Abstract

The performance of oil wells producing water during boundary-dominated flow has been investigated to develop a better understanding of multiphase flow and its effects on single well performance. This understanding can assist the petroleum engineer in predicting performance of oil wells producing under boundary-dominated flow conditions.

An analytical Vogel-type inflow performance relationship (IPR) has been developed from the multiphase flow equations. This relationship is based on the physical nature of the multiphase flow system and leads to a better understanding of the pressure-production behavior of an individual well. The analytical IPR has been verified using simulator information for two- and three-phase flow and yields significant agreement with simulator results. The analytical IPR provides a method for the petroleum engineer to develop individual IPRs for each reservoir.

Based on linear regression of simulator results, generalized IPRs for oil and water during three-phase flow are proposed. These relationships were compared to the three-phase IPR methods of Brown and Sukarno and yielded essentially the same results for the cases studied. The proposed IPR is preferred as it is much simpler to use than these methods while still yielding reliable results.

Methods are also proposed for estimating performance when reservoir conditions are different from the conditions under which the well test was performed. Based on linear regression analysis of simulator results, a relationship is presented to predict future performance from current test information. The method appears to give reliable estimates of future performance if the extrapolation is not taken over wide ranges of reservoir depletion. A method is proposed for studying the effects of changes in flow efficiency on well performance which appears to work well in estimating pressure-production performance over the range of skin values studied.