摘要
鄂尔多斯盆地东南部延长组具有丰富的油气资源,储集层为一套致密低渗透砂岩,油气的富集与致密低渗透背景下的高效储层有关。通过铸体薄片、背散射、扫描电镜及能谱分析,结合孔、渗测定,认为:①延长组高效储层的形成与绿泥石环边有密切关系,绿泥石环边的出现是三角洲前缘沉积环境、富黑云母的长石砂岩和咸—微咸水的湖泊水体在空间上耦合的产物;②绿泥石环边抵消了一部分埋藏过程中上覆地层的机械压实作用,减缓了由于压实作用而引起的原生孔隙的减低,而且有抑制石英次生加大的作用;③同生期形成的方解石可以使颗粒呈嵌晶接触,形成致密层,但是这部分方解石量小且分布不均匀;④自生石英在纵向上变化明显,封闭体系中形成的SiO2由于绿泥石环边的抑制作用,以雏晶的形式产出;而半封闭体系中形成的SiO2可向上发生运移,在绿泥石环边不连续或欠发育的层段以加大边的形式产出。通过成岩体系研究,可以明确高效储层的形成机理,指导岩性油气藏的勘探。
Yanchang Formation sited in the southern-eastern Ordos Basin has been proven a prolific reservoir unit for hydrocarbon resources.Featured by relatively low porosity and effective permeability,the quality of the reservoir has a significant impact on the migration and accumulation of oil and gas.By analyzing the petrophysic data from thin-section samples,BSE,Energy Spectrum Analysis and core plugs,we reached the following conclusions： 1.The rimming of chlorite has an important control on the reservoir quality-such diagenetic process is characterized as a product of delta front depositional environment where is mineralogically rich in black mica and feldspar.2.It effectively reduced the compaction effect from the overburden through burial history,therefore contributed to the preservation of primary porosity,simultaneously,ceased the diagenetic overgrowth of quartz grains.3.The associate presence of calcite re-orientated the grains into porphyroblastic structure,but arbitrarily distributed due to the small quantity.4.Authquartz has a prominent vertical change,which is often observed as small crystal forming with chlorite rimming in a close space.However,in semi-closed spaces,quartz is prone to migrate upwards,stop and develop as overgrowth where the intergranular space is not fully taken by chlorite.Through the study,we sorted out the controls and developing mechanisms of qualified reservoirs in Yanchang Formation,and therefore guide the future exploration.
出处
《沉积学报》
CAS
CSCD
北大核心
2011年第1期97-104,共8页
Acta Sedimentologica Sinica
基金
国家自然科学青年基金项目(批准号:40602012)资助
