Effects of Entire Process Tripping-in Speeds on Formation Fracture Widths During the Entire Process

The trippingin speed affects the wellbore effective pressure, leading to changes in formation fracture widths and posing a risk of mud loss. The trippingin speed and drilling fluid compressibility, along with the well depth, the bottomThe trippingin speed affects the wellbore effective pressure, leading to changes in formation fracture widths and posing a risk of mud loss. The trippingin speed and drilling fluid compressibility, along with the well depth, the bottomhole assembly, the formation petrophysical parameters, and the drilling fluid properties were incorporated to build a mathematical model coupling wellbore pressure transients and fracture deformation. The model was solved with the finite elementfinite volume coupling method and validated with data from the hardbrittle shale formation of the Longmaxi formation in the Zi X well of the Weiyuan Block in the Sichuan Basin. The results show that, i. when the trippingin speed increase from 0.5 m/s to 2.0 m/s, the wellbore pressure will increase from 86.0 MPa to 106.6 MPa, while the fracture width will rise from 0.478 mm to 0.881 mm. ii. Bigger fracture widths go with greater trippingin depths and higher drill string annular ratios. At a trippingin speed of 0.5 m/s, when the tripping depth increases from 1 500 m to 5 500 m, the fracture width will rise from 0.432 mm to 0.478 mm; when the drill string annular ratio increases from 0.59 to 0.65, the fracture width will rise from 0.463 mm to 0.487 mm. iii. As the trippingin speed increases from 0 to 1.5 m/s, at a tripping depth of 1 500 m, the fracture width will rise from 0.4 mm to 0.474 mm; at a tripping depth of 5 500 m, the fracture width will rise from 0.5 mm to 0.624 mm. Bigger fracture widths go with higher trippingin speeds, and the rising trend will be more pronounced once the trippingin speed exceeds 1.0 m/s; further, this rise becomes more pronounced with greater tripping depths. This study provides a theoretical basis for optimizing trippingin operation parameters and offers an important guidance for preventing mud loss incidents during drilling.hole assembly, the formation petrophysical parameters, and the drilling fluid properties were incorporated to build a mathematical model coupling wellbore pressure transients and fracture deformation. The model was solved with the finite elementfinite volume coupling method and validated with data from the hardbrittle shale formation of the Longmaxi formation in the Zi X well of the Weiyuan Block in the Sichuan Basin. The results show that, i. when the trippingin speed increase from 0.5 m/s to 2.0 m/s, the wellbore pressure will increase from 86.0 MPa to 106.6 MPa, while the fracture width will rise from 0.478 mm to 0.881 mm. ii. Bigger fracture widths go with greater trippingin depths and higher drill string annular ratios. At a trippingin speed of 0.5 m/s, when the tripping depth increases from 1 500 m to 5 500 m, the fracture width will rise from 0.432 mm to 0.478 mm; when the drill string annular ratio increases from 0.59 to 0.65, the fracture width will rise from 0.463 mm to 0.487 mm. iii. As the trippingin speed increases from 0 to 1.5 m/s, at a tripping depth of 1 500 m, the fracture width will rise from 0.4 mm to 0.474 mm; at a tripping depth of 5 500 m, the fracture width will rise from 0.5 mm to 0.624 mm. Bigger fracture widths go with higher trippingin speeds, and the rising trend will be more pronounced once the trippingin speed exceeds 1.0 m/s; further, this rise becomes more pronounced with greater tripping depths. This study provides a theoretical basis for optimizing trippingin operation parameters and offers an important guidance for preventing mud loss incidents during drilling.