A novel inversion approach for fracture parameters and inflow rates diagnosis in multistage fractured horizontal wells

摘要

Significant difficulties still exist in fracture parameters and inflow rates diagnosis for multistage fractured horizontal wells (MFHWs) using conventional method. The newly developed distributed temperature sensing (DTS) technology which can monitor the real-time downhole conditions for MFHWs provides enormous potential to solve this problem. However, due to the lack of robust inversion approaches, it's hard to quantitatively translate the DTS data to fracture parameters and inflow rates. In this work, firstly, a comprehensive inversion system combined with a forward and inversion model is proposed. The forward temperature model is developed to simulate the temperature behavior of an MFHW. The inversion model derived from the Markov Chain Monte Carlo(MCMC) algorithm is used to decrease the differences between the measured temperature and the predicted temperature iteratively. Subsequently, a synthetic case is presented to analyze the temperature characteristics and the application of this inversion approach. It has been found that any temperature drop (Delta T) corresponds to a created fracture and the Delta T are basically proportional to the inflow rates. According to that, a convenient equation is formulated to assign the initial inflow rate distribution to improve the computational efficiency of the inversion procedure. Finally, a field application (Well FH_1) is provided to demonstrate the capability of the developed inversion system to diagnose fracture parameters and inflow rates. Satisfactory inversion results are obtained within finite inversion iterations for this MHFW. The maximum temperature errors corresponding to each fractures are less than 0.02K. The inversed total production rate is 10.329 x 10(4) m(3)/d which matches the measured production rate (10.33 x 10(4)m(3)/d) very well that just validates the accuracy of the developed inversion system. The findings of this study can help for better understanding of fracture parameters and inflow rates diagnosis from the downhole temperature measurements for MFHWs.