Research On High-efficiency Barium Sulfate Descaling Agent And Its Descaling Mechanism

Nowadays,the lack of energy is increasing and one of the main energy resources,oil,is becoming scarcer and scarcer.However,a large number of oil still stay underground and cannot be mined because of the production technology.The scaling of pipes,equipment and the interstices between the layers is one of the main causes of the decrease of the oil output.besides;the scaling corrodes the pipelines and equipments and blocksthe formation pores,which has caused huge economic losses in the oil exploitation.According to the report,the economic loss due to scaling was up to more than 1 billion dollars a year only in the United States.And that corrosion and perforatione caused by scaling also lead to oil spill accidents;therefore,scaling is also a great risk to the natural environment including water and soil resources.Existing descaling technology is mainly divided into three categories;they are mechanical descaling,physical descaling and chemical descaling.Acid pickling,one method of chemical descalingtechnology,is very effective for removing the scale such as carbonate and magnesium hydroxide.When it comes to the compact barium sulfate scale,built detergents with ammonia carboxy chelating agentas main agent and some other auxiliary agents are major used detergents.However,barium sulfate scale removes of nowadays also have problems such as low descaling amount and speed,low utilization and poor biodegradability.And it is still very short of studies of the descaling mechanism for ammonia carboxy chelating agent and built detergents.Therefore,researches of the effective and quick barium sulfate detergent and the descaling mechanism forammonia carboxy chelating agent and built detergents have great guiding significance to future studies and practice.Based on the current situation of well plugging caused by barite,this article studied the descaling mechanism and the optimum conditions forammonia carboxy chelating agent and chose the best ammonia carboxy chelating agent asmain agent,selected the best auxiliary agent OT(lab production of low molecular polymer)according to the principle of various factors to promote the descaling effect indifferent descaling period of descaling process with gravimtric analysis and atomic spectrophotometer method,and built a effective and fast barium sulfate descaling detergent STD.The formula of STD barium sulfate detergent for barite broken down is 6%(wt)DTPA + 5%(wt)KOH + 0.3%(wt)OT + 20mg/L imidazoline-3 A,its descaling amount of 7 hours reaches 17.6 g/L-24.0g/L at the temperature of 130??170?,and both the descaling amount and descaling speed achieve leading level in the field when compared to other 5 barium sulfate scale remover at home and abroad.The performance evaluation of STD scale remover showed that it wouldn't become invalid at high temperature of stratum(130??170?),on the contrary,it's descaling amount and descaling speed iacrased a lot.The existence of high concentrations of Ca2+ and Mg2+ decaresed the descaling amount of STD scale remover,but the descaling amount of STD in high concentrations of Ca2+ and Mg2+ conditions still could Ieet the requirements for plug removal caused by barite.It also showed that the corrosion rate of Q235 steel of the STD scale remover with 20 mg/L corrosion inhibitor reached the established corrosion standards for oilfield produced water.A large number of experiments indicated that the reason for scale removers with ammonia carboxy chelating agent as main agent descaling slowly was that the produced chelate have a complex three-dimensional network structure,its existence hindered not only the dissolution of barium salt but also the spread and exchange of the material in the descaling system.STD detergent's additive,OT,has a strong ability to smash barium sulfate crystal and powder into smaller particles,as a result,it possesses the advantages of descaling fast and efficiently and a smaller damage to envirement due to its low main agent concentration.Therefore,the study of STD barium sulfate scale remover and its working mechanism have great significance to solve scaling problems,reduce the economic loss and the risk of environmental damage,and control environmental damages at source.