Scientists have created a virtual model that predicts risk collapse oil wells after acid treatment. This solution will improve the safety and efficiency of mining in complex deposits.
Extraction of hard-to-recover reserves in Western Siberia and the Urals is often carried out using horizontal wells. To increase their productivity, acid treatment is used. However, this technology has a serious side effect. Acid not only cleans the bottomhole zone, but also destroys the cement that holds the rock together. This creates a threat of collapse of the well walls, which existing modeling methods did not take into account.
Specialists from the Perm National Research Polytechnic University, together with the Institute of Oil and Gas Geology and Geophysics of the SB RAS, presented a unique software solution. Their virtual model analyzes how stresses in rock change after exposure to acid. This allows you to identify dangerous areas in advance and prevent an accident.
The development was based on laboratory tests. Researchers have studied how a mixture of hydrochloric and hydrofluoric acids affects sandstones. Based on these data, the ANSYS program simulated the operation of a horizontal well at a depth of one and a half kilometers. The analysis was carried out at different pressures and treatment durations – from 14 minutes to 4 hours.
The results showed that at a certain pressure, zones of increased stress appear in the upper and lower parts of the well, where collapse can begin. Key conclusion: after four hours of processing, the rock retains a strength margin of one and a half times higher than normal, which completely eliminates the risk of destruction.
This information allows oil and gas companies to optimize their processes. The model helps to select safe acid treatment parameters for different geological conditions. The new development has already been successfully tested at one of the fields in the Perm region and is ready for implementation.
The material was prepared with the support of the Russian Ministry of Education and Science as part of the Decade of Science and Technology.
Source: geonews.ru
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