###### Abstract  
Casing damage is a common problem encountered during oil and gas field development due to the complex stress state of the casing. Despite the large number of studies focusing on this problem, the mechanism of non-uniform in-situ stress-induced casing damage in a low-permeability reservoir is still unclear. In this study, casing damage due to non-uniform in-situ stress variations was investigated, and then the tectonic stress coefficients in the study area were determined by an in-situ stress inversion technique, which led to the derivation of formulas for calculating the maximum and minimum horizontal in-situ stresses. Subsequently, finite element numerical simulations were performed to assess the stress distribution during the formation of the casing cement sheath in a G155 block, a typical low-permeability reservoir. The results indicate that casing damage is caused not only by non-uniform in-situ stresses but also by various additional creep-induced loads. Subsequent finite element investigations into casing behavior under mudstone creep conditions indicated that immersion of mudstone in water instigated further shearing and deformation of the casing, culminating in premature well failure prior to water in mudation. Notably, Von Mises stress levels exhibited a positive correlation with injection production ratios, with values exceeding critical thresholds leading to distinct modes of mechanical failure including shear-induced deformations, longitudinal tensile stress, and localized yielding near water wells. Maintenance of an optimal injection production ratio is identified as a key strategy for prolonging casing longevity in the region. To this end, recommendations include augmenting the casing wall thickness or enhancing the steel pressure specifications to mitigate casing damage progression, thereby extending the operational lifespan. This research serves as a pivotal theoretical framework for informing future development strategies aimed at mitigating and preempting casing failures in a low-permeability reservoir. n 2024  
established development procedures, increased safety and environmental hazards, as well as substantial impediments to maintaining stable and efficient oilfield production [13; 14; 15]. Casing damage in oil fields is a prevalent occurrence on a global scale [16; 17; 18]. In the United States, casing damage primarily occurs in northwestern oil fields like California and Montana, including locations such as the Belridge oil field, Wilmington oil field, and Lost Hill oil field, among others. There is also severe casing damage in heavy oil production wells in the Alberta region of Canada [19]. The Groningen Gas Field in the Netherlands, the Bolivar Coastal Oil Field in Venezuela, and the Po Delta Gas Field in Italy have all experienced casing damage, mostly due to significant formation compaction and casing shear damage caused by excessive oil reservoir exploitation. Some oil fields in Asia, such as India and Iran, have also experienced casing damage [16]. In China, casing damage in oil and gas wells was first discovered in the Yumen Oilfield. With the extension of development time, casing damage has been discovered in oilfields such as Daqing, Jilin, and Jianghan [8; 20; 21]. Since the 1990s, large-scale regional casing damage has occurred in oil fields such as Daqing Sazhong, Jilin Fuyu, Yumen Laojunmiao, and Changqing Jurassic, resulting in huge economic losses and forcing some oil wells in certain blocks to be shut down or even scrapped. In 2022, the oil and gas equivalent of the Changqing Oilfield exceeded 65 million tons, becoming the largest oilfield in China. As of the end of 2022, there were a total of 1774 casing-damaged wells in the Changqing Oilfield, resulting in an annual production capacity loss of approximately 1.15 million tons, which is equivalent to a decrease of 1.7% in the annual oil and gas equivalent of the oilfield.