Casing Wear Prediction Model Based on Casing Ellipticity in Oil & Gas Well-Drilling With Complex Structures

Abstract

Any casing with perfect integrity within a complex oil and gas development scenario is subject to formation extrusion resulting in ellipticity. This paper proposes a novel casing wear prediction model, which encompasses ellipticity, geometric structural relationships, and the energy dissipation law at work in the casing. Composite structural wear models are also utilized to determine the influence of different drill pipe combinations on casing wear predictions. The casing wear position is predicted based on casing ellipticity. The proposed model yields more accurate casing wear predictions than previous models which do not properly account for casing ellipticity; to this effect, it may more effectively minimize the cost of drilling engineering and safeguard against accidents. The proposed method also outperformed other methods in a case study on a shale gas development project in Fuling, China. The inversion method is applicable to wells with similar structure to the drilled well, where casing wear position can be evaluated very accurately according to caliper logging system measurements. The proposed method facilitates sound decision-making while guaranteeing secure and reliable oil and gas well-drilling with complex structures.