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?

富液页岩（LRS）油气藏是目前北美最热门的非常规油气藏。在阿尔伯塔省，富含液体的Montney低渗透粉砂岩和Duvernay页岩地区是加拿大石油行业非常感兴趣的地区，但开发主要集中在多裂缝水平井（MFHWs）的初级枯竭上，预计碳氢化合物液体采收率很低。此外，目前的回收过程效率低下，并没有提供减少阿尔伯塔省温室气体（GHG）排放的解决方案。一种潜在的解决方案是将从储层中回收的二氧化碳或贫气（富含CH4）重新注入MFHWs，或将两者结合起来，以同时提高液态烃（凝析油或油）的采收率，并减少温室气体（甲烷和二氧化碳）的排放。循环溶剂注入（CSI）工艺，通常被称为huff'n'puff，以CO2/贫气作为“溶剂”，是一种潜在的有吸引力的温室气体封存/液体回收协同优化机制，因为与全驱（专用注入和生产井）方案不同，不需要在专门设施、现场管道和井转换上花费大量资金。尽管有这些优势，但行业需要关键数据、评估方法和支持性模拟研究，以便决定是否在其运营的井/油田投入资金进行CSI试验。目前的研究项目旨在满足这些需求，同时提高我们对阿尔伯塔省富含液体的非常规油藏的了解。本研究拟采用先进的岩心/岩屑分析和现场数据分析方法，以及储层成分模拟，以达到以下目的：1)评估LRS中溶剂储存和运移的基本控制因素；2)利用数值模拟为CSI评价提供关键数据；3)为CSI提供温室气体固存与烃液回收协同优化的优化设计建议；4)量化增量原油/凝析油采收率和温室气体捕获潜力。Duvernay页岩将是研究的重点。

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.