  Drilling is a requisite operation for many industries to reach a targeted
subsurface zone. Loss of circulation is a common problem that often causes
interruptions to the drilling process and a reduction in efficiency. In this
work, a semi-analytical solution and mud type-curves (MTC) are proposed to
offer a quick and accurate diagnostic model to assess the lost-circulation of
Herschel-Bulkley fluids in fractured media. Based on the observed transient
pressure and mud-loss trends, the model can estimate the effective fracture
conductivity, the time-dependent cumulative mud-loss volume, and the leakage
period. The behavior of lost-circulation into fractured formation can be
quickly evaluated, at the drilling site, to perform useful diagnostics, such as
the rate of fluid leakage, and the associated effective fracture hydraulic
properties. Further, novel derivative-based mud-type-curves (DMTC) are
developed to quantify the leakage of drilling fluid flow into fractures. The
developed model is applied for non-Newtonian fluids exhibiting yield-power-law,
including shear thickening and thinning, and Bingham plastic fluids. Proposing
new dimensionless groups generates the dual type-curves, MTC and DMTC, which
offer superior predictivity compared to traditional methods. Both type-curve
sets are used in a dual trend matching, which significantly reduces the
non-uniqueness issue that is typically encountered in type-curves. Data for
lost circulation from several field cases are presented to demonstrate the
applicability of the proposed method. The semi-analytical solver, combined with
Monte Carlo simulations, is then applied to assess the sensitivity and
uncertainty of various fluid and subsurface parameters. The proposed can serve
as a quick diagnostic tool to evaluate lost-circulation in drilling operations.
