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.

由于全世界的资源估计很大，近年来，非常规紧身或页岩储层的开发受到了很多关注。钻有多阶段液压压裂的水平井，以增强储层接触面积并达到经济生产率。如果由于现有裂缝的存在，液压裂缝可以连接到甜点，则这种刺激技术尤其有效。紧密/页岩储层可以被概念化为具有两个不同子系系统的双中间：矩阵和断裂。由于其渗透性的高对比度，这两个系统中流量的时间尺度显着差异。矩阵的原位渗透性非常低，而断裂是局部不连续性，具有很高的渗透性。裂缝可以很大，可以围绕井眼（例如液压裂缝）或小，并且位于刺激区域（例如微断裂）。应当指出的是，该提案的重点是页岩/紧密的油/天然气储层的原位开发，而没有考虑油页岩的地面采矿。 总体目的是开发一套适合（1）使用基于有限元素的技术模拟离散裂缝中多相流的数值模型的套件； （2）捕获在不同尺度上发生的裂缝的影响； （3）整合动态数据（例如，流量和压力测量值），以在强大的历史匹配工作流程中表征断裂网络。 这项研究提出了一种新型的综合方法，用于在低渗透性多孔介质中分析多相流量和流体分布，其中断裂网络（即液压骨折和微断裂）同时存在于多个尺度上。这项研究将彻底改变当前的实践，该实践主要集中在分析模型上，这些模型通常忽略了多相效应，以及有限体积/有限差异模拟，这些模拟无法处理与紧密/页岩储层有关的裂缝配置中的复杂性。模型质量的这种丢失使数值模拟中断裂系统的描述不完整，而动态数据挑战性的断裂特征的推断。许多熟悉非常规储层开发研究的最先进研究的工业从业人员都表示需要采用更复杂的方法来分析和建模这些储层。可以预期，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，并且可以在不久的将来在商业代码中实施更多计算密集型技术，例如在本提案中开发的技术。结果将影响我们优化断裂设计的能力，这也是地热能源开发的重要考虑因素。