Performance evaluation of reusing produced water as fracking fluid in Angsi field

The demand for freshwater continuously increases with hydraulic fracturing operations, mainly due to unconventional reservoirs. For instance, approximately 7000�18,000m3 of water is required per well for hydraulic fracturing. Meanwhile, almost 100bbl of produced water is produced annually worldwide in oil and gas. This study aims to develop a robust hydraulic fracturing fluid with untreated produced water and to study the feasibility of the produced water as a freshwater substitute for fracking fluid. Produced water from the Angsi field was used as the main produced water with high Total Dissolved Solids. The water was then mixed with guar gum, and crosslinker and polymer degradation after mixing was examined accordingly. The new fracturing fluid has a viscosity of 520cP and 1.015 g/cm3 density. A static adsorption test was carried out, and the fluid-rock interaction was checked. The changes of rock were also investigated using Scanning Electron Microscopy, X-Ray Fluorescence, and Energy-Dispersive X-ray. Apart from that, the rock-fluid interaction was examined through a wettability test, and the properties of fracturing fluid were investigated through interfacial tension and rheometer. The SEM and Poroperm tests revealed that there was no significant physical damage to the sandstone surface. According to the wettability analysis, the contact angles for sandstone surface-produced water�gas and sandstone surface-hydraulic fracturing-gas were 56.2° and 62.8°, respectively. The static adsorption was discovered to be 5.529 g/g. Hence, it is recommended to use the produced water for fracking fluid synthesis, reducing freshwater usage. © 2021, Institute of Chemistry, Slovak Academy of Sciences.