松辽盆地中央古隆起带南部基岩储层特征及油气成藏模式

Characteristics of basement rock reservoir in southern central paleo-uplift belt of Songliao Basin and its hydrocarbon accumulation models

松辽盆地中央古隆起带南部具备良好的油气藏形成条件,是吉林油田油气风险勘探的重要领域之一。笔者综合岩芯、薄片观察,测录井资料分析,孔渗分析和三维地震解释,在大量统计分析和地质研究基础上,探讨了中央古隆起带南部基岩储层特征和油气成藏模式,提出3点认识:①基底岩性主要为花岗岩、花岗闪长岩、闪长岩、片岩、糜棱岩、变质砂岩、安山岩、凝灰岩和灰岩9种,其中花岗岩、花岗闪长岩、安山岩和片岩为成储优势岩性;②基岩主要储集空间为裂缝和溶蚀孔,储层主要发育在基岩顶面风化壳风化淋滤层和裂缝层中;③基岩油气藏可划分为近源缓坡超覆、近源陡坡对接(顺向对接和反向对接)和源内披覆(断阶披覆和背斜披覆)3类成藏模式。该研究明确了中央古隆起带南部基岩油气藏勘探方向,为有利目标区预测提供理论支撑。

The southern central paleo-uplift belt of the Songliao Basin has favorable conditions for oil and gas accumulation,which is one major region of risk exploration of oil and gas in Jilin oilfield.Based on core and thin section observation,logging data analysis,porosity and permeability test and 3D seismic interpretation,along with a large number of statistical analysis and geological researches,the authors discuss the characteristics of basement rock reservoir and hydrocarbon accumulation models in the southern part of the central paleo-uplift belt,and propose three cognitions:①the basement is mainly composed of granite,granodiorite,diorite,schist,mylonite,metamorphic sandstone,andesite,tuff and limestone,of which granite,granodiorite,andesite and schist are the dominant lithologies for reservoir formation;②the main reservoir space of basement rock is fractures and dissolution pores,and the reservoirs are mainly developed in weathering leaching layer and fracture layer of weathering crust on the top of basement rock;③the oil and gas reservoirs of basement rock can be divided into three types of accumulation models:near-source gentle slope overlap,near-source steep slope docking(forward docking and reverse docking)and in-source drape(fault-order drape and anticline drape).The exploration direction of oil and gas reservoirs of basement rock in the southern central paleo-uplift belt is further clarified,which provides theoretical support for the prediction of favorable target areas.