Nonstationary convolution models are widely used as the forward formula of nonstationary seismic reflectivity inversion (NSRI). This forward formula is determined by the convolution of a time-varying wavelet and reflectivity. Previous NSRI algorithms just focus on the estimation of reflectivity according to different sparse regularization strategies. The forward-operator, time-varying wavelet matrix is usually generated using a user-defined constant Q-value. However, the Q-value changes with time and space; therefore, inaccurate reflectivity inversion results will be yielded by the traditional NSRI method. In order to improve the accuracy of the inverted reflectivity, we propose a new forward-operator construction method based on the monotone relationship between the equivalent Q-value (Q_e) and centroid-frequency (CF). We first extract CF from the Gabor time-frequency amplitude spectrum of the seismic signal. Then, we can obtain Q_e through the CF-Q_e template. Hence, the blindness of selecting a Q-value is avoided and a more accurate forward operator can be constructed. Synthetic and field-data examples demonstrate that the proposed method provides a more accurate reflectivity estimation by constructing a more reliable forward operator. Furthermore, the enhanced reflectivity sections enable a clearer delineation of top and bottom interfaces of coalbed methane reservoirs, providing high-resolution seismic support for coal seam interpretation and subsequent mining planning.