Development And Performance Evaluation Of A New High Temperature Resistant And Low Corrosion Cross-Linking Acid

Acid fracturing is the main method for increasing the productivity of carbonate reservoirs,and the performance of acid liquid is the key to the effect of acid fracturing.The Shunbei Oilfield is located in the central and western part of the Tarim Basin in Xinjiang.It is a fractured carbonate reservoir.The average burial depth of the reservoir is more than 7,300 meters.The bottom hole temperature is as high as 160℃.The temperature resistance of conventional crosslinking acid is insufficient and the crosslinking is too fast.,The corrosion is serious and cannot meet the acid fracturing requirements.In response to this,this article carried out research on the delayed cross-linking acid system with high temperature resistance and low corrosion.This article first uses acrylamide（AM）,2-acrylamido-2-methylpropanesulfonic acid（AMPS）,dimethyldiallylammonium chloride（DMDAAC）and acrylic acid as raw materials,and optimizes the reaction conditions to synthesize The thickener SBCH,which has excellent acid solubility and good shear rheological properties,is compared with the crosslinking performance of different organic zirconium crosslinking agent and thickener SBCH.It is determined that zirconium isopropoxide is used as the intermediate,citric acid,The organic zirconium crosslinking agent SBJL was synthesized with diethanolamine as the ligand,and the crosslinking retarder SBYC and the auxiliary crosslinking agent SBZJ were compounded to realize the high temperature resistance of crosslinking acid and delayed crosslinking;Amine,benzaldehyde,cyclohexanone and benzyl chloride are used as raw materials to synthesize Mannich base quaternary ammonium salt corrosion inhibitor SBHS-A under the catalyzed condition of acidic medium.Based on the mechanism of corrosion inhibitor synergist,it is preferred Four types of synergists were formulated,and the corrosion inhibitor synergist SBHS-B was compounded.Finally,other additives of the cross-linking acid system were selected according to industry standards to form a set of cross-linking acids.The specific formula is:20%HCl+0.8%Thickener SBCH+0.8%crosslinking agent+0.8%crosslinking retarder SBYC+0.4%auxiliary crosslinking agent SBZJ+2%high temperature corrosion inhibitor SBHS-A+2%corrosion inhibitor SBHS-B+1%Iron ion stabilizer SKTLZ-1+1%drainage aid SMZP-8+1%demulsifier W-611X.The cross-linking acid system has been tested for performance.The experiment shows that the cross-linking acid system has good compatibility and strong delayed cross-linking performance.It basically does not cross-link at room temperature,and the cross-linking time at90℃reaches 4 min;It has excellent high-temperature shear resistance.The viscosity of this system can be stabilized above 200 m Pa·s after continuous shearing at a shear rate of 170 s^-1 at a temperature of 160℃for 30 min.It has excellent retardation and is compatible with 20%hydrochloric acid.Comparing the reaction rate,the retardation rate of the cross-linking acid reached 96.7%;the corrosion inhibition performance was good.After 4 hours of reaction at160℃,the corrosion inhibition rate was 96.9%;and the gel was broken completely and the viscosity of the gel breaker was small.It can meet the requirements of acid liquid performance for on-site construction.