Gas-assisted plunger lift (GAPL) could be an effective and economically favorable artificial lift (AL) method to be considered during the AL life cycle for North American shale wells. The main advantage of GAPL is that it improves the well production by reducing liquid fallback and boosts the plunger efficiency through gas injection and increases the gas lift efficiency by assisting in delivering the slugs to the surface. The objective of this study is to capture the GAPL dynamic behavior through a transient multiphase flow simulator. The entire GAPL production cycle was modeled, including plunger fall, gas injection, pressure buildup, and production. First, the GAPL well production history was analyzed to evaluate the well operating condition. Then, a transient simulator was used to model the well flow behavior and production performance with GAPL. The study demonstrated the GAPL impact on flowing bottomhole pressure and the improvement in the well productivity.
A Delaware Basin well case study demonstrates the benefits of dynamic modeling and provides a comprehensive comparison between dynamic simulation results and field data. The simulation work provides insights into the fluid flow, GAPL behavior, and pressure and rate transients of a GAPL well.
The modeling results were validated against field data. A commercially available transient multiphase flow simulator was used and produced outcomes that were in alignment with field data collected. The dynamic plunger cycles were reproduced in the simulation, and the results showed the benefits of GAPL in a typical shale oil well. This could extend the gas lift life by delaying the transition to rod pumps or potentially act as an end-of-life AL solution. In the long term, this reduces the overall AL life cycle cost. The use of transient simulation helps validate AL design concepts, especially for unconventional wells where the flow behavior is very dynamic. This study encourages the use of this analysis in the AL selection workflow to help optimize the overall AL life cycle cost and maximize the net present value (NPV).
Gas lift is becoming a predominant, intermediate term, artificial lift system in the Delaware and other basins. Besides the proper selection and management of the gas lift systems, design methodology is still a challenge due to the drastic change in flow conditions in the transient phase. The main objective of this paper is to develop a new methodology to design and optimize gas lift wells in unconventional reservoirs. A case study is provided to review, model, and analyze the current design over different stages of the well's production life. Consequently, application of new designs over different stages of the well's life will be implemented using a performance comparison which includes production and unloading scenarios. Actual well data will be used along with steady-state and dynamic modeling for unloading and production performance estimation. The models will be evaluated using actual data to perform history matching over different stages of the well's production life. This evaluation will also answer the following questions: Is the use of conventional mandrels the best option for these types of wells? Are the number of mandrels deployed using the traditional design methodology the correct solution? Are the tools used to design and analyze these types of wells sufficient? Most importantly, is more data required to create a better design and analysis? Also, this study compares the existing design to modified designs and justifies how the later could perform better. Integration of all data sources including historical performance, flowing bottom hole pressure, inferred dynamic IPR data, and the use of dynamic and nodal analysis tools for modeling while varying production conditions and unloading scenarios.