川中地区侏罗系凉高山组致密砂岩含油性控制因素

Factors controlling oiliness of Jurassic Lianggaoshan tight sands in central Sichuan Basin,SW China

综合分析川中侏罗系凉高山组含油和不含油典型井致密砂岩储集层物性、孔喉结构特征以及源储之间接触关系、储集层荧光照片等资料,研究凉高山组致密砂岩含油性控制因素。研究表明,川中地区侏罗系凉高山组致密砂岩的含油性受如下因素控制:①源储之间输导体系,烃源岩与砂岩储集层之间存在泥质含量高、物性较差的砂泥渐变段时,如无裂缝沟通,油气难以进入上覆储集层;②储集层物性,若砂体与烃源岩直接接触,且储集层物性较好,则油气可直接进入储集层成藏;③裂缝发育程度,储集层物性较差时,若裂缝发育则可改善储集层的孔渗条件,油气也可运移到储集层成藏,如储集层物性较差且无裂缝沟通,则油气难以进入储集层成藏。综合川中侏罗系凉高山组沉积特征、储集层特征以及烃源岩分布,优选出营山—广安和合川—白庙—罗渡2个有利勘探区带。

By comprehensively analyzing oil-bearing and non-oil-bearing tight sandstone reservoir properties, pore structure characteristics and contact between source rock and reservoir, reservoir fluorescent photographs of typical wells of Jurassic Lianggaoshan Formation in central Sichuan Basin, the research tries to f＇md out factors controlling the oiliness of the Jurassic Lianggaoshan tight sandstone reservoir. The oiliness of the Jurassic Lianggaoshan tight sandstone reservoir in central Sichuan Basin is controlled by the following factors： （1） The migration pathway between the source rock and reservoir： when there exist sandstone and mudstone transition zones with high mud content and poor physical property between the source rock and reservoir, without fracture connection, it is difficult for oil and gas to migrate into the overlying reservoir; （2） The reservoir physical property： if the reservoir contacts directly with source rock and has good physical properties, oil and gas can migrate and accumulate directly in the reservoir. （3） Development degree of fractures： when the reservoir physical properties are poor, rich fractures can improve porosity and permeability of the reservoir, oil and gas can still migrate and accumulate in the reservoir; if the reservoir physical property is poor and no fractures developed, oil and gas are difficult to migrate and accumulate in the reservoir. Based on the sedimentary and reservoir characteristics of Jurassic Lianggaoshan Formation in central Sichuan Basin and the distribution of source rocks, Yingshan-Guang＇an and Hechuan-Baimiao-Luodu two favorable exploration zones are selected.