Nearwellbore

Near-wellbore refers to the region surrounding a wellbore in a hydrocarbon reservoir where flow and transport are strongly influenced by the presence of the borehole and its completion. The near-wellbore zone can extend from the immediate vicinity of the casing to several meters into the formation, and its characteristics are critical for accurately predicting well deliverability. This region is affected by drilling, completion, perforation, and stimulation activities, as well as by formation properties and stress changes around the well.

Causes and effects in the near-wellbore zone commonly include formation damage from drilling fluids, which can create a filter cake or immobilize fines and reduce permeability. Cement invasion, improper perforation, mechanical damage, and chemical interactions can also alter rock properties near the well. Such near-wellbore damage increases the apparent flow resistance, often described by a positive skin factor, and lowers production or injectivity. Conversely, stimulation methods such as acidizing or hydraulic fracturing target the near-wellbore region to enhance permeability and improve flow into the well.

Modeling and management: In reservoir engineering, the near-wellbore region is represented by parameters such as the skin factor or a defined near-wellbore radius that separates the disturbed zone from the far-field reservoir. This concept influences pressure transient analysis, production forecasting, and decline curve modeling. Diagnostic tools include well tests, pressure buildup analyses, production logging, and downhole imaging, while remedial actions may involve cleaning, acidizing, perforation, or fracturing to restore or improve near-wellbore flow.