Evaluation of Rubber Composite Casing for Preventing Casing Deformation: An Experiment Study

ABSTRACT: Casing deformation induced by fault slippage, which leading by hydraulic fracturing, poses a significant challenge in shale oil and gas development in China, adversely affecting well productivity and operational longevity. To mitigate this issue, a novel rubber composite casing was engineered, comprising a conventional casing encased in an outer rubber sleeve designed to absorb shear displacement and safeguard the inner casing. Comprehensive indoor experiments were conducted using an Unconventional Gas Wellbore Simulation Test System (UGT) to replicate downhole conditions and evaluate the casing's response to fault slippage-induced shear stresses. The experimental results revealed that, under a 40 mm displacement load, the rubber composite casing exhibited no deformation, whereas conventional casings experienced deformations of up to 15 mm. The rubber composite casing demonstrated exceptional capacity to absorb displacement loads, enduring forces ranging from 98 to 115 tons. These findings substantiate the efficacy of the rubber composite casing in mitigating shear displacement, offering a robust technical solution for preventing casing deformation and enhancing the sustainable development of shale oil and gas resources.