库车山前固井下套管防漏失技术研究

发布时间：2018-06-17 01:51

本文选题：库车山前 + 固井　；参考：《西南石油大学》2015年硕士论文

【摘要】：井漏是一种钻井中较为常见的井下复杂情况,井漏不仅会延长钻井周期,损失大量人力物力,造成储层损害,而且井漏一旦控制不力,还可能会诱发井塌、井喷等重大事故。在固井下套管的过程中发生井漏,会直接导致固井作业不能正常进行,严重影响固井质量,给后期的开采埋下隐患。下套管中的井漏主要发生在套管下放和下至井底后开泵循环过程中,论文从库车山前区域地质条件、常用井身结构、常用钻井液性能和固井下套管工艺等方面分析井漏的影响因素,发现目前库车山前区域设计套管下放速度和循环排量(包括套管下放过程中和下至井底后的循环)以等返速条件法为主,忽略了地层承压能力、钻井液性能和环空间隙的影响,由环空间隙和钻井液性能的变化可能造成设计结果与井下情况存在偏差,进而引发井漏。准确获取地层承压能力值是防漏失设计的基础,目前常用的地层承压能力预测模型方法在库车山前区域并不适用,最准确的获取方法为地层承压能力试验,对于不能做地层承压能力试验的井,提出采用摩阻判断法；钻井液的流变性能会影响钻井液在流动过程中产生激动压力的大小,室内实验研究了塑性粘度随温度变化的规律,并建立了预测模型；通井作业不充分导致井径不规则也会使下套管的过程中产生额外的激动压力；在井漏影响因素分析的基础上,以平衡井下激动压力与地层承压能力的原则上建立了套管下放速度和循环排量的计算模型,模型中考虑了地层承压能力、环空间隙的变化以及钻井液的流变性能,并将塑性粘度由常规使用的某一定量替换为随井深而变化的变量,使得计算结果更加接近井下情况。论文基于研究成果结合库车山前区域工况建立了一套主要包括通井、钻井液流变性能要求和下套管速度与循环排量设计的下套管防漏失工艺技术,并在库车山前区域K1井进行了现场应用,该井在正常钻进过程中多次发生漏失,井底为易漏失点,多次进行堵漏后承压能力仍然较低,若施工过程不当极易发生井漏；整个施工过程顺利,没有发生漏失,准确预测了漏失临界循环排量,验证了该工艺技术具有一定的现场指导意义。
[Abstract]:Well leakage is a common downhole complex condition in drilling. Well leakage can not only prolong the drilling cycle, lose a lot of manpower and material resources, and cause reservoir damage, but also may induce serious accidents such as well collapse and blowout once the well leakage is not well controlled. During the process of downhole casing cementing, well leakage will lead directly to the failure of cementing operation, which will seriously affect the cementing quality and bury hidden trouble in the later stage of production. The well leakage in casing mainly occurs in the process of casing down and back pump circulation from bottom to bottom. From the geological conditions in front of Kuqa Mountain, the structure of well body is commonly used in this paper. Commonly used drilling fluid performance and downhole casing technology, etc., to analyze the factors affecting well leakage, It is found that the current design of casing down-flow velocity and circulation discharge (including the circulation from down-hole to bottom hole) in Kuqa Piedmont region is dominated by the method of equal return velocity condition, and the influence of formation pressure bearing capacity, drilling fluid performance and annulus clearance is neglected. The variation of annulus clearance and drilling fluid performance may cause the deviation between the design result and the downhole condition, and then lead to the well leakage. Accurate determination of bearing capacity is the basis of leakage prevention design. At present, the commonly used prediction model of formation bearing capacity is not applicable in Kuqa Piedmont area. The most accurate method is the formation bearing capacity test. For wells which can not be tested for bearing capacity of formation, the method of judging friction resistance is put forward, the rheological properties of drilling fluid will affect the magnitude of the exciting pressure produced by drilling fluid during the flow process, and the law of plastic viscosity varying with temperature is studied in laboratory. The prediction model is established, the irregular well diameter caused by inadequate well opening operation will also cause additional exciting pressure in the process of casing downhole, and on the basis of the analysis of the influencing factors of well leakage, Based on the principle of balancing downhole excited pressure with formation pressure bearing capacity, the calculation model of casing downhole velocity and circulation displacement is established. The formation pressure bearing capacity, the change of annulus clearance and the rheological properties of drilling fluid are considered in the model. The plastic viscosity is replaced by the variable with the depth of the well from a certain amount of the conventional viscosity, which makes the calculation result closer to the downhole condition. Based on the research results and the working conditions of Kuqa Piedmont region, a set of casing leakage prevention technology is established, which mainly includes the flow performance requirements of through wells, drilling fluid rheological properties and casing speed and circulation displacement design. The field application of K1 well in front of Kuqa mountain area has been carried out. The well has been lost many times during normal drilling, the bottom hole is easy to leak, and the pressure bearing capacity is still low after several times plugging leakage. If the operation process is not proper, the well leakage will occur easily. The whole construction process was smooth and no leakage occurred. The critical circulation discharge of leakage was accurately predicted, and it was verified that the technology had certain guiding significance on the spot.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE28

【参考文献】