It is difficult to apply the encoded simultaneous-source full waveform inversion technique to the marine-streamer data because of acquisition geometry. The difference of acquisition geometry between the observed and modeled data produces unwanted events in the residual seismogram. To avoid these unwanted residuals, the objective function based on global correlation was suggested by several researchers. However, the objective function based on global correlation unpredictably modifies the residual seismogram, which may result in distortion of inverted velocity model. In this paper, we propose an alternative approach to avoid these distorted residual seismograms and to properly cope with the acquisition geometry problem. Our algorithm modifies the offset-limited observed data to full-offset data by combining the original observed data with the modeled data. This modification leads to undistorted residual seismogram for the simultaneous multiple shot data. As a result, we can perform the effective simultaneous-source full waveform inversion even for the marine-streamer acquisition. Through the numerical examples, we show that our inversion algorithm better describes the velocity structure than the global correlation approach does.