Experimental Investigation and Subsequent Modeling of the Cement Microstructure and Integrity of Cement/Casing and Cement/Formation Interfaces Under Downhole Stress Conditions

井下应力条件下水泥微观结构和水泥/套管和水泥/地层界面完整性的实验研究和后续建模

• 批准号: RGPIN-2022-02956
• 负责人: Kuru, Ergun
• 金额: $ 2.84万
• 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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=761100
• 关键词: Experimental; Investigation; Subsequent; Modeling; Cement

Methane is a potent greenhouse gas (GHG) that is 25 times more powerful than carbon dioxide. In Canada, methane emissions make up about 15% of all GHG emissions. Upstream oil and gas facilities are Canada's largest industrial emitters of methane, releasing 44% of the country's total methane emissions. Within the upstream oil and gas industry, a significant fraction of methane emission results from fugitive leaks arising from surface casing vent flow (SCVF) and gas migration (GM). Bulk cement, as well as cement/casing and casing /rock interfaces, are likely to be the weak spots in oil and gas wells in terms of leakage and long term well integrity. Debonding of cement from casing and/or formation, and subsequent loss of zonal isolation, is a significant contributor to fugitive methane emissions from SCVF and GM in oil and gas wells. Understanding the mechanisms of leakage pathway formation is crucial for assessment and improvement of cement performance in oil and gas wells - whether the wells are producing or plugged and abandoned. Comprehensive experimental and numerical studies of the mechanisms of cement failure and debonding, and how these impact fluid movement through the cement microstructure, are therefore proposed. An Advanced Wellbore Simulator capable of investigating flow through cemented wellbore sections under realistic downhole conditions (i.e. 43 MPa and 120 °C) will be used to investigate the integrity of the cement body, as well as the cement/casing interfaces, under representative downhole stress conditions (i.e., cyclic pressure and thermal stress conditions). Nano-CT based digital image processing of downscaled samples simulating cement body and various interface conditions (e.g., cement-casing, cement-rock) will be used to analyze the effect of downhole stress conditions. This technique will be combined with a computational fluid dynamic modelling of formation fluid flow through the 3D microstructures of the samples. Together, this new methodology will assess the permeability of cemented wellbore sections, which represent potential microscale leakage pathways in a well. The experimental investigation and numerical model study proposed in this project will result in an improved understanding of the drivers behind fluid leakage (i.e. stresses creating microchannels along the cement/casing, cement/borehole interfaces and microfractures within the cement body). The results will allow for the design and development of new, more reliable barrier technologies that can be used for more cost-effective mitigation of fugitive methane emissions. As part of the Pan-Canadian Framework on Clean Growth and Climate Change, the Government of Canada reaffirmed its commitment to reduce GHG emissions 40-45% below 2012 levels by 2025. The proposed research is, therefore, well aligned with strategic direction of the Government of Canada's efforts to reduce GHG.

甲烷是一种潜在的温室气体（GHG），其功能是二氧化碳的25倍。在加拿大，甲烷排放量约占所有温室气体排放的15％。上游石油和天然气设施是加拿大最大的甲烷工业发射器，释放了该国甲烷总排放量的44％。在上游的石油和天然气行业中，甲烷排放的很大一部分是由于表面壳体通风口流量（SCVF）和气体迁移（GM）引起的逃逸泄漏引起的。就泄漏和长期井的完整性而言，散装水泥以及水泥 /套管和壳体 /岩石界面可能是油气井的弱点。从壳体和/或形成中剥离水泥，以及随后的区域隔离损失，是油气井中SCVF和GM的逃亡甲烷排放的重要原因。了解形成泄漏途径的机制对于评估和改善石油和天然气井的水泥性能至关重要 - 无论井正在生产，堵塞和堵塞。因此，提出了有关水泥衰竭和脱键机制的全面实验和数值研究，以及这些如何影响通过水泥微观结构的流体运动。一个能够在逼真的井下条件下（即43 MPa和120°C）调查流动的高级孔孔模拟器将用于研究水泥体的完整性，以及水泥/壳体界面的完整性，以及在代表下压力条件下（即环状压力和热压力条件）。基于纳米-CT的数字图像处理模拟水泥体和各种界面条件（例如水泥粘合，水泥岩石）的数字图像处理将用于分析井下应力条件的影响。该技术将与通过样品的3D微结构的地层流动流的计算流体动力学建模相结合。总之，这种新方法将评估胶结孔切片的渗透性，这代表了井中潜在的微观泄漏途径。该项目提出的实验投资和数值模型研究将使人们对流体泄漏背后的驱动因素有了改进的了解（即，在水泥/壳体，水泥/钻孔界面和水泥体内的微骨架上产生微通道的压力）。结果将允许设计和开发新的，更可靠的障碍技术，这些技术可用于更具成本效益的逃亡甲烷排放。作为加拿大泛加拿大泛美框架的一部分，加拿大政府在2025年之前重申了其减少温室气体排放量低于2012年水平的40-45％的承诺。因此，拟议的研究与加拿大政府的战略方向相吻合。