A Comprehensive Study of the Combined Effects of Drilling Fluid Rheological Properties and Near Wall Turbulence on the Particle Removal From Bed Deposits in Horizontal Wells

钻井液流变特性和近壁湍流对水平井床层沉积物颗粒去除的综合影响

• 批准号: RGPIN-2016-04647
• 负责人: Kuru, Ergun
• 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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=682025
• 关键词: Comprehensive; Study; Combined; Effects; Drilling

When drilling long horizontal wells, drilled solids tend to settle down on the low side of the wellbore and form a stationary bed. Presence of stationary cuttings bed causes operational difficulties such as pack-off, excessive torque and drag, slow drilling rate, and in severe cases, stuck pipe, lost circulation, and even loss of the well control. Occasionally, drilling must stop to clean the stationary bed, which is an expensive process and must be done in a timely manner. Despite significant progress made in drilling fluids, tools, and field practices, along with more than 50 years of university and industry research, field experience indicates that hole cleaning is still a major problem in most horizontal wells. The primary motivation of this study is the lack of a reliable model for optimizing hole cleaning process.******As part of the systematic efforts to develop a unified theory of hole cleaning, a comprehensive research plan is proposed here, which calls for experimental investigation of: i-) the near bed turbulence and how it relates to particle removal from bed deposits ; ii-) how the critical flow rate for the particle removal from bed deposits and bed erosion rate change with drilling fluid shear viscosity, gel strength, elastic stresses and other viscoelastic properties. ******Hole cleaning experiments will be conducted using a 9m long horizontal flow loop with concentric annular geometry (Outer Pipe ID= 95 mm, Inner Pipe OD= 38 mm). State of the art flow visualization techniques, Particle Image Velocimetry and Particle Tracking Velocimetry, will be used to determine local fluid and solid particle velocities. ******In addition, a Computational Fluid Dynamic (CFD) simulation study will be conducted to model the cuttings removal from the bed deposits. Specific objectives in this case are to: i-) Develop a CFD model of multiphase solid/liquid flow in horizontal well; ii-) Use the CFD model as a tool for upscaling results from lab to field scale; iii-) Use the CFD model for predicting time required for hole cleaning under given operational conditions and determine best combination of drilling fluid flow rate and rheological properties for minimum hole cleaning time. ******The number of horizontal wells drilled has dramatically increased over the past decades, however, hole cleaning still remains a challenge especially when drilling long horizontal sections. Efficient hole cleaning strategies need to be developed to reduce time associated with well cleaning. The shorter the hole cleaning time, the more time can be spent on actual drilling and, as a result, the drilling cost can be reduced significantly. Delivering an oil well at lower costs is essential in ensuring accessibility of reserves, which otherwise are not economically sound to exploit. Industry's capacity to operate safely and economically will benefit tremendously from a full-scale experimental and numerical research such as the one proposed in this study.**

当钻长水平威尔斯井时，钻取的固体倾向于沉降在井筒的下侧并形成固定床。固定岩屑床的存在会导致操作困难，例如封隔、过大的扭矩和阻力、缓慢的钻井速度，并且在严重的情况下，会导致卡管、井漏，甚至失去井控。有时，钻井必须停止以清洁固定床，这是一个昂贵的过程，必须及时完成。尽管在钻井液、工具和现场实践方面取得了显著进展，沿着超过50年的大学和工业研究，现场经验表明，井眼清洁仍然是大多数水平威尔斯中的主要问题。这项研究的主要动机是缺乏一个可靠的模型来优化孔清洁过程。**作为发展孔清洗统一理论的系统努力的一部分，本文提出了一个全面的研究计划，它要求实验研究：i）近床湍流及其与床层沉积物中颗粒去除的关系; ii-）从床沉积物中去除颗粒的临界流速和床侵蚀速率如何随钻井液剪切粘度，凝胶强度，弹性应力和其它粘弹性。** 将使用具有同心环形几何形状（外管ID= 95 mm，内管OD= 38 mm）的9 m长水平流动回路进行孔清洁实验。最先进的流动可视化技术，粒子图像测速和粒子跟踪测速，将用于确定当地的流体和固体颗粒的速度。** 此外，将进行计算流体动力学（CFD）模拟研究，以模拟从床层沉积物中清除钻屑。在这种情况下的具体目标是：i-）开发水平井中的多相固体/液体流动的CFD模型; ii-）使用CFD模型作为将结果从实验室规模升级到现场规模的工具; iii-）使用CFD模型来预测在给定操作条件下井眼清洁所需的时间，并确定钻井液流速和流变性质的最佳组合以获得最小的井眼清洁时间。** 在过去几十年中，水平威尔斯钻井的数量急剧增加，然而，井眼清洁仍然是一个挑战，特别是在钻长水平段时。需要开发有效的井眼清洁策略以减少与井清洁相关的时间。清孔时间越短，实际钻孔所花费的时间就越多，因此，可以显著降低钻孔成本。以较低的成本交付油井对于确保储量的可获得性至关重要，否则开采这些储量在经济上是不合理的。工业安全和经济运行的能力将极大地受益于全面的实验和数值研究，如本研究中提出的研究。