Structural failure mechanism and strengthening method of fracture plugging zone for lost circulation control in deep naturally fractured reservoirs

XU Chengyuan,YAN Xiaopeng,KANG Yili,YOU Lijun,ZHANG Jingyi

Table 1 Control technology of working fluid lost circulation in fractured formation.

Realization way Lost circula- tion type Scope of application Key points Schematic diagram Adjusting the stress field around the wellbore Stress cage Lost circulation by induced fracture Formation with underdeveloped fractures Formation with high elastic modulus Isotropic formation Support the fracture, isolate the crack tip, stability of plugging zone Increase fracture closure stress Formation with underdeveloped fractures Formation with high elastic modulus Isotropic formation High permeability formation Increase fracture extension pressure Lost circulation due to fracture propagation Formation with naturally developed but not connected fractures Reduce the pressure in the fracture, Control the stress intensity factor, Stability of fracture-plugging zone Plugging the working fluid loss channel Lost circulation through large and medium fractures Formation with naturally developed and connected fractures Formation of plugging zone, Stability of plugging zone Increase the strength of rock mass Rock mass strength, Stability of plugging zone