安徽铜陵早二叠世茅口期Tubiphytes-叶状藻丘储集条件研究

RESERVOIR OF EARLY PERMIAN MAOKOU TUBIPHYTES PHYLLOID-ALGAL MOUND IN TONGLING,ANHUI PROVINCE

茅口期 Tubiphytes—叶状藻丘及其碳酸盐岩组合的储集空间类型包括孔隙、洞穴、缝隙和喉道,形成了孔隙—喉道型、裂隙—喉道型、孔洞—裂隙型等三种类型的储集空间结构。据孔隙度、渗透率、压汞等分析测试认为,叶状藻障积岩可以成为差的储集岩,而亮晶藻屑灰岩、生屑灰泥岩、Tubiphytes 粘结岩等均为非储集岩。研究区藻丘中含有大量的碳沥青(尤其是深埋溶孔中)也说明了在潜伏礁(丘)体中寻找良好油气储层的潜力是很大的。

Primary porosity is developed in Tubiphytes phylloid-al- gal mound complexes in Tongling.Excepting a small num- ber of residual primary pores left,secondary pores that are formed by diagenetic process and tectonic stress consist of the majority owing to diagenetic cementation and filling. Three kinds of reservoir pore geometry may be classified: Type pore-throat,Type fissure-throat and Type pore (and/or cave)-fissure.It is suggested by measurement and analyses that the phylloid-algal bafflestone can serve as poor reservoir rock while the bioclastic packstone,wack- stone and Tubiphytes biocementstone are non-reservoir rocks.It is observed that a good deal of bitumen is filled in solution pores,especially in deep-buried solution pores and tectonic secondary solution pores in the algal mound of this area,which indicates that hydrocarbon migration and accu- mulation has occurred in the algal mound.Buried mounds are favourable to form and protect pores so that it may be ex- pected to prospect for potential reservoirs in the sorts of buried mounds.