Study On The Reaction Kinetics Of HCI / HF System And Sandstone Minerals

Acidizing is a mature and vibrant technology which is widely used in the field to increase the production and injection since1930s. Acidification can be used either in sandstone or carbonate reservoir. However, compared with carbonate rock, the mineral structure and chemical composition of sandstone are more complex. And this makes acid rock reaction mechanism of sandstone much more complex. The reaction between HC1/HF system and sandstone mineral includes heterogeneous solid-liquid reaction and homogeneous liquid-liquid reaction, which makes this reaction so much more complicated.The design of sandstone acidizing is sightless due to the complexity mechanism of acid rock reaction in sandstone acidizing. In fields, the design of acid formula and the optimization of treatment parameters are mainly decided from field experience, which affect the final results of acidification adversely. Therefore, more emphasis should be put on the accurate acquisition of reaction kinetics parameters and dynamic equation, which reflects the actual formation reaction conditions, due to the influence of mineral components, face ratio, temperature, acid concentration, the ratio of hydrochloric acid and hydrofluoric acid, etc. on the reaction rate of acid rock.This paper established an experimental scheme to acquire the reaction kinetics parameters accurately, and in the meantime, reflecting the actual formation condition, the relevant reaction rate mechanism model had also been established. Various factors affecting the acid rock reaction rate had been analyzed comprehensively. The main works were as follows:(1) The study of the main body type in actual reservoir sandstone mineral, and the catalytic action of hydrochloric acid to hydrofluoric acid during the reaction of HC1/HF system with the actual reservoir sandstone mineral.(2) Using the Freundlich adsorption theory, considering the crystal lattice of hydrofluoric to sandstone minerals without the influence of catalytic action caused by hydrochloric acid, and the interaction of adsorption of hydrochloric acid on the lattice catalytic surface, the mechanism model of acid rock reaction rate is established.(3) Simulating the formation temperature, pressure and shear flow reaction, the reaction kinetic parameters of HC1/HF system to the actual reservoir sandstone mineral has been measured and the relevant reaction equation has been established.(4) Compared the Established Freundlich-ARRR mechanism model with the reaction kinetics equation of acid rock reaction rate, theoretical calculation of acid rock reaction rate has been conducted, and the influence laws of temperature, pressure, concentration of hydrofluoric acid, hydrochloric acid concentration, ratio of hydrochloric acid and hydrofluoric acid, rotational speed, the common-ion effect on acid rock reaction rate have been evaluated.(5) Based on the grey correlation analysis, the influence degree of different factors on acid rock reaction rate has been analyzed, the primary and secondary relationship has been determined, and the recommendation to delay acid-rock reaction rate has been put forwardThis study aims to establish a set of research method for reaction between sandstone minerals and HC1/HF system. Overall, this study has great theoretical and practical significance to reveal the reaction mechanism between acid and rock, and provide guidance in the optimization of acid formula and treatment technology.