摘要
致密砂岩气是全球非常规天然气勘探的重要领域，中国致密砂岩气资源丰富。截至2011年底，已探明16个致密砂岩大气田，探明储量占全国大气田总探明储量的49．5％，已成为近些年中国天然气储产量增长的主体。致密砂岩大气田分布在鄂尔多斯、四川i和塔里木盆地，储层时代为石炭纪、二叠纪、三叠纪、侏罗纪、白垩纪和古近纪，气藏的圈闭类型主要包括岩性、构造和岩性一构造或构造一岩性复合等类型，储层平均有效厚度主要分布于5～20m，平均有效孔隙度主要分布在5％～12％，平均渗透率主要为0．12～1．40mD，以低储量丰度为主，压力系数变化大，平均含气饱和度50％～70％，甲烷含量主要为80％～97％；发育源一储大面积交互或紧邻叠置、孔一缝网状输导的成藏地质条件。典型地质解剖与模拟实验结果表明，致密砂岩气的运移充注动力主要来源于源岩的生烃超压，运移方式主要为低速非达西渗流和扩散作用，聚集方式主要表现为“动力圈闭”。致密砂岩大气田表现为准连续充注、一期成藏，具有近源高效聚集的特征，运聚系数可达3．O％～5．2％。这种高效聚集使得大面积致密砂岩在烃源岩生气强度为10×10^8m^3／km2的区域可以形成大气田，突破了大气田形成于生气强度大于20×10^8m^3／km2的认识。致密砂岩大气田的成藏富集主要受四大因素控制，即：构造控制天然气的运移方向与富集程度，储层控制气藏的规模，有效烃源控制气藏的充满度，裂缝控制富集与高产。
Tight sandstone gas（TSG） is the important exploration field of unconventional natural gas in the world. TSG is abundant in China. Sixteen large tight sandstone gas fields （TSGFs） have been discovered by the end of 2011, proved reserves of which account for half of total proved reserves of large gas field. TSG contributes greatly to the reserves and production growth. Large TSGFs distribute in Ordos Basin, Sichuan Basin and Tarim Basin, and have the following common geological characteristics .. tight gas reservoir mainly locates in Carboniferous, Permian, Triassic, Jurassic, Cretaceous and Tertiary ~ trap type mainly includes lithologic, structural, lithologic＇-structural or structural-li- thologic trap~ average effective thickness of reservoir is about 5-20 m~ average effective porosity is about 5%-12%~ average permeability is 0.12-1.40 mD~ reserves abundance of these large TSGFs is low~ pressure coefficient varies greatly~ average gas saturation is about 50%- 70% ~ methane content is about 80%-97%. These large gas fields develop wide-spread interaetively or closely overlying source and reservoir rock~ natural gas mainly transported through net system of pores and fractures. The results of typical geological dissection and simulation ex- periment show that TSG migrates in the form of non-Darcy flow and diffusion, driven by overpressure derived from source rock and accumu- lated in the form of dynamic trap. These large TSGFs are mainly quasi-continuously accumulated during one period, and have characteristics of near-source and highly efficient accumulation. Migration and accumulation ratio of these fields could be as high as 3.0%-5.2%. Large TS- GFs could form in the area where gas generation intensity is higher than 10 x 108 m3 /km2 due to high migration and accumulation ratio, which has made a break though in understanding that large TSGFs could form only in area where gas generation intensity is higher than 20 x 10~m3/km2. Accumulation and concentration of TSG are mainly controlled by four factors.,
出处
《石油学报》
EI
CAS
CSCD
北大核心
2013年第S01期14-28,共15页
Acta Petrolei Sinica
基金
国家重大科技专项(2011ZX05007-002)资助
关键词
致密砂岩气
大气田
动力圈闭
成藏机理
主控因素
四川I盆地
鄂尔多斯盆地
tight sandstone gas
large gas field
dynamic trap
accumulation mechanism
main controlling factor~ Sichuan Basim Ordos Basin
