Characterization of Multi-Scale Discrete Fracture Network Systems in Unconventional Reservoirs Using Dynamic Data

使用动态数据表征非常规油藏多尺度离散裂缝网络系统

• 批准号: RGPIN-2017-05779
• 负责人: Leung, Juliana
• 金额: $ 2.04万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711481
• 关键词: Characterization; Multi; Scale; Discrete; Fracture

Development of unconventional tight or shale reservoirs has received much attention in recent years because of the large resource estimates worldwide. Horizontal wells with multi-stage hydraulic fracturing are drilled to enhance reservoir contact area and to achieve economic production rates. This stimulation technique is particularly efficient if hydraulic fractures can connect to sweet spots due to the presence of existing fractures. A tight/shale reservoir can be conceptualized as a dual-medium with two distinct sub-systems: matrix and fracture. The time scales for flow in the two systems differ significantly due to the high contrast in their permeability. The matrix has a very low in-situ permeability, while the fracture is a local discontinuity with a very high permeability. Fractures can be large and localized around the wellbore (e.g., hydraulic fractures) or small and located away from the stimulated zone (e.g., micro fractures). It should be noted that this proposal focuses on in-situ development of shale/tight oil/gas reservoirs, while surface mining of oil shale is not considered. The overall objective is to develop a suite of numerical models suitable for (1) simulating multi-phase flow in discrete fractures using finite-element based techniques; (2) capturing the impacts of fractures occurring over different scales; and (3) integrating dynamic data (e.g., flow and pressure measurements) for characterizing fracture networks in a robust history-matching workflow. This research proposes a novel integrated approach for analyzing multi-phase flow and fluid distribution in low-permeability porous media, where fracture networks, i.e., hydraulic fractures and micro fractures, are present over multiple scales simultaneously. This research would revolutionize the current practice that focuses predominantly on analytical models, which typically ignore multi-phase effects, and finite-volume/finite-difference simulations, which do not handle the complexities in fracture configuration pertinent to tight/shale reservoirs. This loss of model quality renders the description of fracture systems in numerical simulation incomplete and the inference of fracture characteristics from dynamic data challenging. Many industrial practitioners, who are familiar with the state-of-the-art research in unconventional reservoir development, have expressed the need for more sophisticated approaches to analyze and model these reservoirs. It is expected that computational loads that favor current practice are disappearing with the rapid advances in computing technology, and more computationally-intensive techniques, such as those developed in this proposal, could be implemented in commercial codes in the near future. The outcomes would impact our capability to optimize fracturing design, which is also an important consideration in geothermal energy development.

由于全球资源量巨大，非常规致密油或页岩油藏的开发近年来受到广泛关注。通过多级水力压裂钻探水平井，以增加储层接触面积并实现经济生产率。如果水力裂缝由于现有裂缝的存在而能够连接到最佳点，则这种增产技术特别有效。致密/页岩储层可以被概念化为具有两个不同子系统的双介质：基质和裂缝。由于渗透率的高对比度，两个系统中流动的时间尺度显着不同。基质的原位渗透率非常低，而裂缝是局部不连续性，渗透率非常高。裂缝可以很大并且位于井眼周围（例如，水力裂缝），也可以很小并且远离刺激区域（例如，微裂缝）。需要说明的是，本提案重点关注页岩/致密油气藏的原位开发，未考虑油页岩的地面开采。 总体目标是开发一套数值模型，适用于（1）使用基于有限元的技术模拟离散裂缝中的多相流； (2) 捕获不同尺度上发生的裂缝的影响； (3) 集成动态数据（例如流量和压力测量），以在稳健的历史匹配工作流程中表征裂缝网络。 这项研究提出了一种新颖的综合方法，用于分析低渗透多孔介质中的多相流和流体分布，其中裂缝网络（即水力裂缝和微裂缝）同时存在于多个尺度上。这项研究将彻底改变当前主要关注分析模型的实践，分析模型通常忽略多相效应，以及有限体积/有限差分模拟，而这些模拟不处理与致密/页岩储层相关的裂缝配置的复杂性。模型质量的损失使得数值模拟中裂缝系统的描述不完整，并且从动态数据推断裂缝特征具有挑战性。许多熟悉非常规油藏开发最新研究的工业从业者表示需要更复杂的方法来分析和建模这些油藏。预计随着计算技术的快速进步，有利于当前实践的计算负载正在消失，并且计算密集型技术（例如本提案中开发的技术）可以在不久的将来在商业代码中实现。结果将影响我们优化压裂设计的能力，这也是地热能开发的一个重要考虑因素。