基于新型动态循环堵漏装置的颗粒-凝胶复合堵漏实验研究OA

Experimental devices currently in use for lost circulation control test have such shortages in simulating dynamic circulation and evaluating the performance of lost circulation slurries.To overcome these shortages,a multiparameter dynamic lost circulation control experimental device was developed which integrates heterogeneous tortuous fracture simulation,temperature-pressure coupling control and real-time monitor functions.This device consists of a temperature-pressure controlled reactor(0-150℃)/(0-25 MPa),a work fluid synthesis system,a circulation pump set and a data acquisition and control system.It can be used to reconstruct tortuous fractures with lengths of 50-60 cm,and simulate the alternate migration-plugging process of lost circulation materials under dynamic circulation conditions.Using prefabricated heterogeneous artificial cores and reticulate metal frameworks,experiments were conducted on controlling lost circulation in multiscale fractures and nested frameworks,and the synergistic mechanism of the particle-gel composite system was revealed.Experimental results show that the lost circulation control slurry formulated based on the D90 rule achieves a coordinated improvement of suspension stability and plugging capacity through the"coarse particle bridging-fine particle filling-gel gap plugging"process,with the pressure bearing capacity of the plugging layer being over 12 MPa.The curing of the preinjected gel can significantly shorten the circulation time:the time for plugging a single fracture is shortened to 4 min,a plugging efficiency of at least 45%higher than plugging with single-particle lost circulation slurries,and this time is further reduced to 2.7 min when metal frameworks are used.This study has verified the engineering applicability of time-sequential synergistic process of lost circulation control with composite slurries under dynamic circulation conditions,providing theoretical support for the prevention and control of lost circulation in fractured-vuggy formations.