裂缝性漏失地层可固化堵漏工作液技术研究

发布时间：2018-06-29 16:35

本文选题：井漏 + 裂缝性漏失地层　；参考：《西南石油大学》2017年硕士论文

【摘要】：井漏是石油行业非常严重的问题之一。井漏一旦发生,轻则影响钻井时间,堵漏耗费大量人力物力,重则引发一系列连锁反应,最终可能导致安全事故,而裂缝性漏失则是井漏中影响最深远,后果最严重,后期反复漏失的情况也更加普遍的一种。因此开展裂缝性漏失地层的研究,控制甚至解决漏失问题势在必行。论文首先在分析影响裂缝性地层漏失内外因的基础上,得出了"以堵为防"的结论。针对目前裂缝性地层堵漏技术的不足,要实现漏层裂缝的封堵,工作液必须具有物理封堵、滞留漏层裂缝以及固化胶结裂缝这三个功能。并根据这三个功能提出了工作液应具有受钻井液污染少,能形成有效桥塞,泵送过程容易流动、施工结束停泵一段时间后不易流动,以及固化胶结裂缝这四个特点。接着根据工作液的特点,研究了可固化堵漏工作液的堵漏机理。借鉴桥塞堵漏,根据裂缝宽度的不同,形成了工作液的物理封堵裂缝机理,并选用了两种桥塞堵漏材料,使得工作液对于1-2mm的裂缝能承压6MPa以上。研究了工作液滞留裂缝的机理(强触变性),并选用了触变剂,使得工作液拥有非常强的滞留能力。采用矿渣+硅藻土的固化剂组合赋予了工作液固化胶结裂缝的能力,并使用TG、水化热、XRD、SEM以及EDS等测试手段,研究清楚了工作液的固化机理;研究表明工作液固化体主要成分为层状堆叠的棒状Ⅰ型C-S-H(水化硅酸钙),其中有部分Si4+被Al3+取代。然后根据工作液性能稳定的需要,又选用了悬浮稳定剂、加重剂和分散剂,并以工作液的常温流动度、密度和固化体的抗压强度为研究对象,通过不同条件下三者的差异,优选出一套符合设计特点的密度1.3g/cm3-2.1g/cm3的可固化堵漏工作液。最后对工作液的各项工程性能进行了评价。工作液的稠化时间均≥360min,能够适合大多数堵漏施工情况。通过钻井液污染实验发现,钻井液会降低工作液的常温流动度和抗压强度,同时也会延长工作液的固化时间,但能通过激活剂的用量进行调整。通过高温高压漏失地层模拟封堵测试装置,对工作液固化后实际承压能力进行了评价,结果表明1.5 g/cm3密度工作液2d有7.8MPa的实际承压能力,且实际承压能力与抗压强度呈正相关。再结合1d、2d和7d的抗压强度对长期承压能力进行了评价,结果表明工作液固化后的强度随着时间的增加会不断提高,其长期承压能力能够得到保证。论文的研究成果既为后来的研究者提供了理论参考,又为堵漏施工的成功和地层长期承压能力提供了保障,对有效控制甚至解决裂缝性地层漏失问题具有深远的意义。
[Abstract]:Well leakage is one of the most serious problems in the oil industry. Once the well leakage occurs, the light will affect the drilling time, the plugging will cost a lot of manpower and material resources, and the heavy will lead to a series of chain reactions, which may eventually lead to safety accidents. However, the fractured leakage is the most far-reaching impact and the most serious consequence in the well leakage. Late repeated leakage is also more common. Therefore, it is imperative to study, control and even solve the problem of fractured loss strata. Firstly, based on the analysis of internal and external causes of fractured formation leakage, the conclusion of "taking plugging as precaution" is obtained. In view of the deficiency of the current fractured formation plugging technology, the working fluid must have three functions of physical plugging, residual leakage layer fracture and solidified cemented fracture in order to realize the sealing of the leakage layer fracture. According to these three functions, it is suggested that the working fluid should be less polluted by drilling fluid, can form effective bridge plug, easy to flow in pumping process, difficult to flow after the end of construction, and solidified the cementation crack. Then, according to the characteristics of the working fluid, the plugging mechanism of the solidifiable working fluid is studied. Based on the leakage plugging of bridge plug, the physical sealing mechanism of working fluid is formed according to the difference of crack width, and two kinds of bridge plug plugging materials are selected. The working fluid can bear the pressure above 6 MPA for the fracture of 1-2mm. The mechanism of the working fluid retention crack (strong thixotropy) is studied and the thixotropic agent is selected to make the working fluid have a very strong retention capacity. The curing agent combination of slag diatomite was used to give the working liquid the ability to solidify the cementation crack, and the curing mechanism of the working liquid was studied by means of TG, XRDX SEM and EDS. The results show that the main composition of the working liquid solidified body is a layered stacked rod-like C-S-H (calcium silicate hydrate) in which part of Si4 is replaced by Al3. Then according to the need of stable performance of working fluid, suspension stabilizer, weight agent and dispersant are selected, and the fluidity at room temperature, density and compressive strength of solidified liquid are taken as the research objects. A set of solidifiable working fluid with density 1.3g/cm3-2.1g/cm3 suitable for design characteristics was selected. Finally, the engineering performance of the working fluid is evaluated. The thickening time of the working fluid is more than 360 min, which is suitable for most construction conditions. It is found that the drilling fluid can reduce the fluidity and compressive strength of the working fluid at room temperature and prolong the curing time of the working fluid, but it can be adjusted by the amount of activator. The actual pressure bearing capacity of the working fluid after solidification was evaluated by using the high temperature and high pressure leakage formation simulation plugging test device. The results show that the working fluid with 1.5 g/cm3 density has an actual pressure bearing capacity of 7.8 MPA for 2 days, and the actual pressure bearing capacity is positively related to the compressive strength. Combined with the compressive strength of 1 d ~ 2 d and 7 d, the long-term compressive capacity was evaluated. The results show that the strength of the working liquid after solidification increases with time, and the long-term compressive capacity can be guaranteed. The research results not only provide a theoretical reference for the later researchers, but also provide a guarantee for the success of the plugging construction and the long-term bearing capacity of the formation. It is of far-reaching significance to effectively control and even solve the problem of fractured formation leakage.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE28

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