清洁自生热压裂液技术与实验方法

目前已有的多种自生热压裂液体系,通常需要加入活化剂,配制过程复杂。研究了一种采用疏水聚合物作为稠化剂的清洁自生热压裂液体系,该稠化剂在合成过程中添加了耐盐单体,保证其在盐水中有高溶解性;采用有机锆酸性交联剂,提供酸性交联环境,无需加入生热反应所需要的活化剂和交联反应所需要的调节剂。稠化剂使用浓度为0.6%,具有良好的耐温耐剪切性能、黏弹性能及破胶性能,在100℃、170 s-1下剪切60 min后黏度为140 mPa·s左右,黏弹性与常规瓜胶压裂液相当,残渣含量为11.9 mg/L,残渣伤害小,适用于中低温储层。采用高温高压动态酸化腐蚀仪,通过监测压力变化,计算了生热剂的反应程度,该操作简单,计量准确,可用于自生热压裂液体系配方优化及反应程度的估算。研究结果表明,在40℃时,基液中生热剂之间不发生反应,80℃时反应程度约为55%,120℃时反应完全,因此该体系适合提前配制,实施方法与常规压裂液相同。 

Clear Autogenetic Heat Fracturing Fluid and Its Experiment

Several autogenetic heat fracturing fluids find their use in reservoir fracturing. In autogenetic heat fracturing, activating agent is added into the fracturing fluid for heat generation, and this makes the process much less efficient. A clear autogenetic fracturing fluid was prepared using a hydrophobic polymer as the thickening agent. The thickening agent has a salt-resistant component added during its synthesis, enabling the thickening agent to be readily dissolving in saltwater. Using organo-zirconiumacidic crosslinking agent, activating agent using for heat generation and modifying agent for crosslinking reaction are not necessary anymore. Fracturing fluid treated with 0.6% of the thickening agent has good heat-resistance and shear-resistance, good elasticity and gel breaking capacity. After shearing for 60 min at 100℃ and 170 s-1, the fracturing fluid retains a viscosity of about 140 mPa·s, and its visco-elasticity equivalent to that of conventional guar gum fracturing fluids. Residue of the fracturing fluid is 11.9 mg/L. This fracturing fluid is suitable for use in fracturing medium-to low-temperature reservoirs. By monitoring pressure changes of the reaction, the extent of reaction of heat generators is measured on a HTHP dynamic acidizing corrosion tester, and this measurement is both simple and accurate, suitable for the optimization of the formulation of autogenetic heat fracturing fluids, and the assessment of the extent of reaction of heat generators. The study shows that no reaction has ever taken place between heat generators in base fluid at 40℃, and 55% of the heat generators react at 80℃, while at 120℃, all heat generators react with each other, indicating that the fracturing fluid should be prepared in advance, and the operation process is the same as that of conventional fracturing fluids.