Classification and Analysis of Helium-Bearing Natural Gas Based on Clustering Statistics:A Case Study of Sichuan Basin
Luo Shengyuan
Jiang Shu
Zhang Baomin
Chen Lin
Abstract：The Sichuan basin is rich in oil and gas resources,and many years of exploration and development have accumulated a large amount of gas composition information,which provides good basic conditions for helium research.Helium content associated with natural gas from multiple strata and regions varies significantly.However,the relationship between hydrocarbons and associated helium is unclear.Based on the statistics of natural gas components obtained from oil and gas exploration in the Sichuan basin,it innovatively uses cluster analysis method to conduct Q-type cluster research on the He content and the content of associated gases CH4,N2,and CO2 in natural gas.The study analyzes the content of various types of helium,geological background,distribution pattern,and migration characteristics,then discusses the exploration and development strategies for helium resources.The main findings are as follows.(1)The helium associated with hydrocarbons in the Sichuan basin can be mainly divided into three types,Type Ⅰ is characterized by low He,low N2,low CO2 and high CH4 hydrocarbon gas reservoirs,Type Ⅱ is characterized by He-rich,high N2,medium CO2,medium CH4 hydrocarbon gas reservoirs,and Type Ⅲ is characterized by low He,low N2,high CO2 and low CH4 hydrocarbon gas reservoirs.(2)Gas components of Type Ⅰ are shown as single peaks,with an average He content of 0.033 9％and a poor correlation with the N2 content.Non-hydrocarbon components of Type Ⅱ gases show a multiple-peak distribution,with a high He content(average of 0.158％)and a strong positive correlation with the N2 content(r=0.837,P<0.01),the CO2 content(r=0.662,P<0.01),respectively.(3)Helium reservoirs of Type Ⅰ are composited of shale gas reservoirs and overpressured gas reservoirs from in situ fracking of paleo-oil reservoirs.Low level of exotict helium and dilution from high-intensity gas generation are both responsible for the low helium content in Type Ⅰ gases.Helium-rich reservoirs of Type Ⅱ are recharged with water-soluble helium and nitrogen during hydrocarbon migration.(4)Natural gas or shale gas with abnormally high pressures,heavy hydrocarbon gas,as well as gas with high hydrogen sulfide content,are not favorable for helium accumulation.Successional anticline traps on long-distance flow paths of strata water,and the ancient resevoirs with multiple periods of interaction with stratum fluids,are the targets for helium exploration.The method of cluster analysis established for hydrocarbon-associated helium components can provide new ideas to study the geological characteristics of helium before obtaining a large amount of gas component information.
Keywords：Sichuan basinheliumcluster analysiscoupling relationshipsecondary migrationstratum waterpetroleum geology
Publication Date：2025-06-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：20( 2179-2198 )