Dynamic Load-Optimized Selection Charts for Flexible Ultra-Long Stroke Pumping Units in Low-Yield Oil Wells

Flexible ultra-long stroke pumping units (FULSPUs) are widely adopted in low-yield oil wells due to their structural simplicity and high operational efficiency. However, current equipment selection methods lack precision, leading to mismatched configurations, low utilization rates, and unnecessary costs. To address this challenge, this study develops a systematic optimization framework integrating motion dynamics analysis and empirical data. First, a simplified formula for peak polished rod load (PPRL) is concluded by analyzing the unit’s stable motion characteristics. Second, a multi-parameter selection method incorporating stroke length, frequency, pump efficiency, and dynamic liquid level constraints is developed. This method generates interactive selection charts that map maximum liquid production across varying pumping depths, providing a rapid decision-making tool for optimal equipment pairing. A double-layer circle visualization that quantifies equipment utilization by linking pumping unit load and pump load, offering actionable insights for cost-effective upgrades. The model is validated through a field case, where overdesign risks are reduced. Significantly, this work replaces traditional beam-pump selection models with a tailored solution for flexible FULSPUs, delivering two major contributions: (1) a standardized workflow balancing technical feasibility and economic efficiency and (2) a visual tool that when adopted in the oilfield, the efficiency and applicability of equipment selection are improved. These advancements establish a transformative framework for sustainable resource management in mature low-permeability reservoirs.