Research On The Feasibility Of Polymer Flooding In Conglomerate Reservoirs

Most karamay oilfield reservoir is conglomerate reservoir.In this oilfield,the exploitation method is waterflooding which has been used 40 years.Now its oil production begins to decline and the water cut is very high so that waterflooding can not meet the production requirements and it is difficult for stable development for simplily on the basis of waterflooding.It is necessary to carry out the research of polymer flooding.But at present the use of polymer flooding in sandstone reservoir is more,and related technology is mature,with less used in conglomerate reservoir.Compared to sandstone reservoir,conglomerate reservoir physical property is poor.Contrast can be found by mercury injection curve.The sorting of conglomerate is poorer and capillary radius is smaller.These characteristics had a great influence on polymer flooding effect of mines.Because the feasibility of polymer flooding in conglomerate reservoir can't simply refer to the feasibility of polymer flooding in conventional sandstone reservoir,so it is necessary to carry out feasibility study on polymer flooding conglomerate reservoirs to make the fluid injection are well suited conglomerate reservoir and Give full play to the good performance of polymer flooding.Through the microporous membrane filter method,the hydrodynamic characteristics of size under different pressure gradient feature sizes was measured and the experimental pressure gradient of this study was choosen.On the basis,the static parameters of different molecular weight,different concentrations of polymer system was evaluated.Through the liquidity experiment of polymer solution on constant pressure,the influence of polymer molecular weight,concentration,rock permeability on compatibility is concluded.And the compatibility chart of the rock and different polymer under condition of having oil or without oil has been given.Through evaluation of oil displacement efficiency of different chemical system in different physical properties core,and the influence factors of displacement efficiency or injection pressure were studied.The different characteristics relative permeability curve between water flooding and polymer flooding in conglomerate cores were researched.Finally oil displacement experiment of conglomerate reservoir indoor has been carried to study the feasibility of polymer flooding in conglomerate reservoir.The results show that the hydrodynamic characteristics of size mainly affected by the polymer molecular weight,concentration of the polymer.The compatibility is influenced by the molecular weight,concentration of polymer,the influence of rock permeability.And the compatibility chart of the rock and different polymer under condition of having oil or without oil has been given.The polymer can increase the capillary number of some seepage channel by increasing the displacement pressure,which can increase the oil displacement efficiency.Compared with water flooding relative permeability curve of same saturation,relative permeability of polymer phase is lower,and theright endpoint and isotonic point move to the right.At the same time the span of two phase is larger than that of water flooding.The recovery of polymer flooding can be increased by more than 10% on the basis of waterflooding in uniform thickness model or non-uniform thickness model.This indicates that the implementation of polymer flooding in conglomerate reservoir is feasible.