verified it to apply to history matching of the Iwanohara project. Time lapse bottom-hole pressure data and CO2 arrival time at observation wells were selected as components of the objective function. The summation of their errors between the observed and simulated data was minimized to optimize primary variables: porosity, permeability and pore compressibility of the reservoir. Two cases of history matching including or excluding porosity distribution were conducted using Iterative Latin hypercube sampling as a global optimization algorithm. It was seen from the results of history matching that not only permeability but also porosity distribution are important parameters to predict stored CO2 flow. We concluded that the proposed method allowed us to optimize the reservoir model in CO2 geological storage with limited calculation resources. (C) 2017 The Authors. Published by Elsevier Ltd.