Reservoir Geological Characteristics Of Dongying Formation In SZ36-1 Oil Field And Damage Mechanism Of Polymer-containing Sewage Reinjection

The chemical flooding technology represented by polymer flooding gained tremendous technologic and economic benefits.However,the property and proportion of polymer sewage is more complex than normal produced liquid.Direct draining polymer sewage out will pollute ocean environment,but disposing to the emission standard need high cost,hence that rejecting polymer sewage back to stratum is a common disposal method,because it not only can solve practical water source demand of the exploitation of oil field inject water,but an mandatory stipulation for realizing zero-emission on offshore oil field.Due to separation of seawater to offshore oil field and constraints in time and space of marine platform,offshore oil field can't directly copy the mature technology of inland oil field.Therefore research the reservoir damage mechanism which caused by polymer swage reinjection produced for polymer flooding in offshore oilfield has theoretical and technical support for promoting marine oil field injection,solving the practical demand of water source and coming up with pertinence reservoir protection measure.This paper takes SZ36-1 oilfield as the research object,on the basis of systematic analysis of the geological characteristics of the main reservoir Ed II,classifying the reservoir as five levels with porosity-permeability parameter.Ed ? was mainly constituted by ???.The result of Investigateing and researching the disposal status of oil field water shows Ow,SS and SRB exceeded standard.Implement reservoir sensibility experiment,static and dynamic compatibility evaluation of source water and polymer sewage,adaptability evaluation of different polymer sewage and reservoir,combining the various experiment means such as X-ray diffraction(XRD),casting thin section,scanning electron microscopy(SEM),nuclear magnetic resonance(NMR),to analyze the damage mechanism.The results show that:?Ed ? exist weak velocity sensitivity,strong water sensitivity and salt sensitivity,medium acid sensitivity,weak alkaline sensitivity.?Oil field polymer sewage,formation water of Ed and source water have a degree of scaling ability;there has a slight incompatibility between the polymer sewage and the source water.Through dynamic compatibility experiment comment,it is known that under the dynamic seepage conditions in the formation,the scale particles tend to form larger aggregates,and causing serious clogging of pores.?The increasing damage degree of polymer sewage rejection to the permeability of core grew with the concentration of polymer:while the concentration of polymer is 100mg/L,the damage rate of permeability is 42%;while the concentration of polymer is 200mg/L,the damage rate of permeability is 60%.Polymer sewage has significance influence to reservoir's big pore and those polymers not only absorb on the surface of rock particles,but they also form filamentous adhesions to divide big pore into small pore,decreasing the passing ability of particulate passing.Research achievement has guidance and referential value on sewage disposal and rejection to marine oil field.