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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=656152
• 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.**

钻长的水平井时，钻孔固体往往会在井眼的低侧沉降，并形成固定的床。固定剪裁床的存在会造成操作困难，例如包装，过度扭矩和拖动，缓慢的钻孔速率，并且在严重的情况下，固定管，循环丢失，甚至无法控制井的控制。有时，钻孔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，工具和现场实践以及超过50年的大学和行业研究方面取得了重大进展，但现场经验表明，在大多数水平井中，孔清洁仍然是一个主要问题。这项研究的主要动机是缺乏可靠的模型来优化孔清洁过程。******作为制定统一的孔清洁理论的系统努力的一部分，这里提出了一项全面的研究计划，该计划要求进行实验研究：i-）近床湍流及其与粒子从床位矿床中的关系如何相关； ii-）颗粒从床沉积物中去除粒子的临界流量如何随着钻井液剪切粘度，凝胶强度，弹性应力和其他粘弹性特性而变化。 ******将使用带有同心环形几何形状的9m长的水平流动环（外管ID = 95 mm，内管道OD = 38 mm）进行孔清洁实验。最先进的可视化技术，粒子图像速度法和粒子跟踪速度法将用于确定局部流体和固体粒子速度。 ******此外，还将进行一项计算流体动力学（CFD）模拟研究，以模拟从床沉积物中的剪切清除。在这种情况下，特定目标是：i-）在水平井中开发多相固体/液体流的CFD模型； ii-）使用CFD模型作为用于从实验室到现场尺度的升级结果的工具； iii-）使用CFD模型预测在给定的操作条件下孔清洁所需的时间，并确定钻孔流体流量和流变学特性的最佳组合，以在最小的孔清洁时间内。 ******在过去的几十年中，钻井的水平井数量已大大增加，但是，孔清洁仍然是一个挑战，尤其是在钻长的水平水平部分时。需要制定有效的孔清洁策略，以减少与清洁井相关的时间。孔清洁时间越短，可以花费更多的时间来进行实际的钻孔，从而可以大大降低钻孔成本。以较低的成本交付油井对于确保储量的可及性至关重要，否则在经济上并不是一个可以利用的储备。行业安全和经济运营的能力将从全面的实验和数值研究中受益匪浅，例如本研究中提出的研究。**