Reservoir Characteristics and Controlling Factors of Basement Rock Formation,the Paleo-Central Uplift Belt in Northern Songliao Basin

摘要

The central paleo-uplift belt of the Northern Songliao Basin,as one major region of risk exploration of natural gas,has favorable conditions for natural gas accumulation.However,one of the main reasons why no breakthrough has been achieved was the unclear studing of reservoir characteristics.Based on core,mud logging,well logging,3D seismic,the characteristics of basement rock reservoirs in central paleo-uplift belt were discussed from the perspective of lithological characteristics,physical characteristics and reservoir spatial characteristics,and proposes new four cognitions:① the lithology of the basement rock reservoirs were complex,the reservoir was dominated by granite,metamorphiterocks;② Reservoir heterogeneity was relatively strong and matrix porosity was low,indicating a tight reservoir;③ the types of reservoir space included mainly fractures and dissolution pore,three reservoir types of pore-fracture type,fracture-hole type and fracture type were clearly defined.The pore-fracture type reservoir was the most favorable reservoir type in the base-mentrock potential mountain;④ The controlling factors of reservoir development of basement included tectonics,lithology,weathering leaching and magmatic intrusion.The lithology,weathering leaching and fracture were the most important influencing factors of weathering reservoir.The horizontal well of LP1 of granite weathering crust reservoir was advanced,and the output breakthrough was obtained.It greatly expanded the space for natural gas exploration,strengthened the confidence of the new field to achieve a major breakthrough,and pointed out the direction for the long-term development of risk exploration in the new field of Daqing Oilfield.