塔里木盆地塔中地区上奥陶统储层岩石学及储集空间特征

应用野外工作和室内研究相结合的方法,从储层的岩石学和储集空间等角度对塔中地区储层特征进行了研究。研究表明,研究区内良里塔格组灰岩段岩性主要为颗粒灰岩、骨架礁灰岩、藻粘结灰岩、泥晶灰岩、岩溶角砾岩等,其中颗粒灰岩大多经历了多期多成因成岩作用改造,裂缝较为发育;泥晶灰岩中多期压溶作用和白云石化作用较为常见;藻粘结灰岩受成岩作用改造相对最弱。宏观储集空间主要包括大型溶洞、孔洞及裂缝,其中孔洞多呈孤立、稀疏并沿裂缝分布;构造缝是裂缝的主要类型。微观储集空间主要包括溶孔和微裂缝,其中溶孔主要发育在亮晶颗粒灰岩中,可细分为粒内溶孔、粒间溶孔、晶间溶孔、铸模孔、溶蚀骨架孔、残余粒间孔及沿裂缝扩溶形成的溶孔,粒间溶孔所占比例最高。埋藏期溶蚀作用发育期次多,规模大,分布广泛,对储层物性的改善和油气聚集的影响最为明显。

Late Ordovician Reservoir Petrology and Characteristics of Reservoir Space in Tazhong Area, Tarim Basin

Combining field work with laboratory research,the reservoir petrology and pore characteristics of the Upper Ordovician Lianglitark Formation in Tazhong area have been studied in this paper.The results indicate that limestones in Lianglitark Formation in the study area are mainly framework reef limestone,grain limestone,argillaceous limestone,algae boundstone and karst breccia.Grain limestone mostly experienced multi periods of diagenetic transformation,in which fractures are relatively developed.The multistage pressure dissolution and dolomitization are common in micrite.The diagenetic transformation is the weakest in the algae boundstone.The types of pore space in the carbonate reservoirs are mainly large cavities,holes and cracks,of which holes most develop along the fracture and distributed sparsely and isolately,and crack is the main structural joints.Microscopic reservoir space mainly includes the dissolved pore and microfracture.Dissolution pores,which mainly develop in the grain limestone,can be subdivided into intragranular dissolved pore,intergranular dissolved pore,intercrystalline dissolved pore,moldic pore,dissolution skeleton hole,residual intergranular pore and dissolved microfracture pore,of which the intergranular dissolution pores have the highest proportion.Buried karstification is of large scale and widely distributed,which significantly influence the reservoir quality.