Laboratory experiment for test the separation performance of downhole oil-water separator
The OCUs obtained by the laboratory experiments are 223mg/L (original geometry), 101mg/L (optimized geometry) and 121mg/L (the best geometry in CCF design), respectively. Compared with original geometry and the best geometry in CCF design, the OCU of the optimized geometry is reduced by 54.7% and 16.5%, respectively.
Steps to reproduce
In this experiment, only the separation process is considered to test the separation performance of downhole oil-water separator. Therefore, an experimental joint was specially designed for this experiment (Fig. 4a). The work flow of the system is as follows: the liquid from the pump passes through flow channel g (Fig. 1) into the first DOHC. After the first separation, the oil-rich liquid flows back to the oil tank through the first overflow channel and pipes; the water-rich liquid passes through channel h into the second DOHC. After the second separation, the oil-rich liquid passes through the second overflow channel and pipes into the oil tank; the liquid with trace oil flows back to the oil tank. Globe valve V2, V3, V4 are used to control the outlet pressures of the first overflow, second overflow and underflow for the adjustment of split ratio. Globe valve V1 is served to control the inlet flow rate. Sample valve L1, L2, L3, L4 are used for the collection of samples, including the inlet, first overflow, second overflow and underflow. P1, P2, P3 and P4 represent pressure gauge; Q1, Q2, Q3 and Q4 represent turbine flowmeter. The centrifugal pump is adopted to drive the liquid in this experiment, and its flow rate can be controlled by variable frequency technique. The following steps are proposed to prepare experimental media. Firstly, prepare the oil-water mixture with oil (diesel) concentration of 50000mg/L. Secondly, add OP-12 emulsifier to this mixture until its concentration is up to 15×10-6mg/L. Finally, keep the blender running 70 seconds at the speed of 940r/min. Specific experimental steps are as follows: (1) Open all the Globe valve; (2) Gradually close V1 to make the inlet flow rate is 30m3/d; (3) Adjust the globe valve V1, V2, V3 and V4 to make the outlet pressures of overflow and underflow are up to 15.6 MPa and 16MPa, respectively; (4) Open sample valve L1, L2, L3, L4 and sampling; (5) Detect the oil concentration of the samples using spectrophotometric method with the ultraviolet spectrophotometer (752C); (6) Calculate OCU.