From Reservoir Engineering Handbook, Third Edition


Coning is a term used to describe the mechanism underlying the upward movement of water and/or the down movement of gas into the perforations of a producing well. Coning can seriously impact the well productivity and influence the degree of depletion and the overall recovery efficiency of the oil reservoirs. The specific problems of water and gas coning are listed below.

  • Costly added water and gas handling

  • Gas production from the original or secondary gas cap reduces pressure without obtaining the displacement effects associated with gas drive

  • Reduced efficiency of the depletion mechanism

  • The water is often corrosive and its disposal costly

  • The afflicted well may be abandoned early

  • Loss of the total field overall recovery

Delaying the encroachment and production of gas and water are essentially the controlling factors in maximizing the field's ultimate oil recovery. Since coning can have an important influence on operations, recovery, and economics, it is the objective of this chapter to provide the theoretical analysis of coning and outline many of the practical solutions for calculating water and gas coning behavior.


Coning is primarily the result of movement of reservoir fluids in the direction of least resistance, balanced by a tendency of the fluids to maintain gravity equilibrium. The analysis may be made with respect to either gas or water. Let the original condition of reservoir fluids exist as shown schematically in Figure 9-1, water underlying oil and gas overlying oil. For the purposes of discussion, assume that a well is...

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Topics of Interest

OVERVIEW Nearly all hydrocarbon reservoirs are surrounded by water-bearing rocks called aquifers. These aquifers may be substantially larger than the oil or gas reservoirs they adjoin as to appear...

INTRODUCTION Water and gas coning is a serious problem in many oil field applications. The production of coned water or gas can reduce oil production significantly. Therefore, it is important to...

CRITICAL RATE DEFINITION Since the early days, several experiments and mathematical analyses were conducted to solve coning problems. One of the basic conclusions of many analyses was if oil is...

WATER AND GAS CONING IN HORIZONTAL WELLS For a vertical well the majority of the pressure drawdown is consumed near the wellbore. Therefore, there is a big drawdown around the wellbore in a vertical...

DECLINE CURVE ANALYSIS Many engineers are familiar with the decline curve analysis, which was developed by Arps [6] in the 1940s and was later refined by Fetkovich. [7] The decline curves tell us...