Study On The Technology Of High Temperature Chemical Plugging In Oil Well

In the heavy oil region of Fuyu Oilfield,after the previous stage of water injection,the viscosity of crude oil rises,and the continuous injection of oil wells has poor efficiency.However,the conventional thermal recovery and steam stimulation have little effect.Hard-to-recover reserves have not been effectively developed..In order to achieve stable production in Fuyu Oilfield and effectively exploit the remaining heavy oil,it is imperative to explore new solutions.For this reason,the article puts another way forward and puts forward a proposal for research on high-temperature chemical plugging and sealing of oil wells.The mentioned high-temperature chemical blocking agent is a high-temperature three-phase foam,and the experiment is carried out according to the process of first determining the formulation and then performing the performance measurement.First,the foaming agents and solid particles in high-temperature chemical blocking agents were screened,and the amount of each component was optimized.From the experiment,the foaming agent is AAS,the solid phase particles are lignin fiber,graphite particle and solid phase particle M;the mass fraction of the polymer HPAM is 0.8%,the mass fraction of the crosslinker is 0.5%,the mass fraction of the heat stabilizer is 0.25%,the mass fraction of the foaming agent AAS is 0.3%,the mass fraction of the solid phase particles is 4%(wherein the lignin fiber is 2%,the graphite particle is 1%,and the solid particle M is 1%).Second,we study the influencing factors of high-temperature chemical plugging agents,such as temperature and salinity,etc.According to experiments,in the temperature resistance experiment,for the case of the gelation viscosity,when the temperature is 100° C.<T<250° C.,it increases with the increase of the temperature.And when the temperature is 250°C<T<300°C,it decreases with increasing temperature.As far as the gelation time is concerned,at 100°C<T<300°C,it tends to decrease with increasing temperature.In the salt-tolerance experiment,the degree of salinity of the formation water in this block has little effect on the gelation viscosity and gelation time.In the aging test,the gel was broken for 5 days at 250°C.Again,we study the factors in the gel hydration experiment and the performance of the hydration fluid,such as the ability to wash oil.According to experiments,the hydration time becomes shorter as the temperature rises;at 250°C,the viscosity-time diagram shows that the hydration velocity first increases and then decreases;hydration speed is basically not affected by crude oil;in the experiment of washing ability,the recovery rate can be increased by 13.52%;in the viscosity-reducing rate test,the viscosity-reducing rate reaches 89.97%;in the foaming ability test,the foaming volume and half-life are kept at 480 mL and 43.2 min;in the milk performance experiment,it was shown that heavy oil and condensed water can be prevented from forming a stable W/O emulsion.It can be seen that the performance of hydration fluids all performed better.Finally,we studied the application properties of high temperature chemical plugging agents,including plugging,erosion resistance,thermal stability,and performance compared to other systems.When evaluating the plugging performance of the system,the independent variables were permeability,temperature,and injection volume.When the permeability is in the range of 100mD-800 mD,the plugging rate increases from 90.17% to 95.12%,and the breakthrough pressure gradient increases from 3.25MPa/m to 4.25MPa/m.When the temperature is in the range of 200°C-260°C,the plugging rate increases from 87.52% to 93.12%,and the breakthrough pressure gradient increases from 3.525MPa/m to 3.7MPa/m.When the injection volume was in the range of 0.2PV-0.5PV,the plugging rate increased from 81.21% to 94.58%,and the breakthrough pressure gradient increased from 3.4MPa/m to 4.175MPa/m.When the erosion resistance performance of the system was evaluated,the minimum plugging rates were 89.72% and 89.07% when the injected steam volume was 15 PV and 30 PV,respectively,and they were all at a relatively high level.When the thermal stability of the system was evaluated,the plugging rates of the hypertonic,mesial,and hypotonic tubes on the 4th day were still maintained respectively at 89.85%,87.75%,and 85.85%.Comparing the experimental results of four different steam traps,the high temperature chemical plugging agent has many advantages,including good selectivity,priority to higher permeability formations,good sealing,good stability,and it also does not cause unrecoverable damage to the formation.