临兴气田上古生界致密砂岩储层发育特征及主控因素

Characteristics and main controlling factors of tight sandstonereservoir of upper paleozoic in Linxing gas field

为揭示影响鄂尔多斯东缘上古生界致密砂岩储层物性的主控因素,针对致密砂岩储层非均质性强,难以寻找储层“甜点”发育区等关键问题,通过分析大量岩心分析化验及薄片资料,开展储层岩石学、储层物性及储层储集空间等方面的研究。研究结果表明:①临兴气田上古生界致密砂岩储层类型多样,主体发育反应陆相沉积背景的岩屑长石砂岩、长石岩屑砂岩,太原组海相地层主要表现为为石英砂岩;②整体表现为典型的低渗低孔的特点,局部层段发育相对高孔高渗区,主要发育残余原生粒间孔、粒间溶孔、粒内溶孔、晶间孔以及微裂隙;③沉积微相、砂岩岩性及成岩作用是致密砂岩储层物性的主控因素,粗粒砂岩反应高能沉积环境(潮道、分流河道等),储层物性好,“甜点”区发育。部分层位的强溶蚀作用也对储层起到积极的改造作用。该研究结果对于临兴千亿方气田的成功勘探及商业开发具有极大的指导作用。

To study the characteristics and the main controlling factors of the tight sandstone reservoir of upper paleozoic of Linxing gas field,Ordos basin,the study of reservoir petrology,reservoir physical properties and reservoir space was carried out on the basis of a large number of core analysis and thin section observations.Studies have shown that:①The reservoir type of the upper palaeozoic tight sandstone in the Linxing gas field are mostly lithic arkosic sandstone and feldspathic lithic sandstone,followed by lithic sandstone with quartz sandstone developed in Taiyuan group.②As a whole,results indicate typical characteristics of low permeability and low porosity,while relatively high porosity and high permeability was developed in local layers,with residual primary intergranular pores,intergranular dissolved pores,intergranular dissolved pores,intergranular pores and microcracks pervasively developed in the sandstones.③Sedimentary microfacies,lithology and diagenesis are the main controlling factors for the physical properties of tight sandstone reservoirs.The sandstone formed in the high-energy sedimentary microfacies environment is of coarse lithology,and reservoir with strong dissolution has good physical properties,which is the major targetlayer in the search for"sweet spot".The above findings have a great guiding role for the successful exploration and commercial development of Linxing gas field.