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Drilling in deep formations of salt-gypsum layers is one of the major technical problems in China's petroleum engineering sector. First, because of the peristaltic deformation of the salt paste layer, the complex drilling and completion of the salt paste layer and the accidental collapse of the downhole casing are frequent. Second, it is difficult to determine the mud density and the downhole tube loss is up to 40%. Many deep wells at home and abroad have not yet completed the drilling standards, resulting in a lot of manpower and material waste, and significant economic losses. The deep oilfields in China's proven oilfields, especially in the western regions, are afflicted underneath the salt-gypsum rock formation. Therefore, the drilling and drilling difficulties of the salt-gypsum layer have become a bottleneck restricting the development of China's oil industry.
Scientific and technical personnel through research, the main technical focus on the test and interpretation of ground stress, the law of creep deformation of deep salt gypsum rock and wellbore management and casing damage prevention. From the point of view of three-dimensional formation deformation, the peristaltic law and casing damage mechanism of deep salt grouts were studied. Through the study of the strength design of the casing under triaxial stress and the prediction of service life of salt casing, the corresponding peristaltic pressure of salt gypsum was established. Map. Accurate ground stress measurement, analysis, deep understanding of the mechanism of peristaltic deformation of salt cream layer and the change law of peristaltic pressure provide a reliable basis for accurate analysis of casing external distribution rules and casing design under different conditions downhole.
Through the mechanical analysis of salt rock borehole stability, the simulation test of salt rock wellbore dissolution rate, and the numerical simulation of the optimal mud density during drilling, the researchers established a mud density design map under three-dimensional conditions, and finally successfully solved the mud density. The problems have played a huge role in the oil extraction of Jianghan, Zhongyuan, Tarim, Tabei, Xinjiang, and other areas, accumulatively creating more than 170 million yuan in direct economic benefits and huge social benefits. Only the determination of reasonable drilling flux density for safe drilling in Jianghan Oilfield brings about 43 million yuan in direct and indirect economic benefits. The application of stress and casing damage technology has brought direct and indirect economic benefits of 30 million yuan to Zhongyuan Oilfield.
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