Research On Separate Layer Polymer Injection's Pressure Adjusting Mechanism & Equipment

After the main pays were flooded by polymer in the Daqing Oilfield, the non-pay zones became the major developing targets. The filed tests showed that the injection profile was uneven; polymer solution advanced along the high permeable layers and low permeable layers couldn't fully developed during the course of polymer injection due to the reservoir's non-heterogeneity and well pattern.Testing and logging data including isotope, neutron longevity, and sealed coring well showed that thick, high permeable layers were fully developed; while thin, low permeable laminated layers were poorly developed. In order to ease the contradiction among levels and layers and improve the developing effect to the low permeable layers, separate layer polymer injection's pressure adjusting equipments are urgently researched to meet the demands of polymer injection aiming to non-pay zones and to improve the overall developing effects to the whole Daqing Oilfield.Cuboid homogenous core was made according to the Daqing Oilfield reservoirs'physical properties in this paper.16 million molecular weight polymers were sheared to 6 million and 8 million polymers. In addition, they were individually undergone by polymer flooding tests. The testing results are: The shearing polymer solution's viscoelasticity is worse compared with non-shearing one; and non-shearing polymer's recovery effect is higher than the shearing one. As a result, separate layer polymer injection's pressure adjusting equipments need to be designed low shearing degradation to guarantee the polymer flooding effect.In this paper, related formula and curves between visible-viscidity loss ?ηand flux Q, between pressure drop ?P and flux Q were set up to the polymer solution in the equipments'flow and equipments'sizes were optimized by designing separate layer polymer injection's pressure adjusting equipments and their basic hydraulic properties. Polymer pressure adjusting equipments were run into the wellbore and just changing the blanking plug could regulate choke pressure and control separate injection rate. Separate layer polymer injection highly improves the oilfield's developing effect and has broad application future in the oilfield at present and in the future.