Experimental study on the flowback of a carboxymethyl hydroxypropyl guar gum fracturing fluid with good temperature resistance

For unconventional oil and gas reservoirs such as shale oil and gas as well as tight oil and gas, hydraulic fracturing generally enhances oil recovery. However, the flowback rate of the residual fracturing fluid is low. The residual fracturing fluid in the fracture or the rock matrix can reduce relative permeability of oil and gas, and the production rate will decrease. Therefore, it is necessary to study the factors that affect the flowback rate of the fracturing fluid. Most previous studies used the slot model, and viscous and capillary forces explain stable discharge in porous media. The conclusions were only a primarily qualitative analysis. The factors from experimental studies were not comprehensive, and they did not consider the influence of gravity. There are few studies on unstable drainage in porous media under different displacement directions. This paper presents a carboxymethyl hydroxypropyl guar gum fracturing fluid with good temperature resistance, and a fracturing fluid flowback experiment is carried on. The effects of the displacement direction, injection pressure, interfacial tension, fracturing fluid viscosity, and proppant wettability on the flowback rate are analyzed. The research results can provide formulation of the on-site construction scheme.