Study On Squeeze Injection Technology Of Barium Strontium Scale Formation In LP Oilfield

The water injection development of the LP oil production plant has entered the middle and late stages.Due to changes in formation pressure,temperature and other conditions,and chemical incompatibility of water,the fouling of the mixed pipeline network is becoming increasingly serious.Niobium scale is a kind of inorganic scale that is difficult to remove.It is difficult to remove the pipeline and equipment of the oil field once it is scaled.In this paper,the X-ray diffraction analysis of the scale samples provided in the field is firstly carried out.It is found that the main types of scale in the LP oil field are calcite(Ca CO₃)and barium-containing barite(Ba_0.75Sr_0.25SO₄).The cause of scale formation is contained in the formation.A large amount of calcium-containing substances can easily form calcium carbonate scale.The Ba²⁺and Sr²⁺ions in different wells are mixed with SO₄^2-ions to form a large amount of heavy-weight gold-bearing stones.The solubility products of barium sulfate and barium sulfate are different,resulting in the formation of barium.The eutectic compound;the type and content of each ion in the water sample are determined by chemical titration and chemical precipitation on the water sample provided on site.Analyze and calculate the type of fouling of the LP water sample and predict the scaling trend.It is found that most of the scaling tendency of the water sample generates scale and scale scale,due to the incompatibility and ionic activity of the formation water and the injected water.Different degrees,the water sample is rich in SO₄^2-ions,so there will be scaling tendency of scale and calcium carbonate scale.In-house experimental studies have found that the effect of fouling scale scaling rate is analyzed by studying the effects of reaction temperature,stirring speed,reaction time,and scale ion concentration on the scaling rate of scale.It is found that the scale of sulphate scale is fast and is less affected by temperature and ion concentration.The scaling of sulphate scale is slow.As the reaction time increases,the reaction temperature increases,and the concentration of SO₄^2-increases,the fouling rate increases rapidly.Through the indoor compatibility test,static scale inhibition rate test,dynamic minimumeffective mass concentration experiment and dynamic adsorption/desorption experiment,the scale inhibitors PESA,EDTMPS and TH-607B suitable for LP oilfield are optimized and their scale is prevented.The performance was evaluated.The effects of divalent ions Ca²⁺and Mg²⁺ions on the scale inhibitor were studied.Under the condition of constant Mg²⁺ion concentration,the scale inhibition efficiency of the three scale inhibitors increased with the concentration of Ca²⁺ions in Ca²⁺.When the ion concentration is constant,the increase of Mg²⁺ion concentration leads to a rapid decrease in the anti-scaling efficiency of PESA and EDTMPS,and the anti-scaling rate of TH-607B keeps rising steadily;by these three preferred anti-scaling agents,2:8,4:6,5:5,6:4,8:2 concentration ratios were combined to prepare DQ-2 series anti-scaling agent.When the concentration of anti-scaling agent is 3mg/L,The anti-scaling rate is close to 50%,the anti-scaling rate of sulphate scale is up to 30%;when the concentration of anti-scaling agent is 5 mg/L,the anti-scaling rate of sulphate scale is 90%,and the anti-scaling rate of sulphate scale is 60%.After selecting the DQ-2 type anti-scaling agent in the three wells of the LP oilfield,the concentration of the produced ion concentration of the three wells increased,the anti-scaling period became longer,the well pressure became stable,and the liquid production rate also increased.Stabilizing and reducing the economic loss of the LP oil field,the indoor prepared DQ-2 type anti-scaling agent can be successfully applied to the LP oil field.