摘要
压裂液在压裂过程中起传递压力和携带支撑剂的作用,但也会给储层带来损害,严重时造成油气井减产。研究了压裂液对裂缝损害因素及其抑制方法。压裂使用的破胶剂与聚合物的反应是随机的,不能使聚合物彻底降解,只能形成结构复杂、大小不等的仍有堵塞作用的聚合物碎片,而且反应动力学规律决定了裂缝闭合前聚合物总会有不同程度的降解,影响压裂液的粘弹性和携砂能力。防止方法:使用过氧化物、普通酶、特效酶破胶剂(胶囊化延迟破胶)和低浓度(聚合物浓度≤0.3％)压裂液,可使聚合物彻底降解。滤液损害是通过液相水锁降低基岩中油气的相对渗透率。防止方法:使用表面活性剂降低表面(或界面)张力;用阳离子表面活性剂增加接触角(接近90°);防止裂缝壁及其附近被堵塞,降低末端毛管阻力抑制水锁。根据模拟计算结果,防止基岩堵塞产生的末端毛管效应,对抑制永久性水锁具有重要的作用。
Fracturing fluid transfers the pressure and carries the proppant during fracturing, but it can do some damage to reservoir even leads to oil & gas production reduction, influencing factors of fracturing fluid on fracture damage and its prevention have been studied in this paper. Result showed that reaction of gel breaker with polymer was random, it could not degrade the polymer completely but only formed polymer fragments which were intricate in structure, differ in size and possessed in plugging. Reaction rule of dynamics determined that polymer can be degraded inordinately before the close of crack, and viscoelasticity and proppant carrying capacity of fracturing fluid were influenced. Such cases could be prevented by using peroxide, common enzyme, special enzyme gel breaker (defer gel breaking with micelle) and low concentration(≤0. 3%) fracturing fluid, etc. Filtrate damage was caused by liquid water block in which relative permeability of base rock could be reduced. It could be prevented by using surfactant to decrease surface tension, cationic ion surfactant to increase contact angle (approach 90°) , avoiding side of fracture plugging and depress terminal capillary pressure to inhibit water block, etc. According to the stimulation results, terminal capillary domino effect which produced by preventing base rock plugging plays an important role for inhibiting permanent water block.
出处
《钻井液与完井液》
CAS
北大核心
2003年第1期49-53,共5页
Drilling Fluid & Completion Fluid
