大庆油田扶余油层储层特征及经济甜点分类方案

Reservoir characteristics and economic sweet classification scheme of Fuyu reservoir in Daqing Oilfield

大庆油田扶余油层储量丰富,但是由于储层特征不清以及缺乏科学的“甜点”分类方案,导致研究区“甜点”优选难度大。为了明确研究区储层特征以及“甜点”筛选方案,应用岩心物性测试、全岩分析、铸体薄片、扫描电镜、岩石力学实验、高压压汞实验、测井资料建立了研究区物性和脆性指数计算模型,最终为明确储层特征和“甜点”筛选提供依据。结果表明:①研究区属于特低孔-超低渗致密储层,脆性指数集中在0.5~0.75之间,孔隙结构分为4类,Ⅰ类样品的孔隙度平均大于11%,渗透率平均大于0.7×10^-3μm^2,以大孔为主,平均进汞饱和度大于75%,连通性最好;Ⅱ类样品的孔隙度主要为9%~12%,渗透率主要为0.3×10^-3~0.7×10^-3μm^2,大孔喉减少,小孔喉增加,平均进汞饱和度大于70%;Ⅲ类样品的孔隙度主要为8%~11%,渗透率主要为0.1×10^-3~0.3×10^-3μm^2,平均进汞饱和度大于60%,连通性变差;Ⅳ类样品的孔隙度主要小于9%,渗透率主要小于0.1×10^-3μm^2,平均进汞饱和度小于60%,以小孔喉为主,储集、渗流能力最差。②结合物性、含油性、脆性指数利用灰色关联法建立了研究区经济“甜点”分类标准,Ⅰ类经济“甜点”的综合得分大于0.55,Ⅱ类经济“甜点”得分为0.4~0.55,Ⅲ类经济“甜点”得分为0.25~0.4,无效储层或干层综合得分<0.25,并且根据划分标准对井进行验证,发现该标准有效解决了根据测井判断储层是否含油所带来的误差。③沉积、成岩、断层相互耦合共同控制“甜点”的发育。沉积作用控制储层物性和孔隙结构,成岩作用增加了储层非均质性,断层的存在极大影响了储层含油性。该研究成果建立的“甜点”分类模型为研究区“甜点”筛选提供了科学依据。

The resources of the Fuyu reservoir in the Daqing Oilfield are abundant.Due to the unclear characteristics of reservoir and lack of scientific sweet classification scheme,it is difficult to optimize the sweet in the study area.In order to clarify reservoir characteristics and sweet selection scheme in the study area,this paper uses core physical property,XRD,casting thin section,scanning electron microscope,rock mechanics tests,high pressure mercury intrusion tests and logging data to establish the physical properties and the brittleness model of the study area.,which ultimately provides a basis for clarifying reservoir characteristics and sweet screening.The results reveal①the study area belongs to low hole-ultra low permeability reservoir,brittleness index between 0.5-0.75 and the pore structure of the reservoir in the study area can be divided into four types.TypeⅠreservoirs have more large-pore throats and fewer small-pore throats,with a mean porosity is more than 11%and a permeability is more than 0.7×10^-3μm^2,the mercury saturation is more than 75%and the connectivity is good.Porosity of type II reservoirs mainly locates 9%-12%and a permeability is 0.3×10^-3-0.7×10^-3μm^2,the mercury saturation is more than 70%and the connectivity is good.Type III reservoirs have fewer large-pore throats,but more small-pore throats.The porosity mainly locates 8%-11%and a permeability is 0.1×10^-3-0.3×10^-3μm^2.The mercury saturation is more than 60%and the connectivity is poorer than typeⅠandⅡ.TypeⅣreservoirs have few small-pore throats,with a mean porosity is less than 9%and a permeability is less than 0.1×10^-3μm^2,and the mercury saturation is less than 60%which have poor connectivity and permeability.②Combine physical properties,oily and brittleness of reservoir and use gray relation method to establish the economic sweet classification standard in the study area.The comprehensive score of typeⅠeconomic sweet is more than 0.55,and the comprehensive score of typeⅡeconomic sweet is in 0.4-0.55,and the classⅢeconomic sweet in 0.25-0.4.The non-reservoir or dry layer comprehensive score is less than 0.25.The well was verified by the classification standard and found that the standardeffectively solves the error according to the log to judge whether the reservoir contains oil.③Sedimentation,diagenesis,and faults interaction control the development of economic sweet.Sedimentation controls reservoir physical properties and pore structure,and diagenesis increases reservoir heterogeneity,and the existence of faults greatly affects reservoir oil.The results establish a sweet classification model to provide a scientific basis for the selection of sweet in the study area.