Frictional pressure drop of non-Newtonian flow of CO₂ foam fracturing fluid in vertical downward pipe

CO₂ foam fracturing fluid behaves as a non-Newtonian fluid, whose flow characteristics in vertical oil pipe under the conditions of actual fracturing operation are directly relevant to the accurate evaluations of generated fracture and fracturing effects. The characteristics of fractional pressure drop of CO₂ foam fracturing fluid in vertical downward pipe in the range of 10-20 MPa, 40-80°C were studied experimentally with CO₂ in supercritical state. The frictional pressure drop increases with the mixture velocity, and decreases with the increases of temperature and pressure. One correlation to calculate the frictional factor of such foam fluid was obtained from the test data, the average error of which is 14.8%.