Meaning of zeolites in the formation of the structure of hydrocarbon reservoirs porous-cavernous space is extremely large. Physical and chemical properties of these minerals must be considered as at exploration works carrying out and at fields development. The producing BU15 formation of polar suite of Pyakyakhinskoye oil and gas field is considered as the object of study. The effect of secondary zeolitization on the choice of acid compounds, used for the treatment of bottomhole formation zone, is estimated. Negative impact of rocks zeolitization on the reservoir properties, the results of geophysical research and the processes of wells operation is established experimentally on the basis of comprehensive studies.
The process of transition of zeolite minerals in soluble form is determined by the type and acidity of the medium, temperature, and quantitative content of zeolite in the rock. The results of experiments to assess the effect of different acids on the disintegrated core are given. The content of zeolite in the rock was 18-19%. Exposure temperature corresponded to formation one (81 °C). Pyakyakhinskoye field rock exposure to hydrochloric, hydrofluoric and oxalic acids in atmospheric conditions leads to gelation. Sufficiently thick gels are formed in mineral acids medium in a short time (0.5-2 h). The dissolution of zeolites is difficult at interacting with weak acids and the possibility of the reaction products structuring is minimal. Thus, gels formation in a medium of acetic and sulfamic acids has not been recorded for a prolonged period (10 days) at the reservoir temperature. The gelation in oxalic acid solution is achieved in 15-16 h. Rock reaction with the acid is accompanied by loss of core weight, that indicates on dissolution of the individual components, including zeolite-containing ones. The solubility of the core is low, but it is enough to structure of silica gels. The gelation in the pore space by the action of strong mineral acids is confirmed by the experiments on natural cores in thermobaric conditions of the formation.
It was concluded that the interaction of zeolite-containing rocks with inorganic acids, leading to undesirable reaction products gelation, requires innovative approaches to the selection and use of acidic formulations.
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