石油科学通报2025，Vol.10Issue(6)：1228-1239,12.DOI:10.3969/j.issn.2096-1693.2025.01.032
浅层页岩气试气返排分析及制度优化
Analysis and optimization for shallow shale gas flowback:A case study of the normal pressure shale gas in the Haiba block of Zhaotong demon-stration area
摘要
Abstract
In the Haiba block of the Zhaotong demonstration area,shallow shale gas reservoirs are characterized by shallow burial depth,low formation pressure,and large variation in formation dip angle.The flowback process during well testing in these reservoirs is marked by a long gas breakthrough time,a high gas breakthrough flowback rate,and low stabilized gas testing rates.Improper flowback can lead to wellbore proppant settling,liquid loading,and loss of fracture volume,requiring an optimized flowback strategy to ensure safety and efficiency.This study presents a systematic analysis of flowback data from 71 wells in this block,identifying three distinct flowback stages:pure liquid flowback,gas breakthrough,and stabilized gas flowback.Using a fracture compression model and rate-transient analysis,the variations in effective fracture volume and fracture half-length under different flowback strategies were examined.The results show that a fast flowback strategy can cause an irreversible loss of up to 30%of the effective fracture volume,whereas a slow flowback strategy can reduce this loss to about 12%.To minimize this irreversible fracture loss,key flowback issues and controlling factors for these shallow shale gas wells were addressed.The well-opening pressure was determined by analyzing the effective stress within fractures.A wellbore proppant settling model and a fracture proppant flowback model were developed,yielding the critical flow rate in the wellbore required to carry proppant and the critical flow rate in fractures that triggers proppant flowback.Based on multiphase flow theory,the minimum bottomhole pressure for fluid unloading and the critical gas rate for liquid lifting were also determined.Accordingly,a comprehensive optimization strategy was proposed,encompassing appropriate well opening timing,wellbore sand cleanout,proppant flowback prevention,and assurance of fluid drainage,and the flowback optimization diagram was developed.Field application results indicate that this diagram enables a synergistic optimization of fracturing effectiveness and production efficiency:under similar reservoir conditions and stimulation measures,the estimated ultimate recovery increased by 20%.This study marks a transition of flowback management from an empirical approach to a quantitative one,and the proposed critical criteria and optimization diagram have broad applicability,providing a technical reference for flowback optimization in other unconventional oil and gas wells.关键词
浅层页岩气/试气返排/返排特征/安全返排图版/支撑剂回流Key words
shallow shale gas/flowback/flowback characteristics/safety flowback diagram/proppant flowback分类
能源科技引用本文复制引用
LIU Mingyang,XIAN Chenggang,LIANG Xing,LI Caoxiong,HUANG Xiaoqing,HE Yong,LIU Yang..浅层页岩气试气返排分析及制度优化[J].石油科学通报,2025,10(6):1228-1239,12.基金项目
国家自然科学基金(52104052)、中国博士后科学基金(2021M693496)、国家重点研发计划(2020YFA0710604)联合资助 （52104052）
