Sheet1Critical Oil Flowrate for Gas Coning http://excelcalculations.blogspot.com

This spreadsheet uses the Mayer & Garder equation to calculate the oil flowrate necessary for Gas Coning in a vertical oil well

Oil Density49.9lb ft-3Gas Density7.49lb ft-3Drainage Radius of Well1820ftWell Bore Radius0.499ftEffective Oil Permeability0.99Oil Viscosity2.7cpOil Formation Volume Factor1.4Perforated Interval4.9ftOil Column Thickness30ft

Critical Oil Flow Rate0.0291836679stb day-1

Sheet2Critical Oil Flowrate for Gas Coning

This Excel spreadsheet uses the Mayer and Garder correlation to calculate the oil flowrate necessary to form a stable gas cone in an oil and gas reservoir.

Gas coning references the tendency of gas to flow in the direction in which its face the least resistance, against the flow of gravity. Above the critical oil flowrate, the cone will breakthrough and gas will force the oil flow downwards towards the well perforation. At this point, gas will tend to dominate crude oil production (often to the point where the well is not economically feasibile).

Gas coning is often significant if an oil reservoir is in contact with an aquifer or gas cap.

The critical oil flowrate is sometimes lower than the economical production rate, but techniques have been developed to combat gas coning (including using horizontal wells instead of vertical wells, and infill drilling)

The Mayer and Garder equation and a screengrab of the spreadsheet are given below.

o and g are the densities of the oil and gas in lb ft-3re and rw are the drainage radius and welbore radius in ftBo is the oil formation volume factor (this is almost always above 1)o is the viscosity of the oil in centipoiseko is the effective oil permeabilityQ is the oil flowrate in stb day-1

Sheet3