Analysis Of Deep Natural Gas Accumulation Conditions In The Western Depression Of Liaohe Basin And Optimization Of Favorable Areas

The western depression is a typical oil and gas-rich depression.With the gradual increase in exploration and development,the medium-shallow layer has entered a stage of high exploration maturity,while the deep-seated natural gas reserves below 3500 m only account for 6% of the proven gas reserves of the western depression.The degree of exploration is relatively low.After many years of exploration and development,Liaohe Oil Region is faced with a situation in which high-quality natural gas resources are undersubsidized and the degree of recovery is high under low oil prices.With the introduction and continuous improvement of continuous oil and gas accumulation theory,deep-seated natural gas is important as a gas-rich depression.The types of resources are widely valued.Therefore,it is of great significance to carry out analysis and research on the deep-seated natural gas exploration potential in the West Depression,in terms of production demand,exploration areas expansion,and theoretical progress.In this paper,based on the deep experience of domestic and foreign exploration of natural gas,based on the actual exploration in the region,comprehensive application of geochemistry,reservoir analysis,drilling and logging and test oil production,and other data,for the deep natural gas in the West Sag Resources potential,reservoir potential,and potential for hydrocarbon accumulation have been thoroughly discussed.Based on the geochemical analysis of source rock and deep-seated natural gas,this paper considers that two sets of high-quality mature source rocks in the third and fourth sections of the Shahejie Formation in the western part of the West Depression are developed,with a wide range of spatial distribution and large thickness,which lays a good foundation for deep gas accumulation.Material basis.Combined with reservoir analysis,it is believed that the braided river delta sandstone and the sandstone debris sand glutenite body in the Sha-4 Member are two dominant reservoirs of deep natural gas.By analyzing the process of natural gas accumulation,it is considered that the main accumulation period of deep natural gas is Neogene,and the preservation conditions are good.Based on the analysis of the burial history of reservoirs,the period of deep gas accumulation was identified,and the oil and gas accumulation events in the southern part of the western depression of Liaohe Basin were identified.A deep gas accumulation model was established,the distribution characteristics of gas reservoirs were identified,and the main control factors for deep gas reservoir enrichment were summarized.Based on the close combination of scientific research and production,this study defines the exploration potential of deep natural gas in the West Depression and provides new ideas for exploration,which is of great significance to the deepening exploration of the old oil region.