Nodal Systems Analysis of Oil and Gas Wells

Abstract

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleum engineering. Summary Nodal analysis, defined as a systems approach to the optimization of oil andgas wells, is used to evaluate thoroughly a complete producing system. Every component in a producing well or all wells in a producing system can beoptimized to achieve the producing system can be optimized to achieve theobjective flow rate most economically. All present components-beginning with the static reservoir pressure, ending with the separator, and includingpressure, ending with the separator, and including inflow performance, as wellas flow across the completion, up the tubing string (including any downholerestrictions and safety valves), across the surface choke (if applicable), through horizontal flow lines, and into the separation facilities-areanalyzed. Introduction The objectives of nodal analysis are as follows.To determine the flow rate at which an existing oil or gas well willproduce considering wellbore geometry and completion limitations (first bynatural flow).To determine under what flow conditions (which may be related to time) awell will load or die.To select the most economical time for the installation of artificial lift and to assist in the selection of the optimum lift method.To optimize the system to produce the objective flow rate most economically.To check each component in the well system to determine whether it is restricting the flow rate unnecessarily.To permit quick recognition by the operator's management and engineering staff of ways to increase production rates. production rates. There arenumerous oil and gas wells around the world that have not been optimized toachieve an objective rate efficiently. In fact, many may have been completed insuch a manner that their maximum potential rate cannot be achieved. Also, many wells potential rate cannot be achieved. Also, many wells placed on artificial lift do not achieve the efficiency placed on artificial lift do not achieve theefficiency they should. The production optimization of oil and gas wells by nodal systems analysishas contributed to improved completion techniques, production, and efficiencyfor many wells. Although this type of analysis was proposed by Gilbert in 1954. it has been used proposed by Gilbert in 1954. it has been used extensively inthe U.S. only in the last few years. One principal reason for this was thechanging of allowable producing rates, and another has been the developmentproducing rates, and another has been the development of computer technologythat allows rapid calculation of complex algorithms and provides easilyunderstood data. Past conservation practices in the U.S. more or less restricted operators to2- and 2 1/2-in. [5.08- and 6.35-cm] tubing and 4 shots/ft [13.1 shots/m] forperforating. perforating. JPT P. 1751