Objective In the evaluation of energy efficiency for gathering and transportation pipeline network systems, the impact of gas reservoirs and wellbores is often overlooked. Existing energy efficiency evaluation systems do not adequately account for the interrelationships among these three components, resulting in evaluation outcomes that do not accurately reflect the overall energy efficiency of production systems. The Dongsheng Gas Field, currently in a low-production and low-pressure stage, faces significant challenges, including considerable production disparities among individual wells, high liquid-gas ratios, and accelerated pressure drop rates. Therefore, there is an urgent need to develop targeted evaluation methods capable of identifying weak links that hinder energy efficiency.

Methods Based on current relevant specifications and the production processes utilized in the Dongsheng Gas Field, evaluation indexes related to gas recovery through wellbore drainage and gas reservoir development were established as a complement to the energy efficiency evaluation of gathering and transportation pipeline network systems. This integrated evaluation index system of energy efficiency for the gas reservoir-wellbore-gathering and transmission pipeline network systems encompasses 10 indexes, along with their corresponding boundary values. In light of the characteristics of these indexes, a hybrid algorithm for energy efficiency evaluation was developed, leveraging the analytic hierarchy process (AHP) method, the entropy weight method, and the fuzzy membership function method.

Results The application of the proposed evaluation system and algorithm in Block J of the Dongsheng Gas Field yielded an energy efficiency score of only 58.4 prior to process adjustments. This score indicated that key factors limiting system energy efficiency included substandard gas recovery through drainage, low load rates of compressor units, and inefficient pipeline transportation. To address these challenges, improvement measures were proposed, including optimizing the drainage process and adjusting the pipeline network structure, taking into account the specific production conditions. As a result of these adjustments, the re-scored energy efficiency increased significantly to 81.83, reflecting a substantial improvement in system energy efficiency that aligns with the actual on-site production conditions.

Conclusion This new integrated evaluation system and algorithm for energy efficiency is effective in reflecting the energy efficiency levels of gas fields across various production processes and guiding effective process adjustments for gas fields. The findings of this study validate the efficacy of the proposed index system and evaluation method for energy efficiency.