Study On Water Flooded Zone Evaluation Of PNN+ Saturation Logging In Gasi Oilfield

With the advancement of oilfield development process,more and more oilfields enter into high water cut stage,so it is urgent to identify water flooded zones and excavate potential zones.However,in the process of water flooding,there are some problems,such as uneven degree of water flooding and complex types of water flooding.With the influence of formation structure,conventional logging methods can not accurately evaluate the water flooded layer grade,and can not be used to guide the actual production.At the same time,in the later layer adjustment operation,the open hole well data can not accurately reflect the formation conditions.Therefore,the oilfield testing company has introduced a new logging technology,namely PNN +(pulsed neutron neutron plus)saturation logging technology.PNN + adds two far and near gamma probes in PNN technology to directly detect the oxygen content in the reservoir,so as to avoid the influence of salinity on the capture cross section,thus reflecting the oil saturation in the strong water flooded reservoir.Oilfield developers can make reasonable development and water plugging measures according to the distribution of remaining oil and water production,so as to realize the efficient and sustainable development of the reservoir.In this paper,the working principle of the existing logging instruments for residual oil saturation in casing wells at home and abroad is studied,and the method of measuring residual oil saturation by PNN+ instrument is summarized.Taking the PNN + measure well in Gasikule oilfield as the research object,combined with the production situation,injection and production profile data,and open hole well data,the change characteristics of reservoir capture section,oxygen content,physical and electrical properties in the process of water flooding are understood;All the curve information of PNN + logging is fully exploited,and the systematic error of logging curve caused by different logging companies and logging tools is eliminated by using the method of logging curve standardization.The response characteristics of the standardized single curve or combination curve on the watered out layer are summarized,and a new method suitable for the qualitative evaluation of the target reservoir is studied.The saturation calculation model based on PNN + logging is determined to invert various interpretation parameters and improve interpretation accuracy.According to different strata,blocks or main sub layers,the interpretation chart of water flooded layer is established,and the water flooded layer level is divided,The interpretation chart is verified by using production performance,production profile logging and other related data,and finally a quantitative interpretation chart of water flooded layer can be established for production.