Mechanism on Imbibition of Fracturing Fluid in Nanopore

摘要

In oil and gas wells, hydraulic fracturing technology has been widely applied to increase permeability and enhance oil recovery. However, the transportation of fracturing fluid in gas and oil shale, which is a critical factor, needs further investigation. Herein, the main influence factors, such as the permeability, clay content, fracturing fluid type, capillary pressure, wetting angle and fracture were systematically investigated based on the guar gum fracturing fluid and the slickwater fracturing fluid both commonly used in Ordos basin. The results showed that the clay content was the key factor to control capillary imbibition and osmosis, and the linear relationship between the volume of imbibed fluid and clay content of core sample was observed. In addition, for the loss of fracturing fluid, the important control factors were capillary imbibition and osmotic force. The capillary imbibition was 4.7 times the imbibed mass of osmotic absorption, and the guar gum fracturing fluid was 2 times the imbibition rate of slickwater fracturing fluid. It indicated that the reservoir rock with fracture was advantageous to oil recovery in imbibition process.