Drilling fluid loss is an important engineering and technical problem that restricts deep and ultra-deep drilling

and the well loss in reservoir interval is the most serious reservoir damage mode in drilling and completion stage. It is the main way to control lost circulation to use the bridging plugging material to block the fracture leakage channel. However

the design of bridge plugging formula often adopts the empirical or semi-empirical method

leading to low plugging success rate and poor plugging effect. By the CFD-DEM simulation

it is clear that the bridge retention

accumulation filling and pressurized plugging are three key links in the formation process of fracture sealing layer. Considering the efficient bridging and compact filling of the plugging material

and based on the concept of “absolute bridge addition” and the theory of tight packing

a new experimental formula design method for pressurized plugging is proposed. “Absolute bridging amount” is used as a optimization parameter to determine the bridging material amount in the formula. The traditional compact packing theory is improved by the “complementation method”

which overcomes its defects of poor adaptability to the filling materials with discontinuous or overlapping particle size distribution

and determines the filling material addition in the plugging formula. The results of laboratory and field experiments show that the proposed method can realize the rapid and efficient design of the formula for deep naturally fractured reservoir

effectively ensure the sealing effect of the formula for deep naturally fractured reservoir and reduce the total amount of materials in the formula and save the material cost. The proposed method provides a new idea and theoretical basis for the design of plugging formula for deep naturally fractured reservoir.