A novel approach to investigating the mechanism of permeability-induced borehole breathing in deepwater shallow formations

Abstract Due to the uniqueness of deep-water shallow formations, there is no fracture system around the wellbore when borehole breathing is observed in this part of the formation. Therefore, the inducing mechanism of the opening/closing of the fracture network cannot reasonably explain this type of borehole breathing. In this study, a new mechanism of permeability-induced is proposed to explain borehole breathing, based on the fact that there is no fracture system around the well and the formation has the characteristics of high permeability and porosity. By using the stress and seepage coupling method in the porous elastic medium, a new model is established to simulate and describe permeability-induced borehole breathing. Through comparison with actual cases, this model can effectively simulate the typical characteristics of fluid loss-flow back in borehole breathing. This study also analyzed the influence of factors such as formation parameters and mud rheological parameters on the borehole breathing caused by permeability. According to the results of the study, the use of a smaller diameter wellbore and agents that can adjust related parameters (such as loss-reducing circulating material) can effectively inhibit wellbore breathing while drilling.