Saturation Interpretation Model Study On Fractured Reservoirs

The ultimate goal of logging interpretation is to process a variety of data, calculate reservoir parameters, evaluate reservoir quantitatively, restore the true appearance of underground reservoir. In this process, saturation evaluation has always been the core of quantitative evaluation to oil and gas reservoir.Fractured reservoir is one of the important areas of increasing the oil production in the 21st century. In recent years, people pay more and more attentions to fractured reservoirs. The traditional logging interpretation theory, including saturation evaluation, is mostly based on homogeneous reservoir study. In face of fractured reservoir, the biggest difficulty lies on that fractured reservoir develop complex and varied types of storage space after changed by secondary effect. There are secondary porosities including fractures and corrosion holes, besides primary porosities. So form a reservoir composed by matrix porosity, fracture and non-connected hole. These make the reservoir non-homogeneous, multiple pore structure. Thus, it's the key to build a proper saturation model to improve accuracy and to identify complex reservoirs correctly.Because FMI and NMR has not been applied scaly in the oil fields, conventional logging tools are still the most common tools. Thus in this paper, we start from conventional logging tool to deal with Tahe Oilfield Ordovician fractured carbonate reservoir. We suppose to propose an unprecedented saturation interpretation model for non-homogeneous fractured reservoir based on conventional logging tools.Under the information provided by core data, we calibrate conventional logging curve, then extract conventional logging feature about pore spaces from related reservoir, and build a conventional logging mode for pore spaces. That's the foundation we use to distinguish other logs without core analysis. And it's the premise we build a saturation model in this paper. Under defining pore spaces in reservoir, we build a reservoir mode based on triple porosity model. Theoretical plates will be painted for each mode to help us understanding the relationship between different pore space and the whole system. Propose a theoretical foundation for the final saturation model.At last, we build the final saturation model against different reservoir spaces to verify the effectiveness by production data from Tahe Oilfield.