Study On Synthesis And Performance Evaluation Of Hydrophobic Associating Thickener Used In Acid Fracturing

The development of carbonate reservoirs plays an important role in the field of oil and gas exploration and development.In recent years,the newly discovered carbonate rock oil and gas fields in China mainly have the characteristics of deep burial,poor reservoir physical properties,strong heterogeneity,and poor reservoir connectivity,which have brought new challenges to acid fracturing technology.In order to achieve the ideal acidification effect,retarded acid systems such as gelled acid are commonly used in acid fracturing technology.Acid thickeners,as the most important additive in the retarded acid,have always been a research hotspot in the field of oil and gas field development.Conventional acid thickeners have poor temperature resistance,resulting in fast acid rock reaction rate and unsatisfactory acidification effect.In order to improve the effect of acidification,gelled acid with a high concentration thickener and cross-linked acid thickened with chemical cross-linking are generally used.However,too high viscosity often causes difficulty in pumping and high friction resistance,and this also causes difficult in breaking the gel,resulting great damage to the reservoir.In order to solve the above problems,a zwitterionic hydrophobic associative polymer as a thickener used in acid fracturing fluid is designed and synthesized in this paper,and a self-assembly using a surfactant and a hydrophobic associative polymer is performed to obtain a new type of high-temperature resistant self-assembling retarded acid system.According to the performance requirements of acid thickeners,combining the hydrophobic interaction principle,a zwitterionic hydrophobic associative polymer(ZHAPAM)as an acid thickener is synthesized by acrylamide(AM),2-methyl-2-acrylamidopropanesulfonic acid(AMPS),and N,N-Dimethyl-N-(prop-2-en-1-yl)hexadecan-1-aminium chloride(C16MMAAB),and the synthetic process is optimized.The structure of the synthesized polymer is characterized by FT-IR.The acid solubility,viscosity-increasing properties of ZHAPAM thickener and its compatibility with other additives in acid solution are studied.In order to further improve the temperature resistance and retardation performance of ZHAPAM gelled acid,a surfactant-dodecyl benzene sulfonic acid,sodium salt(SDBS)is selected to self-assemble with ZHAPAM to obtain the SDBS /ZHAPAM self-assembling acid system.SDBS/ZHAPAM self-assembling acid system and ZHAPAM gelled acid system are comprehensively evaluated and compared for their properties of viscosity increasing,high temperature rheology,retardation and gel breaking.The results show that the SDBS / ZHAPAM self-assembled acid liquid system has a good viscosity-increasing effect,excellent temperature resistance and good retardation performance,and can meet the 120 ? high-temperature carbonate reservoir development requirements.It also uses less than conventional thickeners,and the gel can be automatically broken,does not harm to the formation.