塔里木盆地群苦恰克地区石炭系生屑灰岩段储层特征及有利储层控制因素

Characteristics and Control Factors of Carboniferous Bioclast Limestone Member Reservoir in the Qunkuqiake Area,Tarim Basin

从储层的微观特征入手,通过各种实验分析资料认为:塔里木盆地群苦恰克构造带石炭系生屑灰岩段有利储层的岩性为粉晶白云岩、泥粉晶白云岩及灰质白云岩;储集空间以孔(晶间孔、晶间溶孔)+构造溶扩缝组合为主;孔隙度均值为10.4%,渗透率均值为2.6×10-3μm2,属中孔中渗—高孔中渗(Ⅰ～Ⅱ类)储层。蒸发台地潮上云坪及潮间带上部灰云坪环境为有利储层发育的先决因素,白云岩化-大气淡水溶蚀作用、构造裂缝-油气注入对储层的储集空间发育、连通、保存起到主要的建设作用。有利储层的分布纵向上受控于沉积环境,集中发育在生屑灰岩段的上部—顶部的蒸发台地相带,厚度1～5m;平面上既受控于古隆起(群苦恰克地区)的地貌,又受晚海西期、喜马拉雅期构造活动的影响,沿古隆起及晚海西、喜马拉雅期断裂带是有利储层的发育带,也是油气勘探的重点目标区。

Microcosmic characteristic of reservoir and experimental analysis in this study shows that the favorable reservoir of Carboniferous bioclast limestone member in the Qunkuqiake area consists of silt crystal dolomite and clay-silt crystal dolomite. Pore space is dominated by pores （intercrystalline and intercrystalline） and tectonic dissolution fractures, with an average porosity of 10. 4% and an average permeability of 2.6 × 10^-3 /μm^2 , suggesting that reservoir pores belongs to medium to high porosity and permeability. Dolomite of evaporation tableland in the epilittoral zone and limy dolomite in the eulittoral zone are the primary conditions to develop the high quality reservoir, while dolomitisation, meteoric water dissolution, tectonic fracture--hydrocarbon infusion play constructive roles in development, connection and preservation of reservoir space. The favorable reservoir layer vertically controlled by depositional setting is approximately 1-5 meters thick and developed mainly on the evaporation tableland in the upper and top segments of the bioclast limestone member. Horizontally controlled by both paleohigh （the Qunkuqiake area） and late Hercynian and Himalayan tectonic movement, the paleohigh and late Hercynian and Himalayan fracture zones will be potential area for gas developing, which should be the target for oil and gas exploration.