Research progress and challenges on production forecast techniques of fractured horizontal wells in shale oil reservoirs

Due to its rich reserves and potential for effective application, shale oil has been targeted for unconventional oil and gas exploration (Salygin et al., 2019; Podoba and Lavrova, 2021). The main technologies for developing low permeability unconventional reservoirs are multi-fractured horizontal well (MFHW) and stimulated reservoir volume (SRV) fracturing stimulation since they improve low permeability reservoir conductivity for effective production and high recovery. The estimated amount of technically recoverable continental shale oil resources in China was about 60 × 108t by prediction (Zou et al., 2013). However, it is challenging to evaluate the production of shale because of the heterogeneity of reservoir, complex fracture network produced by hydraulic fracturing, and the strong non-linearity of low permeability shale oil flow (Yao et al., 2020).

To match actual performance, we need enough production data for historical matching and choose an appropriate prediction model. Once those geologic parameters, fracture parameters and fluid properties of the share reservoir are obtained from prediction model, we can predict the production decline trend and assess the effectiveness of the completion and stimulation design. In the following section, this paper discussed the physics of fluid storage and flow in shale, and then summarized the current popular production prediction models and techniques for MFHW and SRV in the shale reservoir. Eventually, we point out the problems existing productivity prediction model of horizontal well and emphasize the future research work. It is expected to provide methods and technical reference for the effective development of shale oil and gas resources in the future.