Russian experience with geophysical studies in horizontal wells producing under conditions of low rates and multiphase separated flow shows that traditional methods using mechanical flow rate measurements and temperature logging are not effective in identifying the producing intervals. Results of physical experiments conducted in a laboratory flow loop established that flow structure in horizontal wells producing at rates from 2 to 250 m3/d is mainly determined by the wellbore trajectories and phase rate ratios. In these horizontal wellbores there is a zone of stagnant fluids, as well as significant vertical gradients of fluid velocities and temperatures.
Taking into account actual values of total and phase rates typical for horizontal wells in the Russian Federation, experimental works were carried out in a flow loop at Bashkir State University to develop criteria for flow profiling and methodology for wellbore field measurements in low-rate wells.
Analyses of the laboratory experiments and field data established the need for precise data on wellbore trajectory, taking into account the phase distribution across the flow at the tool location; the need for local velocity measurements in the temperature field along the entire horizontal wellbore trajectory; and the need for different well operational regimes. Based on the results of the experiments, actual field data were reinterpreted. Recommendations were developed for methodical guidelines for field data interpretation, and criteria were formulated for identification of oil and water inflow intervals in low-rate horizontal wells.