Water Breakthrough Time in a Vertical Oil Well

Consider an oil reservoir with an underlying water zone. An oil well that is producing from this reservoir will experience the phenomenon of water breakthrough if the well produces above its critical rate. Since economic considerations often demand high flowrates, this can be a real risk.

This Excel spreadsheet uses the Sobocinski-Cornelius method to calculate the water breakthrough time.  This method was published in 1965, and was derivied from laboratory tests. It uses these equations.

where

• B_o is the oil formation volume factor
• μ_o is the oil viscosity (cp)
• μ_w is the water viscosity (cp)
• φ is the porosity
• h is the oil column thickness (ft)
• h_p is the perforated interval (ft)
• Q_o is the oil production rate (STB day^-1)
• α is 0.5 if M <=1, or 0.6 otherwise
• M is the water-oil mobility ratio
• t_BT is the time to breakthrough
• t_D is the dimensionless time (Sobocinski-Cornelius method)
• Z is the dimensionless cone height
• ρ_w is the water viscosity (lb ft^-3)
• ρ_o is the oil density (lb ft^-3)

Download Excel Spreadsheet to Calculate Water Breakthrough Time with Sobocinski-Cornelius method