Causes Analysis And P Reventions Research Of Corrosion And Scale In Oilfield Water Injection Pipeline

Currently,the Tarim O ilfield water injection development operatio n areas have varying degrees of scaling and corrosion.Especially C operatio n area,fouling and corrosion are extremely serious,a lot of excessive suspended solids,leading to increased injection pressure even blocked pipes,water pipelines occurrence was hout frequently,which seriously affected oilfield injecting water production.For oilfield wastewater in C and D work area and two different waste water treatment processes,start from testing,analyzing composition of oilfield wastewater,Studied phenomena of scale and corrosion systematically and combined with the actual situation,proposed practical prevention measures.The study found that high content of dissolved oxygen,high water temperature leading to the main cause of severe corrosion of water pipelines in C work area.XRD analysis on the water injection pipeline showed,scale sample of water injection pipeline in C work area contains large amounts of iron,CaCO₃ scale,sulfur,etc.Scale sample composition and content of different sampling points coincides with the specific process in the scene,and consistent with the result of scaling trend forecast.C work area scaling seriously is due to the waste water itself has CaCO₃ scaling feature,irrelevant to block produced fluid compatibility;D work area clean water pipeline corrosion is caused by iron bacteria seriously beyond the standard,XRD analysis showed that D work area scale sample mainly BaSO₄ and SrSO₄ scale,consistent with the predicted scaling trend.When the clean water mixed with waste water,not because of compatibility problems led to great changes in the nature of water,but allocation process has an great impact on suspension in outbound waste water;The two work areas suspensions four components analysis found that C operation area has high content of hydrochloric acid soluble fraction,D work area has high content of acid insoluble inorganic component.Simulation oilfield wastewater to study the effects of water erosion factors,The results show that dissolved oxygen and temperature have the largest effect on the corrosion rate,Ca²⁺,Mg²⁺,SO₄^2-,HCO₃-,Cl-,and other inorganic ions have little effect on the corrosion rate.The impact of the corrosion products on water quality also be concerned,the study found that at the presence of dissolved oxygen conditions,the more serious corrosion and scaling,the more turbid the solution is（absorbance increase）,the higher the content of Fe3+ in solution,the higher the suspended solids content is,it is clear that the corrosion and fouling not only undermines equipment and pipelines,also lead to the suspension unqualified and secondary pollution problems.On the basis of systematic analysis of scaling,corrosion and excessive suspended solids causes,combined with on-site waste water treatment process,put forward the following measures: C work area water buffer tank needs additional floating bed as oxygen barrier,in the short term can depend on " only in not going out" process to reduce the dissolved oxygen corrosion and dirty water in buffer tank into the water injection pipelines.Field studies found that bactericide in C work area with a sulfur removal effect,must be continuously added;For outbound water quality unstable in operation area C,D work area clean water buffer tank‘s bacteria can easily be covered with dirt debris or silt,fungicides can’t contact with the bacteria,need to clean up the buffer tank and water injection pipes,and then take the impact of dosing method combined with continuous dosing method,can complete sterilization;When clean water mixed with waste water injection in D work area,should be mixed in the injection valve,avoid water buffer tank water disturbance and dirt sedimentation in tank bottom into the water pipelines.For outbound water quality unstable in operation area C,the iron ion stabilizer also can be used to make the water transport stability,in which ferric ion stabilizer 3# adding about 70 mg·L^-1,the ferric ion stabilizer 4# dosage is 80 mg·L^-1,can play a better stabilization effect.D work area need to clean up the buffer tank and water injecting lines,alternating fungicides,and then take continuous dosing manner binding impacted manner dosing,before bacterial being completely wipe out;When clean water mixed with waste water injection in D work area,it should be change from mixed in waste water buffer tank to refill valve pry,in order to avoid the outbound waste water quality fluctuations.After the site in accordance with the above program adjustments,scaling and corrosion significantly reduced,suspended matter pass rate beyond 95%.