固井水泥浆过渡态演变与浆柱传压能力关系研究

发布时间：2018-01-05 01:21

本文关键词：固井水泥浆过渡态演变与浆柱传压能力关系研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：在固井作业中,常由于水泥浆的静液压力降低而引起一些意想不到的工程事故,轻则降低固井质量,重则引起井喷等严重事故。水泥浆作为一种时变性浆体,在整个硬化阶段将经历从液态、过渡态到固态的结构演变,从而导致水泥浆的性能和传压能力发生改变。因此,本研究利用XRD、TG/DTG、热活性微量热仪、ESEM、EDS、表面积测试及孔径分析仪以及大量的自研设备和方法,从材料科学的角度探究固井水泥浆在前期硬化阶段的性能和结构演变及静液压力降低的机理。实验结果发现,在不同体系水泥浆的水化过程中静液压力降低均会出现,且其受水泥浆沉降稳定性、水化反应速率等的影响。当固井水泥浆开始进入液-固态转变(过渡态)时,水泥浆的静液压力将快速降低。在此阶段水泥浆的水化反应速率加速、生成大量的氢氧化钙(Ca(OH)2)、水化硅酸钙(C-S-H)等水化产物,水泥颗粒的比表面积快速增加,大量的自由水转变成了毛细水和凝胶水。结合超声波技术和ESEM分析过渡态水泥浆的内部结构发现,水泥浆进入过渡态之前,水泥浆以颗粒堆积体的形式存在,仅在水泥颗粒表面形成了一层水化产物壳。当水泥浆处于过渡态时,水化反应加速使水泥颗粒溶解,当孔隙溶液达到饱和状态时大量无定形水化产物在颗粒表面形成,使颗粒表面变得粗糙(增加了水泥颗粒的比表面积)。并且由于水泥颗粒的溶解和水化产物在颗粒表面生成同时进行,在水化产物中形成大量的微孔结构,过饱和的孔隙溶液也会在水泥浆的孔隙中形核、长大,填充部分水泥浆孔隙。水泥浆静液压力的传递遵循帕斯卡定律,只有液体溶液能够有效传递静液压力。而当水泥浆体系的沉降稳定较差时颗粒难于悬浮在孔隙溶液中,而导致其重力较难传递,从而引起传递静液压力的介质密度降低,降水泥浆的静液压力。随着水化反应的进行,当水泥浆处于过渡态时,水泥浆中生成大量的细小孔隙,导致原本用于传递静液压力的自由水溶液转变成了束缚力更强的毛细水、凝胶水等,减少了水泥浆的传压介质。由于部分孔隙被水化产物填充,减少了水泥浆孔隙溶液的高度,导致水泥浆的静液压力降低,甚至损失。
[Abstract]:In cementing operation, often due to cement slurry hydrostatic pressure decrease caused by some unexpected accidents, it will decrease the cementing quality, weight is caused by a serious accident. The blowout cement slurry as a time-varying slurry, the hardening stage will experience from liquid to solid transition state structure evolution, thus lead to performance of the cement slurry and the pressure transmitting ability change. Therefore, this study uses XRD, TG/DTG, thermal activity of micro calorimeter, ESEM, EDS, surface area and pore size analyzer and a large number of research equipment and methods, explore the mechanism of cement slurry evolution and hydrostatic pressure to reduce the performance and structure in the early stage of atherosclerosis from the view of material science. The experimental results show that the hydrostatic pressure in the hydration process of cement slurry in different systems will be reduced, and the cement slurry sedimentation stability, affect the hydration rate when solid. Water mud began to enter the liquid - solid state transformation (transition state), hydrostatic pressure of cement slurry will decrease quickly. At this stage the hydration rate of cement slurry accelerated, generating large amounts of calcium hydroxide (Ca (OH) 2), calcium silicate hydrate (C-S-H) hydration products, cement particle surface the area increased rapidly, a large number of free water into the capillary water and water gel. Found that the internal structure of the combination of ultrasonic technology and ESEM analysis of the transition state of cement slurry, cement slurry before entering the transition state, the cement slurry to the particle accumulation existed only in the cement particle surface to form a layer of hydration products when the shell. Cement slurry in the transition state, to accelerate the hydration reaction of cement particles dissolved when the pore solution saturated bulk amorphous hydration products formed on the surface of the particle, the particle surface roughness (an increase of cement particle surface area) and because. The dissolution and hydration products of cement particles were generated in the particle surface, the microporous structure formed of hydration products, pore solution supersaturated also in cement slurry in the pore nucleation, growth, partially filled with cement slurry pore. Cement slurry hydrostatic transmission according to Pascal's law, only the liquid the solution can effectively transfer the hydrostatic pressure. When the poor stability of settlement of cement slurry particle is suspended in the pore solution, due to the gravity is difficult to transfer, resulting in medium density transfer hydrostatic pressure decreases, the hydrostatic pressure of mud precipitation. With the hydration reaction of cement slurry in the transition, when state, a large number of generated pores in the cement slurry, leading to the original for free water solution change transfer hydrostatic pressure into the capillary water binding, gel water, reducing the cement slurry pressure medium. The pore is filled with the hydrated product, which reduces the height of the pore solution of the cement slurry, which leads to the decrease of the hydrostatic pressure and even the loss of the cement slurry.

【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】：TE256.6

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