水平井段岩屑瞬态运移规律研究

发布时间：2018-12-07 19:45

【摘要】：钻井液携岩效率的高低直接影响一口井钻井的好坏。国内外许多学者通过研究岩屑在不同井斜角下的岩屑运移规律以及现场实践表明,在大斜度井段和水平井段由于钻井液携岩效率低,环空岩屑向井眼低边不断沉积形成岩屑床,如果沉积在下井壁的岩屑床不能得到及时的清洁和控制,就会带来许多严重的问题,这些问题主要包括:憋泵、粘附卡钻、高摩阻、高扭矩、严重时甚至造成钻具断裂脱落等井下安全事故,甚至最终导致整个井眼报废,所以对于大位移井和水平井的大斜度井段和水平井段来说,钻井液携岩效率问题不仅具有理论意义,而且具有重要的现实指导意义,因此本文主要研究了水平井段的岩屑瞬态运移规律,建立了相应的理论数学模型,并做了大量的实验对模型的可靠性加以验证。类比于泥沙休止角的定义,通过对岩屑床下滑运动的描述,定义了岩屑床休止角,并基于楔入堆积模型及床面岩屑颗粒受力模型,建立了静水条件下岩屑床休止角计算模型,为大斜度井段与水平井段的划分提供依据。在固液两相流理论及原有稳定分层携岩模型的基础上,通过对水平井段环空岩屑运移规律的研究,对水平井段岩屑在不同工况下分布状态做了进一步的划分,并建立了不同分布状态下所对应的数学模型,并主要针对稳定三层模型进行了编程求解。基于岩屑床面颗粒的位置随机性分布分研究,建立了岩屑颗粒相对沉陷度的随机分布函数,又因为可以在起动临界流速和颗粒沉陷度之间建立联系,进而可根据其概率分布函数建立起临界起动流速与床层表面颗粒起动百分数之间的定量关系。
[Abstract]:The drilling efficiency of drilling fluid directly affects the drilling quality of a well. Many scholars at home and abroad have studied the cuttings migration law at different inclined angles and the field practice shows that because of the low drilling fluid carrying efficiency, the annulus cuttings are continuously deposited to the low side of the borehole to form cuttings bed. If the cuttings bed deposited on the bottom wall is not cleaned and controlled in a timely manner, there will be many serious problems. These problems mainly include: holding pump, sticking drill, high friction, high torque, When it is serious, it even results in downhole safety accidents, such as drilling tool fracture and falling off, and even leads to the whole hole being abandoned. So for the large deviated and horizontal sections of extended reach wells and horizontal wells, The problem of drilling fluid carrying efficiency is not only of theoretical significance, but also of practical guiding significance. Therefore, this paper mainly studies the cuttings transient migration law in horizontal well section, and establishes the corresponding theoretical mathematical model. A large number of experiments have been done to verify the reliability of the model. Analogous to the definition of sediment angle of repose, by describing the sliding movement of cuttings bed, the angle of repose of cuttings bed is defined. Based on the wedge accumulation model and the stress model of debris particles on the bed surface, the calculation model for the angle of repose of cuttings bed under hydrostatic conditions is established. It provides the basis for the division of large deviated well section and horizontal well section. On the basis of the theory of solid-liquid two-phase flow and the original stable stratified rock carrying model, the distribution of cuttings in horizontal well under different working conditions is further divided by the study of the regularity of cuttings migration in annulus in horizontal well section. The corresponding mathematical models in different distribution states are established, and the stable three-layer model is mainly solved by programming. Based on the study of the random distribution of the position of the debris particles on the bed surface, a random distribution function of the relative subsidence degree of the debris particles is established, and the relation between the starting critical velocity and the particle subsidence degree can be established. According to its probability distribution function, the quantitative relationship between the critical starting velocity and the starting percentage of the bed surface particles can be established.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE243

【相似文献】