基于胶凝态水泥浆性能的防气窜能力评价方法研究

发布时间：2018-08-04 18:03

【摘要】：环空气窜几乎是所有天然气井固井都存在的一个潜在问题,轻则导致井口环空带压,重则发生不可控井喷事故,严重影响油气井的固井质量和安全。准确评价水泥浆凝结过程中的防气窜能力是有效预防潜在环空气窜风险的关键技术。而现有水泥浆防气窜能力评价预测方法主要考虑了水泥浆失水、胶凝过渡时间等性能,对井底地层、套管等相关特定工况对气窜的影响考虑较少,未能很好地解决环空气窜问题。因此,在现有评价方法的基础上,开展胶凝态水泥浆防气窜性能研究,建立更为综合、全面、可操作性强的防气窜能力评价新方法,对固井环空气窜的预防及防止具有重要意义。本文在水泥浆防气窜能力评价方法现状调研的基础上,从水泥凝结水化机理角度入手分析,提出了固井早期气窜防止的关键性能指标；结合胶凝态水泥浆渗透率研究现状,探索形成了胶凝态水泥浆渗透率实验测试方法,并研发了对应的专用实验测试装置；基于土壤学中有关土壤孔隙度的测试原理,结合水泥水化特性与土壤的异同,探索形成了胶凝态水泥浆孔隙度实验测试方法；在现有研究基础上,推导了初凝前塑性态水泥浆体积收缩与孔隙压力之间的量化关系模型,为井底实际工况条件下的气侵危险时间确定提供了依据；基于气体在环空胶凝态水泥浆本体内的驱替渗流过程,建立了对应的气窜渗流物理数学模型,并建立了基于胶凝态水泥浆性能的防气窜能力评价新方法。本文在基于胶凝态水泥浆性能的防气窜能力评价新方法建立的基础上,进一步将论文所涉及的实验数据处理、模型及评价方法编制成了水泥浆防气窜能力评价软件,增强了该评价方法的可操作性和实用性。本文在实验方法研究,理论研究和软件程序编制的基础上,形成的结论如下： (1)本文结合水泥水化凝结过程及机理分析,提出将静胶凝强度、胶凝态水泥浆渗透率、胶凝态水泥浆孔隙度及水泥浆塑性体积收缩等水化凝结过程中的自身材料物理化学特性作为固井早期气窜防止的关键性能指标。 (2)在胶凝态水泥浆渗透率研究基础上,探索形成胶凝态水泥浆渗透率实验测试方法,并研发了对应的实验测试装置。研究认为水泥浆凝结过程中的渗透率性质呈特定函数下降变化趋势,凝结成水泥石后逐渐趋于稳定。 (3)借鉴土壤孔隙度测试原理,结合水泥水化的特殊性,将土壤孔隙度测试方法进行针对性改进,探索形成胶凝态水泥浆孔隙度测试方法。研究认为初凝前的胶凝态水泥浆孔隙度随时间呈降低趋势,并最终趋于稳定。 (4)从水泥浆初凝前的塑性体积收缩影响孔隙压力下降的角度出发,基于候凝过程中的“套管-水泥浆-地层”物理模型的建立,推导了塑性体积收缩对孔隙压力的影响关系模型。结合泥饼气窜启动压力的测试,研究认为真正意义上的气侵危险时间应是从失重压力平衡点至初凝所经历的时间。 (5)在水泥环本体气窜渗流物理数学模型研究的基础上,建立了水泥浆防气窜能力评价新方法,并编制了水泥浆防气窜能力评价软件。该评价方法可有效结合油气井实际工况参数及胶凝态水泥浆性能,综合评价水泥浆防气窜能力；水泥浆防气窜能力评价软件的编制,增强了该方法的可操作性。
[Abstract]:The annular air channeling is almost a potential problem in all natural gas well cementing. The light leads to the pressure of the wellhead and the uncontrollable blowout accident, which seriously affects the cementing quality and safety of the oil and gas wells. It is the key technology to effectively prevent the risk of the potential air channeling by the accurate evaluation of the anti gas channeling ability in the process of cement slurry condensation. The existing evaluation and prediction method of anti gas channeling capability of cement slurry mainly considers the performance of cement slurry water loss and cementitious transition time, which has less influence on gas channeling in the bottom hole formation, casing and other specific conditions, and can not solve the air channeling problem well. Therefore, on the basis of the existing evaluation methods, the anti gas channeling of cement slurry is carried out. It is of great significance for the prevention and prevention of air channeling in cementing ring to study and establish a more comprehensive, comprehensive and operable new evaluation method for gas channeling prevention.
On the basis of the current situation investigation of cement slurry anti gas channeling capability evaluation method, the key performance indexes of early cementing gas channeling prevention are put forward from the angle of cement condensation hydration mechanism, and the permeability test method of cementitious cement slurry is formed by combining with the present situation of cementitious cementitious cement slurry permeability, and the corresponding test method is developed. Based on the testing principle of soil porosity in soil science, combined with the similarities and differences between cement hydration characteristics and soil, an experimental method for testing the porosity of cementitious cement slurry is explored. On the basis of the existing research, the quantitative relation between the volume contraction of the plastic cement slurry and the pore pressure before the initial setting is derived. The system model provides the basis for the determination of the gas invasion time under the actual conditions of the bottom hole, and based on the displacement seepage process of the gas in the annular cementitious cement slurry, the corresponding physical model of gas channeling seepage is established, and a new method of evaluating the anti gas channeling capability based on the properties of cementitious cement slurry is established.
On the basis of the new method of evaluating the anti gas channeling capability based on the properties of cementitious cement slurry, the experimental data processing, model and evaluation method involved in the paper are further developed into a software for evaluating the anti gas channeling capability of cement slurry, which has enhanced the operability and practicability of the evaluation method. On the basis of software programming, the conclusions are as follows:
(1) in this paper, combined with the analysis of cement hydration and condensation process and mechanism, the physical and chemical properties of the material in the process of hydration condensation, such as static gelation strength, cementitious cement slurry permeability, cementitious cement slurry porosity and plastic volume shrinkage of cement slurry, are proposed as the key performance indicators of gas channeling prevention in early cementing.
(2) on the basis of the study of cementitious cement slurry permeability, the experimental test method for forming cementitious cement slurry permeability is explored and the corresponding experimental device is developed. It is considered that the permeability properties of cement slurry in the process of cement slurry show a specific decreasing trend, and gradually tend to be stable after the cementing.
(3) drawing on the principle of soil porosity testing and combining the particularity of cement hydration, the method of soil porosity testing is improved and the porosity testing method of cementitious cement slurry is formed. The porosity of cementitious cement slurry before initial coagulation is reduced and eventually tends to stability.
(4) from the angle of the plastic volume contraction before the initial solidification of cement slurry affects the decrease of pore pressure, based on the establishment of the physical model of "casing cement slurry formation" in the process of weather coagulation, the relationship model of the effect of plastic volume shrinkage to the pore pressure is derived. The danger time should be the time from the balance point of weightlessness to the time of initial solidification.
(5) on the basis of the physical mathematical model of gas channeling seepage in cement ring, a new method for evaluating the anti gas channeling capability of cement slurry is established, and a software for evaluating the anti gas channeling capability of cement slurry is developed. The evaluation method can effectively combine the actual working condition parameters of the oil and gas wells and the cementitious cement slurry performance, and comprehensively evaluate the anti gas channeling capability of cement slurry; The preparation of evaluation software for slurry anti gas channeling capability enhanced the operability of the method.
【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】：TE256

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