低渗透砂岩储集层特征及影响因素——以巴喀油田西山窑组为例

对吐哈盆地巴喀油田西山窑组砂岩储集层特征进行研究后认为:该套储集层岩性为长石岩屑砂岩,成分和结构成熟度都偏低;储集空间以粒间孔和溶蚀孔为主;储集性能差,原始产能低,非均质性强。储集层受沉积微相、成岩作用、微裂缝的综合影响,其中,河口砂坝和水下分流河道为有利储集层发育的微相,成岩早期由于大量粘土膜的形成,有利于部分原生孔隙和喉道的保存,微裂缝的大量存在使各类孔隙有效连通,提高了储集层的渗透性。

Characteristics and Influencing Factors of Low Permeability Sandstone Reservoirs-An example from Xishanyao formation in Baka oilfield

Based on the lab data of cast thin section, scanning electron microscope and high pressure mercury injection, etc., the study of sandstone reservoir of Xishanyao formation in Baka oilfield in Tuha basin is conducted. The result shows that the lithology of this reservoir is feldspar lithic sandstone, with low maturity of composition and texture; the pore space of reservoir is dominated by intergranular pore and dissolved pore, belonging to the reservoir with poor quality, low original productivity and serious heterogeneity. The reservoir is influenced by sedimentary mirofacies, diagenesis, microfracture, among which the channel mouth bar and underwater distributary channel act as favorable microfacies for reservoir development. In the early stage of diagenesis, the large quantities of clay films were formed, which were favorable for preservation of original pores and throats, while existence of numerous microfractures allowed various pores to be efectively connected, thus improving the permeability of the reservoir.