Research On The Corrosion And Control Plan Of The Surface Gathering And Transportation System Of CO₂ Flooding In LS Oilfield

The LS oilfield carried out the CO₂ driving test in the LB block.According to the LB CO₂ driving test plan,there are problems such as the incomplete research on the corrosion law of the ground gathering pipeline and the poor technology of corrosion control.Based on the CO₂ driving ground gathering system of LS oilfield,this paper studies the gathering process and corrosion law.The control strategies are proposed from the aspects of corrosion inhibitor,pipeline material and pipeline inner coating.The main research work is as follows:?1?Investigate and analyze the corrosion control technology and corrosion control of CO₂ driving ground gathering pipelines domesitc and abroad,including the current status of CO₂ driving and gathering systems,C02 corrosion control technology research,and anti-corrosion control of oilfield ground gathering systems domestic and abroad.?2?For the C02 drving well production fluid and associated gas,the general properties of the dewatering crude oil and associated gas samples and the viscosity and temperature characteristics of the crude oil were analyzed and evaluated.From the CO₂ driving ground oil collection system pressure to the production well normal pressure,the hydrate formation limit of the mixture of CO₂ and CH4 was carried out in an indoor experimental study.And obtained the hydrate formation curve under different CO₂ content conditions.By comparing the CO₂ dry method and the wet recovery method with the technology of related manufacturers Exchange,decided to use MEDA solvent to recover CO₂.And designing a complete set of CO₂ recycling process and equipment selection.?3?By Analysing the typical corrosion failure case of the gathering pipeline and studing the influence of water content,CO₂ and flow rate on the gathering pipeline through experiments,and obtained the corrosion law of the gathering pipeline:under the condition of low water content,the crude oil forms a protective film on the sample.So It can slow down the corrosion of the sample to some extent.With the increase of water content,the crude oil can not form a complete protective film on the surface of the sample,and local corrosion will be intensified.The water content of the produced liquid in LS oil field is very high,the flow rate is slow.And the medium is easy to form a laminar flow state of three phases.So the corrosion at the bottom of the pipeline will be intensified.Under the conditions of the ground system of the LS oilfield,the corrosion rate of the pipe increases with the increase of the CO₂ content.?4?By studing the corrosion control technology of CO₂ driving ground gathering and transportation system in LS oilfield,forming a corrosion control scheme suitable for LS oilfield.Evaluating the effect of corrosion inhibitor,developing corrosion inhibitor formula.The effect of the CI-6A corrosion inhibitor increases gradually with increasing concentration.Under the corrosive environment for LS CO₂ driving,when the concentration reaches 200mg/L,the corrosion inhibition effect is close to the best.And the CI-6A corrosion inhibitor has no effect on the demulsifier.Following the principle of point-to-face when adding corrosion inhibitor protection,uniformly and continuously adding a sufficient amount of corrosion inhibitor.And forming a dosing mechanism at G43-23 oil station:adding the corrosion inhibitor before the water pump.The concentration of the drug is 200mg/L.About 50kg of corrosion inhibitor is needed every day.And about 18 tons of corrosion inhibitor is needed for the whole year.?5?Proposing materials for new ground gathering pipelines:using ammonia-cured glass pipes for water-mixing pipelines,glass-steel pipes for oil-filled pipelines.Using stainless steel for inlet valve blocks and import and export of oil and gas separators,etc.Suggestions for the pipeline:on the basis of the carbon steel material of the pipeline,a corrosion inhibitor suitable for the ground gathering system of the LS oilfield is added.And the applicability of the inner coating is evaluated and the inner coating of the CO₂ driving ground gathering pipeline is optimized.