陕北志吴定地区延长组长_6油层组储集层评价

Reservoir evaluation of Chang 6 oil-bearing strata of Yanchang Formation in Zhiwuding area,North Shaanxi

陕北志吴定地区延长组长6油层组是陕北地区中生界主力产油层,研究表明其储集层为湖泊-三角洲沉积体系的沉积砂体,砂岩储集层属典型的长石细砂岩,对孔隙形成和改善具建设性的成岩作用是溶蚀及蚀变作用;孔隙组合类型主要为粒间溶孔型;储层物性总体上为中—低孔隙度和低渗透率,在纵向上自下而上物性逐渐变好,平面上在河口砂坝及水下分流河道发育区物性较好;孔隙结构为小—细孔细喉型和细孔细喉—微喉型.长6油层组砂岩储集层综合分类评价为特低孔隙度、特低渗透率的致密砂岩储集层.

The oil-bearing strata are the main oil production layer of Mesozoic in north Shaanxi.The reservoir is the sedimentary sandbody of a lake-delta sedimentary system,and its lothogy is typical fine feldspathic sandstone.Dissolution and alteration have a constructive effect on the formation and improvement of pore and the main pore type is intergranular dissolution pore.The reservoir is middle-low porosity and low permeability.Its physical property gradually meliorates from down to up,and on plane,the areas in which channel mouth bar and underwater distributary channel are developed have better physical property.The pore structure is small-fine pore & fine throat type and fine pore &fine--micro throat type.The Chang 6 oil-bearing strata are evaluated as a superlow-porosity superlow-permeability tight reservoir.