关键词: 酸液, 预处理, 水力压裂, 压裂液, 瓜胶尺寸, 伤害

Abstract:

Hydraulic fracturing is an effective way to develop low permeability reservoir. However，halfway gelout，fracturing
fluid residue and filtrate damage often reduce stimulation effect. On-site application of acid pretreatment fracturing technology
has been proved to be able to reduce damage during fracturing，but the damage reduction mechanism of acid pretreatment
remains unclear. In this paper，molecular dimensions of guar gum under both conventional and acidic conditions are quantitatively
observed by using laser particle analyzer（LPSA）. Principle factors affecting the damage of gelout fluid to matrix in
acidic environment are also researched here. In addition，microanalysis of damaged core edge after injecting gelout fluid and
acid fluid is conducted by means of scanning electron microscope（SEM）. We can draw conclusions from the results：molecular
dimension of guar gum after gelout is significantly reduced under acidic condition，and the reduction of molecular dimension
plays more important role than acidic environment in decreasing damage；acid fluid is able to effectively remove damage caused
by fracturing fluid，increase core permeability，and form corrosion channels.

Key words: acid fluid, preflushing, hydraulic fracturing, fracturing fluid, guar gum molecular dimensions, damage