低孔低渗裂缝-孔隙型砂岩储层的分类评价——以川中公山庙油田沙一储层为例

Classified Evaluation on Fractured-porous Sandstone Reservoirs with Low Porosity and Low Permeability: a case Study on Sa 1 Reservoir in Gongshanmiao Oil Field in central Sichuan

公山庙油田中侏罗统沙溪庙组一段属三角洲前缘与滨浅湖交互沉积的低孔低渗裂缝-孔隙型砂岩储层。首次提出将表征储层裂缝发育程度的“岩体破坏接近度系数(η)”作为这类储层分类评价的重要指标;认为综合η值、岩石类型、粒度、储层微相、成岩作用特征、孔隙类型、孔隙度、基质渗透率、毛管压力曲线类型和孔隙结构参数等指标的分类评价体系可以较客观的反映该类储层的本质;依据该指标体系将本区沙一段储层分为好(Ⅰ类)、较好(Ⅱ类)、中等(Ⅲ类)和差(Ⅳ类)四类储层,其中Ⅲ类储层通过压裂改造有望成为较典型的裂缝-孔隙型储层,使公山庙油田沙一段储层产能进一步增加。

Segment I of Shaximiao Member of Middle Jurassic in Gongshanmiao Oil Field is a fractured-porous sandstone reservoir with low porosity and low permeability, being delta-front sedimentation and lake shore and shallow lake alternative sedimentation. This paper purposes for the first time to use 'rock body break approaching factor ( η) ' which characterizes development degree of reservoir fractures as an important index for evaluating this type of reservoir. It shows that combination of indexes including η value, rock type, grain size, reservoir micro-face, diagenesis characteristics, pore type, porosity, match permeability, capillary pressure curve type and pore structure can objectively reflect nature of this type of reservoir. According to this index system, it divides Sha I Member into four classes including Class I, Class II, Class III and Class IV. Among them Class III has potential to become typical fractured-porous reservoir by fracturing stimulation so as to improve productivity of this reservoir.