特低渗透储层压裂液微观伤害评价

ASSESSMENT STUDY ON THE MICROCOSMIC DAMAGE OF FRACTURING FLUID IN EXTRA-LOW PERMEABILITY RESERVOIR

正确评价压裂液性能，分析其对特低渗透储层的潜在损害原因及程度，对于压裂液的优选和提高压裂增产效果具有重要意义。选用两种压裂液体系（植物胶、聚合物），3类不同渗透率（0．5×10^-3μm2左右、1．0×10^-3μm2左右、5．0×10^-3μm2左右）岩心，借助扫描电镜、X衍射、恒速压汞、核磁共振等先进实验技术手段，结合常规流动样比对实验，从总体伤害、黏土吸水膨胀与分散运移伤害、水锁伤害以及高分子物质吸附与固相颗粒堵塞伤害等几个方面，对特低渗透储层岩心压裂液伤害机理进行了定量分析评价实验，并对不同压裂液体系不同渗透率岩心进行了对比分析；给出了每种压裂液体系、每类渗透率岩心压裂液伤害的主要机理及其伤害差异；对伤害机理、引起伤害差异的主要原因进行了分析。最后对两种压裂液体系进行了总体评价，从而为压裂液配方优选与改进提供了参考和指导。

The true appreciation of fracturing fluid performances and the analyses on the potential damaged factors and degrees to extra-low permeability reservoir are very important for fracturing fluid optimization and improving stimulation effects. Through choosing two different fracturing fluid systems （ vegetable gum-based, polymer-based } and three different permeability cores （ about 0.5 ×10^-3μm2 , 1.0 ×10^-3μm2, 5.0 ×10^-3μm2 ） and with the help of advanced experimental techniques such as scanning electron microscope, X diffraction, constant velocity mercury penetration, nuclear magnetic resonance and so on, the quantitative analysis and evaluation experiments are conducted in the core damage mechanism of the fracturing fluids used in extra-low permeability reservoirs in the following aspects： total damage, scattered migration and swell damage of clays, water locking injury, macromole- cule substance adsorption and blocking damage of solid particulates and so forth. At the meantime, the contrast an- alyses are caught out for different fracturing liquid systems and different permeability cores; the main damage mechanisms and their differences for each fracturing fluid system and each type of core permeability are presented and moreover the analyses of the major reasons for the above mechanism and differences are also figured out. In the end, the total evaluation of two different fracturing fluid systems are engaged and therefore provides reference andguidance for fracturing fluid dispensation optimization and improvement.