Study On Scale Removal Of ASP Flooding Based On The Comprehensive Thermochemical Action Of The Gas Generator

Alkaline-Surfactant-polymer(ASP)flooding technology is an important technical means for stabilization and increasing of production in Daqing oilfield at present stage.However,during the process of production with ASP flooding technology,the scaling problem has been increasingly prominent,which seriously affected the normal production of the oilfield.The main components of the plugging include petroleum reorganization,carbonate scale and silica scale wrapped by the polymer.Because of the combustion of energetic materials,the liquid in down-hole zone could be transformed into supercritical state,which can cause the upgrading of petroleum reorganization and the polymer.The acid gas that generated from combustion can be turned into acid liquid,which can dissolute carbonate scale and silicon scale so that the blockage removal could be achieved finally.In this paper,the cause of blockage of ASP flooding was analyzed.Due to the reaction of anions and cations in various kinds of water,injected ASP flooding agents and rock composition,a compound of inorganic deposits,silicates and the mixture of co deposition of polymers and sediment could be formed.In addition,the blockage sample in laboratory was analyzed.It could be divided into three parts,which are water,paraffin blocks and complex colloidal material composition.The mass percentage for each part was 67.81%,10.18%,22.01%.Paraffin block could be divided into four parts,which are Saturates,Aromatics,Resins and Asphaltenes,each of them accounting for 78.51%,13.12%,6.39% and 1.98%(wt%).Based on the comprehensive thermochemical effects of gas generator,the state of supercritical water and acid created by energetic material combustion in oil well were simulated in experiments.The pyrolysis of paraffin blocks in supercritical water was studied.The optimum experimental conditions are as follows: the reaction temperature was 430?,the reaction time was 1h,and the density of supercritical water was 0.4g/cm3.The dynamic model was designed and fitted well with experimental data.The pyrolysis of polyacrylamide(PAM)in supercritical water was studied.The optimum operational conditions were as follows: the reaction temperature was 430?,the reaction time was 2h and the mass ratio of PAM:n-octacosanol was 1:1.In acidification experiments,the optimum acid concentrations were 12% hydrochloric acid and 4% hydrofluoric acid(wt%)and the dissolution percentage were 25.6% and 61.5% respectively.Based on the above analysis,the optimum conditions of 430?,1h,the density of water 0.4g/cm3,12% hydrochloric acid and 4% hydrofluoric acid were applied in the experiment of the dissolution of the whole plugging sample.The paraffin oil components were upgraded and removed,the concentration of polyacrylamide became lower and acidification corrosion rate reached 91.9%,which could be considered that the blockage samples in this research were better removed.In addition,the feasibility of application for ASP flooding scaling removal based on the comprehensive thermochemical action of the gas generator was studied.Thus,advanced ideas and techniques of the gas generator for improving the oil quality and plugging removal of oil wells were further verified.