Research On Anti-scaling And Scale-dissolving Technology In Coalbed Methane Mining Process In Qinshui Basin

The part of the site of coalbed methane mining in the Qinshui Basin of Shanxi Province is artificially lifted by a hydraulic pump such as a jet pump.As the drainage continues,corrosion and scaling are gradually appearing in the downhole oil casing,central pipe,and jet pump working cylinder.The pumping efficiency of the jet pump is low due to scaling and corrosion,and it is impossible to achieve conventional drainage.The requirements,resulting in the CBM site can not be continuously discharged.Coalbed methane fouling on the one hand seriously affects production capacity,and on the other hand,continuous workover operations will incur high workover costs.In order to solve the scaling and corrosion problems in the coalbed methane mining site in the Qinshui Basin,a domestic oil company entrusted the author to conduct in-depth exploration of descaling and anti-scaling,and developed a scale-dissolving and anti-scaling system according to the site requirements.The system needs to adapt to drowning.Some of the basin coalbed methane sites use the hydraulic pump system for drainage.This paper firstly analyzes the causes and influencing factors of scaling in the coalbed methane mining process in the Qinshui Basin by consulting the literature and field research.It is found that the scaling of coalbed methane wells is caused by various mechanisms:such as mixing and breaking of incompatible ions.The result of a combination of thermodynamic equilibrium and adsorption principle.The main reasons for breaking the thermodynamic equilibrium and adsorption principle are as follows.Then,the composition of the produced water and scale products in the coalbed methane mining site in the Qinshui Basin is analyzed.It is found that the scale components of the M block in the Qinshui Basin are mainly CaCO₃ and MgCO₃.And a small amount of corrosion products.The 23 produced water samples contained higher levels of Ca²⁺and Mg²⁺ions.Two kinds of scaling trend prediction methods were used to predict the scaling tendency of 23 produced water samples.On the basis of this,the research and screening of the scale-dissolving system and anti-scaling protection liquid were carried out in combination with the cause of scaling.A hydrochloric acid solution with a mass fraction of18%was used as the main agent of the molten scale.The iron ion stabilization system QT-2 was compounded with citric acid and acetic acid at a ratio of 0.5%:1%,and the corrosion inhibition system QH-3 was a polycrystalline winter.The amino acid,HS#1 and urotropine are compounded in a ratio of 1:3:6;the scale-dissolving system is preferably:18%hydrochloric acid+QT-2 iron ion stabilizer+QH-3 corrosion inhibitor.The anti-scaling protection liquid is compounded by ZF#2,ATMP and HPMA in a ratio of 4:1:2,and the optimum concentration is8-14mg/L;at the same time,the influencing factors and effects of the scale-preventing and anti-scaling system are evaluated.The system showed good scale and anti-scaling effect and good compatibility.Finally,the design and research of the coalbed methane scale and anti-scaling technology in Qinshui Basin was carried out.