The Study Of CO₂ Flooding Scaling Cause Analysis And Prevention Measures In Xinghe Block

Xinghe Oilfield Chang 6 reservoir of low pressure,low porosity and permeability,micro-fracture reservoir in waterflooding process,high pressure water injection,water flooding low oil efficiency,effective water drive slow,low reservoir recovery,to increase oil production and oil displacement efficiency,the proposed injection CO2 flooding.However,due to high content of carbonate reservoir formation water Ca2+,Mg2+ content is high,making CO2 flooding process may lead to changes in reservoir properties and fouling and other issues affecting CO2 flooding effect.According to the characteristics of the reservoir and therefore need to carry out carbon dioxide flooding causes and prevention of fouling scale studies,as CO2 flooding technology applications and provide the basis for program design.In this paper,Xinghe Oilfield Chang 6 reservoir in the object,first of all using a variety of analytical methods and means of analysis of the mineral composition of Chang 6 reservoir rock properties and pore structure characteristics,physical characteristics and reservoir formation water,sewage and water reinjection the characteristic properties of the composition;and then through the static and dynamic simulation test fouling and fouling prediction method,analysis of the CO2 flooding process scaling law of the output from the injection well to well;and finally the use of core flow test scale experiments to study the CO2 flooding process Effect of reservoir properties,preferably a suitable scale agents and optimal dosage.The results showed that:(1)Xinghe Chang 6 reservoir fillings in carbonate mineral majority,formation water salinity and Ca2+,Mg2+ content is high and variable amplitude,which Ca2+ content of 900～11000mg/L,Mg2+ content of about 30～900mg/L;(2)CO2 flooding during the impact is mainly due to the scaling of temperature,pressure,carbonate content,salinity and water content of calcium and magnesium ions and other factors;(3)Since apricot River reservoir block there exists carbonates,CO2 injection wells around the injection will dissolve part of the lead carbonate rock reservoir permeability increase;deep into the reservoir,with the injection of water Ca2+ increase and high formation water Ca2+,Mg2+content exists,carbonate dissolution and precipitation of CaCO3 exist,and is accompanied by fines migration will occur,so that the reservoir permeability changes;(4)as the pressure decreases,the oil reservoir and the wellbore surrounding Each CaCO3 fouling phenomenon,so that the reservoir permeability reduction;(5)Za-108,Za-558,YS-201 scale inhibitor for CaCO3 scale the highest rate,by adding a concentration 20mg/L～40mg/L available under satisfactory scale inhibition.