转向剂对岩石破裂压力及裂缝扩展效果影响试验

Experiment on influence of diverting agents to rock fracture pressure and crack extension

转向剂的质量分数和施工排量是油气井压裂设计和施工的重要参数。通过物模试验分析上浮与下沉转向剂单独及共同作用下,转向剂质量分数、施工排量对人工岩心破裂压力及裂缝扩展效果的影响。结果表明:岩心在清水压裂条件下,破裂压力略大于围压且二者呈近似一次函数关系;岩心在不同排量的上浮或下沉转向剂单独作用下,在最佳质量分数范围内,破裂压力随质量分数增大明显提高,较同条件清水压裂增幅为17.30%~93.46%;相同条件下,采用大排量压裂可得到更高的破裂压力;下沉转向剂作用下,岩心的破裂压力受转向剂质量分数和施工排量的影响更加明显;上浮与下沉转向剂共同作用,可更加有效地改善裂缝尖端封堵效果,破裂压力可达单独作用最佳质量分数时的1.88~3.32倍;转向剂压裂较清水压裂而言,更易形成复杂裂缝,从而改善压裂效果。

The mass fraction and construction displacement of the diverting agents are vital parameters in the fracturing design and construction in oil wells.In this study,the influence of mass fraction and displacement of diverting agents on the fracture pressure and crack propagation of artificial cores is analyzed by simulation tests.The experiment is performed under two kinds of situations,i.e.the separate and combined action of the floating and sinking diverting agents.The results show that under the condition of water fracture,the fracture pressure of artificial cores are slightly larger than the confining pressure,and there is an approximately linear function between them.Under the separate actions of the floating or sinking diverting agent with different displacements,in the range of best mass fraction,the fracture pressure of artificial cores increases obviously with the growing of the mass fraction,and increases by 17.30%-93.46% higher than that of the water fracturing under same conditions.Under the same conditions,the higher fracture pressure can be obtained by using larger displacements.Under the action of sinking diverting agent,the fracture pressure is more easily affected by the mass fraction and displacements.Under the combined action of the floating and sinking diverting agents,the blocking effect can be significantly improved,which can make the fracture pressure 1.88-3.32 times than that under separate conditions with best mass fraction.Comparing with the water fracturing,the diverting agent fracturing is more beneficial to form complex cracks,which helps to improve the fracturing effect.