The current research on fracture conductivity ignores
the placement
of the proppant in fractures and relies on single-fracture conductivity
testing and calculation, which cannot represent the overall conductivity
of complex fracture systems. This research proposes a calculation
method for the long-term conductivity of complex fractures based on
proppant placement. This method considers fracture morphology, proppant
placement, proppant embedment, and deformation under high closing
pressure. The research results show that fracture conductivity decreases
with increasing time, which can be divided into three stages: the
embedding stage, the creep stage, and the stabilization stage. The
long-term conductivity of the main fracture is higher than that of
the branching fracture. With increasing closing pressure, the conductivities
of both the main fracture and the branching fracture decrease. This
is because increasing closure stress accelerates proppant embedment
and creep, compressing the fluid flow space and further reducing fracture
conductivity. Fracture conductivity is related to the placement of
the proppant and sand concentration. Increasing the sand ratio can
significantly increase the placement of the proppant in the main fracture
and branching fractures, thereby improving fracture conductivity.
Increasing the fracturing fluid viscosity can increase its proppant
migration capacity. The proppant does not easily settle prematurely
in high-viscosity fracturing fluid and can enter more into branching
fractures, thereby improving their conductivity.