页岩气藏体积改造疏水缔合聚合物压裂液基础研究

发布时间：2018-07-25 16:37

【摘要】：体积改造技术的发展是页岩气藏成功商业开发的必要条件之一,而现用于体积改造的减阻水压裂液由于携砂性能差,导致用水量过大,造成了水资源的极大浪费,带来了一系列严重的生态、环境问题,影响其在我国乃至世界范围内的广泛应用。本文通过对问题根源的分析,提出了在满足体积改造工艺对压裂液低黏度要求的前提下,通过使压裂液同时具备高减阻与携砂能力的方法,减少用于大排量制造湍流来满足携砂需求的那部分用水量,进而达到大幅降低总用水量的目的。基于结构流体内部缔合网状结构湍流减阻、携砂的机理以及研究现状,综合考虑矿场应用及成本,优选出可能满足上述流变性能要求的一类聚合物——疏水缔合聚合物(HAWSP)。并通过对HAWSP水溶液减阻、携砂机理及影响因素的研究,从理论和实验上证明了其作为区别于现有减阻水压裂液的新型压裂液应用到页岩气藏体积改造,解决现有压裂液存在主要问题的可能性,为矿场应用提供了必要的理论基础与实验依据。主要研究内容包括以下几个方面：通过对HAWSP水溶液减阻、携砂性能测试方法的研究,设计了测试不同温度与雷诺数条件下减阻、携带能力的测试装置。研究建立了减阻、携砂性能测试与表征方法,为HAWSP水溶液减阻、携砂机理及影响因素的研究提供了必要手段。运用环境扫描电镜(ESEM)观察了HAWSP水溶液不同质量浓度区域的微观结构,以及不同分子结构特性参数的HAWSP水溶液临界缔合浓度(CAC)附近的微观结构。并以微观结构为依据,结合宏观的减阻性能,系统的研究了HAWSP水溶液湍流减阻机理及影响因素。实验结果表明：HAWSP特殊的分子结构决定了其水溶液同时具备类似于线性高分子聚合物和表面活性剂的减阻机理,因而可能比现用各类减阻剂具有更好的减阻效果。并且不同分子结构的HAWSP在不同的浓度区域均可能表现出不同的减阻特性。通过对与HAWSP水溶液减阻性能相关流变参数的研究,得出可表征其CAC后减阻性能的流变参数——Nl/η2,为HAWSP水溶液减阻性能快速评价及对比提供了有效的手段。根据本文的研究目标,结合溶液微观结构和流变性能的研究,得出了低分子量、高疏水单体质量分数的HAWSP在CAC处的减阻、携砂性能为本文的主要研究对象。通过研究分子量、疏水单体质量分数、水解度对上述HAWSP水溶液减阻性能的影响,得出了水溶液具有高减阻率的HAWSP应有的分子结构。同样以ESEM观察HAWSP水溶液的微观结构为依据,结合宏观的携砂性能,系统的研究了其携砂机理及影响因素。实验结果表明：HAWSP水溶液的携砂性能是由溶液的微观结构决定的,并且在CAC前后具有不同的携砂机理。通过对与HAWSP水溶液携砂性能相关流变参数的研究,得出了表征其CAC后携砂性能的流变参数——G',为HAWSP水溶液携砂性能快速评价及对比提供了有效的手段。通过研究分子量、疏水单体质量分数、水解度对HAWSP水溶液携砂性能的影响,得出了水溶液具有高携砂性能的HAWSP应有的分子结构。综合高减阻性能与高携砂性能对HAWSP分子结构的要求,结合体积改造对压裂液低黏度的要求,得出适合用于体积改造,同时具备高减阻与高携砂性能的HAWSP分子结构特性参数范围：(1)分子量：100×104g/mol-300×104g/mol;(2)疏水单体质量分数：10%-20%；(3)水解度：200%～40%。上述分子结构特性参数范围可指导同时具备高减阻性及良好携砂性能的适用于体积改造的HAWSP压裂液产品的研发和评价。通过在上述范围内对分子结构特性参数的调整,可以得到3种不同性能的新型]SAWSP压裂液,即：(1)在一定程度上提高携砂性能的同时,大幅提高减阻性能：相对与现有进口减阻水压裂液,其减阻率大幅提高(提高11.5%)；悬浮性能一定程度提高(提高27.8%)；携带性能一定程度提高(提高26.8%)。(2)兼顾减阻与携砂性能：减阻率略大于现有进口减阻水压裂液(提高4.3%)；悬浮性能明显提高(提高85.2%)；携带性能明显提高(提高54.2%)。(3)在减阻性能与现有进口减阻水压裂液相当的同时,大幅提升携砂性能：相对于现有进口减阻水压裂液,其减阻率相当(提高-0.46%)；悬浮性能大幅度提高(提高168.5%)；携带性能大幅度提高(提高167%)。上述3种新型HAWSP压裂液为解决现用减阻水压裂液用水量过大的重大技术难题提供了更多的可能性和选择。本文还研究了温度、矿化度对HAWSP减阻及携砂性能的影响以及分子结构特性参数对HAWSP耐温、耐盐性能的影响。得出了可根据使用的不同温度、矿化度条件,通过调节HAWSP的分子结构特性参数,以满足不同应用环境下体积改造压裂液的需要。
[Abstract]:The development of the volume transformation technology is one of the necessary conditions for the successful commercial development of shale gas reservoirs, and the water reducing fluid, which is used in volume transformation, has caused great waste of water resources because of poor sand carrying performance, which brings a series of serious ecological and environmental problems, which affects its wide range in China and in the world. Based on the analysis of the root cause of the problem, this paper puts forward that in order to satisfy the requirement of the low viscosity of the fracturing fluid for the volume transformation process, by making the fracturing fluid with the method of both high drag reduction and sand carrying capacity, the amount of water used in the large displacement manufacturing turbulence to meet the sand carrying demand is reduced, and then the total water consumption is greatly reduced. Objective. Based on the turbulent drag reduction of the structural fluid internal association network structure, the mechanism of sand carrying and the research status, a class of polymer, hydrophobic associating polymer (HAWSP), which may meet the requirements of the above rheological properties, is selected to optimize the application and cost of the field, and the mechanism of sand carrying and the influencing factors are studied by reducing the resistance of HAWSP water solution. It is proved theoretically and experimentally that the new fracturing fluid, which is different from the existing hydraulic fracturing fluid, is applied to the volume transformation of shale gas reservoir, the possibility of solving the main problems in the existing fracturing fluid, and providing the necessary theoretical basis and experimental basis for the field application. The main contents include the following aspects: through the HAWS P water drag reduction and sand carrying performance testing methods have been designed to test the resistance reduction and carrying capacity testing devices under different temperatures and Reynolds numbers. The study established the method of reducing drag, testing and characterizing the performance of sand carrying performance, which provided the necessary means for the study of the drag reduction of HAWSP solution, the mechanism of sand carrying and the influencing factors. The application of environmental scanning electron microscopy (ES) EM) the microstructure of the different mass concentration regions of HAWSP water solution and the microstructure near the critical association concentration (CAC) of HAWSP aqueous solution with different molecular structural properties were observed. The mechanism and influence factors of the turbulence drag reduction in HAWSP aqueous solution were systematically studied on the basis of microstructure and macro drag reduction properties. The experimental results were studied. It is shown that the specific molecular structure of HAWSP determines that the water solution has a similar resistance reduction mechanism similar to linear polymer and surfactant, so it may have better drag reduction effect than all kinds of resistance reducing agents. And the different molecular structure of HAWSP may show different drag reduction characteristics in different concentration regions. After studying the rheological parameters related to the drag reduction performance of HAWSP water solution, the rheological parameters, Nl/ ETA 2, which can characterize the drag reduction performance after CAC, provide an effective means for the rapid evaluation and comparison of the drag reduction performance of HAWSP aqueous solution. According to the research objective of this paper, the low molecular weight of the solution is combined with the study of the microstructure and rheological properties of the solution. The effect of sand carrying capacity of HAWSP at high hydrophobic monomer mass fraction at CAC is the main research object in this paper. By studying the influence of molecular weight, hydrophobic monomer mass fraction and degree of hydrolysis on the drag reduction performance of the HAWSP aqueous solution, the molecular structure of HAWSP with high drag reduction rate in aqueous solution is obtained. The same as ESEM is used to observe the water solubility of HAWSP. The sand carrying mechanism and influencing factors are systematically studied based on the micro structure of the liquid, and the sand carrying mechanism and the influence factors are systematically studied. The experimental results show that the sand carrying property of HAWSP water solution is determined by the microstructure of the solution and has different sand carrying mechanism before and after CAC. The rheological parameters related to the performance of the sand carrying capacity of the HAWSP water solution are related. The rheological parameters, G', which characterizing the performance of the sand carrying capacity after CAC are obtained, which provide an effective means for the rapid evaluation and comparison of the performance of the sand carrying capacity of HAWSP aqueous solution. By studying the effects of molecular weight, hydrophobic monomer mass fraction and the degree of hydrolysis on the performance of the sand carrying capacity of the HAWSP aqueous solution, the HAWSP molecules with high sand carrying properties of the aqueous solution should be obtained. Structure. Combining the requirements of high drag resistance and high sand carrying performance to HAWSP molecular structure, combined with the requirement of volume transformation for low viscosity of fracturing fluid, the parameter range of HAWSP molecular structure suitable for volume modification and high drag reduction and high sand carrying properties is obtained: (1) molecular weight: 100 x 104g/mol-300 x 104g/mol; (2) hydrophobic single constitution Volume fraction: 10%-20%; (3) (3) degree of hydrolysis: the range of molecular structural properties of 200% ~ 40%. can guide the development and evaluation of HAWSP fracturing fluid products with high drag reduction and good sand carrying properties. By adjusting the parameters of molecular structure in the above range, 3 kinds of different properties can be obtained. Type]SAWSP fracturing fluid, that is: (1) to a certain extent, improve the performance of the sand carrying capacity to a certain extent, and greatly improve the drag reduction performance: relative to the existing imported water reducing fluid, the drag reduction rate is greatly increased (up to 11.5%); the suspension performance is improved to a certain degree (27.8%); the portability can be improved to a certain extent (26.8%). (2) both drag reduction and sand carrying ability is taken into account. Ability: the drag reduction rate is slightly greater than that of the existing imported hydraulic fracturing fluid (up to 4.3%), the suspension performance is obviously improved (85.2%), and the carrying performance is obviously improved (54.2%). (3) while the drag reduction performance is equivalent to the existing imported water reducing fluid, the sand carrying capacity is greatly improved: compared with the existing imported water reducing fluid, the drag reduction rate is equal. (increase -0.46%); the suspension performance is greatly improved (168.5%) and the carrying performance is greatly improved (167%). The above 3 new type HAWSP fracturing fluids provide more possibilities and choices to solve the major technical problems of excessive water use in the current reducing water pressure fracturing fluid. The temperature, the salinity and the sand carrying capacity of the HAWSP are also studied in this paper. The influence of energy and molecular structure characteristic parameters on the temperature resistance and salt resistance of HAWSP. The conditions of different temperature and salinity are obtained, and the parameters of molecular structure characteristics of HAWSP are adjusted to meet the needs of the volume transformation of fracturing fluid under different application conditions.
【学位授予单位】：西南石油大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE377

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