A theory to model pseudo steady state water production and predict long-term water recovery from fractured reservoirs

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作   者：

Sabbir Hossain;  Hassan Dehghanpour; 

作者机构：

Department of Civil and Environmental Engineering;  Edmonton;  Canada;  University of Alberta; 

关键词：

Long term water production;  Pressure-normalized rate;  Multiphase flow;  Pseudo steady state flow;  Fractured unconventional reservoirs;  Material balance;  Harmonic decline;  Multi-fractured horizontal wells; 

期刊名称：

Energy

i s s n：

0360-5442

年卷期：

2024 年 288 卷 Feb.1 期

页   码：

129586.1-129586.22

页   码：

摘   要：

The environmental and economic impact of hydraulic fracturing technology in the energy industry remains agrowing concern due to large water consumption and poor water recovery in return. In this study, we propose anovel theory to describe and model the drive mechanisms (fracture closure and fluid expansion) responsible forlong-term water recovery from hydraulically fractured reservoirs. In the literature, pseudo steady state (PSS)flow of water has been explained and modelled under the assumption of negligible fluid influx from matrix,referred to as "supercharge conditions". The preliminary flowback data analysis of 8 different unconventionalreservoirs from North America in this study shows 1) water PSS flow signature is also observed after fluidbreakthrough into fractures, and 2) it can be modelled mathematically, verified with long-term field data, andvalidated with numerical simulation results. These observations suggest that oil and water develop differentnetworks or flow paths through fractures. With time, oil network expands and water network shrinks. Therefore,water continues to be produced from the fractures as oil saturation increases in the fractures with expansion of oilnetwork due to fracture pressure decline. Based on this theory, an integrated semi-analytical workflow isdeveloped by accounting for the changes in the volumes and compressibilities of both fracture and fluid. Theworkflow was applied on early production data (150–200 days) from six multi-fractured horizontal wells in EagleFord. The results show that the workflow can use the early-time data to accurately estimate long-term waterrecovery (325–475 days) from fractured reservoirs (within 6 % of measured field data). However, frequent longshut-ins during the course of long-term production increases the uncertainty in water recovery prediction.