水基钻井液泥饼的增强方法及机理研究

发布时间：2018-09-02 06:30

【摘要】：油井钻井后,在井壁和套管壁上会形成一定厚度的、强度较差的泥饼。泥饼的存在引起井壁和套管壁与水泥浆之间无法良好固化胶结,最终导致固井界面胶结强度下降,严重影响固井质量。本文以改善泥饼性能、提高油井固井质量为目的,以提高泥饼强度、改善泥饼与水泥石的相容性为出发点,以泥饼在水泥滤液中的硬化机理为理论基础,研究了一种有效增加泥饼强度的泥饼改性方法(GX),检验了GX方法对泥饼的改性效果及对固井界面胶结强度的增强效果,并分析了GX法的泥饼改性机理。主要研究结果如下:1.通过分析养护温度、养护时间、水泥滤液中离子对泥饼的作用过程,结合粘土的水化机理建立了水泥滤液对泥饼的作用机制模型。研究发现:养护温度越高,养护时间越长,泥饼强度越大;水泥滤液中,Ca~(2+)、CO32-、OH-三种离子对泥饼有不同程度的增强作用,其中Ca~(2+)在碱性条件下可使泥饼强度增大到空白泥饼的707倍;水泥滤液增强泥饼的机制模型为:水泥滤液促进泥饼内部生成凝胶类物质,该物质将分散的粘土颗粒胶连在一起,同时生成的碳酸钙、氢氧化钙、硅酸钙等物质一部分填充在粘土颗粒间,增大了粘土的抗压力,另一部分包覆在粘土颗粒的表面,减小了粘土的水化膨胀量,进而提高泥饼强度。2.以泥饼在水泥滤液中的硬化模型为基础,研究了一种有效改善泥饼性质的方法(GX),并对其作用机理进行了研究。研究发现:GX法可使搬土浆和现场浆的泥饼强度分别提高到原来的32倍和38倍,泥饼性能得到显著改善;GX方法应用于现场浆可使模拟固井一、二界面的胶结强度分别增大到10.58倍和17.54倍;GX方法中泥饼的硬化-活化机理为:硬化剂LXAB首先在粘土颗粒层间进行骨架支撑,提高泥饼抵抗地层压力的能力,然后活化剂中QX-1破坏粘土表面的Si-O-Si、Al-O-Al、Si-O-Al键,打开泥饼孔道,并生成游离硅,接下来QX-2将游离硅相互结合并形成凝胶物质,粘结粘土颗粒,最后利用QX-3诱导水泥滤液中的离子进入泥饼内部,进一步生成大量C-S-H凝胶、氢氧化钙、碳酸钙等物质,这些类似水泥水化产物物质的生成,增加了泥饼的致密度,提高了泥饼强度,改善了泥饼与固井水泥的相容性。
[Abstract]:After drilling, a certain thickness of mud cake is formed on the well wall and casing wall. Due to the existence of mud cake, the cementing strength of the cementing interface decreases and the cementing quality is seriously affected by the failure of solidification between the well wall and the casing wall and the cement slurry. The purpose of this paper is to improve the performance of mud cake and the cementing quality of oil well, to improve the strength of mud cake, to improve the compatibility between mud cake and cement stone, and to take the hardening mechanism of mud cake in cement filtrate as the theoretical basis. A mud cake modification method, (GX), which can effectively increase the strength of mud cake, was studied. The modification effect of GX method on mud cake and cementing strength at cementing interface was tested. The mechanism of mud cake modification by GX method was analyzed. The main results are as follows: 1. Based on the analysis of curing temperature, curing time and the action process of ions on mud cake in cement filtrate, the mechanism model of cement filtrate acting on mud cake was established in combination with the hydration mechanism of clay. It is found that the higher the curing temperature, the longer the curing time, the greater the strength of mud cake, and the more enhanced the mud cake is by three kinds of ions (Ca2 ~ (2) CO32-OH-) in cement filtrate. Ca~ (2) can increase the strength of mud cake to 707 times that of blank cake under alkaline condition, and the mechanism model of cement filtrate enhancing mud cake is that cement filtrate can promote the formation of gel material inside the cake, which connects the dispersed clay particles together. The formation of calcium carbonate, calcium hydroxide, calcium silicate and other substances partly filled between clay particles, increased clay pressure resistance, the other part coated on the surface of clay particles, reducing the amount of clay hydration expansion, Therefore, the strength of mud cake was increased by 2. 2. Based on the hardening model of mud cake in cement filtrate, an effective method for improving the properties of mud cake, (GX), was studied and its mechanism was studied. It is found that the mud cake strength of the lifting slurry and the field slurry can be increased by 32 times and 38 times of the original mud cake strength, respectively. The performance of mud cake can be significantly improved by using the GX method in the field slurry to simulate cementing. The cementing strength of the two interfaces is increased to 10.58 times and 17.54 times respectively. The hardening and activation mechanism of the mud cake in the GX method is as follows: the hardener LXAB first carries out skeleton support between the clay particles to improve the clay cake's ability to resist formation pressure. Then the QX-1 in the activator breaks the Si-O-Si,Al-O-Al,Si-O-Al bond on the clay surface, opens the mud cake hole, and generates free silicon. Then QX-2 binds the free silicon to form the gel material, which binds the clay particles. Finally, QX-3 was used to induce the ions in the cement filtrate to enter into the mud cake and to produce a large amount of C-S-H gel, calcium hydroxide, calcium carbonate and other substances, which were similar to the formation of cement hydration products, which increased the density of the mud cake. The strength of mud cake is improved and the compatibility of mud cake and cementing cement is improved.
【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】：TE254

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