Polymer Gel Structure-function Relationship And Its Reservoir Adaptability

In recent years,polymer gel has been highly valued by petroleum scientific and technical workers which has played a positive role in improving fluid entry profile of injection wells.However,results of field tests were not satisfactory as a result of the little study on structure and performance of polymer gel and its adaptability to reservoir.Directed by theory of moderm reservoir engineering,macromolecular physics and colloid chemistry,based on instrument analysis and physics simulation,evaluated by molecular dimension,viscoelasticity,molecular aggregative state,flow behavior,displacement efficiency,profile control effect etc,studies on the effect of electrolyte on performance of polymer solution and Cr³⁺ polymer gel,the effect of porous media on polymer gel effect and performance of hypersalinity and extra hypersalinity dissolvent Cr³⁺ polymer gel were carried out and Cr³⁺ polymer gel field tests results were analysed.The results showed that,dissolvent salinity especially concentration of Ca2+ and Mg2+has a great effect on performance of polymer solution and Cr³⁺ polymer gel.Delayed cross-linking system has well injectivity before extensive inter-chain cross-linking reaction occurred,after which injection become difficult.On the static condition,cross-linking reaction can be made between polymer and crosslinker molecular in porous media,while its extent of cross-linking reaction is lower than that in ground glass bottles.On the condition of hypersalinity and extra hypersalinity dissolvent,Cr³⁺ polymer gel which formed mainly by intra-crosslinking reaction has cdose viscosity to polymer solution in the same concentration,a little bigger molecular dimension and better adaptability to reservoir.In addition,as the viscoelasticity of Cr³⁺ polymer gel is improved obviously,and the molecular aggregation of Cr³⁺ polymer gel has changed,there is a significant raise in its resistance coefficient,residual resistance factor,displacement efficiency and profile control effect.The field tests results showed that,Cr³⁺ polymer gel has strong in-depth fluid diverting effect and obvious effect on increasing oil and decreasing water.Thus it can be seen that,the shape and performance of polymer gel congeries have been closely associated with reservoir adaptability and study on their relationship has fundamental significance for the guidance of developing new type of oil displacement agent and profile control agent.