阴离子双子表活剂-纳米粒子构筑耐高温清洁压裂液基础研究

A low damage or no damage clean fracturing fluid is an important guarantee that low permeability and compact hydrocarbon reservoir,shale gas reservior conduct an effective hydraulic fracturing and commercial exploiting.However,commercially existing cationic surfactant clean fracturing fluids have poor temperature-stable ability and an adsorbability wettability reversal damage for oil and gas seepage channel,and normal anionic surfactant clean fracturing fluids have disadvantages of large dosage and bad high temperature stability.Therefore,the stable thickening mechanism and construction method of clean fracturing fluid under high temperature are still a science issue to be solved.This project constructs a low concentration and no damage anionic Gemini surfactant system by utilizing the anionic Gemini surfactant characteristic that it has lower adsorption loss and lower Critical Micelle Concentration(CMC) than normal anionic surfactant,as well as no adsorption wettability reversal damage,researches structure activity relationship between anionic Gemini surfactant molecular structure and its solution viscosity,designs anionic Gemini surfactant molecular structure for thickening in higher temperature.And builds high temperature resistant system of anionic Gemini surfactant and nanoparticle by means of high surface effect and high physical-chemistry activity of nanoparticle,investigates collaborative thickening law between nanoparticle and anionic Gemini surfactant,optimize and select nanoparticle for high temperature thickening.And elaborates the thickening mechanism of nanoparticle-anionic Gemini surfactant visco-elastic fluid in high temperature through studying the influence of nanoparticle on association mode among anionic Gemini surfactants and its micellar structure form,and all that will provide theoretical basis for constructing new inexpensive high temperature stability clean fracturing fluid and its field application.

低或无伤害清洁压裂液是低渗、致密油气藏及页岩气藏实施有效水力压裂并商业开采的重要保证。现有商业用阳离子表面活性剂清洁压裂液耐温差，对油气渗流通道存在吸附润湿反转伤害，常规阴离子表活剂清洁压裂液则用量偏高、高温欠稳定。因此高温下清洁压裂液稳定增稠机制与构建方法仍是待解决的科学问题。本项目利用阴离子双子表面活性剂吸附损失与临界胶束浓度低、无润湿反转伤害特性，构筑无伤害低浓度阴离子双子表面活性剂体系，研究其分子结构与溶液粘度间构效关系，设计耐温增稠表活剂分子结构；借助纳米粒子高表面效应、高物理化学作用活性，构建阴离子双子表面活性剂-纳米粒子耐高温体系，研究纳米粒子-阴离子双子表面活性剂协同增稠规律，优选高温增稠纳米粒子；通过纳米粒子对阴离子双子表面活性剂分子间缔合方式及胶束结构形态影响研究，阐述纳米粒子阴离子双子表面活性剂粘弹流体高温增稠机理，为新型低成本耐高温清洁压裂液研制与应用提供理论依据。

清洁压裂液是低渗、致密油藏实施有效水力压裂并商业开采的重要保证；但现有商用阳离子表活剂清洁压裂液耐温差，对油气渗流通道有吸附润湿反转伤害，常规阴离子表活剂清洁压裂液则用量偏高、高温欠稳定。因此耐高温清洁压裂液构筑及稳定增黏仍有待研究。本研究以吸附损失与临界胶束浓度低、无润湿反转伤害阴离子双子表面活性剂构筑清洁压裂液，研究其分子结构与其溶液黏度间构效关系，优化设计耐温增黏剂分子结构；构建阴离子双子表面活性剂-纳米材料体系，研究纳米材料-阴离子双子表面活性剂协同增黏规律，优选高温增黏纳米材料；并通过扫描电镜冷冻刻蚀及动态光散射技术，研究纳米材料阴离子双子表面活性剂黏弹流体高温增黏微观机理。发现，亲水头基对阴离子双子表面活性剂溶液黏度影响顺序为羧酸盐(DC)＞磺酸盐(DS)＞硫酸酯盐(DAS)，但DS18-2-18和DC16-2-16增黏效果较好，且DS18-3-18(8%，磺酸盐、m=18、s=3)有更好的耐温增黏性(90℃/13.3mPa.s)和黏弹性(65℃/tanδ=0.51)；4%时，DS18-3-18溶液黏度呈突跃式增大，但90℃粘度仅3.1 mPa.s；3%有机醇LA、0.02%纳米MgO/纳米纤维CNF可提高4%DS耐温增黏性(32.8、16.7、6.5mPa.s)，仅LA、CNF、DS三者间可协同耐温增黏(14.2mPa.s)；LA通过增大其浓度(0.5、1、1.5、3%)使4%DS溶液微观结构从层状向富含细长棒状胶束层状、再到棒状胶束致密缠绕层状及条带网络结构过渡，胶束半径增大了52%，使相应溶液黏度增大(81.6、121.0、145.0、214.3mPa.s)；但纳米材料用量均0.02-0.04%(约DS用量的1%)，因此纳米材料更倾向与DS溶液中胶束发生作用而使胶束回旋半径增大(≤30℃)，如4%DS+0.02%CNF胶束回旋半径(179.2nm)大于4%DS(112.4nm)，且CNF+DS体系微观结构呈条带网状形态；温度升高(30-90℃)，均使4%DS及4%DS +0.02%CNF胶束形态由连续致密大尺度结构向疏松、部分解离的小尺度结构转变，但90℃时，后者仍有较多大尺寸、彼此相连的胶束结构形态，导致CNF+DS体系有较好的耐温增黏性。确定了耐高温清洁压裂液构筑组成，阐述了DS/LA/CNF各自耐温增黏机理。