Summary This paper presents a general and unified equation for flowing temperature prediction that is applicable for the entire range of inclination angles. The equation degenerates into Ramey's equations for ideal gas or incompressible liquid and into the Coulter and Bardon equation, with the appropriate assumptions. This work also proposes an approximate method for calculating the Joule-Thomson coefficient for black-oil models. Introduction Flowing temperature distribution often is predicted with different methods for pipelines and wellbores. The Ramey method usually is used for predicting wellbore temperature distribution. This method rigorously incorporates the complex process of transient heat transfer between the wellbore and the reservoir. Ramey's method, however, is limited to either ideal gas or incompressible liquid flow. The Coulter and Bardon equation commonly is used for pipeline temperature prediction. A more rigorous thermodynamic behavior of the flowing fluid is taken into account, incorporating the Joule-Thomson coefficient. Although the Coulter and Bardon equation originally was derived for gas flow, it also is used for single-phase liquid or two-phase flow. This equation is limited, however, by the assumptions of steady-state heat transfer with a constant-temperature environment and horizontal flow.

This paper presents field data that show how continuous gas lift instability is manifested. It also reviews former proposed criteria to predict the phenomenon. The best available criteria are selected and expanded to take into account different flow regimes for the surface gas injection valve and the bottomhole gas-lift valve. The expanded criteria are examined using field data. The criteria clearly show the relative importance of the different factors involved, and thereby help to assure stable flow conditions at the design phase or to decide what actions to take in order to stabilize an unstable gas lift well.

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This paper presents, for the first time, a theoretical model for the bottomhole gas separation efficiency in Electrical Submersible Pump Installations. The model is based only on fundamental physical principles. New experimental data, collected in a field scale apparatus, and covering a wide range of liquid flow rates, GLRs, pressures and rotational speeds, are also presented. Predictions of the model are verified against the experimental data and limited published field data. It was detected that, when rotary separators are used, two possible operating regions exist on a map of separation efficiency versus liquid flow rate and pressure. In one region the separator is quite effective and in the other the separator is not effective at all. The transition from the high efficiency zone to the low efficiency zone, in terms of liquid flow rate, is sharp. This behavior has never been reported in the literature before. The model is simple enough that a small subroutine can be easily written, from the equations presented in the paper, to be included in design and troubleshooting programs for ESP installations. Overall agreement of the model’s predictions with the experimental and field data was good in both high and low efficiency zones.

Operators generally want to reduce well down-time and repair/replacement costs by improving the reliability of their Artificial lift (AL) systems. In order to understand if actions taken to improve reliability are effective, one must track the AL system run-life. This paper discusses run-life measures commonly used in the AL industry and provides recommendations for when each run-life measure should be used. Synthetic data, generated using random runtime and failure data from known statistical distributions, is used to illustrate the effect of various factors, such as selecting equipment with higher inherent reliability, on the resulting measured run-life. This paper also presents several pitfalls that should be avoided when selecting run-life measures for comparing equipment or implementing operator-vendor alliance contracts.