Evaluations of CO2/lean gas huff'n'puff pilot opportunities in liquid-rich shale: an economically viable option for reducing Canada's greenhouse gas emissions?

点击翻译按钮获取中文摘要

Hydrocarbon liquid-rich shale (LRS) plays are currently the hottest unconventional reservoir targets in North America. In Alberta, liquid-rich areas of the Montney low-permeability siltstone and Duvernay shale are of great interest to the Canadian oil industry, but development has focused on primary depletion with multi-fractured horizontal wells (MFHWs), and hydrocarbon liquid recovery is projected to be low. Further, the current recovery process is inefficient, and does not offer a solution to reducing Alberta's greenhouse gas (GHG) emissions. A potential solution is to inject CO2, or reinject lean gas (rich in CH4) recovered from the reservoir, or a combination of both, back into MFHWs for the simultaneous purpose of increasing liquid hydrocarbon recovery (condensate or oil), and reducing GHG (methane and CO2) emissions. The cyclic solvent injection (CSI) process, commonly referred to as huff'n'puff, with CO2/lean gas as the "solvent", is a potentially attractive mechanism for co-optimization of GHG sequestration/liquid recovery because, unlike full flood (dedicated injection and producing wells) scenarios, large expenditures on specialized facilities, in-field pipelines and well conversions are unnecessary. Despite these advantages, industry requires critical data, evaluation methods, and supporting simulation studies in order to make a decision on whether to invest capital in piloting the CSI process in their operated wells/fields. The current research program is designed to meet these needs, while advancing our understanding of Alberta's liquid-rich unconventional reservoirs. ** This research proposal focuses on the use of advanced core/cuttings analysis and field data analysis methods, and compositional reservoir simulation, to: 1) evaluate the fundamental controls on solvent storage and transport in LRS; 2) provide critical data for evaluating CSI using numerical simulation; 3) provide optimal design recommendations for CSI that co-optimizes GHG sequestration and hydrocarbon liquid recovery; 4) quantify incremental oil/condensate recovery and GHG capture potential. The Duvernay shale will be the focus of study.******