Understanding Your Wells: Conventional Nodal Analysis; Not a Solution for Depleting Fields

Modeling fluid behavior using conventional nodal analysis software is a common practice in the oil and gas industry. However, understanding flow physics helps production engineers to understand the difference between predicted and actual flow behavior. This work presents a methodology applied to a depleting oil and gas field in northern Pakistan. The adopted approach not only helped to overcome vertical lift performance issues in the wellbore, but it also resulted in improved and sustained oil and gas production from the well. Based on these results, wells in the field with vertical lift performance issues were identified and evaluated using the analysis approach presented in this work. Basic petroleum engineering concepts are implemented using a multi-tier approach, and a proposal was outlined to understand the sluggish flow behavior from the well. The analysis approach characterizes the problem as "IPR dominated" or "VLP dominated" flow using the well's historical data and nodal analysis results, identifies the requirement for a new data set, and then operations are planned accordingly. During execution, coil tubing with memory gauges was deployed with a provision to simulate Coil Tubing Gas Lift (CTGL) with single point injection. This arrangement not only resulted in sustained production from the well, but it also provided leverage to gather bottomhole data corresponding to multiple flow parameters during sensitivity analysis. The workflow explains the physics behind oil and gas wells with sluggish liquid production and the inadequacy of conventional nodal analysis software in predicting production rates with certainty. The application of this workflow converted a "sick well" into a "sustained production well," which was previously ruled out for the implementation of ALS techniques during initial screening using conventional nodal analysis software. This novel approach highlighted the "domain of applicability" of conventional nodal analysis software and proposed a detailed workflow for artificial lift candidate selection. This workflow served as the blueprint for the overall evaluation of well productivity in depleting fields with VLP issues.