水基冻胶压裂液对致密气层伤害机理

水力压裂是油气井的主要增产措施之一。压裂液对油气层渗透率的损伤是影响压裂增产措施的重要因素。在室内用水基冻胶压裂液浸入致密气层岩心,进行了伤害试验研究。研究表明,影响岩心伤害率的主要因素有岩心的渗透率、压裂液破胶程度和试验条件。由于岩心的液相饱和度增大和高分子聚合物在其壁面上形成的滤饼堵塞而影响油气层渗透率。在对比和选择压裂液时,应采用相同的试验方法,并在相同的试验条件下进行,使试验结果具有可比性。文中论述了岩心的伤害率计算方法。提出以岩心的绝对渗透率和束缚水饱和度条件下的有效渗透率作参考渗透率来计算伤害率。

DAMAGE MECHANISM OF WATER BASE CROSSLINKED GEL FRACTURING FLUID ON TIGHT GAS FORMATION

The damage of producing formation permeability by fracturingfluid is an important factor affecting the effectiveness of hydraulic fracturing. Experiments were carried out on tight gas formation core sample with a water base crosslinked gel fracturing fluid. The main factors affecting the damage ratio of core sample permeability include original permeability, the degree of gel breaking and the experiment conditions. The damage is due to increased liquid saturation and filter cake blockage of high polymer. Fracturing fluids should be tested with the same method and under the same condition to provide comparable results, fn the calculation of the damage ratio of a core sample, its absolute permeability and effective permeability with bound water saturation can be used as reference.