碎屑岩酸化中含铝垢形成机理与预防

Studies on Aluminum Scaling Mechanisms and Prevention in Clastic Reservoir Acidization

3种含5％盐酸的土酸（HCI／0．5％HF，HCI／1．0％HF，HCI／8％HBF4）与6种碎屑岩储层矿物（钾长石，斜长石，蒙脱石，高岭石，伊利石，绿泥石）在60℃静态反应0．5～12小时，测定残酸中可溶Si、Al浓度、残酸蒸发残渣元素组成厦矿物组成、结构。列表给出了残酸中可溶Si、Al浓度范围厦平均值（单位mg／L）并作了分析讨论：残酸中Si、Al浓度很高，在某些情况下Al浓度甚至高于sj啦度；酸．矿物反应初期（0．5～2．0小时）Si、Ai浓度起伏变化，这是各种垢的主要形成期：长石类、高岭石厦蒙脱石与酸反应后的残酸（厦残酸蒸发残渣）的Si／Al比小于原始值，说明长石晶体[AlO4]^5-四面体和黏土晶体[Al4（OH）6]^6＋八面体的酸蚀速率和程度大于相应的[SiO4]^4-四面体；酸蚀后各矿物X衍射峰无明显变化．即矿物结构无大政变，无新矿物生成。根据文献资料讨论了水溶液中各种含铝离子的平衡反应，给出了分布系数与pH的关系，讨论了碎屑岩酸化中含铝垢的形成反应和条件：在酸性介质中形成Na3AIF6、K2AlF5、AlF3等垢．在弱酸性介质中形成Al（OH）3垢，在高温下（91℃）pH=2．5时形成AlF（OH）2垢。讨论了防止碎屑岩酸化中生成含铝垢的措施。图1表1参1l。

The reactions between three mud acids containing 5 % HCI （HCI/0- 5 % HF, HCI/1. 0 % HF, and HCI/8 % HBF6） and six elastic reservoir minerals （potash and plagioclase feldspars, montmorillonite, kaolinite, illite, and chlorite） are conducted under static conditions at 60℃ in 0.5--12 hrs and the concentration of soluble Si and Al, C（Si） and C（Al）, in residual acids （RAs）, the chemical element constitution in RAs evaporites, and the structure and constitution of the minerals, original and acid etched, are determined. The range and average of C（Si） and C（AI） determinations in mg/L are tabulated and some analyses and discussion are made： the C（Si） and C（AI） in RAs are high and C（AI） is higher than C（Si） in some cases： C（Si） and C（AI） vary in a oscilatory way in early reaction stages, or in 0.5--2.0 hrs, in which various scaling processes occur; for RAs （ and their evaporites） from reactions with feldspars, kaolinite, and montmorillonite, value Si/Al is less than original, showing higher rate and extent of acid etching of tetrahedron [AlO4 ]^5- in feldspars crystal and octahedron [Al4（OH）6 ]^6＋ in clay crystal are larger than that of tetrahedron [ SiO4 ]^4- in crystals of these minerals; X-ray diffration data do not show notable changes in peaks, that is, obvious structural changes and novel mineral creation in the acid etching. In terms of data published in literature, the equilibrium reactions between different Al ions in aqueous .solutions are discussed, their distribution in relatioa to pH value is presented and the reactions and conditions of formation of Al scaling substances in clastie reservoir acidization are discussed： Na3AlF6, K2AIF5, AIF3, and other in acidic ,media and AIF（OH）2 in weakly acidic media at higher temperatures （91℃） and pH = 2.5. The measures against Al sealing in acidization are discussed.