阴离子双子表面活性剂作为清洁压裂液的可行性研究

发布时间：2018-08-30 19:55

【摘要】：随着低渗透油气田的不断开发,对压裂液的性能要求也越来越高。最近几年发展起来的清洁压裂液在很大程度上解决了传统压裂液破胶难、滤失高、残渣多等缺点。目前国内外对于清洁压裂液的研究主要针对新型表面活性剂制备和清洁压裂液的粘弹性、伤害性、流变性、摩阻性、控缝高性等的实验研究,同时针对一些低孔、低渗、低压等特殊油藏开始进行研究,但还处在起步阶段,各个研究院所研制的药品大多仅限于实验室内合成,开发的成果也只是在某个油田小范围应用。适用于气井的清洁压裂液对低渗储层具有良好的控滤失作用,能有效控制缝高,施工摩阻低,压裂液效率高,对储层伤害小,增产效果显著,但是目前相对于油井的研究还相对较少,而且耐温性能不高。虽然目前国内外研制和应用的清洁压裂液体系,已从过去单纯的油井应用,逐渐扩展到天然气和煤层气的开发应用中,但在新产品的设计思路上,主要研究使用特殊的表面活性剂在较高浓度下形成棒状胶束进而形成网状结构的原理为主。通过对表面活性剂在不同组成、不同温度和不同剪切速率下的粘度变化以及压裂液滤失性及对地层的伤害性进行评测。目前国内外研制和应用的清洁压裂液,基本组成为粘弹性表面活性剂、盐溶液和稳定剂。在清洁压裂液的研究中,使用的表面活性剂碳链长度多在12-18之间,主要分为阴离子型和阳离子型。由于阳离子表面活性剂成胶性能、抗温性能较好,合成工艺比较成熟,在研究和现场应用中使用较多,但随着研究的深入,发现此类表面活性剂对地层粘土和砂岩的吸附性较强,因此该类压裂液对地层造成润湿伤害的几率较大,从而影响采收率的提高。纵观目前已经研发出的清洁压裂液,虽然可以在一定程度上改善裂缝通道从而提高原油的采收率,但过高的使用成本,以及耐温性较差等极大地限制了它的推广应用。因此开发具有自主知识产权且价格相对低廉的新型清洁压裂液来提高石油的采收率具有着极其重要的意义。针对这一问题,本文以自制的阴离子双子表面活性剂为主剂,氯化钾、水杨酸钠、十二醇、纳米二氧化钛为添加剂,通过筛选复配得到4种压裂液体系,四种压裂液体系的组成为：①5%GA.12+2.0%NaSL+4%十二醇+0.15%TiO2；②3.5%GA-14+1.5%NaSL+3%十二醇+0.2%TiO2；③3%GA.16+2.0%NaSL+3%十二醇+0.15%TiO2；④2%GA.18+1.0%NaSL+3%十二醇+0.15%TiO2。按照SY/T5107—2005《水基压裂液性能评价方法》对四种体系分别进行了流动曲线测试,应力扫描,频率扫描,模量测试,耐温性测试,破胶性能测试,携砂效果测试及耐剪切性能测试,研究发现：四种表面活性剂压裂液流体均属于假塑性流体,随着温度的升高压裂液稠度系数K减小,增稠性能降低；GA-16与GA-14压裂液体系均具有较高的储能模量,具有优良的增粘性,显著的粘弹效应；四种体系中GA-16压裂液耐温性能最好,可以用于90℃地层压裂；四种压裂液体系破胶液粘度均小于5mPa.s,油水界面张力较低,无残渣；悬砂效果明显,陶粒在四种压裂液体系中的沉降速度平均只有其在水中沉降速度的二十分之一；GA-12、GA-14、GA-18压裂液体系的耐剪切性能相近,GA-16压裂液体系耐剪切性最佳。经过150min剪切后各压裂液体系的粘度保留率为：GA-12体系为71.4%,GA-14体系为73.8%,GA-16体系为77.7%,GA-18体系为73%。
[Abstract]:With the continuous development of low permeability oil and gas fields, the performance requirements of fracturing fluids are getting higher and higher. In recent years, the developed clean fracturing fluids have largely solved the shortcomings of traditional fracturing fluids, such as difficult gel breaking, high filtration rate, and many residues. Experimental study on viscoelasticity, damage, rheology, frictional resistance and fracture control of fracturing fluid has been carried out. At the same time, some special reservoirs such as low porosity, low permeability and low pressure have been studied, but they are still in the initial stage. Most of the drugs developed by various research institutes are only synthesized in laboratory, and the results of development are only in a small area of an oilfield. Clean fracturing fluid suitable for gas wells has good filtration control effect on low permeability reservoirs. It can effectively control fracture height, low construction friction, high fracturing fluid efficiency, little damage to reservoirs, and remarkable stimulation effect. However, the research on clean fracturing fluid relative to oil wells is relatively less, and its temperature resistance is not high. Clean fracturing fluid system has been gradually extended from simple oil well application to natural gas and coalbed methane development and application in the past, but in the design of new products, the principle of using special surfactants to form rod micelles at higher concentrations and then form a network structure is mainly studied. At present, the clean fracturing fluids developed and applied at home and abroad are basically composed of viscoelastic surfactants, salt solutions and stabilizers. In the study of clean fracturing fluids, the carbon chain length of surfactants used is mostly 12. Cationic surfactants are mainly classified into anionic and cationic types. Because of their gelling properties, good temperature resistance and mature synthetic technology, cationic surfactants are widely used in research and field application. However, with the further study, it is found that these surfactants have strong adsorbability to formation clay and sandstone, so this kind of fracturing fluid is on the ground. Although the clean fracturing fluid which has been developed can improve the fracture passage to a certain extent and thus enhance the oil recovery, its application is greatly limited by the high cost and poor temperature resistance. New clean fracturing fluids with independent intellectual property rights and relatively low price are of great significance to enhance oil recovery.
In order to solve this problem, four kinds of fracturing fluids were prepared by using anionic gemini surfactant as main agent, potassium chloride, sodium salicylate, dodecanol and nano-titanium dioxide as additives. The compositions of the four fracturing fluids were as follows: (1) 5% GA.12 + 2.0% NaSL + 4% dodecanol + 0.15% TiO2; (2) 3.5% GA-14 + 1.5% NaSL + 3% dodecanol + 3%. According to SY/T5107-2005 < Water-based Fracturing Fluid Performance Evaluation Method >, the flow curves, stress scanning, frequency scanning, modulus testing, temperature resistance testing, gel breaking performance testing, sand carrying effect testing and sand carrying effect testing of the four systems were carried out respectively. The results show that the four surfactant fracturing fluids belong to pseudoplastic fluids, and the consistency coefficient K decreases with the increase of temperature, and the thickening performance decreases. Both GA-16 and GA-14 fracturing fluids have high storage modulus, excellent viscosity and significant viscoelastic effect. Fracturing fluids have the best temperature resistance and can be used for formation fracturing at 90 C. The viscosity of the four fracturing fluids is less than 5 mPa. s, the interfacial tension between oil and water is low, and there is no residue; the suspended sand effect is obvious, the settling velocity of ceramsite in the four fracturing fluids is only one-tenth of its settling velocity in water on average; GA-12, GA-14, GA-18 fracturing fluids. The viscosity retention of GA-12, GA-14, GA-16 and GA-18 systems was 71.4%, 73.8%, 77.7% and 73.8% respectively after 150 minutes of shearing.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TE357.12

【参考文献】