Sensitivity Analysis of CO2 Storage Coefficient and CO2-EOR

Abstract

The CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> capture and storage (CCS) is an important way of reducing greenhouse gas emissions and alleviating global climate change. At present, the geological sites that are suitable for large-scale CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage include: reservoirs, deep saline formation and barren coal seam. For China, the research on the CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage in oil and gas reservoirs is a feasible technology. In this paper, we established a series of evaluation methods based on Fractional Flow Theory for CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sequestration and enhanced recovery (EOR) potential, choosing a typical reservoir as the object, and analyzed the effect of several influence factors on storage coefficient of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage in oil and gas reservoirs, these factors include permeability variation coefficient (DP coefficient) , which is used to describe the reservoir heterogeneity, formation pressure and temperature, minimum miscible phase pressure (MMP) and injection-production patterns etc. Analysis results show that the formation pressure and temperature, permeability variation coefficient, residual oil saturation by water flooding (S???) and the minimum miscible phase pressure have very important influence on CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage coefficient and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -EOR. With lower temperature and the pressure increasing, CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage coefficient and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -EOR are increasing, however, with the DP coefficient increasing, CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage coefficient increases in the first place followed reduces, has the largest peak (in the range of 0.6~0.7), however, oil recovery with the DP coefficient increases gradually decreases. In addition, studied the crude oil viscosity, initial oil saturation(Soi), the mixing coefficient, total injection hydrocarbon pore volume number (HCPV), residual oil saturation by water flooding (S???) and injection-production patterns which influence the CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> storage coefficient and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -EOR directly. Sensitivity analysis of these factors is the basis of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sequestration and EOR potential evaluation, which will play an important role in this field.