岩性油藏特征制约下超低渗透油层快速识别方法与模型

复杂的岩石物理和特殊的渗流机理使得长庆油田超低渗透储层的流体识别比较困难.针对这一问题,基于微观岩石物理机理研究,得出岩性控制物性,物性制约含油性,这一特征与超低渗透岩性油藏的宏观控油规律相符；基于测井曲线响应特征模式的统计分析,在刻度一定前提下,当三孔隙度曲线的重合程度较高时,岩性较纯,对应地层段含油性较好；反之,则岩性不纯,对应地层段含油性较差,并且导致岩性不纯和物性变差的主要原因是泥质和钙质的存在.基于微观岩石物理规律和三孔隙度曲线响应特征,并综合反映流体性质的深感应电阻率和刻画储层物性的声波时差曲线,利用神经元非线性函数Sigmoid的突变性质衍生超低渗透油层的识别参数IpR和产水率Fw.通过对研究区54口井的处理,衍生识别参数IpR和Fw获得了83.33％的准确率.

Method and model of rapidly identifying ultra-low permeability reservoir based on lithologic reservoir characteristics

Due to the complicated petrophysical property and the special percolation mechanism,it is difficult to rapidly identify the ultra-low permeability reservoir.Based on the research of the microscopic petrophysical mechanism,the law that the lithologic character controls the physical property and the physical property restricts the oil saturation is discovered.Moreover,the law is consistent with the controlling rule on oil distribution in the lithologic reservoir.On the basis of the statistics and analysis of logs response characteristics,the rule that when the three porosity curves coincide well with each other in the certain scale and the corresponding stratomere contains more pure rock as well as higher oil saturation is obtained.In addition,the presence of clay and calcium leads to the deterioration of the lithologic character and the physical property.The nature of sudden change of the neuron nonlinear function Sigmoid is applied to constructing the parameter IPR and water productivity of identifying the ultra-low permeability reservoir based on some factors including the microscopic petrophysical law,the three porosity curves’ response characteristics,the deep induction resistivity and the acoustic travel time.Because the deep induction resistivity can reflect the fluid nature the acoustic travel time is able to characterize the physical property of reservoir.By processing the 54 wells in the study area,the accuracy rate of derived parameter IPR and water productivity is 83.33%